GRB 090519

M. Perri (ASDC), S. D. Barthelmy (GSFC), D. N. Burrows (PSU),
C. Gronwall (PSU), S. T. Holland (CRESST/USRA/GSFC),
J. A. Kennea (PSU), F. E. Marshall (NASA/GSFC),
P. T. O'Brien (U Leicester), C. Pagani (PSU), D. M. Palmer (LANL),
A. Rowlinson (U Leicester), M. H. Siegel (PSU),
M. Stamatikos (NASA/ORAU) and T. N. Ukwatta (GSFC/GWU) report on
behalf of the Swift Team:

At 21:08:56 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 090519 (trigger=352648).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 142.293, +0.183 which is 
   RA(J2000)  =  09h 29m 10s
   Dec(J2000) = +00d 10' 58"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows several overlapping peaks
with a duration of about 40 sec.  The peak count rate
was ~1300 counts/sec (15-350 keV), at ~3 sec after the trigger. 

The XRT began observing the field at 21:10:51.3 UT, 114.9 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
uncatalogued X-ray source located at RA, Dec 142.27902, 0.17925 which
is equivalent to:
   RA(J2000)  = 09h 29m 6.96s
   Dec(J2000) = +00d 10' 45.3"
with an uncertainty of 3.7 arcseconds (radius, 90% containment). This
location is 52 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 in excess of the Galactic value (2.96e+20
cm^-2, Kalberla et al. 2005), with an excess column of 1.9
(+2.14/-1.86) x 10^21 cm^-2 (90% confidence). 

The initial flux in the 2.5 s image was 5.77e-10 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 123 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. 
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
0.04. 

Burst Advocate for this burst is M. Perri (perri 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.)

Klotz, A. (CESR-OMP), Gendre, B. (LAM-OAMP),
Boer M. (OHP-OAMP), Atteia J.L. (LATT-OMP) report:

We imaged the field of GRB 090519 detected by SWIFT
(trigger 352648) with the TAROT robotic telescope (D=25cm)
located at the Calern observatory, France.

The observations started 76.0s after the GRB trigger
(6.6s after the notice). The elevation of the field decreased from
21 degrees above horizon and weather conditions
were good.

The date of trigger : t0 = 2009-05-19T21:08:56.5

The first image is trailed with a duration of 60.0s
(see the description in Klotz et al., 2006, A&A 451, L39).
We do not detect any OT at the XRT position mentionned
by Perri et al. 2009 (GCNC 9400) with a limiting magnitude of:
t0+76.0s to t0+136.0s : R > 16.8

The second image is 30.0s exposure in tracking mode:
t0+142.8s to t0+172.8s : R > 17.5

We co-added a series of exposures:
t0+142.8s to t0+319.6s : R > 18.5

Magnitudes were estimated with the nearby USNO-B1 stars
and are not corrected for galactic dust extinction.

N.B. Galactic coordinates are lon=233.3028 lat=+34.5244
and the galactic extinction in R band is 0.1 magnitude
estimated from D. Schlegel et al. 1998ApJ...500..525S.

This message may be cited.

Klotz, A. (CESR-OMP), Kugel, F. (Obs. Chanteperdrix) report:

We imaged the field of GRB 090519 detected by SWIFT
(trigger 352648) with the FARO robotic telescope (D=20cm)
located at the Chante Perdrix Observatory, Banon, France.
FARO stands for Francois & Alain Robotic Observatory:
http://chanteperdrix.dyndns.org

The observations started 122.4s after the GRB trigger
(53.0s after the notice). The elevation of the field decreased
from 22 degrees above horizon and weather conditions
were good.

The date of trigger : t0 = 2009-05-19T21:08:56.5

The first image is 60.0s exposure in tracking mode.
We do not detect any OT at the XRT position mentionned
by Perri et al. 2009 (GCNC 9400) with a limiting magnitude of:
t0+122.4s to t0+182.4s : R > 15.7

Magnitudes were estimated with the nearby USNO-B1 stars
and are not corrected for galactic dust extinction.

This message may be cited.

C.C. Thoene (INAF/Brera), D. Malesani (DARK/NBI), A.J. Levan (Univ. 
Warwick), P. Jakobsson (Univ. Iceland), J. Hjorth (DARK/NBI), N.R. 
Tanvir (Univ. Leicerster), report on behalf of a larger collaboration

We observed the field of GRB 090519 (Perri et al., GCN 9400
Loading...
 
 ) with the 
NOT equipped with ALFOSC.

