1. Large Synoptic Survey Telescope (LSST)
  2. Data Management System
  3. Requirements
  4. Gregory Dubois-Felsmann
  5. LSE-61
  6. Latest Revision Date: October 8, 2013
  7. Change Record
    1. Table of Contents
  8. The LSST Data Management System Requirements
    1. 1 Data Products
      1. 1.1 Data Acquisition
      2. 1.2 Level 1 Data Products
      3. 1.3 Level 2 Data Products
      4. 1.4 Calibration Data Products
    2. 2 Productions
      1. 2.1 Query Repeatibility
      2. 2.2 Uniqueness of IDs Across Data Releases
      3. 2.3 Selection of Datasets
      4. 2.4 Processing of Datasets
      5. 2.5 Transparent Data Access
      6. 2.6 Alert Production
      7. 2.7 Calibration Production
      8. 2.8 Data Release Production
      9. 2.9 Level 3 Production
    3. 3 Software
      1. 3.1 Software Architecture to Enable Community Re-Use
      2. 3.2 Applications Software
      3. 3.3 Middleware Software
    4. 4 Facilities
      1. 4.1 Data Archive
      2. 4.2 Computational Infrastructure
      3. 4.3 Summit Facility
      4. 4.4 Summit to Base
      5. 4.5 Base Facility
      6. 4.6 Base to Archive
      7. 4.7 Archive Center
      8. 4.8 Archive to Data Access Center
      9. 4.9 Data Access Center

LSST Data Management System Requirements
LSE-61
Latest Revision 10/8/2013
The contents of this document are subject to configuration control and may not be changed, altered, or their provisions
waived without prior approval of the LSST Change Control Board.
1
Large Synoptic Survey Telescope (LSST)

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Data Management System

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Requirements

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Gregory Dubois-Felsmann

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LSE-61

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Latest Revision Date: October 8, 2013
This LSST document has been approved as a Content-Controlled Document. Its contents are subject to
configuration control and may not be changed, altered, or their provisions waived without prior
approval. If this document is changed or superseded, the new document will retain the Handle
designation shown above. The control is on the most recent digital document with this Handle in the
LSST digital archive and not printed versions.

LSST Data Management System Requirements
LSE-61
Latest Revision 10/8/2013
The contents of this document are subject to configuration control and may not be changed, altered, or their provisions
waived without prior approval.
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Change Record
Version
Date
Description
Owner name
0.1
2007
Initial version
G. Dubois-Felsmann
0.5
February
2009
Approved as a content-controlled document by the
CCB
G. Dubois-Felsmann
1
6/28/2011
Captured DM Functional Requirements
Specification as version 1 of new document LSE-61
G. Dubois-Felsmann
1.1
8/3/2011
Requirements numbering applied. Original
numbering preserved for a transition period.
G. Dubois-Felsmann
2
10/8/2013
Extensive reorganization and partial rewrite;
corresponds to CVS revision 1.44 in SysArch.
D. Shaw, M. Juric,
G. Dubois-Felsmann
2.0.1
10/8/2013
Corrections affecting DMS-REQ-0176, -0267, -0268,
-0287, and the creation of -0317. CVS revision 1.45.
G. Dubois-Felsmann
2.0.2
10/8/2013
Incorrect statements removed from Discussion in
DMS-REQ-0271 and DMS-REQ-0283, many typos
corrected. CVS revision 1.46.
G. Dubois-Felsmann

LSST Data Management System Requirements
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ii
Table of Contents
Change
Record
...............................................................................................................................................
i
1
Data
Products
..............................................................................................................................
1
1.1
Data
Acquisition
...................................................................................................................
1
1.2
Level
1
Data
Products
.........................................................................................................
2
1.3
Level
2
Data
Products
.........................................................................................................
7
1.4
Calibration
Data
Products
................................................................................................
10
2
Productions
................................................................................................................................
12
2.1
Query
Repeatibility
.............................................................................................................
12
2.2
Uniqueness of IDs Across Data Releases
................................................................... 13
2.3
Selection
of
Datasets
.........................................................................................................
13
2.4
Processing
of
Datasets
.....................................................................................................
13
2.5
Transparent
Data
Access
.................................................................................................
13
2.6
Alert
Production
..................................................................................................................
13
2.7
Calibration
Production
......................................................................................................
16
2.8
Data
Release
Production
..................................................................................................
16
2.9
Level
3
Production
.............................................................................................................
16
3
Software
.......................................................................................................................................
18
3.1
Software Architecture to Enable Community Re-Use
............................................... 18
3.2
Applications
Software
.......................................................................................................
18
3.3
Middleware
Software
.........................................................................................................
20
4
Facilities
......................................................................................................................................
22
4.1
Data
Archive
.........................................................................................................................
22
4.2
Computational
Infrastructure
..........................................................................................
24
4.3
Summit
Facility
...................................................................................................................
26
4.4
Summit
to
Base
...................................................................................................................
27
4.5
Base
Facility
........................................................................................................................
28

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iii
4.6
Base
to
Archive
...................................................................................................................
29
4.7
Archive
Center
.....................................................................................................................
30
4.8
Archive
to
Data
Access
Center
.......................................................................................
31
4.9
Data
Access
Center
...........................................................................................................
32
2
..................................................................................................................................................................
34

LSST Data Management System Requirements
LSE-61
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The contents of this document are subject to configuration control and may not be changed, altered, or their provisions
waived without prior approval.
1

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The LSST Data Management System Requirements
This document contains the top-level requirements for the Data Management subsystem of the LSST,
when combined with the Data Management-related requirements in the LSST System Requirements
(LSR, LSE-29) and Observatory System Specifications (OSS, LSE-30).
1 Data Products
1.1 Data Acquisition
1.1.1
Raw Image Assembly
ID: DM-APP-PL-IP-1
ID: DMS-REQ-0024
Last Modified: 9/26/2013
Specification:
The DMS shall assemble the combination of raw exposure data from all the readout
channels from a single Sensor to form a single image for that sensor. The image data and relevant
exposure metadata shall be integrated into a standard format suitable for down-stream processing,
archiving, and distribution to the user community.
Discussion:
Relevant exposure metadata are those that define the observing context, telescope and
instrument configuration, and provenance.
1.1.2
Raw Science Image Data Acquisition
ID:
ID: DMS-REQ-0018
ID:
Last Modified: 9/26/2013
Specification:
The DMS shall acquire raw Exposure data from the Camera science sensors during
normal operations, calibration data collection, and in any other required engineering modes.
Discussion:
The manner of data acquisition is a matter for the DM-Camera ICDs, LSE-69 and LSE-68, in
this area.
1.1.3
Raw Science Image Metadata
ID: DM-APP-DP-IM-5
ID: DMS-REQ-0068
Last Modified: 10/8/2013
Specification:
For each raw science image, the DMS shall store image metadata including at least:
* Time of exposure start and end, referenced to TAI
* Site metadata (site seeing, transparency, weather)
* Telescope metadata (telescope pointing, active optics state, environmental state)
* Camera metadata (shutter trajectory, wavefront sensors, environmental state)

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1.1.4
Crosstalk Corrected Science Image Data Acquisition
ID:
ID: DMS-REQ-0022
ID:
Last Modified: 9/26/2013
Specification:
The DMS shall acquire crosstalk corrected exposure data from the Camera science
sensors, during normal survey operations and in any other required operating modes.
Discussion:
The manner of data acquisition is a matter for the DM-Camera ICD in this area. It may be
different for that for the raw science sensor data, as it is subject to quite different latency and reliability
requirements.
This data is the input to the main Alert Production pipelines. It is not planned to be archived.
1.1.5
Wavefront Sensor Data Acquisition
ID:
ID: DMS-REQ-0020
ID:
Last Modified: 9/26/2013
Specification:
The DMS shall acquire raw exposure data from the Camera wavefront sensors, during
normal survey operations and in any other required operating modes.
Discussion:
The details of this are a matter for the DM-Camera ICD in this area. However, these data
should be identical in format and in mode of acquisition to the raw science sensor data.
There is no currently established requirement for the acquisition or archiving of any raw guider sensor
data.
1.1.6
Guider Calibration Data Acquisition
ID: DMS-REQ-0265
Last Modified: 10/8/2013
Specification:
The DMS shall acquire raw, full-frame exposures from the camera guider sensors during
calibration.
Discussion:
The DMS shall produce calibration data products for the guide sensors.
1.2 Level 1 Data Products
1.2.1
Nightly Data Accessible Within 24 hrs
ID: DM-APP-DP-GEN-3
ID: DMS-REQ-0004
Last Modified: 10/1/2013
Specification:
With the exception of alerts and Solar System Objects, all Level 1 Data Products shall be
made public within time
L1PublicT
(LSR-REQ-0104) of the acquisition of the raw image data. Alerts shall
be made available within time
OTT1
(LSR-REQ-0101) from the conclusion of readout of the raw
exposures used to generate each alert to the distribution of the alert to community distribution
mechanisms. Solar System Object orbits shall be made available within time
L1PublicT
of the

