Video of Comet C/2019 Y4 (ATLAS)

This is my video of the comet C/2019 Y4 (ATLAS), which I observed for 7.5 hours on the night of the 26–27 March 2020. I took 1194× 20-second frames and then, to make this video, I brought them all together with a frame rate corresponding to 1000× speed. Except for applying calibration frames, and a minor tweak to the histogram to balance the colours, this is basically unedited ‘footage’.

Note that the sky gradually whitens because of building cloud. Also, since the temperature dropped a long way that night, the thermal contraction of the aluminium tube eventually shifted it slightly out of focus. Usually I would refocus at least twice in a night, but in this case, I wanted all the frames with no jumps, so I decided no refocusing.

There are currently two comets in the sky, and this one is the second brightest one. It will, however, gradually brighten as it approaches its closest point to the sun on 31 May, probably eventually becoming visible to the naked eye.

I love observing comets… There is so much processing and calculation that can be done with this data, and this will eventually follow here on my blog.


  • 1194× 20-s light frames
  • 60× dark frames
  • 60× flat frames
  • 54× dark flat frames


  • Explore Scientific ED 102 mm Apo f/7 refractor
  • Sky-Watcher EQ5 PRO SynScan GOTO equatorial mount
  • Altair Hypercam 294C PRO colour fan-cooled camera
  • Altair 60mm guide scope
  • Altair GPCAM2 AR0130 mono guide camera


  • Sharpcap
  • PHD2
  • PIPP
  • Adobe Premiere Pro CC 2019

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