Braved the Cold to Image Comet Catalina

Braved the cold to image this Comet (Comet Catalina C/2013 US10). It is a 20 km diameter piece of rock and ice originating from the Oort Cloud that has been traveling towards sun for approximately 1 million years. It is now moving away from the sun and will probably never return (telescopes.com). The green color comes from cyanogen (CN: a poisonous gas) and diatomic carbon (C2). I love astronomy and astrophotography but I can't stand being out when it is below 40 degrees and breezy. At 4:00 am on Jan 2nd in Monroe CT, it was 26 degrees with a wind chill factor of 19 degrees. I have never imaged a comet before and probably won't again unless it comes when it's warmer out. There are few different methods for doing this: 1) single frame, 2) autoguiding on a background star, 3) autoguiding on the comet, 4) autoguiding on a background star and single point stacking on the comet. For a good summary of these methods visit Astrokev.com, Karlsson's Homepage, Soggy Astronomer, Bernhard Hubl Astrophotography.

Method three (3) is the best and I tried to do this but had a couple of issues. I have always used PHD autoguiding program but figured since PHD2 had a comet setting, I would try it. Unfortunately, the program never calibrated, so I wasted a half hour getting frustrated with that (in the cold). I connected it to PHD and had no problems. The problem was that the autoguider could not see the comet so I could not lock onto it. My guide scope (Orion ST80) is connected to the imaging scope with mounting rings so there is no moving it around, it has some pluses and minuses - this being a minus. I do have guide rings and if I had more time and it was warmer out might have changed it out. Oh well, I was relegated to the second best method, that being method four (4).

Note: It is possible to merge the best comet image from method four with the background stars from method two using photoshop. I tried this but I was unable to do this do to my lack experience with photoshop. Image 2 was using Deep Sky Stacker's Comet stacking function with star background calibration. Image 3 was using Deep Sky Stacker's Comet stacking function without the star background calibration. Image 4 was Deep Sky Stacker's Comet stacking function with additional unguided comet sub exposures.

Image 1 - Guiding on the Background Stars - Method 2


Comet Catalina C/2013 US10
Location: Monroe, CT
Date/Time: 1/2/16 5:00 am
Camera: Canon EOS Rebel T3i, Backyard EOS
Telescope: Orion ED80 80mm Apochromatic Refractor Telescope
Mount: Orion Sirius EQ-G GoTo Telescope Mount
Autoguiding: QHY-5L-II-M attached to and Orion Short Tube 80mm
Focal Length: 600mm

f/7.5
Exposure: 14-60s, (total exposure, 14 min)
ISO: 800
Post Processing: DSS, PS

Image 2 - Guiding on the Background Stars, Stacking on the Comet - Method 4


Comet Catalina C/2013 US10
Location: Monroe, CT
Date/Time: 1/2/16 5:30 am
Camera: Canon EOS Rebel T3i, Backyard EOS
Telescope: Orion ED80 80mm Apochromatic Refractor Telescope
Mount: Orion Sirius EQ-G GoTo Telescope Mount
Autoguiding: QHY-5L-II-M attached to and Orion Short Tube 80mm
Focal Length: 600mm

f/7.5
Exposure: 14-60s, (total exposure, 14 min)
ISO: 800
Post Processing: DSS, PS

Image 3 - Guiding on the Background Stars, Stacking on the Comet - Method 4


Comet Catalina C/2013 US10
Location: Monroe, CT
Date/Time: 1/2/16 5:30 am
Camera: Canon EOS Rebel T3i, Backyard EOS
Telescope: Orion ED80 80mm Apochromatic Refractor Telescope
Mount: Orion Sirius EQ-G GoTo Telescope Mount
Autoguiding: QHY-5L-II-M attached to and Orion Short Tube 80mm
Focal Length: 600mm

f/7.5
Exposure: 14-60s, (total exposure, 14 min)
ISO: 800
Post Processing: DSS, PS

Image 4 - Guiding on the Background Stars, Stacking on the Comet - Method 4


Comet Catalina C/2013 US10
Location: Monroe, CT
Date/Time: 1/2/16 5:30 am
Camera: Canon EOS Rebel T3i, Backyard EOS
Telescope: Orion ED80 80mm Apochromatic Refractor Telescope
Mount: Orion Sirius EQ-G GoTo Telescope Mount
Autoguiding: QHY-5L-II-M attached to and Orion Short Tube 80mm
Focal Length: 600mm

f/7.5
Exposure: 30-60s, (total exposure, 30 min)
ISO: 800
Post Processing: DSS, PS