Webcam widefield

[pete_l]

I finally stopped goofing around with the flashed/modded SPC880NC webcam I got the other day and decided to take it for a spin.

The image below was taken with the camera's factory lens, imaged with wxastrocapture as a YUY2 file. Split into PNG's and glued back together with Deepskystacker. I didn't collect any darks or lights (though, spurred on by this, maybe next time). I then tweaked the resulting TIFF in Photoshop.

Looking at the starfield around Omicron 1 & 2 Cygni, I reckon there are stars down to at least 6.5Mag and one or two pushing Mag 7. Those with particularly optimistic eyesight and a bit of imagination may even be able to convince themselves there's a hint of the North American neb in there, too.

[Digz]

Just goes to show what can be done with a webcam!

What are the blue, red an green streaks?

[pete_l]

What are the blue, red an green streaks?

I don't know. The stacked images were auto-rotated by DeepSkyStacker and the path of the streaks seems to match that rotation (the ones at the top-left have rotated WRT the bottom-right ones), so since the camera was fixed it appears as if the streaks were all coming from the same direction. From their direction relative to Cygnus, they appear to be going E-W (or W-E, I can't tell).

The scale of the image is about 33° vertically and 45° horizontally, so the streak seem to move about 5° in 3 seconds.

My best guess is that they are glints of sunlight from high-flying aircraft as they're too dim to be from ones I normally see overflying my house, which is near Heathrow. I've also noticed the same phenomenon in DSLR frames I've taken at other locations. I asked about them in another place and no-one could come up with a satisfactory explanation. Although there is also a theory that they may be satellite glints. As seen in this image that somebody else took. http://antwrp.gsfc.nasa.gov

/apod/ap100220.html However their streaks seem to repeat int he same path - but that might just be because of the differeing exposure times.

[Starflyer]

I think the streaks are from hot pixels, take some darks in the same sort of temperature, same exposure and that should remove them

[pete_l]

Hmm, it's possible. The documentation says registering / stacking process has removed all the hot pixels already

This is what the hot pixels look like, from a dark frame

It does look like the colours of some of them (and their paths, too) correspond to the streaks when you take the rotation between frames into account. I'll have to look into that possibility - thanks

[pete_l]

Update: After a lot of messin' around (why does a 15 minute astro photo need 3 hours on the computer to "develop" it?) with DeepSkyStacker, I discovered that with the various stacking options the ones that include a median algorithm give nice, smooth images with no streaks. Whereas a plain Kappa-Sigma or Entropy-weighted algorithms show up the streaks. So it does appear to be the got pixels leaving some blemishes on the image. With the median algorithms the hot pixels are averaged out.

p.s. a bit more fiddling gets stars down to 7.5Mag - 3 Magnitudes deeper than my absolute best VLM and 4 Magnitudes better than eyeballing the sky on that particular moonlit night. I think this camer has a future for spotting meteors.