HET End-Trimester Report
Third Period of 2003
August 4 - November 30

This report is composed of five sections:
Instrument Status

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


Observing Statistics

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 tenth columns give how the remaining science time (after removing weather losses) was spent. 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 with Shutter Open E:Fraction of Actual Science Time as Overhead F:Fraction of Actual Science Time Lost due to Alignment G:Fraction of Actual Science Time Lost due to Calibrations H:Fraction of Actual Science Time Lost due to Problems I:Fraction of Actual Science Time Not accounted for or Lost
August 0.063 7.87 0.40 0.45 0.33 0.00 0.02 0.14 0.05
September 0.004 8.94 0.00 0.52 0.31 0.17 0.00 0.00 0.00
October 0.591 9.89 0.24 0.45 0.24 0.07 0.06 0.09 0.09
November 0.790 10.61 0.22 0.49 0.28 0.06 0.04 0.06 0.08

The last column is new and acounts 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
August 0.19 0.00 0.63 0.19 0.00
September 0.43 0.00 0.13 0.00 0.10
October 0.48 0.07 0.19 0.07 0.19
November 0.31 0.24 0.28 0.07 0.07

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 TimesShutter Open (Hours)Type
474107.0 A - Acceptable
317.7 B - Acceptable but Border line conditions
15124.5 4 - Priority 4 visits (does not include 1/2 charge)
41.4 Q - charged but PI error
00.0 C - Acceptable by RA but PI rejects

Uncharged exposures
Number of TimesShutter Open (Hours)Type
192.9 I - Targets observed under otherwise idle conditions
121.9 E - Rejected by RA for Equipment Failure
171.8 H - Rejected for Human failure
8112.8 W - Rejected by RA for Weather
00.0 P - Rejected by PI and confirmed by RA
30.9 N - Rejected due to unknown cause

So this is a total of 20.3 hours of uncharged spectra with an additional possible 7.7 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 charged 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. NOTE: As of 2003-3 the overhead for HRS and MRS attempted visits is capped at 15 minutes.

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".

Instrument Avg Overhead per Actual Visit(min)Avg Charged Overhead per Requested Visit(min) Median Charged Overhead per Requested Visit (min) Avg Exposure (sec)Median Exposure (sec)Max Exposure (sec)Avg Visit (sec)Median Visit (sec)Max Visit (sec)
LRS 14.218.3 17.5 792.61200 1800 1518.513503600
HRS 10.6 13.310.9 714.5 900 2105 1003.29004800
MRS 12.6 10.410.4 1200 600 1800 12006001800

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 seperate 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.

The following is a histogram of the final HET queue visits. The last days of the period there were significant holes.


Observing Programs Status

The following links give the summary for each institution and its programs. The resulting table will give (for each program) the total number of targets in the queue and the number completed, the CCD shutter open hours, average overhead for that program, and the TAC allocated time. This usually will be the best metric for judging completeness but there are times when a PI will tell us that a target is "done" before the total number of visits is complete.