GeorgeCarey

I measured the distance in pixels between the anomalies. 1600.9 pixels for both images.

The original FITS images are here http://geoastro.co.uk/may2013/Fits/

Hi Bernd, The camera is a QSI 683wsg. It was cooled to -30degreesC. I did nothing to the images - no calibration, no rotation. Each exposure was 600 seconds, with a Luminance filter. I have plate solved the images and determined the coordinates. They are slightly different on the two images from 5th May and 8th May. I looked at the RA of the tops of the trails and that shows that the trails are almost exactly North-South.

This is with both images aligned on the edges of the frames - this rules out strange camera effects because the streaks are not in the exact same place.

If I align the stars it can be seen that the anomaly is not in exactly the same place.

I dug out a frame from May5th that had this effect. To my surprise it has the same two trails in almost the same place.

Even stranger- the next frame shows nothing where the two stars were.

Can anyone explain this? From time to time I get an effect on some stars that looks as if the mount has suddenly moved in DEC and come back again. Autoslew does not report any errors. The odd thing is that only some stars show the effect. In this example two stars show 'trailing' but brighter stars in the image do not. How can only two stars show this?

A great image! I was inspired to point my scope in that direction last night. This is a start, 9x10 minutes luminance:

Hello ASA group. I bought one of the early DDM60 mounts. The version I have now is upgraded to the fixed resolution encoders. My telescopes are a William Optics 132 and a homemade 10" reflector. My website is http://geoastro.co.uk/ I am in the UK. I know of only one other UK DDM mount user - are there any more of you out there? George