What causes this ? help please

[greenkat]

Hi peoples

Finaly managed to get out last night and start imaging for first time in a while.

This is 186 15sec images taken with a Skywatcher 200mm f5 reflector plus a Meade DSI IIIc

Any idea whats causing the obvious diaganal line effect all through the image ?

I know the exposure times are very short, but would that cause this effect ?

Any advise would be great

Cheers in advance

[Bizibilder]

Seems to be vibration - look at the two brighter streaks - they zig-zag.

[roundycat]

no idea what the bright streaks are, nav lights on aircraft? Maybe the zig zag effect is down to jaggies in image resolution. The exposures are very short. How are you combining them? The streaky background could well be co-related noise, simply noise in each frame adding up because there is so much of it.

Dennis

[RobH]

Looks like you didn't subtract darks, or if you did, they weren't taken at the same temperature as the lights (2 degrees difference between darks and lights with a DSI makes the darks all but useless)

The bright wiggly lines are hot pixels.

There has been movement between the subs and as the software has lined up using the stars, the hot pixels appear like this.

I've seen exactly the same with my DSI, and for the reasons above.

A combination method such as sigma clip or sd mask will eliminate the hot pixels. but good temperature matched darks are essential with a DSI.

Cheers

Rob

[Ant]

Thanks for the info Rob.

I used to get something similar with the dSLR - although not quite so pronounced, never did find out what caused it till now!

ant