Saturday, August 12, 2017
April 6, 2017
A cold front came through yesterday. Last night was clear and dry but tonight is even better EXCEPT for the nearly full moon looming overhead. Came out at 2000. Set up the ASI071MC-COOL at prime focus with the Lumicon DS filter. I was able to slowly drop the camera's temp to -20.
Synched the model on Dubhe and went to M-109 and started taking 60 second exposures at gain = 400. Frustratingly the camera / computer is still dropping 30 – 50% of the frames! A 60 sec exposure put the light curve maxima at only 15%, so I upped the exposure to 120 sec. Dropped about 7 frames in a row, very frustrating! I gotta change the wiring setup. I'm wasting too much time waiting on frames. Finally got an image and the 2 min exposure moved the luminescence to nearly 30%.
I was using a long active extension USB cable through a USB 3.0 powered hub to connect the camera to the computer. I removed the powered hub and the USB 3.0 extension cable. I hooked the StarShoot guider cam into the ASI071MC-COOL hub and ran a USB 3.0 cable from the ASI071MC-COOL to the laptop. Downloads are much faster and much fewer dropped frames at first with 30 second frames. When I upped the integration to 2 min, still there are too many drops ( nearly 50% of 2 min frames were dropped). Very frustrating. When I finally started imaging the M-109 the image contains an ice crystal, a lot of fogging, and a textile pattern!
I turned the cooling off and after a few minutes the ice, fogging, and textile pattern disappeared. I turned the camera's cooling to -10 C. As M-109 was approaching the meridian so I changed targets to M-101. At 2315 the ambient air temp is 54 F (12.2 C) with 63% humidity and the skymeter reading is 15.0 at the zenith due to the > half moon that is just past zenith. Pointing the skymeter towards Ursa Major the reading is a much more respectable 18.0.
Messier 101, NGC 5457, in Ursa Major is 21 million light years from earth. The face-on spiral galaxy is estimated to contain 1 trillion stars! Started imaging M-101 and got 5 x 120 second frames in and stacked in AstroToaster, looking pretty good. Then the camera / computer dropped the next 10 frames - ARGH !!
Cooled the camera down to 0 and held for 10 + minutes. Found the mount was parked slightly East in RA, so I had to reset counterweight down and now I'll have to rebuild the model; Arturus, Spica, Mizar, Denebola, Vindemiatrix, Castor, Capella, and Alphard.