NLTT (S0): New Luyten Two-Tenths Catalog of Stellar Proper Motions (19930529)
FILE: nltt.s0 (58845 stars)
CONTENTS: New Luyten Two-Tenths Catalog of Stellar Proper Motions
DATASET: This file comes in HyperSky dataset S-17, version 19930529. Availability on HyperSky CD-ROM: Vol. 1 (1993)
DESCRIPTION: This datafile contains a total of 58845 stars from the NLLT Catalog (Luyten 1979, 1980) and its first supplement (Luyten and Hughs 1980) found to have relative annual proper motions exceeding about 0.18 arcsec. (hence the name "two-tenths"). The stars have been found by a study of more than 800 Palomar Proper Motion Survey plates by Luyten and his coworkers. This catalog replaces the LTT Catalogs (Luyten 1957, 1961, 1962), which contained stars in the Bruce Proper Motion Survey having proper motions exceeding 0.2 arcsec. The introduction to the NLTT (Volume I) should be consulted for more information on the NLTT catalog itself, wherein can be found discussion of positional errors, magnitude estimates and designations of stars used in the catalog.
The HyperSky catalog file is based on the machine-readable version of the catalog, as provided on the NASA/GSFC Astronomical Data Center (ADC) cd-rom "Selected Astronomical Catalogs", Volume 1.
Usage note: In order to easily find stars from this catalog in a general star field, you can use HyperSky menu options to highlight all stars from this catalog with horizontal tickmarks, vertical tickmarks, or both.
DATA: The HyperSky datafile contains the following data from the catalog:
POSITION: Right Ascension and Declination are based on the 1950 catalog values, precessed to equinox 2000.
MAG: the photographic magnitude as provided in the catalog, which can range from -1.4 to 21.2.
TY: the catalog spectral type, truncated to two letters if necessary. For most stars only a partial spectral type, or no spectral type, were available.
IDENTIFICATION: The NLTT does not provide its own identification scheme. Instead, stars identifications are provided from a number of alternate existing catalogs. Identifiers without prefixes are DM (Durchmusterung) numbers or Luyten numbers from the Bruce-Palomare Survey (LP numbers). If identifiers from the above catalogs are not available, prefixes are used to indicate alternate catalogs, including but not limited to:
* Oxf = Oxford Astrographic Catalogue [AC]
* Grw = Greenwich AC
* U = Upgren
* R = Ross
The designation "Anon.", for anonymous, will appear in the absence of any catalog identification.
COMMENTS: The comment lines contain the following information, provided if available for each star:
* A line starting with "mr=" giving the red magnitude.
* A line starting with "sp=" giving the untruncated spectral type.
* A line starting with "PM=" giving the annual proper motion in arc seconds, possibly followed by a colon (:) to indicate uncertainty. A second value, following a slash (/), gives the proper motion direction angle in whole degrees, measured from North through East.