F. E. Marshall, Laboratory for High Energy Astrophysics, Goddard Space Flight Center (LHEA/GSFC); J. H. Swank, LHEA/GSFC; B. Thomas, Hughes STX and LHEA/GSFC; L. Angelini, Universities Space Research Association (USRA) and LHEA/GSFC; A. Valinia, National Research Council and LHEA/GSFC; and K. Ebisawa, USRA and LHEA/GSFC, report the discovery of an x-ray nova with the Proportional Counter Array (PCA) onboard the Rossi X-ray Timing Explorer (RXTE). The source was first seen for about 20 s on Jan. 16.016 UT during a satellite maneuver and seen again during a second maneuver on Jan. 18.147. The best-fit position for the source is R.A. = 17h09m.3, Decl. = -26o44' (equinox 2000.0; estimated systematic uncertainty about 6'). During both observations, the 2-10-keV source intensity was about 0.14 times that of the Crab. There is no catalogued hard x-ray source near this position, but the source may be associated with the ROSAT All-Sky Survey (IAUC 6420) source 1RXS J170930.2-263927, which is 5' from the best-fit RXTE position. The ROSAT source was 13 mCrab in the band 1-2.4 keV. Column densities of spectral fits to the PCA slew data depend on the model; a power law has a photon index of 3.06 +/- 0.06 and absorption by a column density of (5.8 +/- 0.6) x 10E22 cmE-2, while a bremsstrahlung model has kT = 4.7 +/- 0.2 keV and half the column density. Additional observations are encouraged, to determine an accurate position of the new source, test the possible association with J170930.2-263927, and determine other properties."
International Astronomical Union Circular
- Pub Date:
- January 1997