Swift J1734.5-3027: a bright burst in March 2013 detected in the long term BAT light curve.
ATel #5646; V. La Parola, A. Segreto, G. Cusumano, A. Maselli (INAF IASF Palermo)
on 10 Dec 2013; 09:33 UT
Credential Certification: Valentina La Parola (laparola@ifc.inaf.it)
Subjects: X-ray, Transient
We have analyzed the long term BAT light curve of Swift J1734.5-3027,
a Galactic X-ray transient discovered in September 2013 after a short duration
burst (ATel# 5354, GCN #15157, GCN #15172, ATel #5361), finding that the source
had a much longer outburst already in May 2013.
The intensity of the source started rising on May 13 2013, reaching a
peak on May 30 and going back to the pre-burst value on June 12. A fainter
outburst (with a
peak intensity a factor of three lower than the main one) was also observed
between April 10 and April 22.
The time averaged BAT spectrum collected between May 13 and June 14 can be fit
with a power-law model with photon index 2.15+/- 0.18, with an average flux of
2.5E-10 erg/cm^2/s (the peak flux is 4.1E-10 erg/cm^2/s). This is consistent with
the spectrum of the emission observed with INTEGRAL in September and reported
in Atel #5361, and much harder than the emission of the short-duration
"superburst" that triggered BAT on September 01, modelled with a 2.5 keV
black body or a power law with photon index 5.8+/-0.7 (with a derived average
flux of 6.02E-9 erg/cm^2/s).
