HET Mid-Trimester Report
Third Period of 2005
August 1 - October 31

The following FWHM image quality statistics were taken from the LRS pre-imaging statistics and FIF acquisition guider for science operations in the night report. These are true FWHM measures using the same software on both the FIF acquisition guider and the LRS pre-images.

For comparison here is the LRS pre-imaging quality for the same period of 2004

Here are the DIMM values reported in the night report.

Month by Month Summary

The following table gives the observing statistics for each month. The second column gives the fraction of the month that was spent attempting science (as opposed to engineering or instrument commissioning). Science time is defined to begin at 18 degree twilight or the first science target. Science time is defined to end at 18 degree twilight or the last science target. The fourth column gives the fraction of the possible science time (A) lost due to weather. The fifth through seventh columns give the amount of remaining science time (after removing weather losses) not spent attempting science targets. Please note that the first stack of the night often occurs before 18 degree twilight.

Month	A:Fraction of the Time that was Possible Science	B:Average Night Length	C:Fraction of Total Science Time Lost due to Weather	D:Fraction of Actual Science Time Spent with Shutter Open	D:Fraction of Actual Science Time Lost due to Overhead	E:Fraction of Actual Science Time Lost due to Calibrations	D:Fraction of Actual Science Time Lost due to Alignment	F:Fraction of Actual Science Time Lost due to Problems	Fraction of Actual Science Time Not accounted for or Lost
August	0.961	7.91	0.39	0.53	0.39	0.01	0.04	0.04	-0.01
September	0.975	8.98	0.55	0.50	0.32	0.01	0.05	0.10	0.02
October	0.981	9.92	0.53	0.53	0.37	0.01	0.05	0.03	0.01

The last column accounts for all of the minutes lost or not used. Some of this time is accounting errors, some is time not charged to any program due to operations inefficiency and some is due to uncharged overheads from observations that did not result in a fits file.

Details on Nightly cloud cover based on the TO's observations of the sky reported 3 times a night in the night report.:

Month	Fraction of the Nights that were Clear	Fraction of the Nights that were Mostly Clear	Fraction of the Nights that were Partly Cloudy	Fraction of the Nights that were Mostly Cloudy	Fraction of the Nights that were Cloudy
August	0.07	0.16	0.36	0.19	0.16
September	0.27	0.27	0.30	0.07	0.10
October	0.32	0.16	0.19	0.03	0.29

Please note that the HET could be closed due to humidity, smoke or high dust count and still have a "Clear" statistic in the night report.

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

Charged exposures
Number of Times	Shutter Open (Hours)	Type
791	128.4	A - Acceptable
18	5.5	B - Acceptable but Border line conditions
271	56.7	4 - Priority 4 visits (does not include 1/2 charge)
2	0.3	Q - charged but PI error
0	0.0	C - Acceptable by RA but PI rejects

Uncharged exposures
Number of Times	Shutter Open (Hours)	Type
7	1.2	I - Targets observed under otherwise idle conditions
9	1.4	E - Rejected by RA for Equipment Failure
19	4.8	H - Rejected for Human failure
20	4.4	W - Rejected by RA for Weather
10	3.0	P - Rejected by PI and confirmed by RA
2	0.8	N - Rejected due to unknown cause

So this is a total of 15.6 hours of uncharged spectra with an additional possible 5.5 hours of spectra that may be rejected.

The following overhead statistics include slew, setup, readout and refocus between exposures (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 PER VISIT and the average and maximum COMPLETED science exposures and visits.

The "Exposure" is defined by when the CCD 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 overhead per actual visit is the overhead for each acceptable priority 0-3 (not borderline, and with overheads > 4 minutes to avoid 2nd half of exposures with unrealisticly low overheads) science target. This number reflects how quickly we can move from object to object on average for each instrument, however, this statistic tends to weight the overhead for programs with large number of targets such as planet search programs.

The average overhead per requested visit is the total charged overhead per requested priority 0-3 visit averaged per program. To get this value we average the average overhead for each program as presented in the program status web pages. The average overhead per visit can be inflated by extra overhead charged for PI mistakes (such as bad finding charts or no targets found at sky detection limits) or for incomplete visits e.g. 2 visits of 1800s are done instead of 1 visit with a CRsplit of 2. The average overhead per visit can be deflated by the 15 minute cap applied to the HRS and MRS. This method tends to weight the overhead to programs with few targets and bad requested visit lengths, ie. very close to the track length.

Instrument	Avg Overhead per Actual Visit(min)	Avg Overhead per Requested Visit(min)	Avg Exposure (sec)	Median Exposure (sec)	Max Exposure (sec)	Avg Visit (sec)	Median Visit (sec)	Max Visit (sec)
LRS	17.9	16.7	813.1	900	1800	1543.4	1800	7200
HRS	9.4	10.4	641.4	740	1826	712.1	760	4020
MRS	12.3	11.0	839.0	600	2200	1146.0	840	2200

NOTE: AS OF 2003-3 THE SETUP TIME FOR AN ATTEMPTED MRS OR HRS TARGET IS CAPPED AT 15 MINUTES. AS OF 2004-3 THE SETUP TIME FOR AN ATTEMPTED LRS TARGET IS CAPPED AT 20 MINUTES.

The overhead statistics can be shortened by multiple setups (each one counted as a separate visit) while on the same target as is the case for planet search programs. The overhead statistics can be lengthened by having multiple tracks that add up to a single htopx visit as can happen for very long tracks where each attempt might only yield a half visit.

A way to improve the overhead accumulated for programs with long exposure times is to add double the above overhead to the requested visit length and make sure that time is shorter than the actual track length. This avoids the RA having to split requested visits between several different tracks.

During this period we have had some trouble with LRS setups which have turned out to be training issues.

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	11.170 (6%)	26.580 (15%)	34.660 (20%)	34.330 (20%)	67.750 (39%)
UT	14.500 (5%)	68.000 (22%)	79.500 (26%)	76.000 (24%)	65.000 (22%)
Stanford	5.000 (14%)	5.000 (14%)	10.000 (28%)	10.000 (28%)	5.000(14%)
Munich	0.000 (0%)	10.000 (29%)	14.000 (40%)	9.000 (26%)	2.000 (6%)
Goetting	0.000 (0%)	5.000 (26%)	8.000 (42%)	6.000 (32%)	0.000 (0%)
SALT	0.000	0.000	0.000	0.000	0.000
DDT	0.000	0.000	0.000	0.000	0.000

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. And does not weight based on any priority scheme (ie. priority 4 are counted at full cost).

CCD shutter Open by Institution (hours)
-TOTAL-	Used	% of All
PSU	76.974	43.7
UT	87.299	44.0
Stanford	30.667	7.1
Munich	2.975	2.2
Goetting	4.667	3.0
NOAO	17.790	--
SALT	0.000	--
DDT	0.000	--

NOTE: At the present time the Stanford lead SN project has not allocated any time to any of the partners so the entire allocation is currently charged to Stanford.

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.

Time Charged by Institution (hours)
-INST-	Used THIS PERIOD	% of All THIS PERIOD	- % ALLOCATION TO DATE-
PSU	84.3	30.1%	29.93%
UT	137.9	49.4%	54.41%
Stanford	43.7	15.7%	6.65%
Munich	5.1	1.8%	4.49%
Goetting	8.3	3.0%	4.50%
NOAO	N/A	--	--
SALT	0.00	--	--
DDT	0.00	--	--

Total to Date starting from Oct 1999. Priority weighting for P4 began in the 2003-2 period.

NOTE: At the present time the Stanford lead SN project has not allocated any time to any of the partners so the entire allocation is currently charged to Stanford.