Re: NSV 10892 Photometry

[Michael Koppelman <lolife@bitstream.net>]

But we're talking about B-V, which isn't really represented in 
the TASS V-I. Although I doubt there is a 1 mag swing in B-V, 
I'm a little afraid of Doug assuming is B-V is "off".  It is 
what it is. Once his color corrections are done we'll know more.

One other question I have: if you take your V observation, then 
you switch filters, re-focus and take your B observation, the 
star may have changed by a substantial amount. It changes by 
0.16 mag/hour between a given max and min, or 0.03 mag in about 
10 minutes. Can't that screw up B-V sorts of measurements?

Michael K.

On Saturday, August 24, 2002, at 10:40  AM, jg wrote:

> You're seriously fogetting something.
>
> The TASS V-Ic data for this object barely has a range of 0.05, from 3
> nights in the August dataset (as Patrick has already pointed out) and
> from the original night's worth Tom sent you (unless that too was part
> of the 3 nights in the August dataset?).
>
> The TASS colour data says colour is stable.  At least at TASS V-Ic.
> Granted TASS V-Ic is wrong/different in comparison to Doug West 
> and Arne
> Henden V-Ic, but it's still stabley so.
>
> Tycho epoch BT and VT photometry are available, so I suppose you could
> take that and calculate average per day to try and get rid of the
> inherent scatter it has, to give multi-epoch colour sampling. Crop out
> stuff with background levels (BTbg and/or VTbg) greater than around 10
> first (arbitrary choice of value).
>
> http://vizier.u-strasbg.fr/viz-bin/nph-
> Plot/Vgraph/htm?I/239/0&445-1993-1