[vsnet-chat 1638] Photometry file update

[bas@lowell.Lowell.Edu (Brian Skiff)]

     Although I've said it before, I've come to a(nother) stopping point in
building my large file of BVRI photometry of faint stars.  It now contains
20,700 stars mostly fainter than V = 10.0, with median V close to 14.0, and
several sequences reaching down to mag. 21.  Among recent additions are regions
in both Clouds and along the southern Milky Way.  An improvement in our star-
catalogue-plotting software has allowed me to more reliably identify stars in
extremely crowded fields near the galactic center, and so I have added a number
of sequences near globulars there that I previously couldn't deal with.
     Since the flat ASCII file has grown to some 1.4Mb, I have made a
gzip-compressed version available, which is only about 400Kb:

http://ftp.lowell.edu/pub/bas/starcats/lonoes.stds     (uncompressed)
http://ftp.lowell.edu/pub/bas/starcats/lonoes.stds.gz  (compressed)

Many Web browsers will automatically decompress the .gz file.

     The idea behind the list is to provide photometric calibration anywhere
in the sky reliable at the 0.05-0.10 mag. level (at worst) especially for
wide-field CCD survey instruments, for use on archival plates/films, and to get
"instant" sequences for transient events such as novae and supernovae.  For
stars brighter than mag. 10, the assumption is that one will use the Tycho BV
photometry.  We're also planning to use the file to recalibrate the USNO-A
series magnitudes in hopes of placing them systematically close to the standard
system.  One can also use the list to make local adjustments to the GSC or
USNO-A catalogue magnitudes if desired.  Note that although many high-weight
bona-fide primary standards are included, most of the stars have not been
observed well enough to call them even secondary standards.  I have, however,
vetted each source as well as I can, and have omitted a number of papers 
containing garbage photometry.  For calibration that is both precise and
accurate, only the primary standards by Cousins and Landolt should be used.
     I am also building a file of references for the data I've added to the
file:

http://ftp.lowell.edu/pub/bas/starcats/lonoes.ref

This is gaining in completeness, but is still lacking mainly the hundreds
of references to papers on open and globular clusters.  Data-hounds may
nevertheless find some obscure but interesting citations there.  If you know
of a good set of photometry that's missing, I'll be glad to add it; just send
me the reference.

\Brian

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