MDM Observatory 2.4m Telescope Observer's Report for 2002 Jun 14

Observer(s): John Thorstensen
Institution(s): Dartmouth

Instrument: Modspec

Worked for 8 hours (all night)
Conditions were Photometric most of the night.
No equipment or software problems were encountered.

Seeing and Weather:
   Beg: Seeing 1 arcsec, Clear, Winds Light & Variable
   Mid: Seeing 1 arcsec, Clear, Winds Light & Variable
   End: Seeing 0.8 arcsec, Clear, Winds Calm

Observing Summary:

Time-series spectroscopy of cataclysmic variables, and a test of
a Marconi L3vision CCD camera in the guide port.  The camera 
worked well on bright stars in twilight, but to show anything 
even moderately faint the gain had to be all the way up.  This
brought out a large number of hot pixels and more importantly
a great deal of noise, presumably because the chip is cooled
to only 5 degrees below ambient, and it was warm tonight.  I 
found I could not work with this setup as is and swapped it out
with the aid of Don Terndrup (who was on the 1.3m).  The old
guide camera was installed successfully and worked normally.
The swap took about 40-50 minutes during the night, since we
worked slowly and carefully.

The lesson from this is that the guide camera sees a very 
dim signal, and requires a great deal of gain.  Any  barefoot 
CCD is going to have to be aggressively cooled to work.  
Marconi has this as an option on their cameras, and we may 
still want to test one of these before we give up on the 
idea.  

Weather was very good all night, the seeing was mostly good 
to excellent.  In the morning twilight I realized that the slit
had been inadvertently opened up to about 2 arcsec rather than
the normal 1 arcsec during the installation of the test camera 
-- while we were testing lenses with the new camera I'd noticed
that the slit looked too large, but I'd attributed that to the
new camera.  I'm hoping that this won't affect the radial 
velocities too much, but the seeing was good which exacerbates 
the velocity error from a too-large slit.  Long ago a radial
velocity spectroscopist famously closed up at Mt. Wilson when
the seeing became too *good* for radial velocity work!

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Submitted on 2002 Jun 15 [5:26:01]