Zdobienie / Decoration

Comet C/2019 Y4 (ATLAS)

Zdobienie / Decoration

Comet C/2019 Y4 (ATLAS)

Comet with a near-parabolic orbit, which rather certainly will be visible to the naked eye at may this year. Was discovered by the ATLAS survey on December 28, 2019. It is possible the comet may be visible to the naked eye sometime in April or May 2020. It will reach its nearest point to Earth on May 23 and come to perihelion (closest to the Sun) on May 31.

Source of some information: https://en.wikipedia.org/wiki/C/2019_Y4_(ATLAS)

Comet C/2019 Y4 (ATLAS) - Crop

I must admit, without beating, that stacking and processing of the comet was a very difficult topic for me. It was a challenge I didn’t have in astrophotography till now. My basic tool for stacking astrophotography images has completely failed. Quite rightly, because the APP has not (yet!) implemented the necessary functions for stacking photos containing comets. A standard stack of photos taken in APP always gives the same result, nicely aligned stars and the comet appeared as a blurred galaxy.

Below you can find some photos, that were created during testing various configuration options available in DSS. Each photo has its own beauty, so I decided to show them all.

Below is a stack with orientation for a comet with the great “HALO” occured.

2019 Y4 (ATLAS) with HALO

After digging up the Internet resources, it turned out that DSS has the necessary functions already for stacking images, containing a comet. I have to admit it’s pretty good at it, if you stack light frames aligned for comet or star-oriented images. BTW the APP software making final stack with stars definitely better. DSS completely disappoints when stacking photos with stars and comet orientation simultaneously. I’ve tested a whole range of configuration options available in DSS and the result was always the same – crap in the final picture.

C/2019 Y4 (ATLAS) with DSS

What to do? How much I was thinking about how to bite this topic. Yes, I know, PixInside will say purists, but I don’t have time to learn another program just to process comets and simply saying, I just don’t want to.

I did not give up the topic. While testing many options available in DSS for stacking, I found that, with a specific DSS options setting, you could get a stack that contains small amounts of star trails but the comet stack was very nice of quality. Going forward I was able to get two stacks with comet of different colors, almost without stars in the background of the comet. With all those of photos with comets and stars made with APP, I could already play with masks in Gimp and put together three different photos into one, which has point stars and the comet as it should be.

Huh! it gave me a hard time processing this comet, like hardly any other subject in the astrophotography. My various struggles with the equipment for this hobby, did not cause me as much trouble as this comet. Even doing modifications of my NEQ6Pro assembly from gears to belts, it was like a nice walk for a beer.

Stack with algorithm oriented for a comet, with star reduction.

2019 Y4 (ATLAS) - HALO shadow

Once again, I greet my colleagues Maciej Pawłowski and Marek Szymoński, who virtually accompanied me at that time and also photographed the sky.

Pictures taken near Bielsko-Biała.


  • Canon EOS 6D with IDAS LPS-D2 48mm LP filter and Coma Corrector not perfect suitable for my Newton telecope model,
  • Newton CT10 250/1200 [mm], F4,8
  • NEQ6Pro mod.


  • Lights – 127 x 1600 ISO, 180[s]
  • Calibration frames: Darks, Flats, Bias


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