4U 0115+63 Observations with RXTE
ATel #337; W. Coburn, E. Kalemci (UCB); P. Kretschmar (MPE/ISDC); I. Kreykenbohm (IAAT/ISDC); R. Rothschild (UCSD); R. Staubert (IAAT); J. Wilms (Warwick)
on 1 Oct 2004; 21:30 UT
Credential Certification: Wayne Coburn (wcoburn@ssl.berkeley.edu)
Subjects: X-ray, Binary, Neutron Star
On MJD 53270.382 we observed the source 4U 0115+63 during outburst for
~20 ks with RXTE. The 2-10 keV flux during the observation was (6.75
+/- 0.06)x10**-9 ergs cm**-2 s**-1. Our preliminary analysis of the
joint PCA/HEXTE phase averaged spectrum indicates the presence of the
known ~12 keV cyclotron line, along with upwards of 4 approximately
harmonically spaced higher harmonics. This is similar to what was seen
in the 1999 outburst. There is also a clear QPO in the lightcurve,
with individual cycles varying from the average by as much as 45%. The
QPO in the power spectrum peaks at ~4.5 mHz, with a ~1 mHz FWHM. This
is similar to the ~2 mHz QPO observed in this source in 1999, and a
mHz frequency QPO is probably a ubiquitous feature of this source during
outburst.