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3
computation of a new or updated orbit from a night's data.
Discussion
: Because of the processing flow of SSObject orbit determination, meeting the base 24-hours-
after-data-acquisition requirement would be far more challenging than for the other L1 Data Products.
1.2.2
Processed Visit Images
ID:
ID: DMS-REQ-0069
Last Modified: 10/8/2013
Specification:
The DMS shall produce Processed Visit Images, in which the corresponding raw sensor
array data has been trimmed of overscan and corrected for instrumental signature. Images obtained in
pairs during a standard visit are combined.
Discussion:
Processed science exposures are not archived, and are retained for only a limited time to
facilitate down-stream processing. They will be re-generated for users on-demand using the latest
processing software and calibrations.
This aspect of the processing for Special Programs data is specific to each program.
1.2.2.1
Processed Visit Image Content
ID: DM-APP-DP-IM-7
ID: DMS-REQ-0072
Last Modified: 10/8/2013
Specification:
Processed visit images shall include the corrected science pixel array, an integer mask
array where each bit-plane represents a logical statement about whether a particular detector pathology
affects the pixel, a variance array which represents the expected variance in the corresponding science
pixel, and a representation of the spatially varying PSF that applies over the extent of the science array.
These images shall also contain metadata that map pixel to world (sky) coordinates (the WCS) as well as
metadata from which photometric measurements can be derived.
1.2.2.2
Generate Photometric Zeropoint for Visit Image
ID:
ID: DMS-REQ-0029
Last Modified: 10/1/2013
Specification:
The DMS shall derive and persist a photometric zeropoint for each visit image, per CCD.
1.2.2.3
Generate WCS for Visit Images
ID:
ID: DMS-REQ-0030
Last Modified: 10/8/2013
Specification:
The DMS shall generate and persist a WCS for each visit image. The absolute accuracy
of the WCS shall be at least
astrometricAccuracy
in all areas of the image, provided that there are at
least
astrometricMinStandards
astrometric standards available in each CCD.
Discussion:
The World Coordinate System for visits will be expressed in terms of a FITS Standard
representation, which provides for named metadata to be interpreted as coefficients of one of a finite set
of coordinate transformations.
astrometricQuality

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ID:
Last Modified: 6/16/2011
Description
Value
Unit
Name
Absolute accuracy of the WCS across the focal plane
(approximately one-quarter of a pixel)
50
mili-
Arcsec
astrometricAccurac
y
Minimum number of astrometric standards per CCD
5
int
astrometricMinStan
dards
1.2.2.4
Generate PSF for Visit Images
ID:
ID: DMS-REQ-0070
Last Modified: 10/1/2013
Specification:
The DMS shall determine a characterization of the PSF for any specified location in
Processed Visit Images.
1.2.3
Difference Exposures
ID: DM-APP-PL-IP-8
ID: DMS-REQ-0010
Last Modified: 10/8/2013
Specification:
The DMS shall create a Difference Exposure from each Processed VIsit Image by
subtracting a re-projected, scaled, PSF-matched Template Image in the same passband.
Discussion
: Difference Exposures are not archived, and are retained for only a limited time to facilitate
Alert processing. They can be re-generated for users on-demand.
1.2.3.1
Difference Exposure Attributes
ID: DM-APP-DP-IM-9
ID: DMS-REQ-0074
Last Modified: 10/1/2013
Specification
: For each Difference Exposure, the DMS shall store: the identify of the input exposures
and related provenance information, and a set of metadata attributes including at least a representation of
the PSF matching kernel used in the differencing.
1.2.4
Exposure Catalog
ID: DMS-REQ-0266
Last Modified: 10/8/2013
Specification:
The DMS shall create an Exposure Catalog containing information for each exposure that
includes the exposure date/time and duration, properties of the filter used, dome and telescope pointing
and orientation, status of calibration apparatus, airmass and zenith distance, telescope and dome status,
environmental information, and information regarding each sensor including an ID, its location in the focal
plane, electronic configuration, and WCS.
1.2.5
DIASource Catalog
ID: DMS-REQ-0269
Last Modified: 10/8/2013
Specification:
The DMS shall construct a catalog of all Sources detected on Difference Exposures with
SNR >
diaSourceThresh
. For each Difference Source (DIASource), the DMS shall be able to provide the

LSST Data Management System Requirements
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5
identity of the Difference Exposure from which it was derived; the identity of the associated SSObject, if
any; the identity of the parent Source from which this DIASource has been deblended, if any. The DMS
shall also measure and record a set of attributes for each DIASource including at least: epoch of the
observation, focal plane position centroid and error (pixel), sky position and associated error (radec), SNR
of the detection; calibrated PS flux and associated error; likelihood of the observed data given the PS
model; calibrated flux and associated error for a trailed source model, and length and angle of the trail;
parameters of an adaptive shape measurement and associated error; a measure of source
extendedness; and flags indicating problems encountered while computing the aforementioned attributes.
The DMS shall also determine and record measurements on the Calibrated exposure the following:
calibrated flux and associated error for the source as measured on the Visit image.
1.2.5.1
diaSourceCat
ID:
Last Modified: 10/8/2013
Description
Value
Unit
Name
Threshold in SNR for detecting sources in Difference Images
5
float
diaSourceThresh
1.2.6
Faint DIASource Measurements
ID: DMS-REQ-0270
Last Modified: 10/8/2013
Specification:
The DMS shall be able to measure and store DIASources fainter than
diaSourceThresh
that satisfy additional criteria. A limited number of such sources shall be made to enable monitoring of
DIA quality.
Discussion:
Some individual faint sources may be of high significance, such as a potentially hazardous
asteroid.
1.2.7
DIAObject Catalog
ID: DMS-REQ-0271
Last Modified: 10/8/2013
Specification:
The DMS shall construct a catalog of all astrophysical objects identified through difference
image analysis (DIAObjects). The DIAObject entries shall include metadata attributes including at least: a
unique identifier; the identifiers of entries in the Object catalog lying within
diaNearbyObjRadius
, the
probability that the DIAObject is the same as the nearby Object; and a set of DIAObject properties.
1.2.7.1
diaObjectCat
ID:
Last Modified: 10/8/2013
Description
Value
Unit
Name
Radius within which an Object is considered to be near, and
possibly coincident with, the DIASource
TBD
Arcsec
diaNearbyObjRadiu
s
1.2.7.2
DIAObject Attributes
ID: DMS-REQ-0272
Last Modified: 10/8/2013

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Specification:
For each DIAObject the DMS shall store summary attributes including at least: sky
position at the time of the observation; astrometric attributes including proper motion, parallax and related
errors; point-source magnitude in each passband and related error; weighted mean forced-photometry
flux and related error; periodic and non-periodic variability measures; and flags that encode special
conditions encountered in measuring the above quantities.
1.2.8
SSObject Catalog
ID: DMS-REQ-0273
Last Modified: 10/8/2013
Specification:
The DMS shall produce a catalog of all Solar System Objects (SSObjects) that have been
identified via Moving Object Processing. The SSObject catalog shall include for each entry attributes
including at least the following: Osculating orbital elements and associated uncertainties, minimum orbit
intersection distance (MOID), mean absolute magnitude and slope parameter per band and associated
errors, and flags that describe conditions of the description.
Discussion:
The magnitude and angular velocity limits for identifying SSObjects are TBD. These limits
may be driven more by computational resource constraints than by the raw reach of the collected data.
The software may well be capable of exceeding the required limits, but at an unacceptable cost.
1.2.9
DIAForcedSource Catalog
ID:
ID: DMS-REQ-0317
ID:
Last Modified: 10/8/2013
Specification:
The DMS shall create a DIAForcedSource Catalog, consisting of measured fluxes for
entries in the DIAObject Catalog on Difference Exposures. Measurements for each forced-source shall
include the DIAObject and visit IDs, the modeled flux and error (given fixed position, shape, and
deblending parameters), and measurement quality flags.
Discussion:
The large number of such forced sources makes it impractical to measure more attributes
than are necessary to construct a light curve for variability studies.
1.2.10
Alert Content
ID: DMS-REQ-0274
Last Modified: 10/8/2013
Specification:
The DMS shall create an Alert for each detected DIASource, to be broadcast using
community protocols, with content that includes: a unique Alert ID, the Level-1 database ID, the
DIASource record that triggered the alert, the DIAObject (or SSObject) record, all previous DIASource
records corresponding to the object (if any), and cut-outs of images of sufficient areal coverage to identify
the DIASource and its immediate surroundings.
Discussion:
The aim for the Alert content is to include sufficient information to be relatively self-
contained, and to minimize the demand for follow-up queries of the Level-1 database. This approach will
likely increase the speed and efficiency of down-stream object classifiers.
1.2.11
Level 1 Data Quality Report Definition
ID: DM-APP-DP-SR-2
ID: DMS-REQ-0097
Last Modified: 10/1/2013

