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[vsnet-chat 2623] RE: Tmz85

Hi Lew,

First of all, good to hear about the change in your weather situation. It's going the different direction over here : after an almost clear week I'm clouded out now.

I'm not sure why you're using exposure times of 16 seconds for such a faint object ? Are there technical limitations to your setup, that prevent you from making longer exposures ? My experience is that, even by stacking frames, you won't get very reliable results on such a faint object by combining 4 * 16 seconds. Unless you switched telescope to a larger aperture too ?

Just for your information. Last night, I really pushed (for the first time) the limits of my telescope and CCD by following TmzV85 while it was varying between mag 17 and 18.5 (unfiltered). I made 240s exposures each. I know this is too long to capture the eclipses in sufficient resolution, but the advantage clearly is that the S/N ratio is very good.

Maybe the perfect solution is to stack exposures of 60s or so, for this type of faint object.

Any experiences from other CCD photometrists ?

Regards and good luck with TmzV85,

Tonny
CBA Belgium Observatory

> -----Original Message-----
> From: owner-vsnet-chat@kusastro.kyoto-u.ac.jp
> [mailto:owner-vsnet-chat@kusastro.kyoto-u.ac.jp]On Behalf Of Lew Cook
> Sent: vrijdag 28 januari 2000 10:07
> To: Taichi Kato; vsnet-chat@kusastro.kyoto-u.ac.jp
> Subject: [vsnet-chat 2617] Tmz85 
> 
> 
> After 3 weeks of cloudy nights, I am finally imaging Tmz85, but it is
> very faint - not visible on the 16 second images which have a limit
> of mag. ~16 - 17. I will have to stack at least 4 frames to do
> photometry on anything at all.
> 
> 
> =====
> Regards, Lew 
> 
> Try Lew's instant automatic observation plotter. 
> Copy a list of observations into Autoplot.xls
> - an Excel spreadsheet - a free download!
> http://vsnet.geocities.com/lcoo/autoplot.htm
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