HET Mid-Trimester Report
First Period of 2004
December 1 - January 2

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

• LRS: LRS was run with G2 for the first days of the period we switched to G3 in order to catch targets at the beginning of the night.

• SAMS and MARS: SAMS and MARS were run during the entire period. Although SAMS runs poorly in our most extreeme cold nights.

• HRS: During two MRS IC nights in this period the HRS cryotiger lost its vacuum and only LRS was available.

• MRS: The MRS CCD has been shipped away and may return late in this period.

• Instrument Commissioning: During this period there has been six nights dedicated to MRS blind offset and multi object IC.

• Engineering: There has been 2 nights of Engineering so far this period.

The following image quality statistics were taken from the statistics recorded for science operations in the night report.

For comparison here is the image quality for the same period of 2002

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
December	0.715	10.94	0.24	0.45	0.26	0.03	0.13	0.03	0.11

The last column is new and accounts for all of the lost or not used minutes. Some of this time is accounting errors and some is time not charged to any program due to operations inefficiency.

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
December	0.39	0.19	0.29	0.10	0.03

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
313	66.0	A - Acceptable
31	8.0	B - Acceptable but Border line conditions
2	0.3	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
Number of Times	Shutter Open (Hours)	Type
0	0.0	I - Targets observed under otherwise idle conditions
9	1.3	E - Rejected by RA for Equipment Failure
12	2.2	H - Rejected for Human failure
38	6.4	W - Rejected by RA for Weather
7	1.2	P - Rejected by PI and confirmed by RA
1	0.3	N - Rejected due to unknown cause

So this is a total of 11.4 hours of uncharged spectra with an additional possible 8.0 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 actual overhead while the average overhead per requested visit is the actual overhead per visit while the overhead per Requested is the charged overhead per completed requested visit (not every actual visits completes 100% of a requested visit).

Instrument	Avg Overhead per Actual Visit(min)	Avg Overhead per Requested Visit(min)	Median Overhead per Requested Visit(min)	Avg Exposure (sec)	Median Exposure (sec)	Max Exposure (sec)	Avg Visit (sec)	Median Visit (sec)	Max Visit (sec)
LRS	11.7	20.4	18.9	1461.2	1800	3000	2131.2	1800	3600
HRS	10.4	10.8	10.0	771.2	900	3100	981.6	900	9420
MRS	0.0	0.0	0.0	0.0	0	0	0.0	0	0

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

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	6.000 (4%)	19.370 (14%)	28.200 (21%)	25.300 (19%)	56.000 (42%)
UT	21.200 (12%)	36.500 (21%)	61.500 (35%)	56.000 (32%)	0.000 (0%)
Stanford	0.000	0.000 (0%)	0.000 (0%)	0.000 (0%)	0.000(0%)
Munich	0.000 (0%)	19.000 (79%)	5.000 (21%)	0.000 (0%)	0.000 (0%)
Goetting	0.000 (0%)	2.300 (19%)	10.000 (81%)	0.000 (0%)	0.000 (0%)
NOAO	0.000	4.000 (14%)	18.600 (65%)	6.000(21%)	0.000
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	18.041	24.6
UT	49.884	68.1
Stanford	0.333	0.5
Munich	3.028	4.1
Goetting	2.000	2.7
NOAO	2.703	--
SALT	0.000	--
DDT	0.000	--

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	-TOTAL TO DATE-	-% TO DATE-
PSU	25.64	22.8	753.1	28.7
UT	79.28	70.6	1512.1	57.7
Stanford	0.90	0.8	188.6	7.2
Munich	4.09	3.6	69.8	2.7
Goetting	2.42	2.2	97.0	3.7
NOAO	N/A	--	--	--
SALT	0.00	--	--	--
DDT	0.00	--	--	--

The original "TOTAL TO DATE" was found to be in error on Dec. 11 2003; it did not include the overhead time. The values given here in red are the corrected totals.
Total to Date starting from Oct 1999. Priority weighting began in the 2003-2 period.