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7
Specification:
The DMS shall produce a Level 1 Data Quality Report that contains indicators of data
quality that result from running the DMS pipelines, including at least: Photometric zero point vs. time for
each utilized filter; Sky brightness vs. time for each utilized filter; seeing vs. time for each utilized filter;
PSF parameters vs. time for each utilized filter; detection efficiency for point sources vs. mag for each
utilized filter.
Discussion:
The seeing report is intended as a broad-brush measure of image quality. The PSF
parameters provide more detail, as they include asymmetries and field location dependence.
1.2.12
Level 1 Performance Report Definition
ID: DM-APP-DP-SR-4
ID: DMS-REQ-0099
Last Modified: 10/2/2013
Specification:
The DMS shall produce a Level 1 Performance Report that provides indicators of how the
DMS has performed in processing the night's observations, including at least: number of observations
successfully processed through each pipeline; number of observations for each pipeline that had
recoverable failures (with a record of the failure type and recovery mechanism); number of observations
for each pipeline that had unrecoverable failures; number of observations archived at each DMS Facility;
number of observations satisfying the science criteria for each active science program.
1.2.13
Level 1 Calibration Report Definition
ID: DM-APP-DP-SR-6
ID: DMS-REQ-0101
Last Modified: 10/8/2013
Specification
: The DMS shall produce a Level 1 Calibration Report that provides a summary of
significant differences in Calibration Images that may indicate evolving problems with the telescope or
camera, including a nightly broad-band flat in each filter.
1.3 Level 2 Data Products
1.3.1
Source Catalog
ID: DMS-REQ-0267
Last Modified: 10/8/2013
Specification:
The DMS shall create a Catalog containing all Sources detected in single (standard) visits
and on Co-Adds, and will contain an identifier of the Exposure on which the Source was detected, as well
as measurements of Source Attributes. The measured attributes (and associated errors) include location
on the focal plane; a static point-source model fit to world coordinates and flux; a centroid and adaptive
moments; and surface brightnesses through elliptical multiple apertures that are concentric, PSF-
homogenized, and logarithmically spaced in intensity.
1.3.2
Object Catalog
ID: DMS-REQ-0275
Last Modified: 10/8/2013
Specification:
The DMS shall create an Object Catalog, based on sources deblended based on
knowledge of CoaddSource, Source, DIASource, DIAObject, and SSObject Catlogs, after multi-epoch
spatial association and characterization.

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8
1.3.2.1
Object Characterization
ID: DMS-REQ-0276
Last Modified: 10/8/2013
Specification:
Each entry in the Object Catalog shall include the following characterization measures: a
point-source model fit, a bulge-disk model fit, standard colors, a centroid, adaptive moments, Petrosian
and Kron fluxes, surface brightness at multiple apertures, and a variability characterization.
Discussion:
These measurements are intended to enable LSST "static sky" science.
1.3.2.2
Provide Photometric Redshifts of Galaxies
ID: DM-APP-PL-DRP-11
ID: DMS-REQ-0046
Last Modified: 10/8/2013
Specification:
The DMS shall compute a photometric redshift for all detected Objects.
1.3.3
Associate Sources to Objects
ID: DM-APP-PL-AP-1
ID: DMS-REQ-0034
Last Modified: 10/2/2013
Specification:
The DMS shall associate sources measured at different times and in different passbands
into data structures that describe astrophysical objects.
Discussion:
The task of association is to relate sources from different times, filters, and sky positions,
into data structures that describe astrophysical objects. Having made these associations, further
measurements can be made on the full object data to generate astronomically useful quantities.
1.3.4
Deep Detection Coadds
ID: DMS-REQ-0279
Last Modified: 10/8/2013
Specification:
The DMS shall periodicaly create Co-added Images in each of the
u,g,r,i,z,y
passbands by
combining all archived exposures taken of the same region of sky and in the same passband that meet
specified quality conditions.
Discussion:
Quality attributes may include thresholds on seeing, sky brightness, wavefront quality, PSF
shape and spatial variability, or date of exposure.
1.3.5
Template Coadds
ID: DMS-REQ-0280
Last Modified: 10/8/2013
Specification:
The DMS shall periodically create Template Images in each of the
u,g,r,i,z,y
passbands
that are constructed identically to Deep Detection Coadds, but where the contributing Calibrated
Exposures are limited to a range of observing epochs
templateMaxTimespan
, the images are partitioned
by airmass into multiple bins, and where the quality criteria may be different.
Discussion:
Image Templates are used by the Image Difference pipeline in the course of identifying
transient or variable sources. The range of epochs must be limited to avoid confusing slowly moving
sources (such as high proper motion stars) with genuine transients. It is anticipated that separate
templates will be created in each passband for 3 separate ranges of airmass.

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9
1.3.5.1
templateCoadds
ID:
Last Modified: 10/8/2013
Description
Value
Unit
Name
Maximum range in observed epoch over which input
Exposures may contribute to a template image
1
Years
templateMaxTimes
pan
1.3.6
Multi-band Coadds
ID: DMS-REQ-0281
Last Modified: 10/8/2013
Specification:
The DMS shall periodically create Multi-band Coadd images which are constructed
similarly to Deep Detection Coadds, but where all passbands are combined.
Discussion:
The multi-color Coadds are intended for very deep detection.
1.3.7
Coadd Image Attributes
ID: DMS-REQ-0278
Last Modified: 10/8/2013
Specification:
Coadd Images shall be created by combining spatially overlapping Processed Exposures
(on which bad pixels and transient sources have been masked), where the contributing Exposures have
been re-projected to a common reference geometry, and matched to a common background level which
best approximates the astrophysical background.
1.3.8
Provide PSF for Coadded Images
ID: DMS-REQ-0047
Last Modified: 10/2/2013
Specification:
The DMS shall determine a characterization of the PSF for any specified location in
coadded images.
Discussion:
The PSF model will be primarily used to perform initial object characterization and
bootstrapping of multi-epoch object characterization (e.g., Multifit).
1.3.9
Coadded Image Provenance
ID: DM-APP-DP-CO-3
ID: DMS-REQ-0106
Last Modified: 10/8/2013
Specification
: For each Coadded Image, DMS shall store: the list of input images and the pipeline
parameters used to derive it, and a sufficient set of metadata attributes for users to re-create them in
whole or in part.
Discussion
: Not all coadded image types will be made available to end-users or retained for the life of
the survey; however. sufficient metadata will be preserved so that they may be recreated by end-users.
1.3.10
Coadd Source Catalog
ID: DMS-REQ-0277
Last Modified: 10/8/2013

LSST Data Management System Requirements
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Latest Revision 10/8/2013
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10
Specification:
The DMS shall, in the course of creating the master Source Catalog, create a catalog of
all sources detected in each passband with a SNR >
coaddDetectThresh
.
Discussion:
Coadd Sources are in general composites of overlapping astrophysical objects. This catalog
is an intermediate product in DR production, and will not be permanently archived nor released to end-
users.
1.3.10.1 coaddSourceCat
ID:
Last Modified: 10/8/2013
Description
Value
Unit
Name
S/N threshold for detecting sources in Co-Add images for
building the Source Catalog
5
float
coaddDetectThresh
1.3.11
Forced-Source Catalog
ID: DMS-REQ-0268
Last Modified: 10/8/2013
Specification:
The DMS shall create a Forced-Source Catalog, consisting of measured fluxes for all
entries in the Object Catalog on all Calibrated Exposures. Measurements for each forced-source shall
include the object and visit IDs, the modelled flux and error (given fixed position, shape, and deblending
parameters), and measurement quality flags.
Discussion:
The large number of Forced Sources makes it impractical to measure more attributes than
are necessary to construct a light curve for variability studies.
1.3.12
Produce Images for EPO
ID:
ID: DMS-REQ-0103
Last Modified: 10/2/2013
Specification:
The DMS shall produce images for EPO purposes, according to the requirements in the
DM-EPO ICD.
Discussion:
This is expected to include polychromatic (e.g., RGB JPEG) images for casual users.
1.4 Calibration Data Products
1.4.1
Calibration Data Products
ID: DM-APP-DP-CI-1
ID: DMS-REQ-0130
Last Modified: 10/2/2013
Specification
: The DMS shall produce and archive Calibration Data Products that capture the signature
of the telescope, camera and detector, including at least: Crosstalk correction matrix, Bias and Dark
correction frames, a set of monochromatic dome flats spanning the wavelength range, a synthetic broad-
band flat per filter, and an illumination correction frame per filter.

