Information on Service 'The PPMXL Catalog'

For a list of all services and tables belonging to this service's resource, see Information on resource 'The PPMXL Catalog'

Service Documentation

To query this data, you can use

• a web form (mainly for cone searches)
• the equivalent SCS service using your favourite VO client (e.g., topcat)
• our web-based crossmatcher to retrieve PPMXL data (e.g., proper motions and photometry) for your object list
• web-based ADQL or, preferentially,
• TAP for more advanced queries.

You can retrieve also the whole data set as a gzipped text file (43.5 GiB) from the download service. The columns in the text file are in database order as documented in the table info in DB order with columns separated by vertical bars ("|").

If you run DaCHS yourself, you can use a C booster kindly provided by Hailong Zhang. Instructions on usage are at the head of the file.

David Tholen kindly provided code to convert this into a collection of files for easy consumption by FORTRAN programs.

In 2016, John Vickers provided a global correction of the PPMXL proper motions based on extragalactic objects (2016AJ....151...99V). The results are given in the vickers_pmra and vickers_pmde columns. The coefficients we used are available at pmr-coefficients.csv and pmd-coefficients.csv. When used with the Code we actually used to compute the corrected values (adding healpix interpolation to the upstream from https://github.com/johnjvickers/PPMXL_Correction), these files have to be renamed pmr.csv and pmd.csv, respectively.

Overview

You can access this service using:

• form -- an interface for web browsers through an HTML form
• scs.xml -- a standard SCS interface as defined by the IVOA to access catalog-type data; SCS clients use http://dc.zah.uni-heidelberg.de/ppmxl/q/cone/scs.xml? to access the service

Copyright, License, Acknowledgements

• To the extent possible under law, the publisher has waived all copyright and related or neighboring rights to PPMXL. For details, see the Creative Commons CC0 1.0 Public Domain dedication. Of course, you should still give proper credit when using this data as required by good scientific practice.

  
• https://spdx.org/licenses/CC0-1.0.html

VOResource XML (that's something exclusively for VO nerds)

Note 1

Magnitudes from USNO-B should be used with care. Photometric calibration may be severely off for some plates.

For objects from PPMX (bit 1 set in flags), these magnitudes have a special meaning as per the following table:

PPMXL column	PPMX column	PPMX content
b1mag	Cmag	Catalogue magnitude from source
b2mag	Bmag	Johnson B magnitude
r1mag	Rmag	calc. Ru magnitude from source
r2mag	N/A	always None
imag	Vmag	Johnson V magnitude

See also the PPMX table info .

Note 2

magSurveys is built by concatenating the digits assigned to the surveys for b1mag, b2mag, r1mag, r2mag, and imag (in this sequence). The digits are those of given in Note h to Table 3 in 2003AJ....125..984M, except we do not distinguish POSS-II N and SERC-I as a part of POSS-I-N (i.e., both 7 and 9 are 7 here).

From this field, you can also see which of the surveys contributing to USNO-B had positions for the object.

Note 3

The flags column contains a bitwise or of warnings and similar conditions. The bit's meaning is as follows:

bit 0:	If set, one of the coordinates had an excessively large chisquare.
bit 1:	Row is from PPMX. These objects are mostly Tycho stars that were masked out of USNO-B. For these, the USNO magnitudes (b1mag through imag) have special meanings. See the note on magnitudes.
bit 2:	Row is from PPMX and replaces a single row from USNO-B. This is done when the astrometry from PPMX was better (in terms of error estimates) than the astrometry of the corresponding PPMXL object.
bit 3:	Row replaces multiple USNO-B1.0 objects. When PPMX contains an object that has more than one counterpart in PPMX-L, all such counterparts are discarded on the assumption that they should have been matched in USNO-B1.0 or result from erroneous matches. For these rows, bit 1 is always 1.

Note 4

nobs may be NULL for stars coming from ARIHIP or Tycho-2 via PPMX (i.e., bit 1 is set in flags).