NLTT - NLTT Catalog & First Supplement
The NLTT Catalogue (Luyten 1979, 1980) is a collection of stars on more than
800 Palomar Proper Motion Survey plates found to have relative annual proper
motions exceeding 0.18 arcsec. The motions have been determined by Luyten and
his coworkers by either hand blinking and measuring or with the automated-
computerized scanner and measuring machine built by Control Data Corporation
and located at the University of Minnesota. The new catalog replaces the LTT
Catalogues (Luyten 1957, 1961, 1962), wherein stars in the Bruce Proper Motion
Survey discovered to have motions exceeding 0.2 arcsec had been compiled. For
further information on the NLTT Catalogue itself, including discussions of
positional errors, estimation of magnitudes, star designations used in the
catalog, completeness, and accuracy of the measured motions, the introduction
to the published NLTT (see Volume I) should be consulted.
The First Supplement to the NLTT Catalogue (Luyten and Hughes 1980) is the
result of continued plate analysis and measurements during printing of the
NLTT. The Supplement contains data for 398 stars having motions larger than
0.179 arcsec annually.
Luyten, W. J. 1979, 1980, New Luyten Catalogue of Stars with Proper Motions
Larger than Two Tenths of an Arcsecond (Minneapolis: University of
Luyten, W. J. and Hughes, H. S. 1980, Proper Motion Survey with the
Forty-Eight Inch Schmidt Telescope. LV. First Supplement to the
NLTT Catalogue (Minneapolis: University of Minnesota).
Star designation in one of a variety of other catalogs. Identifiers from the
Bonner and Cordoba Durchmusterungen are used when they exist. Other
miscellaneous identifiers (Oxf = Oxford Astrographic Catalogue [AC]; Grw =
Greenwich AC; U = Upgren; R = Ross, etc.) are used for non-DM stars.
Identifiers without prefixes are DM or Luyten numbers from the Bruce Proper
Motion Survey (L numbers) or the Luyten-Palomar Survey (LP numbers), the former
in zones -45 to -89 deg and the latter in zones +89 to -44 deg. Alternate
identifiers are sometimes given in the notes. An asterisk (*) in the
identification field indicates that a note will be found in the "notes" file of
the catalog. The miscellaneous designations can be found in Fernandez et al.
(1983) and Lortet and Spite (1986).
The Right Ascension of the object.
The Declination of the object.
The galactic longitude of the object.
The galactic latitude of the object.
Due to the varying precision of the reported positions in the published catalog
(right ascensions in the polar caps [+90 to +80 deg; -45 to -90 deg] are
reported to minutes and tenths only, while other zones are given to seconds of
time) it was necessary to reformat the R.A. data to make them uniform.
Therefore, the right ascensions were computed in both seconds of time and
minutes plus tenths for all stars. The flag denotes the original format:
`1`: Original R.A. reported in minutes and tenths of time
`2`: Original R.A. reported in seconds of time.
Photographic magnitude. Magnitudes were estimated by Luyten for stars fainter
than 10m pg, but some magnitude data fields are blank. Magnitudes for brighter
stars were evidently taken from the source catalogs whose identifiers are
given, or from a variety of sources.
Flag for photographic magnitudes. A "+" indicates a magnitude fainter than the
Red magnitude. Magnitudes were estimated by Luyten for stars fainter than 10m
pg, but some magnitude data fields are blank. Magnitudes for brighter stars
were evidently taken from the source catalogs whose identifiers are given, or
from a variety of sources.
Flag for red magnitudes. A "+" indicates a magnitude fainter than the reported
Lower case letters represent estimated color classes or ranges, while spectral
types are reported where known.
Total proper motion is reported. The proper-motion vector is defined by the
2 2 2 1/2
Mu = ( Mu_a cos(delta) + Mu_d )
where Mu_a and Mu_d are the right ascension and declination components of the
proper motion, respectively, and delta is declination.
A colon (:) indicates uncertainty in the proper motion.
The direction of the proper-motion vector, as measured in the usual way (north
through east). The position angle is defined by the following set of equations:
Mu_a = Mu sin(theta) ; Mu_d = Mu cos(theta)
where Mu_a is the right ascension component of the proper motion, Mu_d is the
declination component of the proper motion, and theta is the position angle.
A colon (:) indicates uncertainty.
The letter "A" indicates that data have been changed for the machine-readable
version, and the record does not entirely match that of the published catalog.
In some cases, the star is entirely new and does not appear in the published
catalog. Deleted stars are listed in a separate table available from the
HEASARC upon request.
A "1" denotes a star from the First Supplement (Luyten and Hughes 1980). The
supplement stars have been merged into the main catalog entirely.
Notes regarding the star. All notes are contained in single records, i.e., no
notes for one star extend to additional records.
Right Ascension in J2000 coordinates, in sexagesimal format.
Declination in J2000 coordinates, in sexagesimal format.
BROWSE classification type. The classification is based on the `Type`
parameter, if one is available.
Questions regarding the NLTT database table can be addressed to the
HEASARC User Hotline.
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