M31 and M81/82 LRGB (Farm XI)

I was not happy with the quality or quantity of the previous night’s M31 and M81/82 data, so I made some slight changes to the NINA script and re-ran it on both targets. This time my data turned out much better. The increase in autofocus exposure time fixed the focus issue that I was experiencing.

No setup was needed. Startup at the scope, which consisted of bringing up Gemini II, and turning on the laptop, took only two or three minutes. I was inside for connecting devices and starting/monitoring the sequence.

Other than to look at the forecast low temperature, which was 24 degrees, I did not check conditions. The sky appeared dark and still. I did not notice any clouds while monitoring the session up until 2200.

The session ran nominally all night with good guiding and good star HFRs.

I woke up at 0445 and could see that the scope was pointing toward M81/82 as expected. I did not check the imaging laptop. I found the scope parked, camera cooled and the flats panel closed when I re-emerged from the camper at 0645.

The take for this session was:

M31: Total integration time: 04:43:30.
L: 99 x 60s = 01:39:00
R: 41 x 90s = 01:01:30
G: 46 x 90s = 01:09:00
B: 36 x 90s = 00:54:00

M81/82: Total integration time: 04:54:00
L: 72 x 60s = 01:12:00
R: 52 x 90s = 01:18:00
G: 16 x 90s = 00:24:00
B: 80 x 90s = 02:00:00

I rejected the last couple of frames due to brightening sky as dawn approached.

Total take for session was 09:37:30 = 9.61 hours.
Session duration was: 1830 to 1815 = 11.75 hours.
Efficiency = 9.61/11.75 = 81.8%.

About 20 autofocus runs occurred through the night, which is somewhat less than the night before, but still seems like a lot after getting autofocus to perform better. Given that Doug’s focus was changing very little over several hours and that mine was triggering a lot of autofocus runs, I suspect that my focuser was slipping through the night. More investigation is required.

In spite of the “excessive” autofocus runs, the session efficiency turned out fair at nearly 82%. To be sure, having good star HFRs for the entire session was worth the cost in autofocus time. This resulted in me rejecting only ten sub exposures during Blink and SfS analysis.

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