[Aavso-photometry] Questions abt Z and Photometry - APD, Vol 50, Issue 3

[Brad Walter]

Steve, if the Reference star values are all zero in the Maxim CSV output
file, then you probably didn't enter the reference star values in the box
below the selection box for the type of star you are checking. If you don't
enter the value, Maxim assumes it is zero. It is a little confusing because
you enter the magnitude after you "click on" the star and before you select
the type for, or click on, the next star. The box is grayed out until you
click on a reference star. 

A reference star in Maxim is a comparison star that you will use to measure
the magnitude of the target and check stars. A check star is a star of known
magnitude - one for which you have sequence data and is known not to be
variable. I usually pick one that is slightly dimmer than the target star
and as close in color as is available after selecting one or more reference
stars. For data submitted to AAVSO you usually use one reference
(comparison) star.  Maxim does differential photometry of the check star as
well as your target star. In a perfect world the measured magnitude of the
check star would not vary. But of course it does due to random and
systematic errors in your measurements. The standard deviation and any
trends in the measured magnitudes of the check star give you a means of
evaluating error and non intrinsic trends in data of your target star. The
standard deviation of the check star is often used as the error estimate of
the target star measurements, which is why you pick one as close as possible
in magnitude and color to the target. 

I have never used an artificial star and can't answer that part of the
question. 
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Message: 3
Date: Tue, 01 Jan 2008 15:11:04 -0500
From: Steven Orlando <sorlando at sorlando.com>
Subject: Re: [Aavso-photometry] Questions about Z And Photometry
To: Aavso-photometry at mira.aavso.org
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	reply-type=original

What is the difference between a reference and a check star?

AIP4WIN doesn't use the term reference star. Maxim DL does, and when you do
photometry in MaximDL, you get in the csv file that the REF all zeros.

When I submit my exoplanet data to Bruce Gary, he likes to use an artifical
star as a reference.

Can someone please sort this out for me? I am confused!

Steve