Observation by Dawson: C/2025 F2 (SWAN)

Uploaded by

Dawson

Observer

Dawson

Observed

2025 Apr 09 - 03:30

Uploaded

2025 Apr 10 - 13:28

Objects

C/2025 F2

Equipment

Askar 120mm refractor
Canon6Dii
0.8x focal reducer

Exposure

ISO 400; 30second

Location

Nottingham

Target name

C/2025 F2 (SWAN)

Title

C/2025 F2 (SWAN)

About this image

Having seen some nice images of this comet and emails circulated in the Comet Section group, I felt compelled to get up early and try and observe it.

From our observatory site there is low north east horizon so I was able to find the comet quite easily, and imaged it from 03:17 (UT) to 03:54 (UT) by which time the sky was far too bright, but even at the start of the observation there was a vast gradient in sky brightness in the morning twilight. I went for 30 second exposures at ISO 400. Tracking wasn't great so I ended up with about 12 minutes worth of data which I've stacked in DSS (with some darks and flats), and adjusted the curves in GIMP; I also desaturated the colour to make it mono and inverted the image so I could more easily see the tail when stretching the data. It's fairly faint, but there is at least about 30 arcseconds of tail.

Files associated with this observation

25Fcropped.png (579.8 kB)

Like this image

Gary Eason, Jeremy Shears, James Weightman, Andy Wilson, Dominic Ford

Comments

Grant Privett, 2025 Apr 10 - 17:25 UTC

If you remove the sky brightness gradient the length of the tail is clearly longer...

Dawson, 2025 Apr 11 - 05:57 UTC

If I stretch the data the tail is clearly much longer, yes. What is the easiest way to reduce the brightness gradient in GIMP?

Dawson, 2025 Apr 12 - 04:51 UTC

I've downloaded GraXpert which is a stand alone, free, package and seems to do an amazing job at normalising gradients.

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