[Aavso-photometry] Banding in flats

[Tom Richards]

Bob,
I had a similar problem with my Apogee U13, but it did not exactly repeat
image to image. It was rather random and some images lacked it. Apogee
concluded it was some sort of electronics issue that could not be resolved,
and did the decent thing by me. In your case I'd suspect electronics, but
that can mean anything. Try shielding your download cable, try keeping mains
power away from it (or very close to it to see if it gets worse), try
imaging with the fan motor turned off, try different on-chip resolutions -
anything that might show a difference for better or worse. I've even found
on my replacement camera I can get banding when running under certain ACP
scripts but not otherwise!
Good luck!
Tom Richards

> -----Original Message-----
> From: aavso-photometry-bounces at aavso.org [mailto:aavso-photometry-
> bounces at aavso.org] On Behalf Of robertjmodic at att.net
> Sent: Tuesday, 14 April 2009 10:54 AM
> To: aavso-photometry at mira.aavso.org
> Subject: [Aavso-photometry] Banding in flats
> 
> Does anyone know what causes the horizontal light and dark bands seen
> on the left side of this image?
> 
> http://chagrinvalleyastronomy.org/images/mflatsky1s-1-
> 10Rc%20MinMaxClip.fts
> 
> This is a master twilight flat made with a Rc filter.
> 
> The banding is present all the time with all my filters and with light box
> flats as well.
> 
> I read somewhere that the banding may be an interference pattern caused by
> the coverslip not being parallel to the CCD.
> 
> The reason I ask about the banding is that it does not always flat out
> properly.
> I have already checked the scope for and eliminated any scattered light in
> the
> system.
> 
> Bob
> 
> _______________________________________________
> 
> Aavso-photometry mailing list
> Aavso-photometry at mira.aavso.org
> To change options or unsubscribe, goto
> http://www.aavso.org/mailman/listinfo/aavso-photometry
> 
> The Santa Barbara Instrument Group (www.sbig.com): Proud Sponsor of the
> American Assocation of Variable Star Observers.