HET Beginning-Trimester Report
  First Period of 2021
December 1 - March 30

This report is primarily to give updates to PIs on recent changes/improvements and to summarize the determination of time allocations for the 21-1 trimester.



Updates on recent changes/improvements:



New forum for PI questions/answers about observations and science

   We have recently introduced a Google Group for HET Observations & Science Support. This forum allows PIs to ask (and search for answers to) frequently asked questions about HET observations (planning, executing, editing) and science (data access, reductions, analysis). This is available at the link below and we encourage as much utilization as possible. Any additional feedback is welcome regarding more ways to help the PIs achieve their scientific goals:
https://groups.google.com/g/het-obs-sci


Updated weather loss statistics

   Now that we have been conducting full science operations on-sky for a number of years after the wide-field upgrade, it was appropriate to update our observing statistics. These updates include statistics about time lost to weather, stacking, and problems, as well as typical seeing, sky brightness, transparency, etc as measured by our guide stars. Since the upgrade we have been amassing a rich and vast collection of data, and these summaries are only the tip of the iceberg.

   These improved statistics are still in progress but will be updated on the following webpage when complete: https://hydra.as.utexas.edu/?a=help&h=7
   Feedback or requests for other metrics or statistics are welcome.

Small update to available science time calculation

   This trimester begins a small update to the calculation of time available. This is motivated by systematic shortfalls in previous trimesters. Summarized below are the estimated available number of hours allocated to partner TAC science, and the total hours charged. Priority-4 targets are charged at 50% of their exposure time with no overhead costs, but these shortfalls are larger than desired. The 20-2 and 20-3 trimesters had significantly better than average weather, which will always be a nice windfall (and mainly improves the lower priority time completion rates).
Trimester
 hours allocated
to TAC science
 hours charged
to TAC science
 % charged
21-1
 401.70
 - -
 - -
20-3
 400.73
 413.64
 103%
20-2
 177.74
 179.92
 101%
20-1
 359.18
 274.80
 77%
19-3
 348.10
 245.77
 71%
19-2
 193.02
 153.80
 80%
19-1
 250.62
 194.22
 77%
18-3
 194.94
 160.40
 82%
18-2
 176.88
 118.13
 80%
18-1
 177.65
 139.27
 78%
In the 21-1 time calculations below, the weather loss estimates from Dec/Jan/Feb/Mar have been updated from losing 35%/34%/32%/33% to a consistent 37% loss, which should allow more programs to complete their observations (and the total allocations will be smaller). The impact of this small update will be closely monitored to be certain that we are giving the TAC science programs the best possible chances to succeed.





Commissioning, Engineering, and Guaranteed Time allocations


The HET Board granted the following allocations for the 21-1 period:


In total the Board granted 310 hours of Comm/Eng/GTO time in 21-1.
   Note that in 20-1 the Board granted 410 hours to these programs, so there is significantly more time available for partner science than there was last year.
 





Breakdown of how science hours for TACs at each partner were determined:



quantity
 Dec
(hrs)
 Jan
(hrs)
 Feb
(hrs)
 Mar
(hrs)
 Total
(hrs)
18deg-18deg times
 339.17
 334.00
 285.43
 289.23
 1247.83
Weather loss frac. 0.37
 0.37
 0.37
 0.37
Efficiency loss frac.
(align+PRs)
 0.094
 0.094
 0.097
 0.094
"Clear science" time
 193.59
 190.64
 162.38
 165.09
 711.70
Com/Eng/GTO time



310.00
"Allowed" hours
given to TACs
for science



401.70




 

Hours allowed for each TAC as determined Sep 26, 2020:


Partner
 Share
 Notes
 Total hours
allowed
Allocated
as of Dec 1
Goettingen
 0.0085
3.37
 3.30
Munich
 0.0590
23.70
 23.70
PSU
 0.2568
 time trade: 103.16 - 4.75
 98.41
 94.40
UT
 0.6757
 time trade: 271.43 + 4.75
 276.18
 255.28

Note that TACs may allocate up to 8.3% at P0, 25% at P1, 33.3% at P2 and 33.3% at P3; P4 allocations are not restricted. Priorities of Com/Eng/GTO time are assigned by the HET Board.

Also note that the PSU and UT TACs have sometimes elected not to allocate a small amount of time which can be allocated to targets-of-opportunity which arise later in the trimester.










SJ, 1 Dec 2020