GRB 130609A

S. T. Holland (STScI) and J. R. Cummings (NASA/UMBC) report on behalf
of the Swift/UVOT team:

    The Swift/UVOT began settled observations of the field of GRB
130609A starting 70 s after the BAT trigger (Cummings et al. 2013,
GCNC 14828).  We do not detect any new source consistent with the
UVOT-enhanced XRT position (Evans 2013, GCNC 14835) in any of the UVOT
exposures.  Preliminary 3-sigma upper limits using the UVOT
photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373)
for the finding chart (FC) exposures and initial summed exposures are
presented below.

Filter      TSTART      TSTOP   Exposure      Mag
-------------------------------------------------
white (FC)      70        220        147    >21.0
               562        582         19    >19.8
u (FC)         282        532        246    >20.3
               686        706         19    >18.6
-------------------------------------------------
v              612       6212        413    >19.9
b              537     18,175       1773    >21.7
u             5191     23,545       2254    >21.4
uvw1          4987     23,257       2164    >21.5
uvm2          4782     22,351       1279    >21.3
uvw2          4372       6007        393    >20.8
white         4166     12,406       1022    >22.0
-------------------------------------------------

    The quoted upper limits have not been corrected for the expected
extinction due to the Galactic reddening along the line of sight to
this burst of E(B-V) = 0.03 mag (Schlafly et al. 2011, ApJS, 737,
103).

B. A. Zauderer, W. Fong, E. Berger and T. Laskar (Harvard) report
on behalf of the CARMA Key Project, "A Millimeter View of the
Transient Universe" and a larger collaboration:

"We observed the position of GRB 130609A (Cummings et al. GCN 14828
Loading...
 
 ;
also detected by Fitzpatrick et al. GCN 14839
Loading...
 
 ) beginning 2013 Jun 9.88 UT
(dt = 0.75 d) with the Very Large Array (VLA) and beginning  2013 Jun 10.05
UT (dt = 0.92 d) with the Combined Array for Research in Millimeter Astronomy
(CARMA).  For this dark burst with deep optical and NIR afterglow upper limits
(e.g. Perley et al. GCN 14830
Loading...
 
  and Butler et al. GCN 14831
Loading...
 
 ), we find no
significant radio emission at the enhanced Swift-XRT position (Evans et al.;
GCN 14835
Loading...
 
 ) with the following three-sigma upper limits:
 5.8  GHz  <35 uJy  (VLA)
21.8  GHz  <60 uJy  (VLA)
84.5  GHz   <0.36 mJy (CARMA).

We thank the VLA and CARMA staff and observers for their support of these
observations."

G. Fitzpatrick (UCD) and J. Michael Burgess (UAH) report
on behalf of the Fermi GBM Team:

At 03:05:10.69 UT on 09 June 2013, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 130609A (trigger 392439913 /130609129),
which was also detected by the Swift/BAT (Cummings et al., GCN Circ. 14828
Loading...
 
 ).
The GBM on-ground location is consistent with the Swift position.

The GBM light curve consists of a single peak
with a duration (T90) of about 5 s (50-300 keV).
The time-averaged spectrum from T0-2.6 s to T0+2.8 s is
adequately fit by a power law function with an exponential
high-energy cutoff.  The power law index is -1.2 +/- 0.2 and
the cutoff energy, parameterized as Epeak, is 59.5 +/- 7.3 keV.

The event fluence (10-1000 keV) in this time interval is
(7.7 +/- 0.6)E-07 erg/cm^2. The 1-sec peak photon flux measured
starting from T0-1.6 s in the 8-1000 keV band is 3.2 +/- 0.3 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog.

J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), C. Pagani (U.
Leicester), A. Maselli	(INAF-IASFPA), V. Mangano (INAF-IASFPA), A.
Melandri (INAF-OAB), J.A. Kennea (PSU), M.C. Stroh (PSU), D.N. Burrows
(PSU) and J.R. Cummings report on behalf of the Swift-XRT team:

We have analysed 10 ks of XRT data for GRB 130609A (Cummings  et al.
GCN Circ. 14828
Loading...
 
 ),  from 52 s to 23.5 ks after the  BAT trigger. The
data comprise 8 s in Windowed Timing (WT) mode (taken while Swift was
slewing), with the remainder in Photon Counting (PC) mode. The enhanced
XRT position for this burst was given by Evans et al. (GCN. Circ
14835).

The light curve can be modelled with  a power-law decay with a decay
index of alpha=0.79 (+/-0.06).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.6 (+0.4, -0.3). The
best-fitting absorption column is  3.3 (+1.0, -0.9) x 10^21 cm^-2, in
excess of the Galactic value of 2.7 x 10^20 cm^-2 (Kalberla et al.
2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 3.2 x 10^-11 (7.9 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     3.3 (+1.0, -0.9) x 10^21 cm^-2
Galactic foreground: 2.7 x 10^20 cm^-2
Excess significance: 5.4 sigma
Photon index:	     2.6 (+0.4, -0.3)

If the light curve continues to decay with a power-law decay index of
0.79, the count rate at T+24 hours will be 3.5 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.1 x
10^-13 (2.8 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/00557782.