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11
1.4.2
Calibration Image Provenance
ID: DM-APP-DP-CI-3
ID: DMS-REQ-0132
Last Modified: 10/2/2013
Specification:
For each Calibration Production data product, DMS shall record: the list of input
exposures and the range of dates over which they were obtained; the processing parameters; the
calibration products used to derive it; and a set of metadata attributes including at least: the date of
creation; the calibration image type (e.g. dome flat, superflat, bias, etc); the provenance of the processing
software; and the instrument configuration including the filter in use, if applicable.
1.4.3
Bad Pixel Map
ID: DM-APP-PL-CAP-7
ID: DMS-REQ-0059
Last Modified: 10/2/2013
Specification:
The DMS shall produce on an as-needed basis a map of detector pixels that are affected
by one or more pathologies, such as non-responsive pixels, charge traps, and hot pixels. The particular
pathologies shall be bit-encoded in 32-bit pixel values, so that additional pathologies may also be
recorded in down-stream processing software.
Discussion:
The fraction of bad pixels is expected to be small. Therefore the Reference Map, while
logically equivalent to an image, may be stored in a more compressible form.
1.4.4
Bias Residual Image
ID: DM-APP-PL-CAP-5
ID: DMS-REQ-0060
Last Modified: 10/2/2013
Specification:
The DMS shall construct on an as-needed basis an image that corrects for any temporally
stable bias structure that remains after overscan correction. The Bias Residual shall be constructed from
multiple, zero-second exposures where the overscan correction has been applied.
1.4.5
Crosstalk Correction Matrix
ID: DM-APP-PL-CAP-6
ID: DMS-REQ-0061
Last Modified: 10/2/2013
Specification:
The DMS shall, on an as-needed basis, determine from appropriate calibration data what
fraction of the signal detected in any given amplifier on each sensor in the focal plane appears in any
other amplifier, and shall record that fraction in a correction matrix. The applicability of the correction
matrix shall be verified in production processing on science data.
Discussion:
The frequency with which the Cross-talk Correction Matrix must be computed will be
determined during Commissioning and monitored during operations.
1.4.6
Dark Current Correction Frame
ID: DMS-REQ-0282
Last Modified: 10/8/2013
Specification:
The DMS shall produce on an as-needed basis a dark current correction image, which is
constructed from multiple, closed-shutter exposures of appropriate duration. The effectiveness of the
Dark Correction shall be verified in production processing on science data.

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12
Discussion:
The need for a dark current correction will have to be quantified during Commissioning.
Collecting closed-dome dark exposures may be deemed necessary to monitor the health of the detectors,
even if not used in calibration processing.
1.4.7
Monochromatic Flatfield Data Cube
ID: DM-APP-PL-CAP-9
ID: DMS-REQ-0063
Last Modified: 10/2/2013
Specification:
The DMS shall produce on an as-needed basis an image that corrects for the color-
dependent, pixel-to-pixel non-uniformity in the detector response. The images in the cube shall be
constructed from exposures at multiple wavelengths of a uniformly illuminated source. The effectiveness
of the flat-field shall be verified in production processing on science data.
Discussion:
Monochromatic flat-fields are expected to be produced no more frequently than monthly,
owing to the time required to obtain the exposures.
1.4.8
Illumination Correction Frame
ID: DM-APP-PL-CAP-8
ID: DMS-REQ-0062
Last Modified: 10/2/2013
Specification:
The DMS shall produce on an as-needed basis an image that corrects for the non-uniform
illumination of the flat-field calibration apparatus on the focal plane. The effectiveness of the Illumination
Correction shall be verified in production processing on science data.
Discussion:
The Illumination correction is anticipated to be quite stable. Updates to the correction should
be no more frequent than monthly.
1.4.9
Fringe Correction Frame
ID: DMS-REQ-0283
Last Modified: 10/8/2013
Specification:
The DMS shall produce on an as-needed basis an image that corrects for detector
fringing. The effectiveness of the Fringe Correction shall be verified in production processing on science
data.
Discussion:
Fringing is likely to affect only the reddest filters, where the CCD substrate becomes semi-
transparent to incident light.
2 Productions
2.1 Query Repeatibility
ID: DMS-REQ-0291
Last Modified: 10/8/2013
Specification:
The DMS shall ensure that any query executed at a particular point in time against any
DMS delivered database shall be repeatable at a later date, and produce results that are either identical
or include additional results (owing to updates from Level-1 processing).

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13
2.2 Uniqueness of IDs Across Data Releases
ID: DMS-REQ-0292
Last Modified: 10/8/2013
Specification:
The identifiers of Sources and Objects of all types shall not be preserved (except
coincidentally) from one data release to the next.
Discussion:
The objective is to dramatically reduce confusion for end-users of Catlogs.
2.3 Selection of Datasets
ID: DMS-REQ-0293
Last Modified: 10/8/2013
Specification:
A Dataset may consist of one or more pixel images, a set of records in a file or database,
or any other grouping of data that are processed or produced as a logical unit. The DMS shall be able to
identify and retrieve complete, consistent datasets for processing.
Discussion:
Logical groupings might be pairs of Exposures in a Visit, along with supporting metadata
and provenance information, or might be groupings defined in the context of Level-3 processing.
2.4 Processing of Datasets
ID: DMS-REQ-0294
Last Modified: 10/8/2013
Specification:
The DMS shall be able to process all datasets meeting specified criteria exactly once.
Discussion:
The criteria may be specified by DMS processing software, or by a scientist end-user for
Level-3 production. "Exactly once" implies processing with a successful conclusion.
2.5 Transparent Data Access
ID: DMS-REQ-0295
Last Modified: 10/8/2013
Specification:
The DMS shall be able to retrieve datasets from a local Facility, or from any remote LSST
Facility.
2.6 Alert Production
2.6.1
Level-1 Production Completeness
ID: DMS-REQ-0284
Last Modified: 10/8/2013
Specification:
The DMS shall ensure that all images taken by the camera and marked for Level-1
processing are eventually retrieved, archived, and processed even in the event of connectivity failure
between downstream Facilities.
2.6.2
Calibration Images Available 1 Hour Before Observing
ID: DM-APP-DP-CI-2
ID: DMS-REQ-0131
Last Modified: 10/8/2013

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14
Specification:
Calibration Images shall be available for nightly observing in the DMS image archive at
least 1 hour prior to the start of observing.
2.6.3
Transient Alert Distribution
ID: DM-APP-DP-GEN-6
ID: DMS-REQ-0002
Last Modified: 10/2/2013
Specification:
Identified transient events shall be made available to end-users in the form of alerts, which
shall be published to community alert distribution networks using community-standard protocols, to be
determined during the LSST construction phase as community standards evolve.
2.6.4
Level 1 Source Association
ID: DMS-REQ-0285
Last Modified: 10/8/2013
Specification:
The DMS shall associate clusters of DIASources detected on multiple visits taken at
different times with either a DIAObject or an SSObject.
Discussion:
The association will represent the underlying astrophysical phenomenon.
2.6.5
SSObject Precovery
ID: DMS-REQ-0286
Last Modified: 10/8/2013
Specification:
Upon identifying a new SSObject, the DMS shall associate additional DIAObjects that are
consistent with the orbital parameters (precovery), and update DIAObject entries so associated.
2.6.6
DIASource Precovery
ID: DMS-REQ-0287
Last Modified: 10/8/2013
Specification:
For all DIASources not associated with either DIAObjects or SSObjects, the DMS shall
perform forced photometry at the location of the new source (precovery) on all Difference Exposures
obtained in the prior
precoveryWindow
, and make the results publicly available within
L1PublicT
.
Discussion:
The
precoveryWindow
is intended to satisfy the most common scientific use cases (e.g.,
Supernovae), without placing an undue burden on the processing infrastructure. For reasons of
practicality and efficiency,
precoveryWindow
<= l
1CacheLifetime
.
2.6.6.1
diaSourcePrecovery
ID:
Last Modified: 10/8/2013
Description
Value
Unit
Name
Maximum look-back time for precovery measurments on prior
Exposures
30
Days
precoveryWindow
2.6.7
Use of External Orbit Catalogs
ID: DMS-REQ-0288
Last Modified: 10/8/2013

