From: stephanie snedden
Subject: Re: 2.5m obslog 20080526 (MJD 54613)
Date: Tue, 27 May 2008 12:00:55 -0600
Hi Dan,
I don't recall anyone saying they lost stars during scale changes.
That would likely be a symptom of it staying stuck during
scaleChange. Very strange. It's as if B was happy moving small
amounts around the offset position.
I just checked the weather forecast, and we'd better make hay while
the stars shine. The last pointing model should still work, so let's
run with that and the old fiducials tonight (and possibly for the
rest of the run). I work tonight, so I can make the switch when I
come in if you are busy with other tasks.
Steph
On May 27, 2008, at 11:41 AM, Dan Long wrote:
> Hi Steph and Audrey,
>
>    It's even weirder than that, because unless scaleChange wasn't
> used or didn't work, the primary _was_ moving, but staying offset
> through the scale changes.  Since Audrey saw the error low after
> homing/relaxing the obvious explanation of an offset due to an
> error in homing isn't it.
>
>    Do you want to take another pointing model or revert to last
> month's fiducials and pointing model?  If a new pointing model is
> the preferred path, would you like to take the data at the start of
> the night, or wait until the moon is up (using the old model/
> fiducials until then)?  Do you want a cartridge to be on for
> afternoon checks and spectro focusing, or just have the engineering
> camera in place from the afternoon on?  Let me know what you would
> like.
>
> 				Cheers,
>
> 				  Dan
>
>
>
>
>> Well, it is interesting that actuator B stayed in the bad position
>> for a few nights of good pointing. It must have been really stuck.
>>
>> Steph
>> On May 27, 2008, at 10:22 AM, asimmons@apo.nmsu.edu wrote:
>>
>>> I apologize that I did not catch this error in the mirror numbers
>>> earlier.
>>> When I homed and relaxed on shakedown, the errors for the
>>> actuators A, B,
>>> and C were 0, -100, 0 respectively, so I am surprised that the
>>> mirror
>>> numbers were off that much.
>>>
>>> Thank you for catching this, and again I apologize for my mistake.
>>>
>>> Audrey
>>>
>>>>
>>>>                        APACHE POINT OBSERVATORY SDSS 2.5M
>>>>
>>>>                                  OBSERVING LOG
>>>>                               Monday May 26, 2008
>>>>
>>>>                                   (MJD 54613)
>>>>
>>>> ---=== OBSERVING TEAM ===---
>>>>
>>>> Howard Brewington
>>>> Shannon Watters
>>>> Steph Snedden (phone support)
>>>>
>>>> ---=== OBSERVING PLAN ===---
>>>>
>>>> 	Science!
>>>>
>>>> ---=== OBSERVING SUMMARY ===---
>>>>
>>>> It was photometric all night.  We finished a plate (2180) and
>>>> acquired
>>>> signal
>>>> on another.
>>>>
>>>> The mirror numbers have been wrong since shakedown (see logs) so
>>>> the
>>>> mirrors
>>>> were homed/relaxed again.  We weren't able to find an FK5 star
>>>> on cart 1
>>>> until
>>>> we used an offset of +50" in Dec and ran a spiral pattern from
>>>> there (see
>>>> offsets). The latest pointing model may have been done with bad
>>>> mirror
>>>> numbers
>>>> and when the primary position was corrected tonight it would
>>>> have altered
>>>> the
>>>> pointing.  We lost ~2 hours trying to find those guide stars.
>>>>
>>>> We were able to easily find an FK5 on cart 8 but didn't find any
>>>> stars on
>>>> cart 3.  We lost ~50 minutes searching for those guide stars before
>>>> twilight.
>>>>
>>>> A new pointing model is probably necessary so we request that the
>>>> engineering
>>>> cam be mounted for tomorrow.
>>>>
>>>> We accumulated ~11k dust hours.
>>>>
>