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NLTT: Help

NLTT - NLTT Catalog & First Supplement


Overview

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.


Catalog Bibcode

1980LP.....55....1L

References

Luyten, W. J. 1979, 1980, New Luyten Catalogue of Stars with Proper Motions
       Larger than Two Tenths of an Arcsecond (Minneapolis:  University of
       Minnesota).

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).

Parameters

Name
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).

RA
The Right Ascension of the object.

Dec
The Declination of the object.

LII
The galactic longitude of the object.

BII
The galactic latitude of the object.

Prec_Flag
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.

Photmag
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.

Photmag_Flag
Flag for photographic magnitudes. A "+" indicates a magnitude fainter than the reported value.

Redmag
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.

Redmag_Flag
Flag for red magnitudes. A "+" indicates a magnitude fainter than the reported value.

Spect_Type
Lower case letters represent estimated color classes or ranges, while spectral types are reported where known.

Tot_Proper_Motion
Total proper motion is reported. The proper-motion vector is defined by the equation:

                  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.

Proper_Motion_Flag
A colon (:) indicates uncertainty in the proper motion.

Angle
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.

Angle_Flag
A colon (:) indicates uncertainty.

Addenda_Flag
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.

Supplement_Flag
A "1" denotes a star from the First Supplement (Luyten and Hughes 1980). The supplement stars have been merged into the main catalog entirely.

Remarks
Notes regarding the star. All notes are contained in single records, i.e., no notes for one star extend to additional records.

RA_J2000
Right Ascension in J2000 coordinates, in sexagesimal format.

Dec_J2000
Declination in J2000 coordinates, in sexagesimal format.

Class
BROWSE classification type. The classification is based on the `Type` parameter, if one is available.


Contact Person

Questions regarding the NLTT database table can be addressed to the HEASARC User Hotline.
If you have any problems, please consult the help page or mail ledas-help@star.le.ac.uk
 
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