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15
Specification:
It shall be possible for DMS to make use of approved external catalogs and observations
to improve the identification of SSObjects, and therefore increase the purity of the transient Alert stream
in nightly processing.
2.6.8
Solar System Objects Available within 24 hours
ID: DM-APP-DP-CA-15
ID:
ID: DMS-REQ-0089
Last Modified: 10/1/2013
Specification
: Detected moving objects and associated metadata shall be available for public access in
the DMS science data archive within time
L1PublicT
of their generation by the DMS.
2.6.9
Generate Data Quality Report within 4 hours
ID: DM-APP-DP-SR-1
ID: DMS-REQ-0096
Last Modified: 10/2/2013
Specification:
The DMS shall generate a nightly Data Quality Report within time
dqReportComplTime
in both human-readable and machine-readable forms.
Discussion:
The Report must be timely in order to evaluate whether changes to hardware, software, or
procedures are needed for the following night's observing.
2.6.9.1
dqReport
ID:
Last Modified: 10/2/2013
Description
Value
Unit
Name
Latency for producing Level 1 Data Quality Report
4
Hour
dqReportComplTim
e
2.6.10
Generate DMS Performance Report within 4 hours
ID: DM-APP-DP-SR-3
ID: DMS-REQ-0098
Last Modified: 10/2/2013
Specification:
The DMS shall generate a nightly DMS Performance Report within time
perfReportComplTime
in both human-readable and machine-readable forms.
Discussion:
The Report must be timely in order to evaluate whether changes to hardware, software, or
procedures are needed for the following night's observing.
2.6.10.1 perfReport
ID:
Last Modified: 10/2/2013
Description
Value
Unit
Name
Latency for producing Level 1 DMS Performance Report
4
Hour
perfReportComplTi
me

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16
2.6.11
Generate Calibration Report within 4 hours
ID: DM-APP-DP-SR-5
ID: DMS-REQ-0100
Last Modified: 10/2/2013
Specification:
The DMS shall generate a nightly Calibration Report within time
calibReportComplTime
in both human-readable and machine-readable forms.
Discussion:
The Report must be timely in order to evaluate whether changes to hardware, software, or
procedures are needed for the following night's observing.
2.6.11.1 calibReport
ID:
Last Modified: 10/2/2013
Description
Value
Unit
Name
Latency for producing Level 1 Calibration Report
4
Hour
calibReportComplTi
me
2.7 Calibration Production
2.7.1
Calibration Production Processing
ID: DMS-REQ-0289
Last Modified: 10/8/2013
Specification:
The DMS shall be capable of producing calibration data products on an as-needed basis,
consistent with monitoring the health and performance of the instrument, the availability of raw calibration
exposures, the temporal stability of the calibrations, and of the SRD requirements for calibration
accuracy.
2.8 Data Release Production
2.8.1
Timely Publication of Level 2 Data Releases
ID: DM-APP-DP-GEN-2
ID: DMS-REQ-0006
Last Modified: 10/2/2013
Specification:
The DMS shall make available to end-users all Level-2 data products as soon as possible
following the execution of the Data Release Production and the verification of science data quality.
2.9 Level 3 Production
2.9.1
Level 3 Data Import

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17
ID: DMS-REQ-0290
Last Modified: 10/8/2013
Specification:
The DMS shall be able to ingest tables from common file formats (e.g. FITS tables, CSV
files with supporting metadata) to facilitate the loading of external catalogs and the production of Level-3
data products.
2.9.2
DAC resource allocation for Level 3 processing
ID: DM-APP-DP-LTG-1
ID: DMS-REQ-0119
Last Modified: 10/2/2013
Specification:
The DMS shall provide a resource allocation mechanism for the DACs that allows the
prioritization and allocation of resources to a variety of Level 3 processing activities.
Discussion:
It is assumed that the DAC Level 3 processing resources will likely be oversubscribed,
making this necessary.
2.9.3
Level 3 Data Product Self Consistency
ID: DM-APP-DP-LTG-2
ID: DMS-REQ-0120
Last Modified: 10/2/2013
Specification
: The DMS shall provide a means for ensuring that users' Level 3 processing tasks can be
carried out on self-consistent inputs - i.e., catalogs, images, metadata, calibrations, camera configuration
data, etc., that match each other and all arise from consistent Level 1 and Level 2 processings.
2.9.4
Provenance for Level 3 processing at DACs
ID: DM-APP-DP-LTG-3
ID: DMS-REQ-0121
Last Modified: 10/2/2013
Specification:
The DMS shall provide a means for recording provenance information for Level 3
processing that is performed at DACs, covering at least all the DMS-provided inputs to the processing
(e.g., catalog data used as inputs, dataset metadata, calibrations and camera data from the EFD).
Discussion:
The DMS should also provide an optional means for Level 3 processing users at DACs to
maintain basic provenance information on their own inputs to a processing task, such as code or
additional calibration data.
Rationale: the DMS should facilitate Level 3 processing users in being able to carry out their work in a
reproducible way.
2.9.5
Software framework for Level 3 catalog processing
ID: DM-APP-DP-LTC-3
ID: DMS-REQ-0125
Last Modified: 10/2/2013
Specification:
The DMS shall provide a software framework that facilitates Level 3 processing of
catalogs. This framework shall provide a means for applying user-provided processing to catalog data,
including measuring and ensuring the completeness of the application - i.e., that the specified processing
was applied to all of, and only, the entire contents of the desired catalog(s).
2.9.6
Software framework for Level 3 image processing

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18
ID: DM-APP-DP-LTI-3
ID: DMS-REQ-0128
Last Modified: 10/2/2013
Specification:
The DMS shall provide a software framework that facilitates Level 3 processing of image
data. This framework shall provide a means for applying user-provided processing to image data,
including measuring and ensuring the completeness of the application - i.e., that the specified processing
was applied to all of, and only, the entire contents of the desired dataset.
3 Software
3.1 Software Architecture to Enable Community Re-Use
ID: DMS-REQ-0308
Last Modified: 10/8/2013
Specification:
The DMS software architecture shall be designed to enable high throughput on high-
performance compute platforms, while also enabling the use of science-specific algorithms by science
users on commodity desktop compute platforms.
Discussion:
The high data volume and short processing timeline for LSST Productions anticipates the
use of high-performance compute infrastructure, while the need to make the science algorithms
immediately applicable to science teams for Level-3 processing drives the need for easy interoperability
with desktop compute environments.
3.2 Applications Software
3.2.1
Simulated Data
ID: DM-APP-PL-3
ID: DMS-REQ-0009
Last Modified: 10/2/2013
Specification:
The DMS shall provide the ability to inject artificial or simulated data into data products to
assess the functional and temporal performance of the production processing software.
3.2.2
Pre-cursor, and Real Data
ID: DMS-REQ-0296
Last Modified: 10/8/2013
Specification:
The DMS shall provide for the ability to process data from other electronic, pixel-oriented
astronomical imaging cameras.
Discussion:
A comparison of DMS products to that produced by similar systems for other cameras
provides an essential validation of DMS algorithms and techniques.
3.2.3
Image Differencing
ID:
ID: DMS-REQ-0032
ID:
Last Modified: 10/2/2013

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19
Specification:
The DMS shall provide software to perform image differencing, generating Difference
Exposures from the comparison of single exposures and/or coadded images.
3.2.4
Provide Source Detection Software
ID: DM-APP-PL-DP-1
ID: DMS-REQ-0033
Last Modified: 10/2/2013
Specification:
The DMS shall provide software for the detection of sources in a calibrated image, which
may be a Difference Image or a Co-Add image.
3.2.5
Provide Calibrated Photometry
ID: DM-APP-PL-DRP-7
ID: DMS-REQ-0043
Last Modified: 10/2/2013
Specification:
The DMS shall provide calibrated photometry in each observed passband for all
measured entities (e.g., DIASources, Sources, Objects), measuring the AB magnitude of the equivalent
flat-SED source, above the atmosphere.
Discussion:
Note that the SED is only assumed to be flat within the passband of the measurement.
3.2.6
Provide Astrometric Model
ID: DM-APP-PL-DRP-6
ID: DMS-REQ-0042
Last Modified: 10/2/2013
Specification:
An astrometric model shall be provided for every Object and DIAObject which specifies at
least the proper motion and parallax, and the estimated uncertainties on these quantities.
3.2.7
Enable a Range of Shape Measurement Approaches
ID:
ID: DMS-REQ-0052
ID:
Last Modified: 10/2/2013
Specification:
The DMS shall provide for the use of a variety of shape models on multiple kinds of input
data to measure sources: measurement on coadds; measurement on coadds using information (e.g.,
PSFs) extracted from the individual exposures; measurement based on all the information from the
individual Exposures simultaneously.
Discussion:
The most appropriate measurement model to apply depends upon the nature of the
composite source.
3.2.8
Provide User Interface Services
ID: DM-MW-6
ID: DMS-REQ-0160
Last Modified: 10/7/2013
Specification:
The DMS shall provide software for User Interface Services, including services to: browse
LSST data products through astronomical views or visualizations; create and serve "best" images of
selectable regions of the sky; resample and re-project images, and visualize catalog content.

