orbits). All orbits have been
graded on a 1 - 5 scale, as in earlier catalogs; the grading scheme has been modified,
however, as described below. Ephemerides are included for all orbits with complete
elements, as are plots including all associated data in the current Washington Double Star
database.
<br><br><br>
<font color = green>2005 Mar:</font> The format of the catalog was extensively modifed. A
description of the new format is given <a href="orb6/format.html">here</a>.
<br><br>
<font color = green>2007 Aug/Sep:</font> Orbit catalog notes were merged with those of the
Washington Double Star Catalog and later the Fourth Interferometric Catalog, in order to
create a common notes file (and file format) for all USNO double star catalogs. Cleanup of
old notes is never really completed, of course - we welcome notification of any errors you
may run across.
<br><br>
<font color = green>2013 Aug:</font> A version of the elements file was created which
includes delimiters, for those users who work with SQL-type databases. This is a work in
progress - please let us know of any problems with this file.
<br><br>
<font color = green>2013 Nov:</font> A link was added to the "master file" database of all
orbits. A few comments are in order. First, the grade (col. 244-246) is here a decimal;
the range of grades is 0.0 - 5.5 (rounded to an integer value in the main catalog) and
differences in grade of a few tenths are usually insignificant. A grade of 6.0 is given
for orbits considered too old to be worth grading; vales of 7.0 are reserved for orbits
with incomplete elements, values of 8.0 for interferometric orbits lacking rho/theta information;
and values of 9.0 for astrometric orbits. Column 248 is a flag indicating a note, while column
250 is a yes/no flag indicating the solution considered currently "best".
<br><br>
<font color = green>2014 Sep:</font> A new flag "m" was added for values of T0 expressed in
modified Julian date. Although MJD (= JD-2,400,000.5) differs by only 0.5d from the truncated
JD values (JD-2,400,000) flagged with "d", it was felt that a separate code for T0 values
published in this unit would be less confusing than modifying published values for the catalog.
<font color = green>2015 Mar:</font> The routine for generating ephemerides was extensively
modified by George Kaplan (USNO), who converted it to double precision, with IAU expressions
for Besselian epochs. This mainly affects those orbits with very short periods, resulting
in changes to predicted theta values at the 0.1deg level or smaller. Also, separations for any
set of ephemerides where the minimum value of rho is 0.01" or less are converted to mas; a
flag "m" is added to the right of the last value. (Separations greater than 999" will similarly
be converted to arcmin - with an "M" flag - although no such pairs are currently included in
the catalog.)
<font color = green>2017 Sep:</font> The routine for weighting individual measures was
modified. All orbits were then regraded, and new figures were generated which included all
measures in the WDS. The new weighting scheme is described in the "grading" section below.
<br><br><br>
<h3>Contents:</h3>
<ul>
<li> <a href="orb6/orb6text.html#intro"> Introduction </a>
<li> <a href="orb6/orb6text.html#grading"> Orbit grading method </a>
<li> <a href="orb6/orb6text.html#description"> Description of the catalog </a>
<li> <a href="orb6/orb6text.html#stats"> Catalog statistics </a>
<li> <a href="orb6/orb6text.html#thanks"> Acknowledgments and references </a>
<br>
<br>
<li> <b><font color = green>Orbital elements:</font></b> <a href="orb6/orb6orbits.html">html</a> ,
<a href="orb6/orb6orbits.txt">text</a> ,
<a href="orb6/orb6orbits.sql">sql</a> (text file with delimiters)
<li> <b><font color = green>Ephemerides:</font></b> <a href="orb6/orb6ephem.html">html</a> ,
<a href="orb6/orb6ephem.txt">text</a>
<li> <b><font color = green>Notes:</font></b> <a href="orb6/orb6notes.html">html</a> ,
<a href="orb6/orb6notes.txt">text</a>
<li> <b><font color = green>References:</font></b> <a href="orb6/wdsref.html">html</a> ,
<a href="orb6/wdsref.txt">text</a>
<br>
<br>
<li> <b><font color = green>Orbital elements:</font></b> <a href="orb6/orb6frames.html">frames version</a> *
<br>
<br>
<li> <a href="orb6/orb6format.txt"> Formats of elements and ephemerides files</a> (text versions)
<li> <a href="orb6/orb6c.html"> Calibration Candidates </a>
<li> <a href="orb6/top_25.txt"> Top 25 Orbit Calculators</a>
<li> <a href="orb6/orb6.master"> "Master file" database</a>
</ul>
<br>
* Please note: The frames version of the orbit catalog appears to be incompatible with some operating systems / browsers. <i>Cavaeat emptor!</i>
<br>
<br>
Your comments regarding either style or substance are welcome. Please inform the authors
of any errors you run across in the catalog, as well as missing orbits, etc. We would also
welcome notification (and/or copies) of any newly published elements.
<br><br><br>
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