[Aavso-photometry] SX Lib sequence star 114!

[arne]

arne wrote:
> Yenal Ogmen wrote:
>> Hi all,
>> Last night I observed SX Lib through v-band and while doing photometry I realized that my check star's mag differs from its seq value. This is 114 star with seq value 11.355 for V-band. I checked my previous obs of field and I got approx. same value of 11.15. This means 0.2 mag of difference. This cant be due to error I think. I didnt submit this as an chart error and wanted to ask you all first. Anyone noticed this before?
>>
> The 114 star, AUID  000-BBV-615, has B and V magnitudes as converted
> from the Tycho2 catalog.  This is near the faint limit of Tycho2, as
> evidenced by the quoted photometric error of 0.109mag.  I could believe
> that its true magnitude is 0.2mag brighter than this.  Remember that
> the original chart, a preliminary chart from 1981, had this star
> with a magnitude of 10.6, so we are certainly closer to the correct
> magnitude!  SX Lib is on the SRO calibration program and so all of
> its photometry will be updated in a future release.

Just as a heads-up, from one night of SRO all-sky calibration,
star 000-BBV-615 has V=11.13, B-V = 0.63, so closely matching
Yenal.  Hopefully we will get additional nights before updating
VSD so that we can change this incorrect magnitude currently
in the compDB.
Arne