Comet Observing
Observation Data
Location: Arabia Mountain (33.6651° N, 84.1182° W); Decatur, GA (33.7748° N, 84.2963° W)
Date and Time: 2024-10-13, 19:50 – 20:12 EDT; 2024-10-16, 19:42 – 20:07 EDT; 2024-10-19, 19:56 – 20:42 EDT
Sky conditions: Seeing – Good, Transparency – Mag 3
Instrument: (2024-10-16) Apertura 60mm FPL-53 Doublet APO Refractor @ f/6 – Aperture: 60mm, Focal Length: 360mm, (2024-10-19) Celestron C8 SCT @f/10, Aperture 203.3mm, Focal length: 2023, 6.3x reducer
Mount: Advanced VX
Eyepiece: N/A (Imaging + Naked eye observations)
Reticle Device: N/A
Imaging Equipment: Canon T7i, Canon EF 75-300mm f/4-5.6
Image type and sensor: Canon T7i – 1.06″ CMOS sensor
Image capture details: (2024-10-13) 113 frames at 1.3s 110mm f/5, ISO 1600; (2024-10-16) 46 frames at 10s, ISO 800, and 30 each of flats/darks/bias frames; (2024-10-19) 141 frames at 15s, ISO 800. Software: PixInsight, Photoshop
Project Objectives
Comets are dirty snowballs that get too close to the sun and when they heat up, they leave a trail of dust and gas pointing outward from the sun. Comets originate from the Kuiper Belt (out past Neptune) or from the Oort Cloud (thousands of AUs from the sun). Short Period Comets, usually from the Kuiper Belt have orbits that bring them past the sun every 200 years or less. Long Period Comets are those with periods over 200 years and are usually from the Oort Cloud. Comet Halley is the most well known of the short period comets, returning every 76 years or so. Observe a comet. This may be done naked-eye, with binoculars, or with a telescope. If the comet has a coma and a tail, sketch what you see. If it is starlike, then take two observations on two different nights and sketch the starfield including the comet. Note the date and time of your observation and the name of the comet. If you are interested in further study of comets, see the Astronomical League’s Comet Program webpage.
Impressions
2024-10-13, Sunset 19:05
My partner and I went to Arabia Mountain in Stonecrest, GA to try to get a clear, unobstructed view of C/2023 A3 (Tsuchinshan–ATLAS). We got there before sunset, took a short hike to the top, and saw the beautiful view of the Belt of Venus and the 83% illuminated waxing gibbous moon rising behind us.
As the sky got darker, Venus and other bright stars started to appear. I started shooting about 45 minutes after sunset, experimenting with exposure, ISO, and focal length settings. I ended up shooting at 110mm f/5, 1.3 second exposure, and a ISO of 1600 with a Canon T7i and Canon EF 75-300mm lens. It was around this time that our eyes had adapted to the low light setting, and we actually saw the comet with our naked eyes! It was pretty faint, but once found, it was easy to spot. It looked somewhat like the “naked eye” visual from the post below.
EXPECTATION VS. REALITY: Stunning photos of our comet are already circulating around social media. Make no mistake, most of these images are legitimate. But they're also not representative of what most of you are going to see.
— Eric Snitil (@EricSnitilWx) October 17, 2024
While this comet does qualify as "naked eye"… pic.twitter.com/1RquKU1u6Y
I ended up manually aligning and stacking 113 frames in Photoshop. After stacking, I did some final editing to produce the image below.
As the sky got darker and the moon got brighter, it got harder to see the comet. But it helped create this pretty, dream-like gradient that is seen in the final image.
2024-10-16, sunset 19:01
I wanted to shoot the comet from the comfort of home a few days later when it was higher in the sky. I also wanted to use a telescope this time to see if I could capture more detail. So, I set up my Apertura 60mm with my Canon T7i and captured 46 frames at 10 second exposure, ISO 800, and 30 each of flats/darks/bias frames. I calibrated and stacked my data in PixInsight and ended up with two separate images – one comet-less with stars aligned and one starless with comet aligned. I was able to combine them and make my final edits in Photoshop.
I was able to bring out the anti-tail with about 7.6 minutes of total integration time.
2024-10-19, sunset 18:58
I then wanted to shoot the comet again, but several days later so it would be even higher in the sky allowing me to gather more data. This time I used my C8 and a 6.3X focal reducer, and captured 141 frames at 15 second exposure, ISO 800. As with the last image, I combined two images – comet-less and starless – together in Photoshop and made my final edits.
I was able to capture more detail in the tail, and around the coma and nucleus of the comet with around 35 minutes of integration time.