XTE J1118+480
Abstract
R. Remillard, E. Morgan, D. Smith, and E. Smith report for the RXTE ASM team at the Massachusetts Institute of Technology and at Goddard Space Flight Center, NASA: "The RXTE All-Sky Monitor has detected x-ray emission from a new source, XTE J1118+480. The ASM position is centered at R.A. = 11h18m17s, Decl. = +48o03'.0 (equinox 2000.0; 90-percent-confidence radius 6'). The average x-ray intensity (2-12 keV) was 39(8) mCrab on Mar. 29. Retrospective ASM analysis indicates that the x-ray flux has been slowly rising since Mar. 5. Another modest outburst had previously occurred during Jan. 2-29, peaking at 37(3) mCrab on Jan. 6. The SIMBAD database lists only an unremarkable guide star (V about 11) near the x-ray position. The source was confirmed in an 800-s RXTE pointed observation beginning on Mar. 29.968 UT. Rapid flares (e.g., 10 s) were seen, reaching a factor of 5 above the baseline flux near 25 mCrab and suggesting a Galactic x-ray source. No pulsations were detected. The x-ray spectrum does not vary appreciably during intense flares. Preliminary spectral analysis indicates a power law visible to 30 keV. The photon index is roughly 1.8, which is similar to Cyg X-1 in its hard state. The high galactic latitude (+62 deg) and x-ray properties present a puzzling combination, and observations at other wavelengths are urgently needed."
- Publication:
-
International Astronomical Union Circular
- Pub Date:
- March 2000
- Bibcode:
- 2000IAUC.7389....2R