Observation by Nick James: How faint can you go?

Uploaded by

Nick James

Observer

Nick James

Observed

2025 Mar 30 - 22:20

Uploaded

2025 Apr 01 - 01:03

Equipment

ASI6200MM + Celestron HD11

Exposure

130x60s

Location

Chelmsford, UK

Target name

C/2025 D1 (Groeller)

Title

How faint can you go?

About this image

I observe from a fairly dark garden which is near the centre of a large town so the skies here are not great but the night of March 30/31 was very transparent and the seeing was pretty good too so I decided to try to image a faint comet, C/2025 D1 (Groeller). This had a last reported magnitude of around 20. This image shows the result of a 130x60s stack on the field. The top image is stacked with no offset and the bottom is stacked with the comet's predicted offset (0.14 "/min in PA 228). I did detect the fuzzy comet although the SNR is low and the two estimates I got from 65 min stacks were 20.3 and 20.7. I've tried to determine the limiting stellar magnitude of this unfiltered 130 minute stack in comparison with Panstarrs Sloan magnitudes and I think it must be fainter than 21.

Files associated with this observation

2025d1_20250330_2220_ndj.jpg (932.9 kB)

Like this image

Callum Potter, Dominic Ford, Robin Leadbeater, Jeremy Shears

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