LSR Changes

LSR-REQ-0025

Note that the title, "Transient Filtering", does not match the requirement content.  The title goes back to the earliest editions of the LSR.  The original requirement text appears to have been accidentally overwritten in March of 2011 by text intended as an update to LSR-REQ-0028, "Alert Production Reliability".  This intent is clearly documented in the CCB notes in Document-10810.  The faulty edit is clearly visible in a comparison of the February 22 and March 17, 2011 versions (Docushare v9 and v10, respectively).  This left LSR-REQ-0025 and LSR-REQ-0028 saying almost the same thing.  This duplication was noticed in October 2013, as part of the larger LSR revision in LCR-144, but the origin of the duplication wasn't understood at the time.  Instead of correcting the 2011 error, then, the apparently duplicate LSR-REQ-0028 was removed from the document - but, oddly, the inappropriate title of LSR-REQ-0025 was retained.

Restoring this lost requirement is essential to providing support for DMS-REQ-0342, Alert Filtering Service.

  1. Restore the CCB-approved text from 2011's Document-10810, except omitting the reference to pre-filtering being able to query the Science Database.
    "Specification: LSST shall enable users to obtain a query-like pre-filtering of the transient alert data stream.
    "Discussion: This capability will allow users to "select likely candidates for specific transient type[s]" (as specified in the SRD).  We expect that the direct subscribers to LSST alerts will be other alert dissemination networks/brokers, not individual users. The user-level filtering functionality should accordingly be mediated by such community mechanisms to the extent possible (see LSR-REQ-0054)."

LSR-REQ-0028 (Restore)

  1. Along with the above, we should save the text that was erroneously attached to LSR-REQ-0025 and restore it as LSR-REQ-0028.

LSR-REQ-0101

  1. Replace the existing Discussion text ("It is unclear whether the SRD specification of transN refers to the number of alerts that can be generated for a single visit (i.e. an instantaneous limit), or the number per visit averaged over time.") with:
    "In flowing this down to lower-level requirements, the SRD specification for transN is to be interpreted conservatively, as a requirement on the alert capacity averaged over a night.  Lower-level documents will set more stringent requirements for peak per-visit capacity."

OSS Changes

DMSR Changes

DMS-REQ-0393

  1. Append to the Discussion the following text:
    "The requirement on the system capacity averaged over a night derives directly from the OSS.  The requirement on the capacity for a single visit, nAlertVisitPeak, is added at this level and is set four times higher to provide operational margin for occasional crowded fields and other sources of variance in the alert rate."
  2. Drop the flowdown link to LSR-REQ-0101, leaving only OSS-REQ-0193.