[BlackWidow (Mardy)]

I had my very first shot at the Horse Head Neb the other night. I only took this single image and has streched the heck out of it to show the problem even more..

I want to know what this light band is running up my image and how I can stop it from happening? I had no lights around to cause this and it only happened on this object. As soon as I went to any other object the problem was gone.. Is the bright star nearby causing this problem? and how do I stop it if it is?

I am using a Meade LX200GPS guided with PHD. I had a 6.3 focal reducer and this image was for around 300 sec

Any help would be great please

Regards
Mardy