Chasing Comet C/2020 F3 NEOWISE
Comet C/2020 F3 NEOWISE became a spectacular photographic target in July 2020. Over successive nights I tried a range of equipment to capture different images of this comet as its appearance, size and position changed each evening. These are all shot in Bortle 5 skies on the edge of Bath.
The name comes from the instrument used in it’s discovery: NASA’s Near-Earth Object Wide-field Infrared Survey Explorer.
11th July: Garden at Home, 3am-4am
My imaging rig
Equipment: Panasonic GX7 with 45-200mm telephoto lens on MSM SiFo rotator
My first clear night to look for the comet was the early hours of July 11th. I set an alarm for 3am and looked out the window - not sure if I’d see anything. I could see the comet with the naked eye so I took my equipment out to the garden. This was already prepared the evening before. Looking NE towards the glow of the dawn, I rattled off a number of exposures at various ISO settings. Given the brightness of the sky, it was the lower setting at short exposures that worked out best: say ISO 200 or 400 for 5-10 seconds. I used free software Sequator to stack, freeze the foreground and reduce noise.
GX7 with 45-200mm lens, stack of 5-10 frames
GX7 45-200mm static tripod. Hint of noctilucent clouds below.
GX7 45-200mm static tripod, stack of 5-10 images
By 3.45am NEOWISE was almost lost to the dawn. Bright star top right is Capella
12th July: Field near home, 2.45am - 3.45am
Equipment:
WO51mm APO refractor with Canon 600D DSLR tracking on MSM SiFo rotator.
GoPro Hero5 on static tripod
On this second evening, I started by getting up earlier as I was surprised by how light it was by 3.45am the previous night. I had done a daytime reccy of a position 5mins from my house and packed up my equipment ready to go. In contrast to the first night, I went for very wide and very narrow FOV, utilising my GoPro and WhiteCat51 respectively. This small refractor was pushing the capacity of the MSM so I was only taking short 3-5sec exposures at ISO1600. The comet did not yet have a noticeable ion tail.
Stack of short exposures at 250mm focal length. The low cloud on the horizon makes the shot feel moody
Single 30sec Night Lapse exposure
Selfie with Venus low to the left and Mars above the Moon
20th July: Home, 1am - 2am
Set up for the wide shot
Equipment:
GX7 with 20mm lens, tracking on MSM SiFo rotator.
WO51 APO refractor with CMOS single shot colour camera, tracked on equatorial pier.
I started around 11pm, but had to wait until around 1am for the comet to clear my neighbour’s roof. I tried stack a bunch of frames but the processing wasn't working, so I limited it only 8x 60sec frames. What I failed to realise until doing the same on the 22nd July was how much the comet was moving between frames, meaning the stacking software was trying to fix onto a moving target.
Faint ion tail visible in a wide tracked shot
15x 60sec subs manually stacked in Photoshop to freeze the comet head and allow the stars to trail
5 x 120 exposures, stacked with the background static
22nd July: 12.30am-1.30am
Equipment:
WO51 APO refractor with CMOS single shot colour camera, tracked and guided on iOptron Skyguider.
GoPro Hero5 on static tripod
I ran off three sets of subs: 30 sec, 120sec and 300sec. For the last two sets, I was unable to stack these due to too much movement, hence I created GIFs of these having calibrated each individual frame. This was my first time using an iOptron Skyguider Pro and using off axis guiding on my WhiteCat 51. Having performed a polar alignment by eye with the polar scope, there was no star trailing in 300sec subs which was something I have never got close to before. The only downside of longer subs I can see is a greater chance of them being ruined by satellites or aircraft.
iOptron Skyguider Pro with William Optics WhiteCat51
This combines around 30mins data, keeping the comet still and allowing the stars to trail, drawing out some very subtle detail in the tails
5x 300sec subs. This stack clearly shows the comet head in green and ion tail in blue.
Fixed GoPro facing NW, combined into an animated GIF
Astro Pixel Processor Beta 1.084 Comet Stacker
APP have just launched a beta of their next software release with a Comet registration & stacking setting. This basically replicated what I was doing manually in Photoshop; keeping the comet still and allowing the stars to trail. I used all my images from the night of 22nd July mixing 30 /120 /300sec exposures into one image below.