ING La Palma Technical Note no. 95

Landolt Faint Photometric Standards

Introduction:    Positions uniformly accurate to 1 arcsecond have been measured for the 526 photometric standards in Landolt's (1992) list. The stars are located round the celestial equator, and are in the magnitude range mv 11.5 to 16.0.

The table
Printable version of the table (gzipped Postscript)

Star Positions:    All the positions given in the table are for equinox J2000.0. Where the proper motions are known the positions are given for epoch and equinox J2000.0; otherwise the epoch is that of the observational data. The positions held in the system catalogue of the telescope control computers are all at the epoch of the observation. The proper motions, where known, are listed and in these cases the epoch of the position is given. Most of the positions given here have been re-determined at the RGO in order to ensure compatibility with the setting accuracy of modern telescopes. The majority of the positions south of declination +02o were measured on copies of United Kingdom Schmidt Telescope Unit (UKSTU) Equatorial Survey J plates taken between 1979 and 1990. Positions north of declination +02o were measured using copies of the Palomar Observatory Sky Survey (POSS). The remainder of the positions were obtained from catalogues; notes to the table indicate where these other sources were used. Position measurements were made interactively using the PDS measuring machine at the RGO, and are based on the machine-readable B1950 version of the final Positions and Proper Motions (PPM) catalogue (Röser & Bastian, 1993). Coordinate transformations were based on measurements of 12 PPM stars, usually the faintest in the field accessible to the machine. Conversion to equinox J2000.0 was performed using the Starlink COCO package, (Wallace & Bly, 1991).

Proper Motions:    Catalogues were searched to see if proper motions of the photometric standards were already known. The Lowell Observatory Bulletins were used for proper motions of the Giclas named stars, and the Radcliffe Catalogue of Proper Motions for the Selected Area stars. The New Luyten Two Tenths catalogue (NLTT) was used to check for comments. These proper motions have been adopted here, except where noted. Stars with high proper motion were measured, where possible, on both POSS and UKSTU plates.

Names:    The name given to a star in the column LP name in the tables can be entered directly at the control console of any one of the WHT, INT or JKT. If no object of the same name exists in the user's own catalogue the telescope will automatically set at a position based on the data presented here. On the WHT the catalogue does not have to be read in explicitly, but is accessed automatically by typing GOCAT followed by the object name (eg 92-309). On the INT and JKT, however, it is necessary to input the catalogue, then request the object (eg INPUT SP0_5.CAT followed by NEXT 92-309 and then GO). On the INT and JKT no more than 500 sources can be held in memory, so the catalogue has been split, at Reynier Peletier's suggestion, into four parts. They are 0--5 hours inclusive; 6--11 hours; 12--17 hours; and 18--23 hours. Users can then read in any three parts and have sufficient coverage for the night. The files are:

  Catalogue Name No. of entries
  Lan05.CAT 136
  Lan611.CAT 134
  Lan1217.CAT 120
  Lan1823.CAT 136

Other catalogues available to the INT and JKT are listed in Technical Note 85.

Magnitudes and colours:    The table lists positions of the standard stars and the photoelectric photometric data measured by Landolt on the 1.5m telescope at the Cerro Tololo Observatory. Magnitudes as well as colours are given to help the observer determine a suitable exposure. The UBV photometry is based on the Landolt (1973 & 1983) system which was tied to the Johnson and Morgan (1953) system. The RI photometry is based on the Cousins (1976) system, which was derived from the Kron et al. (1953) data.


Cousins, A.W.J. 1976, Mem. R. Astron. Soc., 81, 25.

Giclas, H.L., 1963. Lowell Obs. Bulls. No. 120 and following.

Johnson, H.L. & Morgan, W.W. 1953, Astrophys. J., 117, 313.

Knox-Shaw, H., & Barrett, H.G.Scott, 1934, The Radcliffe Catalogue of Proper Motions in the Selected Areas 1-115, Oxford University Press, London.

Kron, G.E., White, H.S. & Gascoigne, S.C.B. 1953 Astrophys. J, 118, 502.

Landolt, A.U., 1973, Astron. J., 78, 959.

Landolt, A.U., 1983, Astron. J., 88, 439.

Landolt, A.U., 1992, Astron. J., 104, 340.

Luyten, W.J., 1979. New Luyten Two Tenths Catalogue, (NLTT), Minneapolis, Minn.

Pickering, E.C. & Kapteyn, J.C., 1918, Durchmusterung of Selected Areas between 0o and 90o, Annals of the Harvard College Observatory. Vol 101.

Röser, S., & Bastian, U.,1993, PPM Star Catalogue, Astronomisches Rechen-Institut, Heidelberg, Germany.

Wallace, P.T., & Bly, M.J.,1991 COCO--Conversion of Celestial Coordinates, Starlink User Note 56.7

Janet Sinclair