[vsnet-chat 4337] Re: [vsnet-be 53] Of comp stars, extinction, and colors...

["Sebastian Otero" <varsao@fullzero.com.ar>]

About theta CrB comparison stars, obviously I don't observe it but i think
that the best choices for comparisons are:

zeta Boo   V= 3.78, B-V= 0.05
eps Her    V= 3.91, B-V= -0.02
eps CrB   V= 4.14, B-V=  1.23

The last one is very good because it is near and is similar in brightness.
If you used my color techniques, there would  be no problem.
It happens that theta CrB stays most of the time at V= 4.14 !!! the same
magnitude, although with a -0.13 color index.


Thom wrote:

> Iot Ser and Eps Her are the two primary comparison stars I plan to
use, and Eta CrB and Chi Boo will be the check stars.  Here are my
reasons for choosing those stars.  The logic of my reasons have
applicability to choosing comparison stars in general, especially
for blue variables.


BUT again the brightness differencies are too big and I think this is the
most important point.
iota Ser=  V= 4.52, B-V= 0.04
0.1, 0.2 mag. is good. 0.4 mag. difference is too much, at least if we want
(and we want!!) to be accurate.

eta CrB=  V= 4.98, B-V = 0.58
This is impossible!! Are we talking' bout visual observation or PEP??

chi Boo= V= 5.26, B-V = 0.03
????


Cheers,
Sebastian.


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