HET Mid-Trimester Report
Third Period of 2002
August 1 - September 30

In this section we will discuss the status of each instrument and any limitation to configurations that occurred during the period.

• LRS: No new HgCdZn lamps have been found to be purchased. After the Hex-bolt problem and the PFIP was brought down the LRS cryotiger fittings were broken. Repairing and priming the cryotiger lines kept the LRS down 2 days beyond the days where PFIP was offline.

• SAMS and MARS: The MARS pellical was broken on 29 Aug and replaced the next day.

• HRS: During one night in this period the HRS cryotiger lost the vacuum and half a night was lost including one priority zero synoptic target. The HRS cryotiger was repumped and ready for science the next night. The main limitation for HRS science is the cross-dispenser failures to move from 316g to 600g without moving it by hand.

• Instrument Commissioning: During this period there were 3 nights scheduled for LRS IC, of which 3 were used. During this period there were 8 nights scheduled for MRS IC, of which 2 were used. During this period there were 0 nights scheduled for HRS IC.

• Engineering: During this period there were 5 nights of engineering scheduled: 4 nights of SAMS engineering and 1 night of MARS engineering. On a number of nights during this period small engineering tests were conducted along side science observations or during cloudy weather.

The image quality of the HET has improved a bit over last year.

For comparison here is the image quality for the same period of 2001

Here are the DIMM values reported in the night report. NOTE: There are a large number of nights when the DIMM was not operated; there is also times when the DIMM failed due to wind shake or extremely bad seeing.

Month by Month Summary

Month	A:Fraction of the Time that was Possible Science	B:Average Night Length	C:Fraction of Time Lost due to Weather	D:Fraction of Science Time Lost due to Alignment	E:Fraction of Science Time Lost due to Calibrations	F:Fraction of Science Time Lost due to Problems
August	0.884	7:52	0.38	0.24	0.02	0.09
September	0.843	8:56	0.27	0.13	0.04	0.53

The total number of 386 acceptable shutter open science exposures during this period for a total of 55.3 hours. There were a number of rejected spectra obtained during this period as well the following table give the total number of rejected spectra and the category that each falls into.

Number of Times	Time Lost (Hours)	Type
11	1.9	E - Rejected by RA for Equipment Failure
2	0.5	H - Rejected by RA for Human failure
18	3.4	W - Rejected by RA for Weather
1	0.6	P - Rejected by PI and confirmed by RA
0	0.0	Q - Rejected due to error in the queue
0	0.0	C - Acceptable by RA but PI rejects
0	0.0	N - Acceptable but NOT charged due to weather or hole in queue
26	3.2	B - Acceptable but Border line conditions

So this is a total of 6.4 hours of rejected spectra with an additional possible 3.2 hours of spectra that may be rejected.

This was the first period that we have kept accurate statistics on the overhead for each science visit. This overhead includes slew, setup, and readout (if there are multiple exposures per visit). In the summary page for each program the average setup time is calculated. The table below gives the average setup time for each instrument and the average and maximum science exposures.

Instrument	Avg Overhead (min)	Avg Exposure (sec)	Max Exposure (sec)
LRS	12.4	829.8	2222
HRS	11.5	833.0	1800

The following is a summary of the Acceptable CCD shutter time for each institution based on our htopx data base. It does not include any overhead.

Time Usage by Institution (hours)
-TOTAL-	Used	% of All
PSU	11.236	15.4
UT	51.664	72.9
Stanford	6.500	8.9
Munich	0.000	0.0
Goetting	2.000	2.7
NOAO	3.383	--
SALT	0.000	--
DDT	0.000	--

This is how each institution has allocated its time by priority.

Time Allocation by Institution (hours)
Institution	Priority 0	Priority 1	Priority 2	Priority 3	Priority 4
PSU	3.000 (3%)	31.500 (30%)	35.000 (34%)	35.000 (34%)	0.000
UT	19.200 (10%)	51.000 (26%)	101.500 (51%)	27.000 (14%)	0.000
Stanford	0.000	5.000 (24%)	12.000 (57%)	3.000 (14%)	1.000(5%)
Munich	0.000	4.083 (41%)	2.917 (29%)	3.000 (30%)	0.000
Goetting	0.000	0.000	0.000	0.000	0.000
NOAO	0.000	53.700 (56%)	42.600 (44%)	0.000	0.000
SALT	0.000	0.000	0.000	0.000	0.000
DDT	0.000	0.000	0.000	0.000	0.000