HET Beginning-Trimester Report
Third Period of 2004
August 1 - November 30

This report is composed of five sections:
Facility Status

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


Expected Observing Conditions

NOTE: We are now using FWHM which is measured off both the LRS "pre" images and the FIF bent prime guider.

Here is a histogram from the last period.

For comparison here is the image quality for the period last year.

We expect to do a few tenths better than last year; about as good as the previous period.

We expect to have a similar overhead to last period. 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 REQUESTED VISIT AND PER ACTUAL VISIT. The table also gives the average and maximum PROPOSED science exposures and visit lengths.

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 unrealistically 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 13.2 (from last period)19.5 (from last period) 677.1 600 2400 1340.890012600
HRS 9.3 (from last period)10.6 (from last period) 699.1 780 1800 826.47803000
MRS 10.6 (from last period)8.6 (from last period) nonenone nonenonenonenone

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

NOTE: STARTING IN 2004-3 THE SETUP TIME FOR AN ATTEMPTED LRS TARGET WILL 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.


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.


Institution Status

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

Time Allocation by Institution (hours)
Institution Priority 0 Priority 1 Priority 2Priority 3 Priority 4
PSU 7.000 (6%) 25.220 (21%) 25.480 (21%) 15.000 (12%) 49.960 (41%)
UT 8.000 (4%) 64.500 (33%) 47.000 (24%) 48.000 (25%) 28.000 (14%)
Stanford 4.000 (11%) 6.000 (17%) 10.000 (29%) 10.000 (29%) 5.000(14%)
Munich 0.000 (0%) 5.000 (50%) 0.000 (0%) 5.000 (50%) 0.000 (0%)
Goetting 0.000 (0%) 1.000 (8%) 12.000 (92%) 0.000 (20%) 0.000 (0%)
NOAO 0.000 0.000 0.000 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

UT, Munich and Goetting have under allocated time to their institutional share.


Future Priorities

The following are the high priority targets for the rest of the period for each institution:

UT04-3
RankProgram Constraints
1 UT03-3-011 Many targets LRS g2, EE50 < 2.0, Vsky > 21.0
2 UT03-3-001 PG2103 and PG2132 HRS, EE50 < 2.0, Vsky > 20.8
3 UT03-3-004 RRLyrae HRS synoptic, EE50 < 2.5, Vsky > 17.0

PSU04-3
RankProgramConstraints
1 PSU04-3-009 CSO_643, 3C_303, 3C_332 LRS G3, EE50 < 2.0, Vsky > 20.6
2 PSU04-3-005 J1540-0205 J1605-0109 J1718+5933 LRS G3 EE50 < 2.2, Vsky > 20.4 near twilight now
3 PSU04-3-006 VVSer V1685Cyg HRS synoptic, EE50 < 2.5, Vsky > 14.0

STA04-3
RankProgramConstraints
1 STA04-3-003 J2102+6015 LRS EE50 < 2.0, Vsky > 20.0
2 STA04-3-003 J1500+4751 LRS EE50 < 2.0, Vsky > 20.0

M04-3
RankProgramConstraints
1 M04-3-001 S2F5 LRS g1 mos EE50 < 2.0, Vsky > 21.5, observable in mid Sept

G04-3
RankProgramConstraints
1 G04-3-003 V396Her LRS EE50 < 4.0, Vsky > 18.0
2 G04-3-003 E1821+643 LRS g2 EE50 < 4.0, Vsky > 18.0



The following is a histogram of the current HET queue visits for the rest of the period. A line has been drawn at the expected number of hour long visits that we hope to achieve in each hour bin.

The following histogram shows some of the extrema in observing conditions: good seeing dark time, bright time and bad seeing dark time. A line has been drawn at the expected number of hour long visits that we hope to achieve in each hour bin.

The following histogram shows the bright time priority 0-3 contribution from each partner. The dashed line is a rough estimate of the number of hour long visits one could complete during the remainder of the period given each partner's institutional share.

The following histogram shows the dark time priority 0-3 contribution from each partner. The dashed line is a rough estimate of the number of hour long visits one could complete during the remainder of the period given each partner's institutional share.

The following histogram shows the use of LRS_g2 vs. LRS_g3 for priority 0-3 programs in this period.

From the above plots I have determined that:

  • Future IC and Engineering:
    The current plan is to do 3% IC, 7% Engineering and 90% Science during the remainder of this trimester. Much of the engineering will be during bright time.

    TAC Response