C/2023 P1 (Nishimura)
Japanese amateur astronomer Hideo Nishimura discovered the comet in images he obtained using a 200-mm f/3 telephoto lens mounted on a Canon EOS 6D on 12 August 2023, when the comet was 1.0 AU from the Sun. He also found it in images he exposed the previous night.

Pre-discovery images from 19, 24, and 25 January 2023 from PanSTARRS were identified by Robert Weryk extending the observation arc to seven months. The comet appeared in them as a stellar object with an apparent magnitude of about 22

Is a long-period comet and will not leave the Solar System, will come to aphelion (farthest distance from the Sun) in 2227, and return around the year 2430. On September 17th, C/2023 P1 will reach its closest point to the Sun, called perihelion. It will be really close to our star, at a distance of about 0.23 AU from it.
https://en.wikipedia.org/wiki/C/2023_P1_(Nishimura) 
https://science.nasa.gov/introducing-comet-nishimura
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We couldn't pass up the opportunity to try to capture this comet, so at dawn on September 7 Maurizio went to a field near the outskirts of our city to manage to capture it.

The first difficulty was establishing the alignment with the Polar Star. The repair of the mount that arrived at the end of April, Maurizio was not able to check it until mid-August, finding that the internal camera of Cem 70 for alignment with the Polar, does not work. He also stated that the mount continues to have an electronic problem that affects the motor declination...

The alignment of the Polar was done with the indication of the degrees that the cell phone gave it and then correcting with the pad until the star was centered in the best way on the Ra camera screen first and then he did the triangulation with three stars until they were well centered. That took a lot of time away from getting the mount to correctly target the targets he indicated.

Then towards dawn, the horizon was full of stratosphere clouds and he could not locate the comet but fortunately the clouds dissipated and he was able to find it but it was already dawn. And due to the limited time available he had to take the shots manually by touching the camera screen and mentally calculating the seconds... (I could see that Mauri has the screen touch!)

Despite the inconveniences of the session, Maurizio managed to make about 104 frames of which I discarded 8 due to satellite passes, airplanes, and only 5 moves and used 91 frames to make a flowery stack (1x5'' 4x7'' 13x8'' 10x9'' 20x10'' 9x11'' 24x12'' 3x13'' 2x14'' 3x15'' 1x16' 1x20'') which gives an average of 11 sec/frame, a total of almost 16.8 min of shots to the comet in total.

I made a first stack in DSS to get the stars base and then another to get the comet stack alone. Using GraXpert to do a background extraction I found an unpleasant surprise, apparently the Newton has an internal reflection problem or it is probably also due to the extreme declination of the shots on the horizon and the fact that it was already dawn which caused circumferences internal reflections adding additional noise to the poor signal captured from the comet.

Additionally, there were the typical donats and checking the coma corrector Maurizio later realized that the lens that faces the camera sensor was dirty...

I made another stack without using flats and only dark frames since on this occasion the 'creative' flats really increased the base noise that the internal reflection was already causing, achieving a slightly cleaner stack. However, I chose to make another stack using Rich's workflow that he made for Siril 1.0.6 since I have not yet updated the program with the latest version precisely because of this workflow that works very well to achieve the isolated comet from stars stack.

In order to enhance the weak signal of the comet I had to make a fairly strong stretch and local curves that considerably increased the base noise of the image but allowed to distinguish at least the inherent characteristics of the comet's tail to some degree. To isolate the internal reflection noise I had to make a mask to isolate the comet signal from the background as best I could and it was quite difficult. Then a partial noise reduction was applied (the only tool that achieved a slightly acceptable result was Topaz). And as you can see, more than two-thirds of the comet's tail has notable punctured noise. It is the best I could achieve with the weak signal captured.

At least it remains for the record of special targets that we have managed to photograph.

Maurizio tried to do another session on 9/11 without success being in a mountain place at almost 1,200 meters above sea level but unfortunately in the place where the comet could be seen there was a chain mountain that prevented its visualization until well after dawn... he made six pics as a souvenir

Thank you for visiting us and have all Clear Skies.


Processed September 2023.

https://twitter.com/AstroOtus/status/1702828290304508051