Fourth RXTE Observation of RS Oph in Outburst: Continued Fading
ATel #754; J. L. Sokoloski, G. J. M. Luna (SAO), K. Mukai (GSFC)
on 28 Feb 2006; 22:19 UT
Credential Certification: Jennifer L. Sokoloski (jsokolos@cfa.harvard.edu)
Subjects: X-ray, Binary, Cataclysmic Variable, Nova, Star, Transient, Variables
We report on the fourth Rossi X-Ray Timing Explorer (RXTE) observation
of the symbiotic recurrent nova RS Oph in outburst. A preliminary
analysis of this 3.42 ks observation, performed on Feb 26.87 UT
(approximately 14 days after optical maximum), reveals that the source
is continuing to both soften and fade in the hard X-rays. We find a
2-10 keV flux of (3.48+0.02/-0.11) e-10 erg/cm/cm/s and a 2-20 keV
flux of (3.59+/-0.1) e-10 erg/cm/cm/s. The fluxes have dropped by
about a factor of 2 in four days, as they did between Feb 18 and Feb
22 (outburst days 6 and 10; see ATel #741 and ATel #747). Taking a
distance of 1.6 kpc, the absorbed 2-20 keV luminosity is (1.1+/-0.05)
e35 erg/s. The absorbed 2-20 keV luminosity has fallen from a peak
value of (6.0+/-0.1) e35 erg/s 3 days after optical maximum (see ATel
#737). The hard X-ray spectrum can be roughly characterized by
thermal emission from a plasma with kT = 2.8 keV. The equivalent
width of the Fe complex near 6.6 keV is now less than 0.7 keV.
Although the RXTE data do not place strong constraints on the column
density, the spectrum is consistent with absorption solely from the
interstellar medium.