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20
3.3 Middleware Software
3.3.1
DMS Initialization Component
ID: DMS-REQ-0297
Last Modified: 10/8/2013
Specification:
The DMS shall contain a component that, at each Center, can initialize the DM Subsystem
into a well-defined safe state when powered up.
Discussion:
A safe state is one that does not permit the corruption or loss of previously archived data,
nor of sending spurious information over any interface.
3.3.2
Provide Data Access Services
ID: DM-MW-1
ID: DMS-REQ-0155
Last Modified: 10/2/2013
(This is a composite requirement in the SysML model, which simply aggregates its children.)
3.3.2.1
Data Product Access
ID: DMS-REQ-0298
Last Modified: 10/8/2013
Specification:
The DMS shall provide software for Data Access Services to list and retrieve image, file,
and catalog data products (including raw telescope images), their associated metadata, their provenance,
or any combination thereof, independent of their actual storage location.
3.3.2.2
Data Product Ingest
ID: DMS-REQ-0299
Last Modified: 10/8/2013
Specification:
The DMS shall provide software to ingest data products into the Science Data Archive.
3.3.2.3
Bulk Download Service
ID: DMS-REQ-0300
Last Modified: 10/8/2013
Specification:
The DMS shall provide software to enable bulk download of data products, subject to
network bandwidth.
3.3.3
Provide Image Access Services
ID: DM-APP-DP-IM-3
ID: DMS-REQ-0065
Last Modified: 10/2/2013
Specification:
The DMS shall provide software for Image Access through community data access
protocols, to support programmatic search and retrieval of images or image cut-outs. The service shall
support one or more community standard formats, including the LSST pipeline input format.
Discussion:
At least the FITS image format will be supported though an IVOA-standard service such as
SIAP. Other image formats such as JPG may be more compatible with education/public outreach needs.

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21
3.3.4
Control of Level-1 Production
ID: DMS-REQ-0301
Last Modified: 10/8/2013
Specification:
The DMS shall contain a component to control all Level-1 Data Product production.
Discussion:
This specifically addresses the need to control the Alert Production across all DMS facilities.
3.3.5
Provide Pipeline Execution Services
ID: DM-MW-2
ID: DMS-REQ-0156
Last Modified: 10/2/2013
(This is a composite requirement in the SysML model, which simply aggregates its children.)
3.3.5.1
Production Orchestration
ID: DMS-REQ-0302
Last Modified: 10/8/2013
Specification:
The DMS shall provide software to orchestrate execution of productions, including
deploying pipelines on a computing platform.
3.3.5.2
Production Monitoring
ID: DMS-REQ-0303
Last Modified: 10/8/2013
Specification:
The DMS shall provide software to monitor execution of pipelines in real time.
3.3.5.3
Production Fault Tolerance
ID: DMS-REQ-0304
Last Modified: 10/8/2013
Specification:
The DMS shall provide software to detect faults in pipeline execution and recover when
possible.
3.3.6
Provide Pipeline Construction Services
ID: DM-MW-4
ID: DMS-REQ-0158
Last Modified: 10/2/2013
(This is a composite requirement in the SysML model, which simply aggregates its children.)
3.3.6.1
Task Specification
ID: DMS-REQ-0305
Last Modified: 10/8/2013
Specification:
The DMS shall provide software to define (and redefine without recompilation) a pipeline
task containing a science algorithm, which may in turn consist of the execution of other subtasks.
3.3.6.2
Task Configuration
ID: DMS-REQ-0306
Last Modified: 10/8/2013
Specification:
The DMS shall provide software to define, override components of, and verify the
suitability of the configuration for a task.

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22
3.3.7
Unique Processing Coverage
ID: DMS-REQ-0307
Last Modified: 10/8/2013
Specification:
The DMS shall enable applications to process every record in a table meeting user-
specified criteria exactly once.
4 Facilities
4.1 Data Archive
4.1.1
Raw Data Archiving Reliability
ID: DMS-REQ-0309
Last Modified: 10/8/2013
Specification:
The DMS system shall archive all data, including science, wavefront, and guider images
and associated metadata, that are presented for archiving by up-stream systems, with a rate of
permanent data loss or corruption not to exceed
dataLossMax
.
Discussion:
Data "presented for archiving" means data that have been successfully transferred from
upstream systems to DMS, and that are intended for permanent archiving. Data obtained for diagnostic
and other limited-use engineering purposes are specifically excluded from this requirement.
4.1.1.1
rawArchiveReliability
ID:
Last Modified: 10/8/2013
Description
Value
Unit
Name
Maximum fraction of raw images that are permitted to be
permanently lost or corrupted, including the loss or corruption
of essential associated metadata, once acquired by the DMS
1.0e-5
float
dataLossMax
4.1.2
Keep Historical Alert Archive
ID: DM-APP-DP-AL-4
ID: DMS-REQ-0094
Last Modified: 10/2/2013
Specification:
The DMS shall preserve and keep in an accessible state an alert archive with all issued
alerts for a historical record and for false alert analysis.
4.1.3
Un-Archived Data Product Cache
ID: DMS-REQ-0310
Last Modified: 10/8/2013
Specification:
The DMS shall provide low-latency storage for un-archived data products of at least
l1CacheLifetime
to enable efficient precovery and other Level-1 production measurements.

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23
4.1.3.1
l1Cache
ID:
Last Modified: 10/8/2013
Description
Value
Unit
Name
Lifetime in the cache of un-archived Level-1 data products
30
Days
l1CacheLifetime
4.1.4
Regenerate Un-archived Data Products
ID: DMS-REQ-0311
Last Modified: 10/8/2013
Specification:
The DMS shall be able to regenerate unarchived data products to within scientifically
reasonable tolerances.
Discussion:
Unarchived data products currently include Processed Exposures for single visits, and
Difference Images. Scientifically reasonable tolerances means well within the formal uncertainties of the
data product, given the same production software, calibrations, and compute platform, all of which are
expected to change (and improve) during the course of the survey.
4.1.5
Level 1 Data Product Access
ID: DMS-REQ-0312
Last Modified: 10/8/2013
Specification:
The DMS shall maintain a "live" Level 1 Database for query by science users, updated as
a result of Alert Production processing.
4.1.6
Level 1 & 2 Catalog Access
ID: DMS-REQ-0313
Last Modified: 10/8/2013
Specification:
The DMS shall maintain both the Level-2 catalog and the reprocessed Level-1 catalog
from the most recent two Data Releases for query by science users.
4.1.7
Provide Engineering & Facility Database Archive
ID: DM-APP-DP-EF-1
ID: DMS-REQ-0102
Last Modified: 10/2/2013
Specification:
Engineering and Facility data from the Observatory Control System and associated
metadata shall be permanently archived by the DMS and available for public access within 24 hours of
their generation by the OCS.
4.1.8
Catalog Queries
ID:
ID: DMS-REQ-0075
Last Modified: 10/2/2013
Specification:
The catalogs shall be queryable with a structured language, such as SQL.
Discussion:
Queries are expected to be generated via Science User Interfaces, and software within and
external to DMS, including VO clients. The queries may be translated to (and optimized for) the native
query language of the DMS database server.

