It is always frustrating to see good weather pass without the opportunity to do some photography – especially astro-photography. So even if time does not permit a trip to the darker spots in reasonable distance from my home, it is worth a try to setup the telescope on the balcony.
This time, clouds cleared throughout the day (and happend to reappear before midnight). So I had to take the chance to spot Comet C/2018 Y1 Iwamoto. Unfortunately, I was unable to spot the comet through the eyepiece. The sky was far too bright (approximately 18mpss) watching straight over the citys light dome and having a 60% illuminated moon shining bright. Fortunately, through the camera I could make out a smudge, being brighter than the sky.
Processing the 180s subs with 1 hour total exposure time, I could achieve this result (compare to the unprocessed image!):
Image is a composite of 2 stacks (one aligned on stars, second aligned on comet). The comet moved more than 1.5 degrees during the 1 hour capturing time!
Above the comet: NGC 2903 (mag 9 galaxy)
At left: NGC 2916 (mag 12.1 galaxy)
Imaging setup: 800mm f/4.0 Newton, Sony A6000 full spectrum modified, UV/IR block filter, UHC filter, coma corrector (at wrong distance).
20x 180s @ ISO800, darks and flats
Conditions: +2°C, 60% moon, 18-18.5mpss sky in suburban location (with ample street light)
After 2 weeks of thick cloud coverage, I had the chance to spend the evening at the observatory. Actually I jumped in to hold the guided tour this evening…
As there was almost full moon and some cloud coverage (which got steadily thinner) I played a bit around with the setup. I thought – deep sky at full moon is a waste of time. But how about the comets 46/P Wirtanen and 38/P Stephan-Oterma? How brigth are the comets still? Would they shine through the moon lit sky?
Well… I could not make out Stephen-Oterma. But Wirtanen was barely (in)visible. I had some other tasks to do, so I attached the camera to the scope and let it run to see, what may be gathered under these conditions.
Despite of the Moon and the corona of Moon, a little bit of the comets was still possible to process from 90 minutes of total exposure time each:
The following timelapses show, how much angular distance the comet 46/P Wirtanen makes, when closest to earth. From my data I see approximately a stunning 1° during 4 hours!
85mm photo lens with 1.5x crop sensor
93 exposures, each 60 seconds long (93 min total)
200mm photo lens with full frame sensor
160 exposures, each 90 seconds long (240 min total)
715mm/f7 APO with 1.5x crop sensor
71 exposures, 30 and 60 seconds over 80 min
After several days with clouds, there has finally been a window of a few hours with stars visible. Unfortunately I had no chance to reach acceptable dark skies. So I had to deal with a more or less 5.5mag sky and some clouds passing by in eastern Austria. This image shows a bit more detail of Comet 46/P Wirtanen, as I used a 200mm telephoto lens. The result is not yet the image I am looking for. So I hope that clouds will clear up the next days for a better and longer imaging session…
Finally the full moon is over. The first chance to properly see some fainter objects like the comet 46/P Wirtanen. Comet 46/P Wirtanen started to rise more and more from the horizon. At November 10 the comet reached only 10° above the horizon. Now it is at approximately 20°. As for one day on November 28 the sticky clouds opened up above Austria. So I packed my gear and headed to the mountains. I ended up at a snow covered mountain top near Lachtal at 1857m a.s.l. At -8°C seeing, transparency and sky darknes were exceptionally! A really treat to observe 🙂
I set up my camera with a 85mm lens and captured 90 minutes of data until the moon rose. I chose the 85mm as I expected to see a tail extending from the comet. But as it seems, the tail is not extening sideways (seen from Earth) at the moment.
I am really pleased with the results and hope for another chance of good weather within the next few days…