Date: Fri, 3 Dec 2010 14:44:17 -0700
From: Dan Long
Subject: Re: 2.5m obslog 20101202 (MJD 55533)
Hi Audrey,
   Thanks.  Yes that matches my interpretation of the dewar plots.
			Cheers,
			  Dan
>The spectrographs automatically filled during the afternoon. We force
>filled the spectrographs as normal after we opened. Dmitry then manually
>forced another fill to both spectrographs and watched until nitrogren
>began spilling from both spectrographs.
>
>We received the critical alert at 12:00Z (ish).
>
>Does this help?
>
>Audrey
>
>>>                         APACHE POINT OBSERVATORY SDSS 2.5M
>>>
>>>                                   OBSERVING LOG
>>>                             Thursday December  2, 2010
>>>
>>>                                    (MJD 55533)
>>>
>>>---=== OBSERVING TEAM ===---
>>>
>>>Audrey Simmons
>>>Dmitry Bizyaev
>>>Kaike Pan (afternoon)
>>>
>>>
>>>---=== OBSERVING PLAN ===---
>>>
>>>Test cartridge 18 in twilight.
>>>Then BOSS science.
>>>
>>>
>>>---=== OBSERVING SUMMARY ===---
>>>
>>>A "model" SDSS-III night: seeing ~ 1", clear sky, ALL plates plugged
>>>(8) were finished from scratch.
>>>
>>>.
>>
>>   .
>>   .
>>   .
>>
>>>LN2 system needs an attention form day crew.
>>>Today, again, in auto mode it filled only ~5 lbs. Then we repeated
>>>  filling in
>>>manual mode until spewing, and each spectrograph got ~ 25 lbs.
>>
>>   .
>>   .
>>   .
>>>
>>>We got the critical alert on SP2 secondary ln2 dewar again, as yesterday.
>>>  Note
>>>that in the evening we DID fill the dewars manually, and wait until the
>>>spitting. Please check the SP2 secondary dewar!
>>>
>>
>>  Hi Dmitry and Audrey,
>>
>>      We figured out why SP2's 10L wasn't making through the night.  It
>>  was a misbehaving full sensor on R2 (see day log for details).
>>
>>     I don't understand however, the comment about the auto fill.  The
>>  dewar plots from last night show a ~15lb fill on opening and about 10
>>  minutes later a ~4 lb fill.  I read that as a normal auto fill
>>  followed by a manual topping off.  The ~4 lb fill would be an
>>  indication that the auto fill worked as it should and that the amount
>>  used on the top off was cooling the lines back down to LN2
>>  temperatures.  Is that not what you saw?
>>
>>
>>				Cheers,
>>
>>				  Dan
>>
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