The first shots of the night of Dec 10, 2018 were some 30 second ISO 6400 sub-images of Comet 46P/Wirtanen and the last 4 shots were 5 minute subs at ISO 3200 of the same, but guided on the comet instead of the stars. The first image above is a combination of the two sets. The second image is just the 30 second subs alone in a star streaks rendition.
Before I could even start shooting, I had to take the mount apart in the field and unstick a stuck motor that was giving me lots of trouble. I almost thought I would scratch and not get any shots of this naked eye comet. Luckily, I had tools and was able to rectify the situation.
I had trouble seeing it naked eye at first, but as soon as it rose high enough out of the muck, I was able to spot it without optical aid. I was at my Bortle 4/Green zone site and it was probably the clearest night so far this season. So, conditions were exceptional and it was cold enough to use ISO 6400 without too much noise.
I still have two other sets of 1 minute, ISO 6400 subs and 1 minute ISO 3200 subs left to process. These first two sets were the easiest to start creating images with.
Here is 64P/Swift-Gehrels, a comet that was near M33 recently. I missed it then, but I finally caught up with it Saturday night, Dec 1, 2018.
I used 4 minute subs and I could have gone even longer at this location, but my guiding was iffy with bad seeing. Out of 20 minutes of subs, I lost one, so this is only 16 minutes of exposure.
Since it was so few, I just stacked the subs once while aligned on the stars and then used one sub of the central core to hide the streak caused by the comet’s movement in the sky. A quick and dirty star-freeze job. lol 🙂
I shot two sets of data for this comet. Both were 40 sub-images. The first image and the image below are from the first set. The moon/comet comparison image above was done from the second set.
Taking another crack at processing the first data set, I made this version below that has a slightly different comet position, is a little lighter and shows more coma, but less tail:
Here’s the second set of data with a star streaks and star freeze version of the data with minimal processing:
Finally, here are both sets of the comet together, but with the background stars from only one set of 40 x 2 min subs:
Lots more coma is visible, plus the tail from the fist set of subs shows as well. I think here we have a coma that is so bright it is blowing out the faint tail as seen in the second set above. Not as much coma was picked up when it was lower in the sky muck, but the wavelengths from the tail got through and made it more obvious, as seen in the first set of subs.
So, it is possible that shorter “core” sub-images mixed in with longer exposures to get the coma might be a way to tame this comet and get a good final image with DSLR equipment. I will try that the next time I get to image this beast.
New comet Machholz-Fujikawa-Iwamoto (C/2018 V1) showing two tails. I took this right at the end of the best time for observations before the moon interfered. Unfortunately, I did not have much time to shoot it, since it didn’t rise out of the low-elevation muck until after astronomical twilight started. Oh, well… I did my best. 28 subs is not too bad.
I was at my “dark” site shooting this. Could have gone better. I had equipment problems and other issues and wasted lots of time trying to get the mount calibrated. To top it off, my dead-end road spot was invaded by duck hunters arriving before dawn to hunt. I lost about 10 subs from their vehicle headlights.