[vsnet-chat 1851] Re: [vsnet-chart 155] Re: Chart of SN1999by

[Taichi Kato <tkato>]

Re: [vsnet-chart 155] Re: Chart of SN1999by

> USNO mag seems not to gleatly differ except NGC 2841 2 star (it is on
> the edge of NGC 2841), but I agree that observers should use Brian's
> list as comparison.

    In this case, it looks USNO r magnitudes better fit V magnitudes than
our formal transformation (V = r + 0.375(b-r)).  The large and incorrect
color indices in USNO magnitudes suggest the poor color calibration
may have been the principal cause of the discrepancy.  I don't see why
NGC 2841 2 so largely differs in these catalogs (observers may as well
check its variability).  H/T magnitudes is consistent with the ground-based
BV measurement.

092150.7 +510036 (2000.0) 1105 TYC3431.625.1
092150.7 +510036 (2000.0) 1105H 0.56 HIP045922 plx=6.65(4.01) (0.00 0.07)

Regards,
Taichi Kato

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