Comet 3I Atlas (C2025 N1) :

 Comet 3I Atlas  (C2025 N1) : 

On the night of the 1st of August I attempted a capture and animation over a one hour period of Comet 3I Atlas (C2025 N1) using separate red green and blue filters on my ASI 533MM Pro camera attached to a Sky-Watcher Esprit 80 ED triplet refractor fitted with a field flattener.

The scope was driven with an iOptron CEM 26 mount with guiding done in PHD using an ASI462MC camera with Nina used to capture data and control guiding. The precise location of the comet was obtained from "The Sky" software with Right Ascension and Declination manually entered into Nina by referencing accurately timed predictions.

Some 10 x 2 minute subs of each red, green and blue blue channel were captured over a period of one hour and 14 minutes (with autofocusing done between filter changes and HFR swings taking the additional 14 minutes). Data were integrated and processed in Pixinsight as a red green blue colour image using gradient correction, Blurxterminator, Noisexterminator, Automatic Background Extraction with unlinked stretching done using Generalised Hyperbolic Stretch, using Arcsinh for transformation.

As the comet was located in the densely populated area of the Milky Way near to the Ophiuchal star cloud, it was virtually impossible to pick out this extremely faint (mag 17) comet against the myriad background of stars. Using Pixinsight's Blink function, I used the 30 registered XISF files to blink each frame at a rate of 0.05 seconds and scoured the area targeted in my image to try to reveal movement of any faint object against the background stars. It took a considerable amount of time to locate the comet’s path, but eventually (as if by magic) the combination of time adjusted animation with the accuracy of the human eye revealed the comet’s movement over the one hour 14 minute period.

An animation was made using the Blink utility to produce a small GIF file showing what I had observed and recorded. The location of the comet was then marked up on the RGB image where a faint RGB smudge was visible. An elliptical ident was chosen to show the comet's position along with associated text.

This truly remarkable observation of a dim and distant extra- solar system comet approaching our solar system at a speed of 60 km/s was most rewarding to achieve. The comet is believed to be 7 miles in diameter and at the time of observation was at a distance of ~260,000,000 miles from Earth.

Chris Bowden