Lucifer February Com Night 1, February 7 2009
Observers: N.Ageorges, W.Seifert, V.Knierem (LUCIFER), DThompson
Telescope Operator: DGonzalez-Huerta
SW Support: CBiddick until 22:00, on call afterward
Telescope Support: JRousseau
Details (Times in MST):
18:20 Open Dome, T=-0.9 degC. DewPt
=-11.2 degC, Wind (LBTO) 10 m/sec.
18:52 Found MSC running on 107 with GCSL. Chris said it should be OK.
18:55 GCSL saying "Lost connection" on guider images, restarting GCSL only.
18:57 Sending preset again, ACTIVE mode.
GCS Log: I saw the timing line in the log, so I looked into how long the noted parts took while guiding was running between 19:00:03 and 19:14:46. All exposures were 2000ms during this period, and there were 158 guider images. There should have been no acquisition images taken during this time, only guider images (preset sent at 18:57). I've roundeded the numbers from the syslog for this table:
# nrows mean stddev median min max max-1
158 0.21463 0.0487 0.23165 0.0656 0.3392 0.3392 effective Guide Rate (Hz)
158 0.21479 0.0488 0.23182 0.0656 0.3396 0.3396 max. Guide Rate (Hz)
158 0.25021 0.2068 0.21716 0.1109 2.6448 0.7619 time4PCSxfer (seconds)
158 2.44481 0.6232 2.16970 2.1455 6.8296 5.5826 time4ImgAcq (seconds)
158 2.31941 1.1683 1.88923 0.6647 8.8392 6.7199 processing overhead (seconds)
So it seems that the biggest sources of overheads are coming from delays in completing the time4ImgAcq (presumably exposure time plus transfer time) and processing overheads (which varied up to 8.8 seconds!). At least in this relatively small sample. We must understand why the processing is so slow here on the mountain. If we can cut out these very large processing overheads we will significantly speed up guiding.
From 19:00 to 20:00 the seeing on the guider was around 1 arcsec FWHM. It was windy, and gusty. The guiding ran at 140mas rms with max offsets from the hotspot of about a third of an arcsecond. The WFS was mostly below 400nm (vent doors are closed).
Closed for high winds at 20:15
Gusts over 20m/s. Still closed at 22:00.
HH:MM Close dome T=?degC, D=?degC, wind (LBTO) ? m/sec.
- 15 Jan 2009