Observation by Peter Tickner: C/2025 A6 Lemmon and the perils of moder...

Uploaded by

Peter Tickner

Observer

Peter Tickner

Observed

2025 Sep 23 - 03:17

Uploaded

2025 Sep 23 - 22:55

Objects

C/2025 A6

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Constellation

Lynx

Field centre

RA: 08^h55^m
Dec: +37°09'
Position angle: +6°09'

Field size

0°29' × 0°33'

Equipment

ZWO ASI2600MM Pro
ZWO luminance
14 inch f/10 Meade LX200 ACF SCT
OAG - Lodestar X2
Mesu E200 Mk 2 Mount

Exposure

50x30seconds

Location

urban Berkshire

Target name

A6 Lemmon and the modern curse

Title

C/2025 A6 Lemmon and the perils of modern imaging

About this image

Imaged over 25 minutes in the early hours and showing the typical problems we now face with any deep sky object from stray satellites and aircraft.

Apart from that a nice comet!

Peter

Files associated with this observation

cA6 Lemon .png (2.4 MB)

Like this image

Nick Quinn, Dominic Ford, Andy Wilson, Brendan Tynan

Comments

Nick James, 2025 Sep 24 - 02:50 UTC

Yes. Satellites and aircraft are a pain for comets since we are imaging objects that are at relatively low altitude in a brightening sky. The fact that you are stacking multiple short images is the solution to this. Rather than using a simple average for each pixel you can use a stacking mode that clips pixels that are "abnormal" in each image. Something like a sigma-clip tends to work well. Here is an example from yesterday. The image on the left is a clipped stack, the image on the right is a straight average. The clip does a really good job of getting rid of the trails.

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