GRB 150722A

S. Dichiara, C. Guidorzi (U. Ferrara), D. Kopac (LJMU),
on behalf of a large collaboration report:

One of the LCOGT 1-m telescopes in Sutherland (South Africa)
began observing GRB 150722A (Marshall et al. GCN 18042
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 )
on July 22 at 17:01:14 UT, i.e. ~7 hours after the BAT
trigger with the r' and i' filters.

Within the XRT error circle (Evans et al. GCN 18044
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 )
we found no new source down to the following limit:

Mid time from  Total Exp   Filter    Magnitude
trigger (hr)   (s)
-------------------------------------------------
7.46           120x15        r'        > 20.0
7.90           120x6         i'        > 18.8
-------------------------------------------------

Values have been calibrated against nearby USNOB-1 stars
(R2 and I).

C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC),  J. R. Cummings (CPI),
N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (GSFC/UMBC),
D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU),
T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):

Using the data set from T-240 to T+243 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 150722A (trigger #649916)
(Marshall, et al., GCN Circ. 18042
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 ).  The BAT ground-calculated position is
RA, Dec = 218.297, -35.196 deg which is
    RA(J2000)  =  14h 33m 11.3s
    Dec(J2000) = -35d 11' 45.1"
with an uncertainty of 2.8 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 94%.

The mask-weighted light curve shows weak, variable emission from prior to T-200
to about T+55 seconds.  T90 (15-350 keV) is 67 +- 12 sec (estimated error
including systematics).

The time-averaged spectrum from T-26.00 to T+48.00 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.79 +- 0.26.  The fluence in the 15-150 keV band is 6.1 +- 0.9 x 10^-07  erg/cm2.
The 1-sec peak photon flux measured from T+15.00 sec in the 15-150 keV band
is 0.4 +- 0.1 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/649916/BA/

[GCN OPS NOTE(22jul15): Per an author's request, the "T-60" was corrected
to "T-240".]

D.N. Burrows (PSU), T.G.R. Roegiers (PSU), B.P. Gompertz (U.
Leicester), J.P. Osborne (U. Leicester), A. Melandri (INAF-OAB), P.
D'Avanzo (INAF-OAB), V. D'Elia (ASDC), L.M. McCauley (PSU), 
A. Amaral-Rogers (U. Leicester) and F. E. Marshall (NASA/GSFC) report
on behalf of the Swift-XRT team:

We have analysed 5.7 ks of XRT data for GRB 150722A (Marshall et al.
GCN Circ. 18042
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 ), from 3.2 ks to 17.3 ks after the  BAT trigger. The
data are entirely in Photon Counting (PC) mode. The enhanced XRT
position for this burst was given by Evans et al. (GCN Circ. 18044
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 ).

The light curve can be modelled with a power-law decay with a decay
index of alpha=0.90 (+0.14, -0.13).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.08 (+/-0.13). The
best-fitting absorption column is  1.4 (+0.4, -0.3) x 10^21 cm^-2, in
excess of the Galactic value of 5.9 x 10^20 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 3.2 x 10^-11 (4.3 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     1.4 (+0.4, -0.3) x 10^21 cm^-2
Galactic foreground: 5.9 x 10^20 cm^-2
Excess significance: 3.6 sigma
Photon index:	     2.08 (+/-0.13)

If the light curve continues to decay with a power-law decay index of
0.90, the count rate at T+24 hours will be 0.013 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.2 x
10^-13 (5.6 x 10^-13) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00649916.

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

N. P. M. Kuin (UCL-MSSL) and F. E. Marshall (NASA/GSFC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 150722A
3238 s after the BAT trigger (Marshall et al., GCN Circ. 18042
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 ).
No optical afterglow consistent with the XRT position (Evans et al.
GCN Circ. No. 18044) is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC          3238         3388          147         >20.6
white             3238         5442          541         >21.6
v                 4217         5791          333         >20.0
b                 3602         5237          393         >21.0
u                 3396         5031          393         >20.6
w1                4627         4827          197         >20.1
m2                4422         4622          197         >20.3
w2                4012         5647          393         >21.4

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.06 in the direction of the burst
(Schlegel et al. 1998).

P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 2194 s of XRT Photon Counting mode data and 6 UVOT
images for GRB 150722A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 218.27800, -35.19588 which is equivalent
to:

RA (J2000): 14h 33m 6.72s
Dec (J2000): -35d 11' 45.2"

with an uncertainty of 1.7 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.

S. Campana (INAF-OAB), P.A. Evans (U. Leicester), J.P. Osborne (U.
Leicester), D.N. Burrows (PSU), J.A. Kennea (PSU) and G. Tagliaferri
(INAF-OAB) report on behalf of the Swift-XRT team:

The XRT began observing the field of GRB 150722A at 10:51:48.0 UT,
3234.9 seconds after the BAT trigger. Using promptly downlinked data we
find a fading, uncatalogued X-ray source located at RA, Dec 218.27775,
-35.19644 which is equivalent to:
   RA(J2000)  = 14h 33m 06.66s
   Dec(J2000) = -35d 11' 47.2"
with an uncertainty of 3.6 arcseconds (radius, 90% containment). This
location is 17 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at http://www.swift.ac.uk/sper. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density consistent with the Galactic value of 5.92
x 10^20 cm^-2 (Willingale et al. 2013).

F. E. Marshall (NASA/GSFC), S. D. Barthelmy (GSFC),
D. N. Burrows (PSU), J. R. Cummings (NASA/UMBC) and
K. L. Page (U Leicester) report on behalf of the Swift Team:

At 09:57:53 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 150722A (trigger=649916).  Swift did not slew immediately
due to earth limb observing constraint.  The BAT on-board calculated location is 
RA, Dec 218.272, -35.197 which is 
   RA(J2000)  =  14h 33m 05s
   Dec(J2000) = -35d 11' 46"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  As is usual for an image trigger (64-sec),
there is nothing significant in the real-time TDRSS light curve. 

Due to an observing constraint, Swift will not slew until T0+50.9
minutes. There will be no XRT or UVOT data until this time. 

Burst Advocate for this burst is F. E. Marshall (marshall AT milkyway.gsfc.nasa.gov). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)