HET End-Trimester Report
Third Period of 2017
August 1 - November 30

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
2057	236.52	A - Acceptable
22	5.80	B - Acceptable but Border line conditions
252	69.60	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
7	1.18	N - Rejected due to unknown cause
78	14.47	E - Rejected for Equipment Failure
65	14.80	W - Rejected for Weather
49	13.35	H - Rejected for Human failure

Uncharged exposures caught by PI
Number of Times	Shutter Open (Hours)	Type
0	0.0	P - Rejected for weather
0	0.0	F - Rejected for Equipment Failure
0	0.0	T - Rejected for poor track choice
0	0.0	X - Rejected for Human failure

Acceptable but Uncharged exposures
Number of Times	Shutter Open (Hours)	Type
15	3.83	I - Targets observed under otherwise idle conditions

So this is a total of 47.63 hours of uncharged spectra with an additional possible 5.8 hours of spectra that may be rejected.

The following overhead statistics include slew, setup, and readout. The table below gives the average setup time for each instrument PER ACTUAL 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) 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.

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 take the total charged overhead and divide by the total number of completed 0-3 visits. 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.

Instrument	Avg Overhead per Visit(min)	Avg Completed Exposure (sec)	Max Completed Exposure (sec)	Avg Completed Visit (sec)	Max Completed Visit (sec)
LRS2	6.8	651.8	2520	887.4	3600
VIRUS	7.9	360.0	360	1080	1080

The overhead 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. 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.