Tuesday, March 29, 2016

#29 - Tuesday, March 29th, 2016 - Bad Behavior

I moved to a new spot at the state park – that dirt parking lot out front of the gate on the road to the observatory.  The trees are kind of high, but it’s much more secluded than my previous spot, and I’m more comfortable being back there alone.  It’s also closer to the compost toilet, which I finally found a few trips back (which was open during the winter!). 
It was in the lower 40s, but the trees shielded me from the wind.  Putting the telescope together by myself took a lot longer than I had anticipated, so I didn’t start getting images until almost 10 PM.  I came up with a clever idea to keep the battery from getting cold – I wrapped the 8-inch dew heater around it, and covered it in a fleece blanket, and turned up the heat.  The alignment process worked well and worked the first time, for once.  Its initial guesses at the two alignment stars and the first calibration star were terrible, but it cleaned up pretty well by the third calibration star.  I used Sirius for the all-star polar alignment.
I started with one more go at the Orion Nebula, although it’s in the western sky now, toward the city, where there’s lots of skyglow from the city lights.  There were also some high clouds I could only see in long-exposure images.  So my Orion photos came out terrible.  After about 35 of those, I slewed to the Cigar Galaxy, M82.  It wasn’t showing up in my photos though, even after fishing around for a bit, so on a hunch I tested whether it was still aligned – I had it slew to Polaris.  It was most definitely not.  So, without power-cycling, I re-added the alignment and calibration stars, and it stuck.  I found M82 with no problem.  So I started that set going, and went and read in the car.  I forgot to check what time it crossed the meridian – I only got about 20 images before it did, and another 20 had massive star trails since the scope had stopped moving.  So I had it slew to M82 again – and again, it was way super off.  So I power-cycled and re-aligned (I didn’t have to re-polar-align, since I hadn’t moved it), but it wasn’t working; it was way off on goto.  By this point, it was about 11:45 PM, close to quitting time.  So I gave up and packed up. 

The battery was nice and warm, so I think we can rule out the battery being cold as a cause for it getting lost.  It sounded again rather terrible when it was slewing, more in declination than right ascension, though.  This is in part caused by the fact that I balance the telescope with the camera attached, and I align using the star diagonal and 25mm eyepiece, so it’s not balanced when I’m doing that, but it sounded worse than it did earlier in the evening when I was aligning the first time.  It really sounds like it’s not getting enough juice, but I don’t think that that’s the problem, unless the battery is crapping out on me.  My next suspicion is that the grease in the gears gets too viscous when it’s cold, so it’s working against that as well.  So I’ll have to wait until a warmer night to go again, I think.

On the bright side, the 20-or-so pictures I got of M82 yielded 18 decent ones (I’m pretty liberal with how much star asymmetry I allow at this point, since I haven’t yet had a good night with a lot of pictures to choose from).  Even with only 18x30 sec images, it came out pretty well!

M82 Cigar Galaxy, Nikon D3100 on C11, f/6.3 focal reducer
18x30s, ISO-3200, no flat [I just made the background really dark in post-processing to hid the vignetting]

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