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24
4.1.9
Catalog Export Formats
ID: DM-APP-DP-CA-3
ID: DMS-REQ-0078
Last Modified: 10/2/2013
Specification:
The DMS catalog archive shall provide catalog data and associated metadata on request
in community standard formats:
* Comma-separated ASCII text
* eXtensible Markup Language (XML) format, including VOTable
(http://www.ivoa.net/twiki/bin/view/IVOA/IvoaVOTable), and
* FITS tables.
4.1.10
Maintain Archive Publicly Accessible
ID: DM-APP-DP-CA-2
ID: DMS-REQ-0077
Last Modified: 10/2/2013
Specification:
All releases of the DMS catalog archive shall be maintained and preserved in a publicly
accessible state for the entire operational life of the LSST observatory.
Discussion:
The scientific intent is satisfied by keeping data products from the current DRP release and
the one prior available with low-latency, in a form readily queryable by the public. Earlier releases may be
available from deep-store with potentially high latency, for bulk download by users.
4.2 Computational Infrastructure
4.2.1
Optimization of Cost, Reliability and Availability in Order
ID: DM-INF-1
ID: DMS-REQ-0161
Last Modified: 10/2/2013
Specification:
Within a fixed cost envelope for the Data Management subsystem, the allocation of
processing and storage facilities will optimize reliability over availability to end users.
4.2.2
Compute Platform Heterogeneity
ID: DMS-REQ-0314
Last Modified: 10/8/2013
Specification:
At any given LSST computational facility the DMS shall be capable of operations on a
heterogeneous cluster of machines. The hardware, operating system, and other machine parameters
shall be limited to a project-approved set.
Discussion:
The necessity of replacing hardware throughout the course of the survey essentially
guarantees heterogeneity within a cluster.
4.2.3
Pipeline Throughput
ID: DM-INF-2
ID: DMS-REQ-0162
Last Modified: 10/2/2013
Specification:
The infrastructure will be sized such that the net throughput of the data processing

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waived without prior approval.
25
pipelines will permit a complete processing of a night’s observing data prior to the start of the next
observing night, assuming no system outages
4.2.4
Pipeline Availability
ID: DM-APP-PL-2
ID: DMS-REQ-0008
Last Modified: 10/2/2013
Specification:
Except in cases of major disaster, the DMS shall have no unscheduled outages of the
DMS pipelines extending over a period greater than
productionMaxDowntime
. A major disaster is
defined as a natural disaster or act of war (e.g. flood, fire, hostile acts) that compromises or threatens to
compromise the health and integrity of the DMS physical facility, computing equipment, or operational
personnel.
Discussion:
This applies to active productions only. It is allowed for the Alert Production to be down for
longer periods during observatory scheduled maintenance, and for the Data Release Production to be
down during development and validation periods between productions.
4.2.4.1
productionAvailability
ID:
Last Modified: 9/19/2010
Description
Value
Unit
Name
Maximum allowable outage of active DM production.
24
Hour
productionMaxDow
ntime
4.2.5
Re-processing Capacity
ID: DM-INF-3
ID: DMS-REQ-0163
Last Modified: 10/8/2013
Specification:
The DMS shall provide Processing, Storage, and Network resources capable of executing
the DMS Data Release Production over all pre-existing survey data in a time no greater than
drProcessingPeriod
, without impacting observatory operations.
4.2.5.1
drProductionInfrastructure
ID:
Last Modified: 10/2/2013
Description
Value
Unit
Name
Duration of the Data Release Production, including quality
validation.
1
Years
drProcessingPeriod
4.2.6
Temporary Storage for Communications Links
ID: DM-INF-4
ID: DMS-REQ-0164
Last Modified: 10/2/2013
Specification:
The infrastructure will provide for temporary storage for a minimum of 200% of the mean
time to repair of any communications network link at the source end of that link.

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26
4.2.7
Infrastructure Sizing for "catching up"
ID: DM-INF-5
ID: DMS-REQ-0165
Last Modified: 10/2/2013
Specification:
The infrastructure will be sized such that after outages, "catch up" processing of the
temporarily stored raw image data may occur at the rate of one night’s observing data processed per day,
without interrupting the current day's observatory operations.
4.2.8
Incorporate Fault-Tolerance
ID: DM-INF-6
ID: DMS-REQ-0166
Last Modified: 10/2/2013
Specification:
The infrastructure will incorporate as fault-tolerance features to prevent loss of data in the
event of hardware or software failure.
4.2.9
Incorporate Autonomics
ID: DM-INF-7
ID: DMS-REQ-0167
Last Modified: 10/2/2013
Specification:
The infrastructure will incorporate sufficient capability for self-diagnostics and recovery to
provide for continuation of processing in the event of partial hardware or software failures.
Discussion:
It is understood that the system performance may degrade with increasing numbers of
failures.
4.3 Summit Facility
4.3.1
Summit Facility Data Communications
ID: DM-INF-MS-1
ID: DMS-REQ-0168
Last Modified: 10/2/2013
Specification
: The DMS shall provide data communications infrastructure to accept science data and
associated metadata read-outs, and the collection of ancillary and engineering data, for transfer to the
base facility.
4.3.2
Prefer Computing and Storage Down
ID: DM-INF-MS-3
ID: DMS-REQ-0170
Last Modified: 10/2/2013
Specification:
The DMS computing and storage equipment will be preferentially located at a lower
altitude Facility (Base or Archive Center) versus the Summit Facility due to lower support costs and fewer
reliability issues. Therefore any processing that can be done in either location will be allocated to a lower
altitude Facility.
4.3.3
DMS Communication with OCS
ID: DMS-REQ-0315
Last Modified: 10/8/2013

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waived without prior approval.
27
Specification:
The DMS at the Base Site shall contain a component to accept control commands from
and communicate with the OCS.
4.4 Summit to Base
4.4.1
Summit to Base Network
ID: DM-INF-MB-1
ID: DMS-REQ-0171
Last Modified: 10/2/2013
Specification:
The DMS shall provide communications infrastructure between the Summit Facility and
the Base Facility sufficient to carry scientific data and associated metadata for each image in no more
than time
summToBaseMaxTransferTime
.
4.4.1.1
summToBaseNetwork
ID:
Last Modified: 10/2/2013
Description
Value
Unit
Name
Maximum time interval to transfer a full Raw Exposure and all
related metadata from the Summit Facility to the Base facility.
6
Seconds
summToBaseMaxT
ransferTime
4.4.2
Summit to Base Network Availability
ID: DM-INF-MB-2
ID: DMS-REQ-0172
Last Modified: 10/2/2013
Specification:
The Summit to Base communications shall be highly available, with Mean Time Between
Failures (MTBF) >
summToBaseNetMTBF
.
4.4.2.1
summToBaseAvailability
ID:
Last Modified: 10/2/2013
Description
Value
Unit
Name
Mean time between failures, measured over a 1-yr period.
90
Days
summToBaseNetM
TBF
4.4.3
Summit to Base Network Reliability
ID: DM-INF-MB-3
ID: DMS-REQ-0173
Last Modified: 10/2/2013
Specification:
The Summit to Base communications shall be highly reliable, with Mean Time to Repair
(MTTR) <
summToBaseNetMTTR
.
4.4.3.1
summToBaseReliability

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28
ID:
Last Modified: 10/2/2013
Description
Value
Unit
Name
Mean time to repair, measured over a 1-yr period.
24
Hour
summToBaseNetM
TTR
4.4.4
Summit to Base Network Secondary Link
ID: DM-INF-MB-4
ID: DMS-REQ-0174
Last Modified: 10/2/2013
Specification:
The Summit to Base communications shall provide at least one secondary link or transport
mechanism for minimal operations support in the event of extended outage. This link may include
redundant fiber optics, microwaves, or transportable media. It shall be capable of transferring one night's
worth of raw data in
summToBaseNet2TransMax
or less.
4.4.4.1
summToBaseSecNetwork
ID:
Last Modified: 10/2/2013
Description
Value
Unit
Name
Maximum time to transfer one night of data via the network
secondary link.
72
Hour
summToBaseNet2
TransMax
4.4.5
Summit to Base Network Ownership and Operation
ID: DM-INF-MB-5
ID: DMS-REQ-0175
Last Modified: 10/2/2013
Specification:
The Summit to Base communications link shall be owned and operated by LSST and/or
the operations entity to ensure responsiveness of support.
4.5 Base Facility
4.5.1
Base Facility Infrastructure
ID: DM-INF-BF-1
ID: DMS-REQ-0176
Last Modified: 10/8/2013
Specification:
The Base Facility shall provide sufficient computing, storage, and network infrastructure to
support buffering and forwarding of all raw and crosstalk-corrected image data to the Archive Facility, a
complete copy of the Archive Facility data holdings, and compute facilities to support Commissioning
activities.
Discussion:
The Base Facility is co-located with the Chilean DAC, and also serves as a back-up for the
Archive Center in the event of disaster.
4.5.2
Base Facility Temporary Storage

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29
ID: DM-INF-BF-2
ID: DMS-REQ-0177
Last Modified: 10/2/2013
Specification:
The Base Facility shall provide at least a time
minBaseStorage
(or half of that amount,
redundantly) of raw data storage in the event of Base to Archive Center network outage.
4.5.2.1
baseStorage
ID:
Last Modified: 10/2/2013
Description
Value
Unit
Name
Low-latency storage buffer capacity, expressed in units of
data volume equivalent for a typical day's data collection.
14
Days
minBaseDataStora
ge
4.5.3
Base Facility Co-Location with Existing Facility
ID: DM-INF-BF-3
ID: DMS-REQ-0178
Last Modified: 10/2/2013
Specification:
The Base Facility shall be co-located at an existing facility to leverage existing support
and facility resources
4.5.4
Commissioning Cluster
ID: DMS-REQ-0316
Last Modified: 10/8/2013
Specification:
The Base Facility shall include a compute cluster to be made available to the Systems
Engineering group for use in commissioning. Data Management will not administer or otherwise maintain
this cluster following hardware installation. The budget for this cluster shall be at least 10% of the budget
for Alert Production hardware.
4.6 Base to Archive
4.6.1
Base to Archive Network
ID: DM-INF-BA-1
ID: DMS-REQ-0180
Last Modified: 10/2/2013
Specification:
The DMS shall provide communications infrastructure between the Base Facility and the
Archive Center sufficient to carry scientific data and associated metadata for a given night to support the
Alert Production and related Level-1 processing at the Archive Center.
4.6.2
Base to Archive Network Availability
ID: DM-INF-BA-2
ID: DMS-REQ-0181
Last Modified: 10/2/2013
Specification:
The Base to Archive communications shall be highly available, with MTBF >
baseToArchNetMTBF
.

