[Aavso-photometry] Comps for VZ Sgr

[arne]

arne wrote:
> Jim Roe wrote:
> 
>>I've taken some images of VZ Sgr in V and Ic but I can't find comps.  I 
>>notice that some folks are reporting I in the "recent observations" 
>>file.  Where are you getting the comps?
>>
> 
Giorgio Di Scala has been kind enough to send me calibrations for
three of the stars in the AAVSO sequence, based on a number of clear
nights and Landolt standards.  For those who are following this
RCB star as it fades, here are some bright comparison stars.  Use
the old 'e' chart for their identification.
ID       V            B-V          V-Rc         Rc-Ic        V-Ic
L 109  10.98 (0.016)  0.33 (0.02)  0.20 (0.02)  0.24 (0.02)  0.44 (0.02)
N 115  11.58 (0.016)  1.22 (0.02)  0.64 (0.02)  0.55 (0.02)  1.19 (0.02)
P 117  11.78 (0.016)  0.28 (0.02)  0.19 (0.02)  0.22 (0.02)  0.41 (0.02)

The (B-V) colors on this calibration agree nicely with David Kilkenny's
photoelectric calibration in 1983.  The V magnitudes are 0.04 fainter
than Kilkenny; my guess is that this is due to the crowded nature of
this field.  Use Di Scala's values for now for CCD work, and place
"Di Scala" in the comment field of your submission.
Arne