GRB 150530B

J. R. Cummings (CPI) and D. M. Palmer (LANL)
report on behalf of the Swift science team:

At 13:28:38 during a preplanned Swift slew, GRB 150530B caused a rate
increase in Swift-BAT.  Photon event data were collected during the slew.
In ground analysis, we detect a significant source in a mosaic image.
The source was at RA, Dec 7.496, +44.290 which is:

RA (J2000)   00h 29m 59.0s
Dec (J2000) +44d 17' 25"

with an estimated 90% containment radius of 3 arcmin.

In BAT, the burst lasted 2.0 +- 0.4 seconds.  The spectrum was soft, with
no detected excess above 100 keV.

The best fit to the spectrum from 15-150 keV is a simple power law with
a photon index of 1.7 +- 0.2.  The fluence in 2 seconds was
(1.25 +- 0.2) x 10^-7 ergs/cm^2.  The uncertainties quoted are estimated
90% confidence.

P. A. Evans (U. Leicester) reports on behalf of the Swift team:

Swift has initiated a ToO observation of the Swift/BAT GRB 150530B. 
Automated analysis of the XRT data will be presented online at
http://www.swift.ac.uk/ToO_GRBs/00020522

Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. These are
not necessarily related to the Swift/BAT event. Any X-ray source
considered to be a probable afterglow candidate will be reported via a 
GCN Circular after manual consideration.

Details of the XRT automated analysis methods are detailed in Evans et
al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).

This circular is an official product of the Swift-XRT team.

P. D'Avanzo (INAF-OAB), B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows
(PSU), J.A. Kennea (PSU), C. Pagani (U. Leicester), A.P. Beardmore (U.
Leicester), V. D'Elia (ASDC), A. D'a� (INAF-IASFPA) and P.A. Evans (U.
Leicester) report on behalf of the Swift-XRT team:

Swift-XRT has performed follow-up observations of the
Swift/BAT-detected burst GRB 150530B (Cummings et al. GCN Circ. 17895
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 ),
collecting 4.8 ks of Photon Counting (PC) mode data between T0+239.2 ks
and T0+247.3 ks. 

No X-ray sources have been detected inside or close to the Swift/BAT
error region. The 3-sigma upper limit in the field ranges from ~0.003
to ~0.004 ct s^-1, corresponding to a 0.3-10 keV observed flux of
1.0e-13 to 1.5e-13 erg cm^-2 s^-1 (assuming a typical GRB spectrum).

Four uncatalogued sources were detected too far from the GRB position
to be likely afterglow candidates.

The results of the XRT-team automatic analysis of the XRT observations,
including a position-specific upper limit calculator, are available at
http://www.swift.ac.uk/ToO_GRBs/00020522.

This circular is an official product of the Swift-XRT team.