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

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

Using 3372 s of XRT Photon Counting mode data and 4 UVOT
images for GRB 130609A, 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 = 152.66941, +24.13195 which is equivalent
to:

RA (J2000): 10h 10m 40.66s
Dec (J2000): +24d 07' 55.0"

with an uncertainty of 2.3 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.

J. R. Cummings (GSFC/UMBC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA),
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-60 to T+243 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 130609A (trigger #557782)
(Cummings, et al., GCN Circ. 14828
Loading...
 
 ).  The BAT ground-calculated position is
RA, Dec = 152.680, 24.124 deg which is
    RA(J2000)  =  10h 10m 43.2s
    Dec(J2000) = +24d 07' 27.1"
with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 87%.
  
The mask-weighted light curve shows a single FRED peak.  T90 (15-350 keV) is
7.0 +- 0.8 sec (estimated error including systematics).
  
The time-averaged spectrum from T-1.19 to T+7.28 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.88 +- 0.11.  The fluence in the 15-150 keV band is 5.7 +- 0.4 x 10^-07 erg/cm2.
The 1-sec peak photon flux measured from T+0.52 sec in the 15-150 keV band
is 1.8 +- 0.2 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/557782/BA/

Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William
H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB)
J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UCSC),
Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC),
José A. de Diego (UNAM), Leonid Georgiev (UNAM), Jesús González (UNAM),
Carlos Román-Zúñiga (UNAM), Neil Gehrels (GSFC), and Harvey Moseley (GSFC)
report:

We observed the field of GRB 130609A (Cummings, et al., GCN 14828
Loading...
 
 ) with the
Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the
1.5m Harold Johnson Telescope at the Observatorio Astronómico Nacional on
Sierra San Pedro Mártir from 2013/06 9.15 to 2013/06 9.23 UTC (0.56 to 2.52
hours after the BAT trigger), obtaining a total of 1.24 hours exposure in
the r' and i' bands and 0.60 hours exposure in the Z, Y, J, and H bands.

For a source within the Swift-XRT error circle, in comparison with SDSS DR9
and 2MASS, we obtain the following upper limits (3-sigma):

  r'    > 23.34
  i'    > 23.27
  Z     > 22.39
  Y     > 21.91
  J     > 21.72
  H     > 21.06

These magnitudes are in the AB system and not corrected for Galactic
extinction in the direction of the GRB.

We thank the staff of the Observatorio Astronómico Nacional in San Pedro
Mártir.

D. A. Perley (Caltech) and S. B. Cenko (GSFC) report:

The Palomar 60-inch telescope automatically responded to GRB 130609A 
(Cummings et al., GCN 14828
Loading...
 
 ) and began taking observations at 04:03:23 
UT (58.25 minutes after the BAT trigger) as soon as the sky became dark. 
  A sequence of cycled 60-second r, i, and z images was acquired.  We 
detect no source consistent with the XRT localization in either 
individual images or in combined stacks of the first 6 images in each 
filter.  Approximate 5-sigma limiting magnitudes from the combined 
images at an approximate mean time of 4:20 UT (75 minutes after the GRB 
trigger) are:

r > 22.5
i > 21.5
z > 20.9

These limits are suggestive of a dark GRB.  Cummings et al. report a 
detection of significant excess absorption in the XRT spectrum, which 
may indicate a dust-extinguished (as opposed to high-redshift) event, 
although given the quoted errors there the excess may be only marginal.

NIR follow-up is highly encouraged.

J. R. Cummings (NASA/UMBC), W. H. Baumgartner (GSFC/UMBC),
N. Gehrels (NASA/GSFC), H. A. Krimm (CRESST/GSFC/USRA),
D. Malesani (DARK/NBI), F. E. Marshall (NASA/GSFC),
A. Maselli (INAF-IASFPA), D. M. Palmer (LANL), M. H. Siegel (PSU) and
C. A. Swenson (PSU) report on behalf of the Swift Team:

At 03:05:08 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 130609A (trigger=557782).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 152.676, +24.101 which is 
   RA(J2000) = 10h 10m 42s
   Dec(J2000) = +24d 06' 05"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single-peaked
structure with a duration of about 10 sec.  The peak count rate
was ~2500 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 03:06:15.4 UT, 66.8 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 152.67159, 24.13359 which is equivalent
to:
   RA(J2000)  = 10h 10m 41.18s
   Dec(J2000) = +24d 08' 00.9"
with an uncertainty of 3.9 arcseconds (radius, 90% containment). This
location is 118 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.  We cannot determine whether the source is
fading at the present time. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (2.67 x
10^20 cm^-2, Kalberla et al. 2005), with an excess column of 2.4
(+2.79/-2.37) x 10^21 cm^-2 (90% confidence). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 70 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 none of
the XRT error circle. The 8'x8' region for the list of sources generated
on-board covers 100% of the XRT error circle. The list of sources is typically
complete to about 18 mag. No correction has been made for the expected
extinction corresponding to E(B-V) of 0.03. 

Burst Advocate for this burst is J. R. Cummings (jayc 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.)