GRB 130529A

V. D'Elia (ASDC), S. D. Barthelmy (GSFC), J. A. Kennea (PSU),
C. Pagani (U Leicester) and M. H. Siegel (PSU) report on behalf of the
Swift Team:

At 11:15:25 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 130529A (trigger=556930).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 24.259, -64.138, which is 
   RA(J2000)  =  01h 37m 02s
   Dec(J2000) = -64d 08' 17"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  As is typical for image triggers, the real-time
TDRSS lightcurve does not show anything significant. 

The XRT began observing the field at 11:17:18.0 UT, 112.6 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 24.2798, -64.1493 which is equivalent to:
   RA(J2000)  = +01h 37m 7.15s
   Dec(J2000) = -64d 08' 57.5"
with an uncertainty of 5.4 arcseconds (radius, 90% containment). This
location is 52 arcseconds from the BAT onboard position, within the BAT
error circle. No event data are yet available to determine the column
density using X-ray spectroscopy. 

The initial flux in the 2.5 s image was 1.24e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 122 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of
the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. 
Data from the list of sources generated on-board are not available at this
time. No correction has been made for the expected extinction corresponding to
E(B-V) of 0.02. 

Burst Advocate for this burst is V. D'Elia (delia AT asdc.asi.it). 
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.)

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

Using  promptly downlinked XRT event data for GRB 130529A, we find an
enhanced XRT position of the afterglow: RA, Dec: 24.2820, -64.1473
which is equivalent to:
   RA (J2000)  = 01 37 07.69
   Dec (J2000) = -64 08 50.2
with an uncertainty of 2.0 arcseconds (radius, 90% confidence).
Analysis of the promptly available data is online at
http://www.swift.ac.uk/sper/556930.

Position enhancement is is described by Goad et al. (2007, A&A, 476,
1401) and Evans et al. (2009, MNRAS, 397, 1177).

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

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

Using 7658 s of XRT Photon Counting mode data and 9 UVOT
images for GRB 130529A, 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 = 24.28192, -64.14745 which is equivalent
to:

RA (J2000): 01h 37m 7.66s
Dec (J2000): -64d 08' 50.8"

with an uncertainty of 1.4 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.

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

We have analysed 8.6 ks of XRT data for GRB 130529A (D'Elia  et al. GCN
Circ. 14717
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 ),  from 118 s to 19.2 ks after the	BAT trigger. The data
comprise 300 s in Windowed Timing (WT) mode with the remainder in
Photon Counting (PC) mode. The enhanced XRT position for this burst was
given by Osborne et al. (GCN. Circ 14719).

The light curve can be modelled with an initial power-law decay with an
index of alpha=1.67 (+/-0.04), followed by a break at T+1862 s to an
alpha of 0.97 (+0.08, -0.14).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index	of 1.36 (+0.08, -0.07). The
best-fitting absorption column is  6.8 (+2.2, -2.0) x 10^20 cm^-2, in
excess of the Galactic value of 2.7 x 10^20 cm^-2 (Kalberla et al.
2005). The PC mode spectrum has a photon index of 1.32 (+0.15, -0.14)
and a best-fitting absorption column of 6.9 (+4.5, -4.0) x 10^20 cm^-2.
The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 5.3 x 10^-11 (5.7 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     6.9 (+4.5, -4.0) x 10^20 cm^-2
Galactic foreground: 2.7 x 10^20 cm^-2
Excess significance: 1.7 sigma
Photon index:	     1.32 (+0.15, -0.14)

If the light curve continues to decay with a power-law decay index of
0.97, the count rate at T+24 hours will be 8.1 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.3 x
10^-13 (4.7 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/00556930.

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

H. A. Krimm (GSFC/USRA), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), V. D'Elia (ASDC), E. E. Fenimore (LANL),
N. Gehrels (GSFC), A. Y. Lien (NASA/GSFC/ORAU), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), T. Sakamoto (AGU), G. Sato (ISAS),
M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU)
(i.e. the Swift-BAT team):
 
Using the data set from T-239 to T+464 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 130529A (trigger #556930)
(D'Elia, et al., GCN Circ. 14717
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 ).  The BAT ground-calculated position is
RA, Dec = 24.274, -64.143 deg, which is 
   RA(J2000)  =  01h 37m 05.7s 
   Dec(J2000) = -64d 08' 34.8" 
with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 100%.
 
The mask-weighted light curve shows the burst starting at ~T-20 sec,
peaking at about T+80 sec, and ending at ~T+260 sec.
T90 (15-350 keV) is 128 +- 35 sec (estimated error including systematics).
 
The time-averaged spectrum from T-15.02 to T+150.62 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.56 +- 0.17.  The fluence in the 15-150 keV band is 1.4 +- 0.2 x 10^-06 erg/cm2.
The 1-sec peak photon flux measured from T+64.28 sec in the 15-150 keV band
is 0.5 +- 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/556930/BA/

S. R. Oates (MSSL-UCL) and V. D'Elia (ASDC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 130529A
123 s after the BAT trigger (D'Elia et al., GCN Circ. 14717
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 ).
No optical afterglow consistent with the XRT position
(Osborne et al. GCN Circ. 14723
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 )
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           123          272          147         >21.6
u_FC               281          530          246         >20.8
white              123         7633          824         >22.1
v                  611        12979         1237         >20.8
b                  536        19245         1031         >21.1
u                  281        18726         1641         >21.5
w1                 660        17812         1415         >21.6
m2                 635        13481          822         >21.0
w2                 587        12064         1275         >21.8

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.02 in the direction of the burst
(Schlegel et al. 1998).

K. Varela (MPE Garching), S. Klose, A. Nicuesa Guelbenzu (both TLS 
Tautenburg), and J. Greiner (MPE Garching) report on behalf of the GROND 
team:

We observed the field GRB 130529A (Swift trigger 556930; D' Elia et al., 
GCN 14717
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 ) simultaneously in g'r'i'z'JHKs with GROND (Greiner et al. 
2008, PASP 120, 405) mounted at the 2.2m MPG/ESO telescope at La Silla 
Observatory (Chile).

Observations started at 07:10 UT on May 30, about 20 hours after the 
trigger at a mean seeing of 1.7 arcsec and a mean airmass of 2. Inside 
the enhanced 1".4 XRT error circle (Osborne et al., GCN 14723
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 ), we do not 
detect any source. Based on an observation with 150 min integration time 
in g'r'i'z' and 124 min integration time in JHKs, we estimate preliminary 
3-sigma upper limits (all in the AB system) of

g' > 24.3,
r' > 24.6,
J  > 21.8,
H  > 21.1.

We note that the field is rich in galaxies. Within 10 arcsec around the 
XRT error circle are at least three objects (also visible on DSS2), with 
the most extended one an edge-on galaxy about 6" in diameter. The bad 
seeing prevents at the moment a more detailed classification of the other 
objects.

Magnitudes are calibrated against GROND zero points (g'r'i'z') as well as 
2MASS field stars (JHKs) and, as usual, are not corrected for Galactic 
extinction along the line of sight.