P. Esposito (INAF-IASF Milano), G. L. Israel (INAF-O.A.Roma), M. Burgay
(INAF-O.A.Cagliari), A. Possenti (INAF-O.A.Cagliari), D. Gotz
(Irfu/SAp/CEA Saclay), N. Rea (CSIC-ICE Barcelona), S. Mereghetti
(INAF-IASF Mi), A. Tiengo (INAF-IASF Mi), L. Stella (INAF-0.A.Roma), R.
Turolla (U. Padua), S. Zane (MSSL/UCL) on behalf of a larger collaboration
We observed the new soft gamma-ray repeater SGR 1833-0832 with XMM-Newton
on 2010 March 23 (for about 22 ks) and on 2010 April 02 (for about 21 ks).
By merging these data sets with those collected since the discovery of the
source (GCN #10526) with RossiXTE and Swift, we were able to refine the
period measurement reported in ATEL #2494 (see also ATEL #2493), also
including in the phase-coherent timing solution a first period derivative
According to our preliminary analysis the period and first period
derivative of SGR 1833-0832 are: P= 7.565406(2) s and Pdot= 7(2) x
10^-12 s/s (1 sigma uncertainties; epoch 55274.0 MJD). Under the standard
assumption that the neutron star slows down because of magnetic braking,
we infer a dipole magnetic field of B = 2.4(3) x 10^14 G for a neutron
star with radius of 10 km and mass of 1.4 solar masses, confirming the SGR
as a new magnetar candidate.
We will monitor the source both with XMM-Newton and Swift until the end
of the current observability window (about end of April 2010).
[GCN OPS NOTE(13apr10): Per author's request, a typo for the Pdot value
was corrected from 7.4(2) to 7(2).]