HET Beginning-Trimester Report
  Second Period of 2021
April 1 - July 31

This report is primarily to give updates to PIs on recent changes/improvements and to summarize the determination of time allocations for the 21-2 trimester.

Updates on recent changes/improvements:

Updates to documentation

   Recent work to improve the Hydra documentation is underway. One example of an improved page describing weather and observing statistics is here: https://hydra.as.utexas.edu/?a=help&h=7  Additional updates and improvements are also underway. Feedback or requests for other metrics or statistics are welcome.


Improvements to Target Submission Language (TSL)

We are phasing out the use of NUMEXP in TSL, given the frequent confusion it causes. In order to specify multiple exposures, please submit your total exposure time per visit as EXP and the number of subdivisions ("splits") with CRSPLIT.


Continuing monitoring of available science time calculation

   In this trimester we continue monitoring and making small adjustments 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. In 20-1 and earlier, these shortfalls were 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
21-2
 213.80
 - -
 - -
21-1
 401.70
 376.04
 94%
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 21-2 time calculations below, the weather loss estimates from Dec/Jan/Feb/Mar have been updated based on the average statistics over the past ~4 years. 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 21-2 period:


In total the Board granted 280 hours of Comm/Eng/GTO time in 21-2.
   Note that in 20-2 the Board granted 343 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
 Apr
(hrs)
 May
(hrs)
 Jun
(hrs)
 Jul
(hrs)
 Total
(hrs)
18deg-18deg times
 248.20
 224.58
 199.88
 215.15
 887.82
Weather loss frac. 0.352
 0.345
 0.438
 0.489
Efficiency loss frac.
(align+PRs)
 0.07
 0.08
 0.08
 0.04
"Clear science" time
 149.58
 135.33
 103.35
 105.54
 493.80
Com/Eng/GTO time



280.00
"Allowed" hours
given to TACs
for science



213.80




 

Hours allowed for each TAC as determined Feb 5, 2021:
Partner
 Share
 Notes
 Total hours
allowed
Allocated
as of Apr 1
Goettingen
 0.00845
1.81
 1.80
Munich
 0.05904
12.62 12.60
PSU
 0.25678
 time trade: 54.90 - 4.75
 50.15
 49.00
UT
 0.67573
 time trade: 144.47 + 4.75
-20h TESLA allocation per
   HET Board 22-Feb 2021
 129.22
 129.20

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 Apr 2021