[vsnet-chat 1531] Re: Comparison star of R CrB (McAdam)

[Taichi Kato <tkato>]

Re: [vsnet-chat 1530] Comparison star of R CrB (McAdam)

Date: Sun, 03 Jan 1999 10:11:54 GMT
From: dave@telf-ast.demon.co.uk (Dave McAdam)
Subject: Re: [vsnet-chat 1530] Comparison star of R CrB

In message <199901030922.SAA25138@ceres.kusastro.kyoto-u.ac.jp>
       Taichi Kato wrote:
> Comparison star of R CrB
> 
>    Some of our observers have noted that the following comparison star of
> R CrB (closer of the two nearby 7-th mag stars)
> 
> GSC2039.642 154740.76 +282810.0 (2000.0)  7.50 4
> GSC2039.642 154740.82 +282809.5 (2000.0)  7.17 1
> 154740.8 +282807 (2000.0) SAO84005 7.8 7.3 F2
> 154742.6 +282731 (2000.0) HD141352 7.43 7.77 F2
> 154740.8 +282809 (2000.0) 743H 0.47 HIP077373 plx=10.81(0.87) (0.01 0.01)
> 
> has been recently assigned a magnitude of 7.4 in "The AAVSO Variable Star
> Atlas, Second Edition", while older AAVSO charts assigned it the magnitude
> of 7.2.  There have been arisen several questions:
> 
>   1) When and on what charts this revision was made?
> 
>   2) When individual observers have switched the magnitude from 7.2 to 7.4?
> 
>   3) What magnitudes were/are used for this star in VS organizations of the
> world?  (The VSOLJ has traditionally used the magnitude 7.2, as taken
> from the old domestic handbook of selected AAVSO charts, published under
> permission of the AAVSO).
> 
>   4) If the switch to the new magnitude has been made, how have been older
> estimates treated?  Have they been rescaled, or left as original?
> 
> Regards,
> Taichi Kato
> 

This is comparison 'G' on the current BAAVSS sequence charts 041.02.
Earlier BAAVSS charts (R G Andrews 1959 and previous) identified this
comparison with the Hagen number '1' (= Harvard 'f').

The Harvard magnitude of 7.18 has been used by the BAAVSS since the 1890's
and our records are referred to 041.02 with only a small re-reduction prior
to 1981 due to the amendment of comparison 'D' from 6.15 to 6.28m.
Re-reduction took into account extra (fainter) Hagen numbered comparisons
used by some observers in the 1930's.

The charts and long-term lightcurve are available on BAAVSS home pages.
Regards,
Dave
-- 
Dave McAdam                                   dave@telf-ast.demon.co.uk
BAAVSS Secretary                       http://vsnet.telf-ast.demon.co.uk/

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