At the edge of the XRT error circle, we detect a fading source at 
coordinates (J2000):

RA = 09:29:07.0
Dec = +00:10:49.1

with an error of ~0.5". The source faded by ~0.3 +- 0.10 mag between 
19.8 and 44.4 min after the GRB, suggesting that this is indeed the 
afterglow of GRB 090519. A (fainter) object is seen at the position of 
the candidate in the SDSS, which may be a bright host galaxy. On May 
19.897 UT, the source had R ~ 21.6.

Martin Jelinek (IAA Granada) and Petr Kubanek (IPL Valencia) 
on behalf of the BOOTES team.

report

    We observed the errorbox of the GRB 090519 (Perri et al,
GCN9400
Loading...
 
 ) with the 30cm robotic telescope BOOTES-1B in Spain.
The observation  started 99s  after the GRB  trigger. In our
unfiltered images we do not detect any new object within the
BAT or XRT errorbox with the following limits:

Tstart-Tgrb  exposure  limit
99s           3.5s     15.1
108s          30s      16.5
108s         23x30s    17.6

This message may be cited

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

Using 2178 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 090519, 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 = 142.27878, +0.18020 which is equivalent
to:

RA (J2000): 09h 29m 6.91s
Dec (J2000): +00d 10' 48.7"

with an uncertainty of 1.8 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, arXiv:0812.3662).

This circular was automatically generated, and 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), 
E. E. Fenimore (LANL), N. Gehrels (GSFC), C. B. Markwardt (GSFC/UMD), 
D. M. Palmer (LANL), A. M. Parsons (GSFC), M. Perri (ASDC), 
T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (GSFC/ORAU), 
J. Tueller (GSFC), T. N. Ukwatta (GWU)
(i.e. the Swift-BAT team):
 
Using the data set from T-119 to T+276 sec from the recent telemetry 
downlink, we report further analysis of BAT GRB 090519 (trigger #352648)
(Perri, et al., GCN Circ. 9400
Loading...
 
 ).  The BAT ground-calculated position is
RA, Dec = 142.317, 0.190 deg which is
   RA(J2000)  =  09h 29m 16.2s
   Dec(J2000) = +00d 11' 23.9"
with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment).
This is 0.8 arcmin from the enhanced XRT afterglow position (Goad et al.
GCN Circ #9405
Loading...
 
 ).  The partial coding was 57%.
 
The mask-weighted lightcurve shows multiple overlapping peaks starting 
at about T-17 sec and ending about T+95 sec.  T90 (15-350 keV) is 
64 +- 10 sec (estimated error including systematics).
 
The time-averaged spectrum from T-12.4 to T+60.4 sec is best fit by a 
simple power-law model.  The power law index of the time-averaged 
spectrum is 1.02 +- 0.20.  The fluence in the 15-150 keV band is 
1.2 +- 0.1 x 10-06 erg/cm2.  The 1-sec peak photon flux measured from 
T-10 sec in the 15-150 keV band is 0.6 +- 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/352648/BA/

S. Immler (NASA/CRESST/GSFC) and M. Perri (ASDC) report on
behalf of the Swift/UVOT team:

The Swift/UVOT observed the field of GRB 090519 starting 106 s after
the BAT trigger (Perri et al., GCN Circ. 9400
Loading...
 
 ). No optical afterglow
is detected in the initial UVOT exposures at the enhanced position
of the X-ray afterglow (Goad et al., GCN Circ. 9405
Loading...
 
 ) or the position
of the NOT afterglow candidate (Thoene et al. GCN Circ. 9403
Loading...
 
 ).
Three-sigma upper limits using the UVOT photometric system
(Poole et al. 2008, MNRAS, 383, 627) are:

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

white              123         7430          862         >21.5
v                  106         7841          597         >19.8
b                  536         7224          568         >20.6
u                  281         7019          617         >20.4
uvw1               662         8131          469         >20.3
uvm2               637         8046          587         >20.4
uvw2               588         7636          549         >20.6

The values quoted above are not corrected for the Galactic extinction due
to the reddening of E(B-V) = 0.04 in the direction of the burst
(Schlegel et al. 1998).

A. Rossi (Tautenburg), T. Kruehler, J. Greiner and A. Yoldas (all MPE Garching)
report on behalf of the GROND team:

We observed the field of GRB 090519 (Swift trigger 352648, M. Perri et al.,
GCN #9400
Loading...
 
 ) simultaneously in g'r'i'z'JHK with GROND mounted at the 2.2m
ESO/MPI telescope at La Silla Observatory (Chile). Observations started on
19 May 2009 at 23:44 UT, 2.5 h after the burst, under challenging sky 
conditions with cirrus.

We detect the afterglow at a position consistent with the enhanced XRT error 
circle and NOT (Thoene et al., GCN #9403
Loading...
 
