[vsnet-chat 4816] Re: v553 lyr

[Brian Skiff <bas@lowell.edu>]

     If the star is mostly around mag. 10, then it is reasonable to use
Tycho-2 stars.  Use VizieR...

http://vizier.u-strasbg.fr/cgi-bin/VizieR

... to search Tycho-2 (catalogue i/259) within a 10' radius on the variable's
position (19 13 39.670  +27 18 22.01).  There are perhaps a dozen stars
in the field in the same brightness range.
     Correct the Tycho-2 VT to standard V using this table:

http://ftp.lowell.edu/pub/bas/starcats/bessell.tyc

...interpolating as necessary.  You will need to calculate BT-VT to use this
table.  Look also at the uncertainties associated with each Tycho magnitude.
If either BT or VT is > 0.05, I would not use that star even for visual
observations.  Usually stars fainter than mag. 10.5 to 11 fall in this
category.

\Brian

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