Re: color terms for Rochester Mark IV

[Tom Droege <tdroege2@earthlink.net>]

This is great news.  This means that you are running MICHAEL and actually 
pointing it where you want to point it.  This is better than I am doing 
with TOM2.

Tom Droege

At 05:27 PM 9/1/02 -0400, you wrote:

>   I've taken images of the stars in SA 110 and SA 112 calibrated
>by Landolt.  Based on a photometric solution which includes about
>90 measurements in each passband, I find the following color terms:
>
>             V  =  v  -  0.046 * (v - i)
>             I  =  i  +  0.055 * (v - i)
>
>My photometric solution doesn't use extinction: instead, it assigns
>each frame a different zero-point, which removes the bulk of the
>atmospheric extinction (the differential extinction across the frame
>is small enough that I can ignore it for these rough purposes).
>
>   It's good news: the natural response of the TASS systems is
>pretty close to the Johnson-Cousins V and I passbands.
>
>   What I've discovered is that I need to find a better set of
>calibrators.  There aren't all that many stars in either SA 110 or
>SA 112 which are bright enough for my Mark IV to get a decent signal
>in a 60-second exposure.  What I'd really like is a dense set of 10 or
>so stars within a single 4x4-degree field, with good calibrated
>magnitudes, in the range 7 < V < 10.
>
>   Anyone know of such fields?
>
>                                         Michael Richmond