Antiblooming cameras for photometry: particularly STXL 11002

Tue, 09/11/2018 - 13:40

Aloha!  Our college observatory has been involved in minor planet observations, but I'd like to get some students involved in variable star observations.

We recently obtained an SBIG STXL11002 camera for the observatory, and I'm wondering how suitable it is for photometry work.  I've been under the impression that antiblooming cameras were a no-no for photometry, but the AAVSO photometry guide suggests that if we stay under the linearity limit such a camera might be all right. 

Our alternate camera is a NABG STL1001E that is no longer supported by SBIG, and we think may be having some driver issues that could be causing our control software to hang up on image downloads. 

My other big concern is that the full-well depth on the STXL 110002 is only 60,000 e- compared to the 1001e's 150,000 e-.  I suspect this is a function of the ABG drain, but it remains an issue.

Does anyone have any thoughts/recommendations?  The hanging problem we're experiencing is not insignificant.  I'd appreciate any thought anyone might be able to share.

Mahalo!

-Charlie

Affiliation
Vereniging Voor Sterrenkunde, Werkgroep Veranderlijke Sterren (Belgium) (VVS)

Hi,

I have used several years the STL11k CCD from SBIG with very good results. As you mention if you stay below the linearity limit, then you should get good photometry of this CCD. My present FLI 16803 CCD is also ABG an performs very well. The full well depth should also not be a problem either. Just go ahead and use it.

Regards,

Josch

Affiliation
American Association of Variable Star Observers (AAVSO)

My STL 1001E camera has had no problems with downloads.   I use TheSkyX now, but it also worked fine with CCDSoft 5.  Are you using the latest driver?  It's available from the SBIG (Diffraction Limiited) web site. 

I think DL has a support forum for the SBIG cameras, including the older cameras.  (...could be wrong about this since I haven't had any issues recently.)

For your antiblooming camera, just do a careful linearity test and keep your targets and comps below the limit.  Then your camera should do fine with photometry. 

Phil

Phil - I've updated drivers (regularly) with the SBIG driver update utility.  We're seeing problems that on occasion TheSkyX hangs (unrecoverable) while the camera is at 83% image downloaded.  This most regularly happens during a scripted @focus run.  I haven't been able to find anyone else who has reported this, and it really has the feeling of a driver/hardware issue. 

I was thinking of trying our STXL11002 to see if we experienced the problem with that camera, and because switching cameras requires rebalancing (and recalibrating) the mount, it is a test that I wasn't approaching *lightly*.

Affiliation
American Association of Variable Star Observers (AAVSO)

Charlie,

I'm sorry about this delay in responding.  I'm not subscribed to the visual observing forum so I missed your last post.  (Thanks, Sara, for moving this discussion.)   Perhaps you have already solved your problem.  If so, I would be interested in learning what was wrong and how you fixed it.

Have you posted the image download problem to the Bisque support forum?  I've found the Bisque people to be very responsive and helpful.  

You mentioned that the problem may be related to scripted @Focus operations while the download is in progress.   I noticed some other problems with the focuser control tool in SkyX which seemed to happen when the focuser was operating and another process (i.e. changing filters) was also called for.  I went back to using the native Optec TCF control software instead.  This seemed to speed up the whole imaging process in SkyX.  I wouldn't be surprised if this also would fix your download problem. 

ABG cameras and photometry:  I agree with Josch, but you really should to do a linearity test yourself before using any camera for photometry, and especially an AGB camera. 

Phil