Subject:  LRPG ops-deliverables for CASM/APT Cycle 28 Phase 2 are ready

Hi, Bob, Karla, Developers,

The CASM constraint-sets, control-files, and MOSS files for use in the upcoming 
APT 28 Phase 2 = APT 2020.3 release are ready and may be found on SOGS at 
/data/lrp/ops-deliverables/phase2/mar20 .  Release notes detailing changes are 
in the file RELEASE_NOTES.TXT and some construction and validation information 
can be found in working_material/ including a more detailed process description
for construction in mar20_construction_notes.txt .  None of the content in the 
working_material/ area is required--retention downstream is at your discretion.  

The motivating change for this release is an update to constraint-sets for some 
parameter alterations and a new CASM orbit model.  This new orbit model 
increases the pad between Operations (SPSS/Spike) and APT by 30-seconds to 
accommodate possible changes during Cycle 28 which may result from deteriorating 
Gyro 3 performance.  These changes have the net effect of reducing visibility 
time available for users to construct science observations.  

On the up-side, the new orbit model should result in a lower incidence of 
false-negatives for targets in and near CVZ opportunities.  

On the down-side, users can expect that the span of Visit-Planner suitable 
intervals for packed visibility usage will shrink by an average of about 13%.  
Approximately 5% of visits suitable under previous CASM releases will become 
unschedulable and require exposure time cuts.  The suitability shrinkage
of 13% is not only due to the new orbit model, but is also a result of 
the increased duration of guide star acquisitions/reacquisitions that
are being delivered in TRANS.  Exposure time cuts as large as 50-120 
seconds may be necessary to restore suitability for visits that become 
unschedulable in this Cycle 28 Phase 2 APT release.

---

It is important to draw attention to the fact that --unlike previous 
deliveries-- both Phase 1 and Phase 2 constraint sets have been updated.  
This means that new Phase 1 proposals will reflect these updates as well 
as Phase 2s.

MOSS files remain unchanged.  As was the case in all recent deliveries, no 
sub-3-gyro grid files are included in the products (per R. Douglas, Nov. 4, 2016).  

Filename conventions are unchanged from previous LRPG ops deliverables.  The
filenames for Phase 1 and Phase 2 constraint-sets have been set to the prefix 
"mar20" to match the unique orbit model name.  This, as usual, reflects 
internal changes to those constraint sets, in keeping with past convention.

...

For the constraint-sets, the following check-list was followed in implementing
changes contained in this release:

    Constraint-set checklist:
		1.  Update the orbit model to the 'mar20' parameters.
        2.  Update planning-start and/or planning-end (superfluous, but done anyway).
        3.  Update the comments.
		4.  Ensure updated define-pcs-substitutions form properly defined.

For the control files, the following checklist was followed:

    Control-file checklist:
        1.  Update constraint-set-name.
        2.  Update the comments.

If problems are found with the content, please contact us.

Ian Jordan & Brigette Hesman
x5037, x2946
jordan@stsci.edu, bhesman@stsci.edu





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To: "Robert M. Boyer" <rmboyer@stsci.edu>, 
spike-developers <spike-developers@stsci.edu>, 
Karla Peterson <peterson@stsci.edu> 
Cc: apt-developer@stsci.edu, 
Bill Workman <workman@stsci.edu>, 
Robert Hawkins <rhawkins@stsci.edu>,
Christine Ritchie <ritchie@stsci.edu>
Merle Reinhart <reinhart@stsci.edu>,
Denise C. Taylor <dctaylor@stsci.edu>,
Mark Giuliano <giuliano@stsci.edu>,
Tony Roman <aroman@stsci.edu>