 ). With an exposure time of 40min in 
JHK and 49min in griz, preliminary photometry yields the following AB 
magnitudes:
 
g =25.0 +-0.4
r =23.5 +-0.2
i =23.5 +-0.3
z >23.6
J >21.9
H >20.7
K >19.9

calibrated using SDSS and 2MASS field stars. The quoted magnitudes are not 
corrected for the galactic foreground extinction corresponding to a 
reddening of E_(B-V)=0.04.

The large g-i color as compared to r-i indicates that the Lyman break may
be located in the g' band. Fitting the SED with Hyper-Z results in a 
preliminary photometric redshift of z = 3.9+0.4-0.7, assuming no intrinsic 
extinction.

A. J. Levan (Univ. Warwick), P. Jakobsson (U. Iceland), C. C. Thoene
(INAF/OAB), P. D'Avanzo (U.  Bicocca & INAF/OAB), A. De Cia (U. Iceland),
J. P. U. Fynbo, J. Hjorth, D. Malesani (DARK/NBI), D. Fugazza (INAF/OAB),
N. R. Tanvir (U. Leicester) report on behalf of a larger collaboration:

Using FORS2 on the ESO Very Large Telescope, we have obtained 
low-resolution spectra (3 x 30 min) of the optical afterglow of GRB 
090519 (Perri et al., GCN 9400
Loading...
 
 ; Thoene et al., GCN 9403
Loading...
 
 ) with the grism 
300V, covering the wavelength range 3500-9200 AA. In the acquisition 
image  the afterglow has a magnitude of R ~ 23.5. The first spectrum 
was  taken approximately 4 hours after the burst.

In a preliminary analysis we detect a break around 4400 AA and strong 
absorption features around 5000 AA and 5900 AA. We interpret these 
features as the Lyman limit, Lyman-beta and Lyman-alpha at a redshift of 
z = 3.85. This is in agreement with the photometric redshift reported by 
Rossi et al. (GCN 9408
Loading...
 
 ).

We thank the Paranal staff for excellent support, in particular Gianni 
Marconi, Kieran O'Brien and Patricia Guajardo.

[GCN OPS NOTE(20may09): Per the original first-author's (CCT) request,
the author list was changed.]

D. Malesani (DARK/NBI), C.C. Thoene (INAF/Brera), P. Jakobsson (Univ. 
Iceland), A.J. Levan (Univ. Warwick) J.P.U. Fynbo, B. Milvang-Jensen 
(DARK/NBI), report on behalf of a larger collaboration.

We provide further analysis of the photometric data on the afterglow of 
GRB 090519 (Perri et al., GCN 9400
Loading...
 
 ) taken at the NOT and VLT (Thoene et 
al., GCN 9403
Loading...
 
 ; Levan et al., GCN 9409
Loading...
 
 ).

Calibration of the field based on archival VLT zeropoints yields a 
significantly fainter magnitude for the afterglow with respect to our 
previous GCN 9403
Loading...
 
 , which was based on USNO stars. The new calibration is 
consistent with SDSS stars and with the value reported by Rossi et al. 
(GCN 9408
Loading...
 
 ). We find for the afterglow R = 22.8 on 2009 May 19.897 UT 
(0.33 hr after the GRB).

The decay of the afterglow is well described by a power law with index 
alpha = 0.44 +- 0.03 between 0.33 and 3.6 hr after the GRB.

M. Perri, V. D'Elia, G. Stratta (ASDC) report on behalf of the
Swift-XRT team:

We have analysed the first 17 ks of XRT data for GRB 090519 (Perri et al.,
GCN Circ. 9400
Loading...
 
 ), from 121 s to 37 ks after the BAT trigger. The first
41 seconds of data are in Windowed Timing (WT) mode and at later times
in Photon Counting (PC) mode. The enhanced XRT position for this burst
was given by Goad et al. (GCN. Circ. 9405).

The light curve can be modelled with a series of power-law decays. The
initial decay index is alpha=2.8 (+/-0.2). At around T+580 s the decay
flattens to an alpha of 0.6 (+/-0.3) before breaking again at about
T+2 ks to a final decay with index alpha=1.4 (+0.3)(-0.2).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.5 (+/-0.2). The best-fitting
intrinsic absorption column at z=3.85 (Thoene et al., GCN Circ. 9409
Loading...
 
 )
is 1.9(+1.7,-1.6)e22 cm^-2, in excess of the Galactic value of
3.0e20 cm^-2 (Kalberla et al. 2005). The counts-to-observed (-unabsorbed)
0.3-10 keV flux conversion factor deduced from this spectrum is
4.9e-11 (5.4e-11) erg cm^-2 count^-1.

If the light curve continues to decay with a power-law decay index of
1.4, the count rate at T+24 hours will be 3e-4 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of
1.5e-14 (1.6e-14) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00352648.

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