[vsnet-chat 5345] Landolt coords revised

[Brian Skiff <Brian.Skiff@lowell.edu>]

     I have made a comprehensive revision of my list of accurate coordinates
for the ~1150 Landolt standard stars.  The main effect is to bring the list
into the post-Hipparcos era, and to improve both the precision and the accuracy
of the positions.  Nearly all the large proper motion stars now have precise
positions for both epoch and equinox 2000 using recently published catalogues
of high precision.  The final list was matched against the GCVS v4.1 in VizieR
to look for variable-star names.
     Stars are included from four papers:

L73    1973AJ.....78..959L
L83a   1983AJ.....88..439L
L83b   1983AJ.....88..853L
L92    1992AJ....104..340L

Note that this includes the "equipment stability" paper (L83b), which contains
observations made in the same series as went into the main 1983 standards
paper.  These stars include a substantial number of excellent UBV standards
located from -75 to +30 Dec, though the R,I observations are not numerous
enough to consider them high-weight standards for the redder passbands (but
okay for extinction determinations and photometry at the ~0.02 mag. level).
     A 10-line sample is shown below.  The first column shows the name used
by Landolt, followed by coordinates at 0".1 precision.  Most of the positions
are reliable at the 0".2 level or better.  Column 's' shows a code for the
source of the position, given in the main list.  GSC and HD/DM numbers are
shown next, with the Durchmusterung names following the HD convention.  The
remarks contain additional IDs relevant to the identification (AG, ADS, etc)
or photometric stability of the star, viz. GCVS and NSV numbers.  More
extensive remarks are contained in a separate file of notes.  The notes, in
particular, show "best" proper motions for the many large-motion stars, and
provide a compendium of comments about variability among the standards reported
in papers other than Landolt's.
     I found two errors in my previous list:  a 1' Dec typo, and another star
that was misidentified.  Both involve faint, little-used standards.
     The flat-ASCII files are copied to the Lowell ftp area at:

http://ftp.lowell.edu/pub/bas/starcats/landolt.all     (66Kb)
http://ftp.lowell.edu/pub/bas/starcats/landolt.notes   (9Kb)

I will be pleased to e-mail the files to you if you have problems copying
them on-line.

\Brian

-------------------------------------------------------------------------------

Landolt           RA   (2000)   Dec    s     GSC       HD/DM      Remarks
SA 140-84       0 03 38.09 -28 41 47.0 U  6418-1076  CD-29 18942
SA 140-85       0 03 38.51 -28 37 25.4 U  6418-0783  CD-29 18943
HD 315          0 07 44.11 -02 32 55.2 T  4666-0548  HD 315       NSV 15027
SA 116-99       0 17 40.70 -13 53 41.8 U  5267-1060
SA 68-280       0 18 04.83 +15 54 20.4 B  1179-0537
SA 116-180      0 18 04.84 -13 57 22.7 U  5267-0745
SA 68-216       0 18 18.37 +15 49 15.6 B  1179-0394
SA 200-1172     0 25 47.57 -74 12 07.1 U  9140-0687
SA 200-1173     0 25 49.11 -74 08 33.5 U  9140-1404
SA 44-28        0 29 04.55 +30 23 06.4 T  2262-1382

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