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Soft X-ray decline and cessation of pulsation in RS Oph

ATel #801; J Osborne, K Page, A Beardmore, M Goad (Leicester), M Bode (Liverpool John Moores), T O'Brien (Manchester), G Schwarz (West Chester), S Starrfield, J-U Ness (Arizona State), J Krautter (Heidelberg), J Drake (SAO), A Evans (Keele), S P S Eyres (Central Lancashire)
on 1 May 2006; 18:22 UT
Credential Certification: Julian P Osborne (julo@star.le.ac.uk)

Subjects: X-ray, Nova

Referred to by ATel #: 838

The very bright super-soft X-ray phase of the recurrent nova RS Oph has been extensively observed by the Swift XRT. The highly variable soft X-ray flux reported in ATEL #764 and ATEL#770 stabilised significantly after 2006 Mar 31.4; the XRT observations have subsequently shown a linear decline between Apr 12.1 and Apr 28.7 from 208 to 98 c/s (0.2-10 keV, 100 c/s corresponds to 1.95e-8 erg/cm^2/s unabsorbed in this band). The XRT flux is very substantially dominated by the soft spectral component, although this region of the spectrum has exhibited a slow hardening trend with time.

The quasi-periodic modulation with a period around 35 seconds is present during most observations when the source is bright, but not all. Some early low flux episodes did not generally show this modulation (eg Mar 23.6-26.4), nor has any observation since Apr 17.0 to the most recent on Apr 28.7.

Swift observations of RS Oph continue. We thank the Swift PI, Neil Gehrels, the Swift science team, and the Swift mission operations team for their support of this observing campaign.