From: <waltc
Date: Fri, 7 Apr 2006 14:27:09 -0400

Chris,


Clearest skies,
Walt Cooney

> 
> From: Michael Koppelman <lolife
> Date: 2006/04/07 Fri AM 10:44:07 EDT
> Date: 2006/04/07 Fri AM 10:44:07 EDT
> To: "Chris Sauer" <chris
> 
> Try it both ways: do the photometry on the individual images and also  
> try it on a sum of all the images. The average of the individual  
> frames should roughly equal the value you get on a combined image.
> 
> It is shocking how many photons you lose through a V filter,  
> especially if you don't have the "E" chip. You get used to it.
> 
> If I were you, I would do ensemble photometry, meaning more than one  
> comp star, but many folks just use a single comp star, which is  
> easier and virtually all software will do it for you (such as  
> CCDSoft, which you used to acquire the images).
> 
> What software did you use to reduce the data? You didn't apply flat  
> darks and flat bias to the data frames, right? The HISTORY headers  
> are a little confusing in that regard.
> 
> Cheers,
> Michael
> http://www.lolife.com/astronomy/
> 
> 
> On Apr 7, 2006, at 5:53 AM, Chris Sauer wrote:
> 
> > Hi,
> >
> > The skies cleared and I was able to get 30 minutes of data on RS  
> > Leonis last
> > evening.  First off, I was amazed at how much the V filter  
> > attenuates the
> > light.  In 1 X 1 binning, I needed three minute subs to get decent ADU
> > counts on RS Leo itself.
> >
> > So my question now is what to do with the data?  I've calibrated  
> > the sub
> > frames separately via dark subtraction/flat division and I'm left  
> > wondering
> > what to do next.
> >
> > Do I combine all 10 images into one averaged final and perform the
> > photometry or do I approach each image separately?
> >
> > Also, what's the best way to perform the photometry?
> >
> > I've placed one of my calibrated images on my website in case  
> > someone would
> > like to check my work.  North is up.
> >
> >
> > Thanks for your help,
> >
> > Chris
> >
> > Sauer
> > Sent: Thursday, March 30, 2006 5:39 AM
> >
> > Hi,
> >
> > As most of you already know, this winter has been horrific for  
> > astronomical
> > imaging here in the northeast.  As a result, I'm only now getting  
> > to the
> > stage where I need to ask these questions despite having completed an
> > observatory back around Thanksgiving.
> >
> > Just this past week, I finally got a chance to finalize bringing the
> > observatory into an online mode.  My primary scope is mounted and  
> > working
> > well, polar alignment has been refined so that 2 minute unguided  
> > images are
> > showing no noticeable drift and the mechanism I devised for flats  
> > seems to
> > be working well.  In other words, I think I'm ready to begin my  
> > first "real"
> > imaging session of a variable star.
> >
> > I'm looking for suggestions on a good first target in the eastern  
> > part of
> > the sky (west is light polluted) between the hours of 19:00 & 00:00  
> > EST.
> > Additionally, I could use a little tutelage on exactly what to do  
> > with the
> > data once my images are calibrated with darks/flats.
> >
> > Are there any takers out there willing to assist a fledgling  
> > variable star
> > observer in coming up to speed?
> >
> > Thank you,
> >
> > Chris
> > _______________________________________________
> >
> >
> > _______________________________________________
> >
> 
> _______________________________________________
>