Hot pixels?

[JamesF]

This is a (WIP) RGB image of M13 from last night. My first ever RGB image Am I correct in assuming that the bright red, green and blue pixels near the top of the frame and to the right of the core are due to hot pixels my 314L+?

James

[rfdesigner]

probably.. if your guide point changes from shot to shot and colour to colour then you might get what you've got here.

If you've guided the whole lot on one star and it hasn't moved across the guide cam, then I would expect little RGB stripes very close together.

Derek

[JamesF]

This was completely unguided.

James

[rfdesigner]

Hot pixels it is then.

Sigma should help, as would a hot pixel map

[mallorcasaint]

I would say they were hot pixels. I sometimes get them on my 314L but RC Astros Maxim DL filter takes them out!

[JamesF]

Back to stage 1 then

James

[mallorcasaint]

What temperature did you image at? I found that my HP's disappeared once the temp went below -10.

[JamesF]

I had it set to 0.5C as the ambient temperature was over 22C when I started.

James

[mallorcasaint]

I would say that is nowhere near enough James. As it is "set point" cooling set it to -10 or 15 for best results.

[rfdesigner]

If you take a dark frame at 0.5C then use that to generate a hot pixel map, you can deal with anything showing through.

Agree with the 'low as you can' philosophy though

[JamesF]

I shall try a lower setpoint next time in that case. In the meantime it looks like sigma stacking has sorted it

James

[SnakeyJ]

nice natural looking colour in that image James (other than the odd hotpixels), though suspect this would benefit from more subs to reduce the noise (appreciating this is a test run) I'm sorely tempted to get one of these cameras and Bazza's just re-dangled the carrot that I managed to avoid earlier in the week! From what I've read the published max deltaT is a little conservative, so -5 should be easilly achievable from an Ambient air temp of 22, but I'd push it as low as you can get it at this time of year.

Are you looking to setup the zwo for guiding with this?

[JamesF]

More frames would have been good, but the clouds had other ideas. Fortunately I was rotating through the filters doing a few of each at a time, so I didn't end up with L (not in this image) and R, but only a few G and no B

I've not really got my head around what I'm going to do as regards guiding yet. The 120MM is the obvious choice of the kit I already have which is a big point in its favour, certainly. I was planning on sorting all this stuff once I had an obsy, but construction didn't happen last summer mainly because it was so wet, and now it's a prickly subject with "her indoors" who wants stuff finishing around the house before I embark on another project

James