[Aavso-photometry] RE: Dark-subtracting flat frames

[Tandy, David]

 Donn,

I'd like to hear a description as well.  I am in the process of setting up
my observatory and have recently been bouncing around ideas on which
technique to use to obtain good flat fields.

I have two large pieces of white coreboard and I have a large piece of
semi-transparent white plastic.  I was thinking of using the white plastic
over the aperture of the scope and the white boards to reflect light from a
halogen source (a powerful bicycle light, actually).  The plastic has a few
scratches and several small bubbles but I figure that since the scope is
focused at infinity that those imperfections will hopefully be so diffuse as
to make no difference. But, I do have a couple of those light ropes laying
around, though, and that sounds like a pretty easy setup to implement.

- Dave

-----Original Message-----
From: aavso-photometry-bounces at mira.aavso.org
[mailto:aavso-photometry-bounces at mira.aavso.org] On Behalf Of Tom Richards
Sent: Tuesday, January 11, 2005 10:53 PM
To: aavso-photometry at mira.aavso.org
Subject: RE: [Aavso-photometry] RE: Dark-subtracting flat frames

> I have been using a 'rope light' string from Home Depot as a light 
> source for my flats.  It is on a dimmer and is wrapped in a circle at 
> the end ring of my RC-16.  The light bounces off of a white screen on 
> the dome and back into the scope.  The allows me to use low power for 
> IR and R band flats and full power for those pesky Blue band flats.
> 
> Donn
> 
[TJR] Fascinating idea, Donn. What color and how long is your rope?

Tom Richards

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