[vsnet 1386] Re: Identification of VX Cas

[Jan Manek <jmanek@mbox.vol.cz>]

       A note to VX Cas identification
  (and reply to message by Bjorn H. Granslo)

Although I don't have this star at my working list, I have checked 
the situation. There are at least three identification charts for 
VX Cas (with number 2 being recommended by GCVS - reference 197):
1) Harvard Bulletin No 883, (1931)
2) Izvestia Astromicheskoi Engelgardskoj Observatorii No.26 (1951)
3) Peremennye Zvezdy Vol.22, No.1, page 9 (1983)

Unfortunately I don't have at my disposal the recommended chart 
number 2) and the charts 1) and 3) give different identifications.
Following table gives positions of the two stars from A1.0 catalogue:

   R.A.  (2000.0)  Dec     magnitudes
  h  m  s       o  '  "      b    r       GSC     Comment
 0 31 41.246 +61 59 39.25  14.5  12.3  4019.0331  star from HB 883 (1931)
 0 31 30.785 +61 58 51.12  11.9  11.3  4019.1525  star from PZ 22, 1, 9 (1983)

Check of other references giving photometric observations shows that the
identification in HB 883 is incorrect, the star being too much red, while 
the second star probably conforms average maximum magnitude and color index 
of VX Cas (according to selected comparison stars and other published 
photometry). 

I suppose that GSC 4019.1525 is the correct star - VX Cas. As Bjorn
mentioned this star is also in TYCHO and althought photometry is not on
HIPPARCHOS/TYCHO CDROM disks set, it can be obtained from CDS.

Balanovsky's position in discovery note in AN 208, 35 (1918) is very 
approximate being reported as 0h 23.2m  +61o 12' (1855.0), because this 
star is not in BD and he probably only estimated the position from Bonner 
Durchmusterung charts. As he also gived no identification chart, he made 
possible the confusing identifications in later times.

In publication 3) are given secondary photoelectric photometric standards 
for VX Cas. These are listed in another table (positions and data from A1.0):

   R.A.  (2000.0)  Dec     magnitudes
  h  m  s       o  '  "      b    r       GSC     Comment
 0 31 37.383 +61 52 42.85  11.3  11.6  4019.1540  Star 1
 0 32 49.914 +61 59 11.29  11.0  11.2  4019.0271  Star 6

For these two stars are given in PZ 22,1,9 following values:

             U        B        V        R     
Star 1     11.435   11.436   11.201   10.933 
            0.007    0.007    0.008    0.006
Star 6     11.263   11.429   11.045   10.686   
            0.008    0.005    0.006    0.009

Best regards, Jan

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Jan Manek
Stefanik Observatory                Private :
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