MDM Trouble Report for 2006 Oct 20

Telescope: 2.4m
Observer(s): Prieto & Watson (OSU)
Instrument: CCDS

Problem(s) Encountered:
We started the night with the new 50g/mm grating.  When 
observing standard stars with an 8 arcsecond slit, we noticed 
that longer exposures were needed to reach the same counts as 
achieved with the 150g/mm grating (2 arcsecond slit).  Strange! 
We integrated on a faint and then a relatively bright SNe.  In 
the faint one, there was no signal.  In the bright one, there 
was a very faint signal.  These SNe would have been easily visible with 
the 150g/mm, so they certainly should have been visible with
the lower dispersion grating.  We're stumped on what's going on.
We computed the count rate (electrons/s/Angstrom) for the 
grating using bd284211 and found that the curve is lower than 
the curves for all the other gratings shown in the CCDS manual.
There is also a funny shape to it 
(see www.astronomy.ohio-state.edu/~prieto/50gmm_rate.ps).
We moved onto imaging and later switched back to the 150g/mm,
without solving the 50g/mm problem.

We initialized the 150g/mm using the procedure Rick sent today
for testing the 50g/mm grating (startup, greset, gratzero, grsetup).  We
then centered on 5700 Angstroms (tilt 56061), where we saw the 
zeroth order on the blue side of the image.  We centered on
9000 Angstroms and found that this corresponded to a real 
central wavelength of 5185 Angstroms.  We recentered and then
went to center 5700 (tilt 54032).  For reference, yesterday's 
central wavelength was 6000 Angstroms (tilt 55901).

One more thing, the headers shows the Retrocam mirror as being 
in when it is not. 

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Submitted on 2006 Oct 21 [6:25:23]