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30
4.6.2.1
baseToArchAvailability
ID:
Last Modified: 10/2/2013
Description
Value
Unit
Name
Mean time between failures, measured over a 1-yr period.
180
Days
baseToArchNetMT
BF
4.6.3
Base to Archive Network Reliability
ID: DM-INF-BA-3
ID: DMS-REQ-0182
Last Modified: 10/2/2013
Specification:
The Base to Archive communications shall be highly reliable, with MTTR <
baseToArchNetMTTR
.
4.6.3.1
baseToArchReliability
ID:
Last Modified: 10/2/2013
Description
Value
Unit
Name
Mean time to repair, measured over a 1-yr period.
48
Hour
baseToArchNetMT
TR
4.6.4
Base to Archive Network Secondary Link
ID: DM-INF-BA-4
ID: DMS-REQ-0183
Last Modified: 10/2/2013
Specification:
The Base to Archive communications shall provide secondary link or transport mechanism
(e.g. protected circuit) for operations support and "catch up" in the event of extended outage. This
secondary link shall be capable of "bursting" to at least twice the capacity of the primary link.
4.7 Archive Center
4.7.1
Archive Center
ID: DM-INF-AC-1
ID: DMS-REQ-0185
Last Modified: 10/2/2013
Specification:
The Archive Center shall provide computing, storage, and network infrastructure to
support, simultaneously: nightly processing including image processing, detection, association, and
moving object pipelines, and the generation of all time-critical data products, i.e. alerts; the data release
production, including Level-2 data product creation, permanent storage for all data products (with
provenance), including federated Level-3 products; and serve data for replication to data centers and end
user sites.
4.7.2
Archive Center Disaster Recovery

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31
ID: DM-INF-AC-2
ID: DMS-REQ-0186
Last Modified: 10/2/2013
Specification:
The Archive Center shall provide disaster recovery support preventing loss of LSST data
in the case of infrastructure or facility-threatening events. This support shall enable recovery of all LSST
archived data from backed up sources, including Data Access Centers.
4.7.3
Archive Center Co-Location with Existing Facility
ID: DM-INF-AC-3
ID: DMS-REQ-0187
Last Modified: 10/2/2013
Specification:
The Archive Center shall be hosted at an existing NSF/DOE-funded supercomputing
center.
4.8 Archive to Data Access Center
4.8.1
Archive to Data Access Center Network
ID: DM-INF-AD-1
ID: DMS-REQ-0188
Last Modified: 10/8/2013
Specification:
The DMS shall provide communications infrastructure between the Archive Center and
Data Access Centers sufficient to carry scientific data and associated metadata in support of community
and EPO access. Aggregate bandwidth for data transfers from the Archive Center to Data Centers shall
be at least
archToDacBandwidth
.
4.8.1.1
archToDacNetwork
ID:
Last Modified: 10/2/2013
Description
Value
Unit
Name
Aggregate bandwidth capacity for data transfers between the
Archive and Data Access Centers.
10000
Mbit/sec
archToDacBandwid
th
4.8.2
Archive to Data Access Center Network Availability
ID: DM-INF-AD-2
ID: DMS-REQ-0189
Last Modified: 10/2/2013
Specification:
The Archive to Data Access Center communications shall be highly available, with MTBF
>
archToDacNetMTBF
.
4.8.2.1
archToDacAvailability
ID:
Last Modified: 10/2/2013
Description
Value
Unit
Name

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32
Description
Value
Unit
Name
Mean Time Between Failures for data link between Archive
and DACs, averaged over a one-year period.
180
Days
archToDacNetMTB
F
4.8.3
Archive to Data Access Center Network Reliability
ID: DM-INF-AD-3
ID: DMS-REQ-0190
Last Modified: 10/2/2013
Specification:
The Archive to Data Access Center communications shall be highly reliable, with MTTR <
archToDacNetMTTR
.
4.8.3.1
archToDacReliability
ID:
Last Modified: 10/2/2013
Description
Value
Unit
Name
Mean time to repair, measured over a 1-yr period.
48
Hour
archToDacNetMTT
R
4.8.4
Archive to Data Access Center Network Secondary Link
ID: DM-INF-AD-4
ID: DMS-REQ-0191
Last Modified: 10/2/2013
Specification:
The Archive to Data Access Center communications shall provide secondary link or
transport mechanism (e.g. protected circuit) for operations support and "catch up" in the event of
extended outage.
4.9 Data Access Center
4.9.1
Data Access Centers
ID: DM-INF-DC-1
ID: DMS-REQ-0193
Last Modified: 10/2/2013
Specification:
The Data Access Centers shall provide computing, storage, and network infrastructure to
support open access to LSST data products (with provenance) by end users.
4.9.2
Data Access Center Simultaneous Connections
ID: DM-INF-DC-2
ID: DMS-REQ-0194
Last Modified: 10/2/2013
Specification:
At least
dacMinConnections
simultaneous connections shall be supported at each Data
Access Center.
4.9.2.1
dacConnections
ID:
Last Modified: 10/2/2013

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33
Description
Value
Unit
Name
Minimum simultaneous connections to end-users.
300
int
dacMinConnections
4.9.3
Access to catalogs for external Level 3 processing
ID: DM-APP-DP-LTC-2
ID: DMS-REQ-0122
Last Modified: 10/2/2013
Specification:
The DMS shall facilitate Level 3 catalog processing that may take place at external
facilities outside the DACs. This will principally be by facilitating the export of catalogs and the provision
of tools for maintaining and validating exported data.
4.9.4
Access to images for external Level 3 processing
ID: DM-APP-DP-LTI-2
ID: DMS-REQ-0126
Last Modified: 10/2/2013
Specification:
The DMS shall facilitate Level 3 image processing that may take place at external facilities
outside the DACs. This will principally be by facilitating the export of image datasets and the provision of
tools for maintaining and validating exported data.
4.9.5
Access to input catalogs for DAC-based Level 3 processing
ID: DM-APP-DP-LTC-1
ID: DMS-REQ-0123
Last Modified: 10/2/2013
Specification:
The DMS shall provide access to all Level 1 and Level 2 catalog products through the
LSST project's Data Access Centers, and any others that have been established and funded, for Level 3
processing that takes place at the DACs.
4.9.6
Access to input images for DAC-based Level 3 processing
ID: DM-APP-DP-LTI-1
ID: DMS-REQ-0127
Last Modified: 10/2/2013
Specification:
The DMS shall provide access to all Level 1 and Level 2 image products through the
LSST project's Data Access Centers, and any others that have been established and funded, for Level 3
processing that takes place at the DACs.
4.9.7
Federation with external catalogs
ID: DM-APP-DP-LTC-4
ID: DMS-REQ-0124
Last Modified: 10/2/2013
Specification:
The DMS shall provide a means for federating Level 1, 2, and 3 catalogs with externally
provided catalogs, for joint analysis. The DMS shall provide specifications for how external data must be
provided in order for this to be achieved. The DMS shall strive to support community standards in this
regard, including, but not limited to, virtual observatory facilities that may be available during the project
lifetime.

LSST Data Management System Requirements
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34
4.9.8
Data Access Center Geographical Distribution
ID: DM-INF-DC-4
ID: DMS-REQ-0196
Last Modified: 10/2/2013
Specification:
The Data Access Centers will be hosted at facilities selected in at least the U.S. and the
observatory host country to permit widest possible access to LSST data with the fewest possible network
hops.
4.9.9
No Limit on Data Access Centers
ID: DM-INF-DC-5
ID: DMS-REQ-0197
Last Modified: 10/2/2013
Specification:
The number of Data Access Centers shall be limited only by available internal or external
funding. No architectural constraints will be placed on the DMS that prohibit the addition of Data Access
Centers at any time, subject to funding.
1

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