Great Basin School of Photography

Comet C/2021 A1 Leonard will probably get a lot brighter over the next week as it approaches its closest pass by earth on December 12. If it doesn’t break up as it approaches the sun, it could continue to brighten even further as it approaches the sun through December 18. But just in case you don’t have clear skies, you might want to try to catch Comet Leonard in the pre-dawn sky to the east now. And comets are notoriously unpredictable, so it’s best to capture photos early, and then upgrade them as it gets better.

This morning I found it in a 70mm shot, just above and to the left of Arcturus. It’s just north of due east, and about halfw2ay up in the sky (42 degrees), dropping a bit each dy on the upcoming mornings.

I also tried a few shots zoomed in to 100mm & 200mm. At 200mm f/2.8 I set my ISO to 12,800 and shutter speed to 2.5 seconds. From then on (300mm, 400mm) a sky-tracking mount would be best.

So I set exposure bracketing to 5 images, 1/3 stop apart. I adjusted the results in Lightroom and saved them as 100% JPGs. I have a PC, so I used the free Sequator software to align, stack (noise reduce) and do some HDR processing on the images, saving a TIFF file. (Starry Landscape Stacker on the Mac would work, but you would want 10 identical exposures.)  I “synchronized” my folder in Lightroom to find the new file, adjusted it a bit, and saved this result.

I tried other focal lengths. I could barely see the green fuzzy head of the comet at 24mm, could see it with a tiny tail at 70mm, better at 100mm. It’ll get brighter over the next 7-10 days, may get harder to see as it approaches its December 18 pass by the sun.

Where to find it in the sky EarthSky): https://earthsky.org/astronomy-essentials/comet-leonard-might-become-2021s-brightest-2022/