Observation by Grant Privett: Satellites

Uploaded by

Grant Privett

Observer

Grant Privett

Observed

2021 Mar 06 - 22:40

Uploaded

2021 Mar 08 - 15:23

Objects

NGC2237
Spacecraft

Equipment

SkyWatcher 114mm f5 Newtonian
Starlight Xpress Lodestar
NEQ6 + Rowan upgrade

Exposure

30s x10

Location

Salisbury

Target name

Rosette nebula

Title

Satellites

About this image

It was a silly idea imaging a big object with a scope with a wobbly focuser and a Lodestar but it was just a bit of fun. When I came to reduce the images I found I had captured lots of satellites over the course of an hour or so. Here they are shown. Looked like about 5% of my images had one. Yeah, median stacking helps but bright ones often leave a low level residue that takes lots of frames to eliminate entirely.

Files associated with this observation

Rosette satellites.jpg (242.2 kB)

Like this image

Mike Harlow, David Swan, David Basey, Dr Paul Leyland

Comments

Nick James, 2021 Mar 08 - 21:38 UTC

Sigma clipping is a lot better than median stacking and it effectively removes bright trails too since their clipped pixels do not bias the mean (medians are statistically horrible in this context). I have found this very effective on stacks of 30 frames or more. It is occasionally necessary to delete a frame altogether but this is much more often due to aircraft than satellites. CMOS cameras help a lot since you can take a lot of short frames with minimal dead time and read noise.

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