Positions of galactic X-ray sources: -20° < lII < + 6°
Abstract
THE precise (20-60'') positions of nine X-ray sources, in the vicinity of the galactic centre are reported here. The data were obtained as part of the comprehensive survey of the galactic plane performed with the rotating modulation collimator (RMC) detectors on the SAS-3 X-ray observatory1-6. One of the nine is the binary X-ray source 4U1700-37 which has a well established optical counterpart that lies 7'' from the position reported here. This supports the validity of our calibration procedures2. The other eight sources GX349+2, 4U1702-42, 4U1705-44, MX1716-31, A1742-294, 4U1755-33, GX5-1, and 2S1803-245 lack established counterparts at other wavelengths. Our position for GX5-1 adds confidence to the previously proposed radio counterpart7 and our position for 4U1755-33 excludes its proposed optical counterpart8. Three of the unidentified sources have distinguishing X-ray properties : MX1716-31 is a flaring source9,10 and possibly an X-ray burst source11; A1742-294 is a transient12 and possibly also the X-ray burst source MXB1742-29 (ref. 13); and 2S1803-245 (MX 1803-24) is a very bright transient discovered14 in the course of this work.
- Publication:
-
Nature
- Pub Date:
- April 1978
- DOI:
- 10.1038/272701a0
- Bibcode:
- 1978Natur.272..701J
- Keywords:
-
- Astrometry;
- Position (Location);
- X Ray Sources;
- Collimators;
- Galactic Nuclei;
- Radiant Flux Density;
- Astrophysics