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Comet C/2020 F8 (SWAN), 20 May 2020

Comet C/2020 F8 (SWAN) was discovered on 13 April 2020 by M. Mattiazzo in the public website of low-resolution hydrogen Lyman-alpha images obtained with the Solar Wind Anisotropies (SWAN) camera on the Solar and Heliospheric Observer (SOHO) spacecraft.

On the morning of 20 May I ventured into the countryside north of Ipswich to gain a clear NW horizon, primarily to photograph comet SWAN, and with a secondary objective to attempt to capture both comets SWAN and ATLAS in the same field of view. (There had been hopes earlier in the the year that C/2019 Y4 (ATLAS) would appear spectacular in May. Unfortunately, the comet disintegrated, so did not become prominent; however the remnants are still in orbit around the Sun.)

I could not see the comet either with the naked eye nor binoculars. Fortunately, it was located near the bright star Algol, so was relatively easy to locate in the camera screen and, from just after 01:00 UT, for the best part of an hour, I recorded it as a faint smudge.

There were three obstacles to stacking the images:

I used predictions from JPL Horizons for the rate of movement of the comet across the sky.


In the following image, Comet SWAN is easily visible to the right of the image and, to the left is a faint smudge that is Comet ATLAS. Realigning the images on ATLAS does not really improve things.


Nigel Evans