HET End-Trimester Report
Second Period of 2022
April 1 - July 31

• Facility Status
• Observing Statistics
• Observing Programs Status
• Institution Status
• TAC Response

• VIRUS:
• Mostly normal operations, except some small variations in the exact number of units online as maintenance and upgrades continue (usually at least 75-76 units alive most nights)
  

• HPF:
• The HPF vacuum-jacketed LN2 lines were pumped and low-precision targets only were observed on a few nights.
  
• HPF fiber scrambler motor was replaced 7 Apr 2022, during the afternoon when it stopped turning the drive belt
  
• May 20 to June 14 2022, HPF offline for engineering work
• Electronics work on the detector to address rising pedestal level
• Dewar work to recharge the LN2 getters
• Updates to replace vacuum sensors and fittings on vacuum jacketed lines for easier pumping
• Prepare and test spare HPF server
  
• Pedestal level has stabilized after this work! Problem was in the Macie card
• June 15 2022 low-precision HPF observations resumed (chemical abundances, etc)
• August 1 2022 high-precision HPF observations resumed (at start of 22-3 trimester)
  

• Facility:
• Nearly-normal operations have returned with very few COVID-19 adjustments still in place.
• Wavefront Sensor 1 (WFS1) has remained offline since October 17th due to a mechanical/electrical issue. As in the previous trimester we have relied exclusively on WFS2, which likely causes a reduction in our delivered image quality until WFS1 can be returned to service.
• For several weeks our Guider 1 probe was unavailable due to a mechanical/electrical problem with its drive system. It was later restored with a limited range of motion.
  

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
3158	434.58	A - Acceptable
65	15.65	B - Acceptable but Border line conditions
423	102.42	4 - Priority 4 visits (does not include 1/2 charge)
0	0.0	Q - charged but PI error
0	0.0	C - Acceptable by RA but PI rejects

Uncharged exposures caught by RA
Number of Times	Shutter Open (Hours)	Type
2	0.82	N - Rejected due to unknown cause
49	6.32	E - Rejected for Equipment Failure
238	52.72	W - Rejected for Weather
19	5.88	H - Rejected for Human Errors

Uncharged exposures caught by PI
Number of Times	Shutter Open (Hours)	Type
2	0.62	P - Rejected for weather
0	0.00	F - Rejected for Equipment Failure
0	0.00	T - Rejected for poor track choice
2	0.67	X - Rejected for Human failure

Acceptable but Uncharged exposures
Number of Times	Shutter Open (Hours)	Type
0	0.0	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	4.28	168.57	24.41%
LRS2	5.66	77.45	29.47%
HPF	6.57	133.40	33.20%

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.

Within the times when HETDEX shots were available on-sky for >20 minutes, the following percentages summarize how the time was used:

• 39.7% HETDEX (30.7% exposures, 8.97% overhead)
• 25.2% weather losses
  
• 27.1% sci/GTO/eng/comm (1.66% engineering/commissioning, 18.6% science/GTO exposures, 6.78% science/GTO overheads)
• 55.2% at P0 (60.4h)
• 19.5% at P1 (21.3h)
• 13.9% at P2 (15.2h)
• 7.3% at P3 (8.0h)
• 4.1% at P4 (4.6h)
  
• 4.8% mirror alignment
• 3.2% problems

Overall time charged: 253.2 (eng/comm/GTO) + 254.3h (sci) = 507.5h
Total estimated science time available (in TAC time determinations): 480.6h
   Conclusion: weather in 22-2 was better than expectations by ~27 hours.
     This is our best 2nd trimester in 5 years. In previous years we saw 390.3; 478.9; 469.2; 459.8 hours charged.

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/TD)
Priority	Average Completion	Median Completion
P0	92.8%*	100%
P1	98.9%	100%
P2	99.8%	100%
P3	84.6%	100%

*one PSU time domain program never observed any of their Pr0 time allocation this trimester

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	0.80	2.20	3.10	3.10	-	9.20	99.8%
Munich	1.40	4.20	5.60	3.60	-	14.80	88.0%
PSU	4.00	12.29	17.90	17.90	20.16	52.09	97.1%
UT	12.10	39.10	51.90	48.70	113.00	151.80	104.0%
Other allocations
GTO	195.00	10.00	11.00	2.00	-	218.00	100.0%

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 22-2	Allocated total to date including 22-2	Charged in 22-2	Charged total to date including 22-2
HETDEX (HETYY-P-100)	190.0	2704.0	189.9	2071.4
LRS2 GTO (HETYY-P-2XX)	8.0	199.9	8.1	124.5
HPF GTO (HETYY-P-3XX)	20.0	240.4	20.7	241.3
GW (HETYY-P-400)	0.0	70.0	0.0	12.4

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

Significant time losses to problems during the trimester

The following are our most significant problems in terms of their time lost, keeping those with >60min lost:

SJ, 9 Aug 2022