Date: Thu, 23 Jun 2022 14:03:46 -0600
Subject: Re: [sloan-25mlog 6146] Re: 2.5m obslog 20220622 (SJD 59753)
From: "Daniel Oravetz"
Hi José,
Unfortunately, we couldn't come up with anything different in last night's
setup compared to the night before. In both cases the enclosure was on,
telescope at stow, doors closed, the IEB cover was off.
We reproduced a couple of the sequences from the previous night, too --
toggling the FBI LEDs on and off, configuring the positioners, etc. -- but
still nothing.
If we get an opportunity to open tonight we'll take sequences of FVC
images during BOSS exposures as you and Tom suggested. I like the idea of
taking a higher number of shorter FVC exposures to help constrain a
narrower time range to investigate should the feature reappear. We were
able to see the FVC "blobs" very easily with 5-minute exposures, and I
believe even at 100s we were seeing them fairly easily night before last,
too.
Dan
>>
>> Scattered-light tests
>> =====================
>> See the Log for exposure-by-exposure details.
>>
>> We did NOT see the light feature in any of the test exposures tonight.
>> The
>> only feature we saw in 900s open-shutter BOSS exposures was very faint
>> red
>> light from the E-stops, but this is considerably fainter (~20x) than the
>> light feature we've been trying to track down. And when we pulled the
>> E-stops later on, that feature disappeared altogether.
>>
>> We also did NOT see the reflection/light feature in any test FVC images
>> tonight, so at least that appears to be correlated with the lack of the
>> light feature in the BOSS r1 test images tonight.
>>
>>
> This is quite interesting and more definitively seems to point to an
> outside source. I guess in both days (when you say the signal and
> yesterday) the telescope was parked at the same position and the enclosure
> closed? Can you think of any difference in the setup? Was the IEB lid
> installed both nights (I remember Ryan mentioning that with the new
> chiller
> working he was going to reinstall it, but not sure when and if that
> happened).
>
> José
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