MDM Observatory 2.4m Telescope Observing Report for 2014 Jan 30

Observer(s): Hainline, French
Institution(s): Dartmouth College

Instrument: OSMOS

Worked for 8 hours (first half of the night)
Conditions were Overcast most of the night.
Problems were encountered, see the separate trouble report for details.

Seeing and Weather:
   Beg: Seeing 1.0 arcsec, Cirrus, Winds Light & Variable
   Mid: Seeing 1.5 arcsec, Patchy Clouds, Winds Moderate
   End: Seeing 2.0 arcsec, Patchy Clouds, Winds Moderate

Observing Summary:

We were productive at the beginning of the night, even though we had the 
occasional cloud. 

When we took images of the whole field, the bottom right chip (south-west?) 
seemingly was covered by a diagonal shadow that blocked the light in the bottom
right corner of the chip. This was not caused by the guider, since it persisted even
when we sent the guide probe to the origin. This shadow was not seen on the
images from the last two nights. I don't think this caused issues with the spectra
we took, where the important information was on the other chips.

We observed two different objects for 1.5 hours each. However, a little
after midnight, we ran into another problem seemingly randomly. When we went
to an object at somewhat of a high airmass (1.3ish) and attempted to move the
guide probe to a star, it did not appear in the guide camera window. We tried to 
look at another star, but nothing. Stars would whiz by as we moved the probe,
and JSkyCalc24m was pointed to the correct field with the correct rotator angle
input, but we couldn't find a guide star. We sent the probe to the origin, and then
tried again, but still, we were not able to find a guide star. We sent the telescope to
a nearby bright star, and sent the probe to the origin, and then hunted for the 
bright star, finding that we had to input a dx: -864 and dy: 337 in order to get the
guide probe to find the central star, and then verified that these offsets would 
work when trying to find guide stars.

At this point, we went to SN2014J in M82, but found that clouds were rolling in,
and while we were able to place the supernova on the slit, the requested 3 minute
exposure had very low S/N. Also, guiding was spotty, as even the brightest guide
star (which we centered using the dx/dy offsets) would sometimes be lost. We took
one nice 15 minute spectrum of the supernova, but then the clouds were too
thick for us to observe it any more, and we had to park the telescope at zenith
and wait until conditions cleared.

After a while, as the wind was picking up, we decided to close the dome and watch
the skies, and at around 5:00, the clouds parted such that we opened the dome 
and mirror covers (the wind was given at around ~20 mph), and went to one final
target. We were surprised to find that the guider no longer required that offset,
and the shadow across the portion of the image was gone. We were able to put
the target on the slit (there was considerable sky brightness from thin clouds), and
take spectra of this object. We got two 1800s spectra, arcs, a standard, and twilight
flats, too! I don't know the quality of the data, however.

It seems, though, that by sending the telescope to zenith and the guide probe to
the origin and leaving it for a few hours we solved the issues we were having in
the middle of the night.


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Submitted on 2014 Jan 31 [7:18:51]