GS 1843+00
Abstract
T. Takeshima, Goddard Space Flight Center and Universities Space Research Association, reports: "The countrate history of the transient x-ray binary pulsar GS 1843+009 obtained with ASM onboard RXTE indicates that the source intensity rose between 1997 Jan. 26 and Feb. 1 to a flux level of 15 mCrab in the band 2-10 keV and remained at 15-30 mCrab level since then. This is the first time that the source has been seen in the x-ray band since the discovery with Ginga in Apr. 1988 (IAUC 4583, 4587). An RXTE observation with PCA and HEXTE was carried out on Mar. 5.0875-5.2549 UT. The averaged source countrate in PCA (2-60 keV) was 806 counts/s, corresponding to a flux level of 62 mCrab. The pulse period (barycentric) was 29.565 +/- 0.002 s at the epoch of Mar. 5.1712, which is consistent with the recent BATSE results (IAUC 6586). The obtained pulse period is about 0.2 percent longer than that reported from Ginga observations. The pulse fraction is 31 percent (peak to bottom). The pulse profile is double-peaked, but the secondary minimum is 2.6 percent above the average. The energy spectrum (2-60 keV) is expressed as a sum of an exponential cut-off power-law component [photon index -0.20 +/- 0.06, cut-off energy 13.0 +/- 0.4 keV, and 2-10-keV flux of (1.09 +/- 0.12) x 10E-6 erg sE-1 cmE-2] and a blackbody component [kT = 1.16 +/- 0.07 keV and 2-10-keV flux (2.4 +/- 0.2) x 10E-6 erg sE-1 cmE-2] with photoelectric absorption by cold matter of nH = (6.2 +/- 0.5) x 10E22 cmE-2."
- Publication:
-
International Astronomical Union Circular
- Pub Date:
- March 1997
- Bibcode:
- 1997IAUC.6595....2T