This wiki page is a guide to use the Differential Image Motion Sensor Using Multiapertures (DIMSUM) instrumentation that was installed to Aux Tel between December 6th and 16th. I am currently writing this as a wiki page to be able to get feedback during the process of documentation. Once everything is finalized I can create a pdf file if requested.
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- Check that all the steps through 1 to 7 are correctly done. That is making sure the flash trigger is on, flash receiver is on, the power to flash lamp is on.
- If the receiver or the trigger cannot be turned on or do not show anything when they are turned off and on, replace their batteries. Spare batteries were left on the table close to staircase.(batteries were replaced with AC adapter in Dec 2023)
- Sometimes, if the camera was operated via EOS utility on the computer, it can be left in Live Mode. That needs to be off (affects mirror lock) in order for flash to trigger.
Flashes are flashing but they are clearly out of sync with the camera. Pictures taken ended up being all black.
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The SMA threads are 1/4-36. Digikey sells them, part number A104989-ND. Bought 100 of them.
Asked Helen to place this order since credit card failed.
Feb 14 2024 Pachon, Stubbs
Changed optical fiber configuration to have Xenon source feed attenuator module to 600- micron 1:4 fiber then 4 of 200 micron 1:4 bundles. This gives us 16 sources 200 microns in diameter.
I did find one fiber that was flopping/loose in the pegboard, that was presumably the one that showed anomalous behavior in analysis done Feb 2024 by Ali K.
Checked using headlamp that all fibers look comparable.
When running remotely on data collection using gphoto-2 to interrogate aperture worked fine, after power cycling the camera.
But the
./CommunicateTrial.sh
script failed.
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1600 Boston time:
Kicked off a test collection with file xfer to LaCie.
Verified with image 5993 that it's working well!
Started a long term run
Feb 16 10:38 local Pachon time.
The cores of the images from Feb 14-morning of Feb 16 are saturated.
I installed an aluminum foil attenuator in one of the filter holders, replaced the Kapton tape that was in there.
This should reduce light level by at least a factor of two.
We can adjust f-number remotely to get desired light levels. Note high f-number makes us less sensitive to thermally driven focus changes.
We also have less aperture averaging and a smaller beam cone. Currently operating at f/20. With 220mm focal length our input aperture is 220/20 ~ 11mm.
I think this is better than operating at low f-number and cutting light level at the source.
Tasks:
OK to let it stop running over the weekend.
review performance and adjust f-number as needed to attain desired light level.
Imaged obtained after 1030 pachon time on Feb 16 should be OK to look at.
Image 6636 is most recent on disk, now. Wait for 6637 and verify light level. 6642 is a good test- grabbing that one.
Also now that we know how to extract dome shutter status from EFD (See image quality dashboard) we can better correlate that with measurements.
Well, that definitely cut light out! Peak is now around 600 ADU. So we should open up f-number more. Each f-stop is factor of two in flux.
So going from f/20 to f/10 should be 4x the light. Going from f/20 to f/5 should be 16x the light. That would give us around 9500 peak.