Observers: G. De Rosa, S. J. Schmidt, D. Berg
Telescope Operator: G. Bechetti
Support Astronomer: Olga Kuhn

Instrument: MODS

Summary: 

During the afternoon MODS was powered off so that Elliot could swap in
CSR1 for the blue HEB.  Powered back up and tested: everything was
fine. Problems with the all sky camera, solved at UT 00:34.  We opened
at UT 00:39 and started observing with MODS. We tried to observe the
Uva_RCurve program, but the seeing was too low. We observed mainly
during the first part of the night. Observed programs: ND_COSLLS
(j2253), OSU_highz, UM_RMHstars (M31_004444, M33_7292, M31_004425),
OSU_Clash (0717, 2 good exposures out of 5), OSU_RMAGN (PG 0953, 2 good
exposures out of 4), Standard stars (Feige 110, G191b2b). The shell
ripped 4 times during the night. The problem doesn’t seem to
be directly related to weather conditions.

Weather: 

Clouds during the afternoon. Cleared up at sunset. First part of the
night was mostly clear with relatively good seeing (0.9-1.2). The
transparency dropped around UT 09, when clouds started to move
in. During the rest of the night, the clouds got thicker and thicker.
We tried to move to a bright target, but at UT 10:40 the guiding became
impossible. Kept watching the weather for a decrease in transparency,,
but it did not improve. Closed dome at UT 12:15. Taken calibrations:
biases and lamps.

UT 01:23, Standard star: Feige110
UT 01:32 seeing 1"

UT 02:05, Uva_RCurve:
   NGC6701_pos1 tried to observe it, but seeing was around 1.1 at that
   hour angle (and the hour angle would increase over the course of the
   observation) so we didn't think the conditions were good
   enough.

UT 02:10, ND_COSLLS j2253:
   Since |HA|<1, we have changed PA to 10 and re-selected guiding star
   (as requested by the PI) average seeing ~0.9

UT 02:53 humidity going up ~70% - cirrus coming in

UT 03:08, OSU_highz:
   1st exposure, average seeing 1.3"
   2nd exposure, average seeing 1.4"
UT 03:30 humidity 80%
UT 04:12 seeing 2"
UT 04:20 humidity close to 85%
UT 04:21 slewing to telluric standard
   issues with collimation @ elevation 46 (small tail)
   Alignment failed on X direction, move of 0.8". first image taken when
   star was off slit. moved back in, taking one more 90 sec exposure.

UT 04:43, UM_RMHstars: M31_004425
UT 04:47, humidity ~80%, seeing 1.1", source slightly difficult to
   identify in the wide field finding chart (mainly due to orientation)
1st exposure, average seeing ~ 1.5"-1.6"
2nd exposure, average seeing ~ 1.4"-1.5"
3rd exposure, average seeing ~ 1.3"-1.4"

UT 05:28, M31_004444   
   source slightly difficult to identify in the wide field finding chart
   (mainly due to orientation)
UT 05:38, shell RIP
UT 05:40 shell set, re-collimating
   1st exposure, average seeing ~ 1.2"-1.3"
   2nd exposure, average seeing ~1.4"-1.5"
   3rd exposure, average seeing ~1.4"-1.5"

UT 06:17, M33_7292:
   Clouds at the horizon

UT 06:30 source looks elongated in confirmation image so we took a
   second image - also difficult to identify the source due to the
   orientation of the finding chart.

   the source IS elongated - we suspect it might be a double star - we
   placed the center of the elongated source on the slit

   1st exposure, average seeing ~1.-1.1"
   2nd exposure, average seeing ~1.1"
   3rd exposure, average seeing ~1.2"
water vapor coming in

UT 07:03, standard star, g191b2b:
UT 07:11, seeing 1.5"
   small X offset: -0.2"
UT 07:39 average seeing ~1"

UT 08:00, OSU_CLASH (0717) :
   Before the exposure started, we moved down (DeltaY) of -0.4" to center
   the stars in the boxes
   1st exposure, average seeing ~1.1"-1.2" (alignment looks fine: star
      spectra centered in the boxes, few faint objects visible)
   2nd exposure, average seeing ~ 1.1"
   Began third exposure, but didn't finish it:

UT 09:03, clouds coming in, but guide star still fine, seeing ~1.1"

UT 09:20 big drop in transparency (1.5 mag) - clouds coming in from the
   west, we paused the exposure and monitored the transparency
   shell RIP - shell reset - recollimating

UT 09:31, transparency gets better, exposure resumed,
UT 09:41 - shell RIP, observation paused
UT 09:43 - shell set - re-collimating
UT 09:45 transparency down (~1.5 mag)
UT 09:50 shell RIP again, cloudy.

UT 10:05 tried to resume the exposure, but it read out the image with
   300 second remaining on the exposure (is there a maximum exposure
   time due to cosmic rays?)

UT 10:09 OSU_RMAGN, PG0953
   Try to move to a bright object and get usable data
UT 10:28 difficult to align source: the source is offsetting more than
   supposed, most probably due to jumps of the guiding star > 1"
UT 10:32 exposure started, average seeing ~1.4"
   1st exposure, average seeing ~1.4"
   2nd exposure, average seeing ~1.5"
   3rd exposure, low transparency bad seeing
   4th exposure: seeing 1.8" , transparency too low
UT 10:50 standby observations, wait for any possible improvement in
   transparency and seeing to repeat 3rd and 4th exposures
UT 11:20 try to get another exposure, but still very low signal.
   completely cloudy. we keep watching it, in case of a miracle
   happening.

UT 12:15 give up, dome closed.

UT 12:30 started calibration script
   bias 8kx3k
   bias 3kx3k
   Red Grating arc lamps
   Dual Grating arc lamps
   Blue Grating lamps
   Blue Grating, bin 2x2, lamps