From: Greg Aldering (aldering@panisse.lbl.gov)
Date: Thu Nov 07 2002 - 18:03:44 PST
At Keck they have begun archiving the guider FWHM values into a database.
I looked at the trends from last night, and they track our other sources
of information, namely the our own measurements from the guider, and the
trends at Gemini and Subaru.
Roughly speaking, the seeing was quite variable. Although the webpage warns
not to trust the FWHM values as seeing measurements, here is what the data show:
5:00 - 7:00 UT stable at 0.9 (pointed to 98eq field)
7:00 - 7:40 UT highly variable 0.9 - 1.8 (pointed at SXDF)
7:40 - 8:30 UT fairly stable at around 1 (pointed at SXDF)
8:30 - 9:10 UT another period of variable seeing 1 - 1.2 (pointed at SXDF)
9:10 - 12:20 UT fairly stable at 0.9 (pointed at SXDF)
12:20 - 13:00 UT grossly unstable, ranging up to 2.5 (pointed at SXDF)
13:00 - 14:20 UT slow degradation as SXDF set 1.1 - 1.4 (pointed at SXDF)
14:20 - 16:00 UT fairly stable at around 1 (other targets)
Based on our measurements and the results of the Keck focus and align procedures,
I would estimage the the above values are too large by about a factor of 1.5.
This could just be a scale error, since someone has converted from FWHM in pixels
to "seeing"
- Greg
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