From: stephanie snedden
Subject: Re: 2.5m obslog 20090107 (MJD 54839)
Date: Thu, 8 Jan 2009 16:42:49 -0700
Audrey and I are at a at a loss, too.We checked everything we could
think of. One of our spiralPatterns went to a radius of 50 arcsec (!)
and we saw nothing, so this was not a small pointing error.
We've had it happen before that one night no stars are found on a
plate, and the next night they are. I don't know if we've ever figured
that mystery out.
Steph
On Jan 8, 2009, at 9:32 AM, Dan Long wrote:
>   I'm not sure what happened last night with 3090 and 3091.  They
> have been successfully observed before (54811, and 54816).  This
> would indicate that the problem is not intrinsic to the plate.  I
> didn't see any difference in coordinates between the plugMapM file
> on host2 and the original plugMapP file on plate-mapper for 3090
> (didn't check 3091), so I am at a loss to explain the problems
> finding the field last night.
>
> -Dan
>
>>                       APACHE POINT OBSERVATORY SDSS 2.5M
>>
>>                                 OBSERVING LOG
>>                           Wednesday January  7, 2009
>>
>>                                  (MJD 54839)
>>
>> ---=== OBSERVING TEAM ===---
>>
>> Audrey Simmons
>> Steph Snedden
>> Kaike Pan (swing)
>> JiWei Xue (UF)
>>
>> ---=== OBSERVING PLAN ===---
>>
>> MARVELS Science!
>>
>> ---=== OBSERVING SUMMARY ===---
>>
>> Observed and got data on five MARVELS survey fields, but clouds
>> affected data
>> early, and poor seeing toward and through second half. Two more
>> MARVELS plates
>> were tried, but no guide stars were found. One SEGUE plate exposure
>> was taken
>> at the end of the night.
>>
>> ---=== OBSERVING LOG ===---
>>
>
> .
> .
> .
>
>> 08:25Z Cartridge 6, plate 3090 field A - MARVELS Survey
>> -------------------------------------------------------
>> No guide stars, no FK5. We tried spiralPatterns in different
>> fibers, we tried
>> old offsets for this field plus spiralPatterns. We tried going to
>> the B field
>> and couldn't find guide stars there either. We occasionally saw
>> random stars
>> in a fiber, so we know the guider was working. All the fiducial
>> crossings were
>> made during the slews to both fields. We tried mounting and
>> unmounting the
>> cartridge in case there was some odd tilt from poor latching. We
>> then checked
>> the mirror numbers to see if we had a stuck actuator that caused a
>> tilt.
>>
>> At this point, it was time to move on to the next cartridge.
>>
>> 10:16Z - Cartridge 1, plate 3091 field A - MARVELS Survey
>> ---------------------------------------------------------
>> Again, no guide stars. We went to the nearest FK5 and found a star,
>> but it was
>> too faint to be an FK5. We centered on it anyway, went back to the
>> field, and
>> no guide stars. We were grasping at straws at this point. We did more
>> spiralPatterns, a soft reboot of the MCP and rechecked the fiducial
>> crossing
>> errors. Still no guide stars.
>> We checked the TCC clock and it was giving correct LST, so that
>> wasn't the
>> problem either.
>>
>> 3.3 hours lost trying to get data on these plates.
>>
>> There was really only one thing left to do and that was to check
>> the pointing
>> with our late-night known good SEGUE plate that was still plugged.
>>
>> 11:44Z - Cartridge 8, plate 3178 - SEGUE2
>> -----------------------------------------
>> Guide stars on goToField. Guess that rules out telescope pointing
>> problems and
>> indicates the problems with 3090 and 3091 are in the design or the
>> plugMap
>> files.
> .
> .
> .