SD (S0): Southern Durchmusterung (19950102)
FILES:
Name Magnitude range Dec (2000) range #Stars
sd70.s0 1.0 <= mag <= 7.0 -24 < Dec < -01 2569
sd7180.s0 7.1 <= mag <= 8.0 -24 < Dec < -01 5402
sd8185.s0 8.1 <= mag <= 8.5 -24 < Dec < -01 7681
sd8690.s0 8.6 <= mag <= 9.0 -24 < Dec < -01 18814
sd91a.s0 9.1 <= mag <=10.0 -13 < Dec < -01 50889
sd91b.s0 9.1 <= mag <=10.0 -24 < Dec <= -13 49400
sd_nomag.s0 NO MAGNITUDES -24 < Dec < -01 79
CONTENTS: Southern Durchmusterung; NSSDC 1989 version (134834 stars)
DATASET: These files compose HyperSky dataset S-20, version 19950102. Availability on HyperSky CD-ROM: Vol. 2 (1995)
DESCRIPTION: These datafiles contain the Southern Durchmusterung (SD) star catalog. The SD (SD, Schoenfeld 1886, Becker 1949, Schmidt 1967) is a visual survey of stars in declination zones -02 to -23 degrees (equinox 1875), completed as an extension to Argelander's (1859-62) monumental Bonner Durchmusterung (BD). Schoenfeld's survey was carried out using the same methods as had been used for the BD, which Schoenfeld had helped to compile as one of Argelander's assistants. The procedure consisted of allowing the telescope to drift along the mean declination of each zone and recording the positions and magnitudes of stars crossing the transit line of each field.
The SD survey goal was to extend the BD to declination -23 degrees (a plan originally adopted by Argelander) with approximately the same magnitude limits, although the primary instrument was of larger aperture (159 mm) than the 78-mm telescope used for the BD. Thus, where the BD magnitude estimates extend to 9.4 mag with all fainter stars assigned a magnitude of 9.5, the SD magnitude estimates extend to 9.9 mag with all fainter stars assigned a magnitude of 10. The fainter limit of the SD results in an increase in the average number of stars in each zone of a thousand or more over the BD. As with the BD, the SD contains a rather large number of stars fainter than 10.0 mag and even occasionally as faint as 11 mag. Positions are given to the nearest 0.1 sec in right ascension and 0.1 arcmin in declination as in the BD.
The National Space Science Data Center (NSSDC) 1989 machine-readable version of the SD is a result of collaborative efforts by the Centre de Donnees Astronomiques de Strasbourg and the Astronomical Data Center (ADC) at the NASA/Goddard Space Flight Center. Corrigenda listed in the original SD volume and published by Kuestner and Sticker were also incorporated into the machine file.
The HyperSky files are based on the version of the catalog available as NASA/GSFC Astronomical Data Center (ADC) catalog #1119.
DATA: The HyperSky datafiles contain the following data from the SD catalog:
POSITION: Right Ascension and Declination are based on the 1855 catalog values, precessed to equinox 2000. The 1855 SD positions are given to 0.1 min of RA and 0.1 arcmin of Declination. Thus the precessed RA and Declination are also limited to this accuracy.
MAG: Visual magnitude estimate. Note that the SD bright magnitude limit is 1.0. Stars brighter than 1.0 have been assigned this value, for example, Sirius (ALPHA CMa).
TY: not provided, since no (spectral) types are given by the SD.
IDENTIFICATION: The SD number of the star, in the form +DD NNNN, where DD (+ or -) is the Declination zone number, and NNNN is the assigned number of the star within the Declination zone. A single code letter may be optionally be appended to this number. Lower case code letters represent supplemental (footnoted) stars added to the catalog via published corregenda. Upper case letters and other characters are flags that indicate changes to the original data or to the status of a star in the catalog. Notes and lists associated with these flags are available in the ADC catalog documentation. The codes have the following meanings:
* Data were corrected as a result of corrigenda, or there are special notes associated with the star.
D The star has been deleted in a later edition of the catalog. This was done by overstriking entries with horizontal lines.
M The star was noted as "missing" in a list published by Pickering (1907). There is only one such star in the SD. This entry was verified by R. A. Downes and at the ADC.
COMMENTS: A single comment line will appear only for stars in the file sd_nomag.s0, where the magnitude was replaced by a code. The code translation appears as a one-word comment, which can be one of "nebula", "variable", "nova", or "cluster".