HET End-Trimester Report
  Second Period of 2024
  April 1 - July 31

• Facility Status
• Observing Statistics
• Observing Programs Status
• Institution Status

• Special Note:  Update to HET Publication Policy:
  
• All users of HET data should take note of the update to HET Publication Policy, as adopted by the HET Board of Directors.
• This document can be found at this link: 

  https://hydra.as.utexas.edu/?a=help&h=61

• LRS2:
•  Successful controler swaps on July 22, 2024.
  

• VIRUS:
• Mostly normal operations with steady number of units online as only minor maintenance and upgrades continue (usually 76-77 units working well)

• HPF:
• HPF was in a stuck exposure state for one night (2024-07-08 UT, civil night of July 7th civil). The detector was restarted shortly after the state was discovered but we lost high-precision for HPF that night.
  

The following tables give a break down of all attempted science visits as well as the category that each falls into.

Charged exposures
Number of Times	Shutter Open (Hours)	Type
3733	528.75	A - Acceptable
138	19.28	B - Acceptable but Border line conditions
661	144.28	4 - Priority 4 visits (does not include 1/2 charge)
1	0.22	Q - charged but PI error
0	0.00	C - Acceptable by RA but PI rejects

Uncharged exposures caught by RA
Number of Times	Shutter Open (Hours)	Type
1	0.17	N - Rejected due to unknown cause
5	1.53	E - Rejected for Equipment Failure
247	53.40	W - Rejected for Weather
7	2.18	H - Rejected for Human Errors

Uncharged exposures caught by PI
Number of Times	Shutter Open (Hours)	Type
0	0.00	P - Rejected for weather
0	0.00	F - Rejected for Equipment Failure
0	0.00	T - Rejected for poor track choice
0	0.00	X - Rejected for Human Errors

Acceptable but Uncharged exposures
Number of Times	Shutter Open (Hours)	Type
0	0.00	I - Targets observed under otherwise idle conditions

The following setup statistics include slew, acquisition, and starting data collection script. The table below gives the average setup time for each instrument PER ACTUAL VISIT and the average and maximum COMPLETED charged science exposures and visits.

The "Exposure" is defined by when the (CCD) shutter opens and closes. A "Visit" is the requested total CCD shutter open time during a track and might be made up of several "Exposures". "Visit" as defined here contains no overhead. To calculate one type of observing efficiency metric one might divide the "Visit" by the sum of "Visit" + "Overhead".

The average setup per visit is calculated from acceptable priority 0-3 (not borderline) science targets. This number reflects how quickly we can move from object to object on average for each instrument, however, this statistic tends to weight the setup for programs with large number of targets.

The average overhead percentage is calculated for each instrument and shows how much of that instrument's total time on sky (overhead+exposure) was overhead. NB: LRS2 has the smallest overhead %, but typical LRS2 observations use much longer exposures than VIRUS, even though VIRUS has a faster average setup time.

Instrument	Avg Setup per Visit (min)	Total time exposed (hrs)	Overhead %
VIRUS	4.07	132.33	25.04%
LRS2	6.13	36.85	35.14%
HPF	7.03	198.55	30.56%

The setup statistics can be shortened by multiple setups (each one counted as a separate visit) while on the same target such as moving from LRS2-B to LRS2-R.

This calculation is temporarily unavailable for the 24-2 trimester. It may be able to be added retroactively in the future.

Overall time charged: 9.22h (eng) + 457.54h (sci/GTO) = 466.76h
Total estimated science time available (in TAC time determinations): 490.78h
   Conclusion: the weather was consistent with past 2nd trimesters, and the estimate was only 4.9% too high. This was a typical trimester.

Observing Programs Status

In the table below we show the breakdown of the charged time for each program submitted. The "Total %" is the completion of the entire TAC time including P4 time. The last four columns show the completion rate for targets submitted in each priority bin. This completion rate is the greater of the targets completed percentage and the TAC allocation completed percentage in each priority bin.

Program Completion Rates (sci only, removing NT/HC/SI/TD/DT)
Priority	Average Completion	Median Completion	Sci. hrs alloc. (UT+PSU+M+G)	Sci. hrs obs. (%)
P0	89%	100%	29.83	29.32 (97.9%)
P1	97%	100%	59.08	58.98 (99.8%)
P2	87%	100%	100.10	89.03 (88.9%)
P3	91%	100%	85.35	88.98 (104.2%)

Institution Status

Below we show how the TAC allocations were determined.

This is how each institution had allocated its time by priority:

Time Allocation by Institution (hours)
Institution	Priority 0	Priority 1	Priority 2	Priority 3	Priority 4	Total P0-P3	Frac. of allowed
Goettingen	1.70	2.40	4.20	4.20	0.00	12.50	100.0%
Munich	2.60	4.00	6.50	6.50	0.00	19.60	100.0%
PSU	10.02	13.28	23.80	23.80	14.08	70.90	100.0%
UT	25.71	39.40	65.60	50.85	71.25	181.56	98.7%
Other allocations
GTO	190.00	-	-	-	-	190.00

Notes:
1) Allocations in joint programs are reported separately for each partner here

The following is a summary of the total charged time for each institution based on our htopx data base (for shutter open) and night reports (for overhead). It includes shutter open time (weighting priority four by half) and overhead (no overhead for priority 4 observations). Recently this calculation was re-derived using a deficit/surplus model. For each financial year the share paid is compared with the time charged - any discrepancy between the two is tracked and carried forward as a deficit. A negative deficit means more time was observed for that partner than their financial share; a positive deficit means less time was observed. These deficits are calculated in each previous financial year; the table below also includes a preliminary total for the current financial year so far.

Below are the summaries of the Guaranteed Time Observations (GTO) programs granted by the Board:

GTO and Special Time Charged by Project (hours)
Project	Allocated in 24-1	Allocated total to date including 24-1	Charged in 24-1	Charged total to date including 24-1
HETDEX (HETYY-P-100)	190.0	3629.0	147.8	+2799.5

(Totals to date start from the 11-2 period)

*LRS2 GTO was completed in the 23-1 trimester; HPF GTO was completed in the 23-2 trimester; LIGHETR GTO time stopped after the 23-1 trimester

SJ, updated 27 Apr 2024 with complete trimester information.