GRB 061110B

D. B. Fox (PSU), S. D. Barthelmy (GSFC), M. M. Chester (PSU),
N. Gehrels (NASA/GSFC), D. Grupe (PSU), J. A. Kennea (PSU),
K. M. McLean (LANL/UTD), C. Pagani (PSU), D. M. Palmer (LANL),
P. Roming (PSU), T. Sakamoto (NASA/ORAU), G. Sato (GSFC/ISAS),
M. Stamatikos (NASA/ORAU), R. L. C. Starling (U Leicester) and
L. Vetere (PSU) report on behalf of the Swift Team:

At 21:58:45 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 061110B (trigger=238174).  The BAT on-board calculated
location is  RA,Dec 323.901, +6.877 {21h 35m 36s, +06d 52' 37"}
(J2000) with an uncertainty of 3 arcmin (radius, 90% containment,
including  systematic uncertainty). The BAT light curve shows several
peaks starting at ~T-18 sec and ending at ~T+30 sec with a duration of
about 45 sec. The peak count rate was ~1500 counts/sec (15-350 keV),
at ~8 sec after the trigger. 

Because of an Earth limb constraint, the spacecraft did not slew promptly
to the BAT position, and so there are no immediate XRT or UVOT data products
to analyze. The XRT and UVOT will begin observing this field at 22:52 UT.

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

We imaged the field of GRB 061110B detected by SWIFT
(trigger 238174) with the TAROT robotic telescope (D=25cm)
located at the Calern observatory, France.

The observations started 621.9s after the GRB trigger
(6.1s after the notice). The elevation of the field decreased from
from 22 degrees above horizon and weather conditions
were good.

The date of trigger : t0 = 2006-11-10T21:58:45.120

The first image is 90.0s exposure in tracking mode.
We do not detect any OT with a limiting magnitude of:
t0+622s to t0+712s : R > 16.6

We co-added a series of exposures:
t0+622s to t0+1098s : R > 16.9

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

Further observations are planed.

N.B. Galactic coordinates are lon= 61.2688 lat=-31.7065
and the galactic extinction in R band is 0.2 magnitudes
estimated from D. Schlegel et al. 1998ApJ...500..525S.

This message may be cited.

P. Roming (PSU), F. Marshall (GSFC), M. Chester (PSU) report on behalf of the
Swift UVOT team:

UVOT took a finding chart exposure of 131 seconds with the White (160-650 nm)
filter starting 3046 seconds after the BAT trigger. No afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 25% of
the BAT error circle. The typical 3-sigma upper limit has been about 18.5 mag.
The 8'x8' region for the list of sources generated on-board covers 100% of the
BAT 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.

A.Melandri, C.G. Mundell,  S. Kobayashi, C.J. Mottram, I.A. Steele, 
R.J. Smith, D. Carter, D. Bersier, M.F. Bode (Liverpool JMU) report:


The 2-m Liverpool Telescope robotically followed up GRB 061110B 
(Fox et al. GCN 5800
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 , trigger=238174) beginning 20.0 min after the 
GRB trigger time (UT:22:18:45.51).

We find a fading source with R=19.5 +/- 0.3 mag (T+25 min) located at

RA = 21:35:40.4
Dec = +06:52:34.1 (0.5" uncertainty)

that we identify as the possible optical afterglow of GRB061110B.
Magnitude was estimated with respect to USNO B1 catalog.

Further observations are on going.

J. A. Kennea, J. L. Racusin, D. N. Burrows and D. Grupe (PSU) report on
behalf of the Swift/XRT team:

At 22:52UT the Swift/XRT began observing GRB 061110B (GCN 5800
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 ). In
analysis of quicklook data we detect a faint uncatalogue point source at
the following location:

RA(J2000):  21h 35m 40.4s
Dec(J2000): +6d 52m 36.0s

with an estimated uncertainty of 9.6 arcseconds radius (90% containment).
This position lies 1.9 arcseconds from the Liverpool Telescope afterglow
candidate (GCN 5804
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 ) and 62 arcseconds from the BAT position. It is not
possible to determine at this time if this source is fading.

Christina C. Thoene, Daniele Malesani, Johan P. U. Fynbo (DARK Cosmology
Centre), Christina Henriksen (DARK, NOT) and Dimitri Sharapov (NOT)
report:

We observed the OT of GRB061110B (GCN 5804
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 ) starting Nov. 10, UT 23:20 (1h
after the burst), with ALFOSC at the NOT on La Palma in R and i.

From two sets of 3x300s stacked images, we determined magnitudes of R=22.0
and i=21.5 using preliminary photometric zeropoints from the NOT webpages.
Compared to the R-band magnitude reported in GCN 5804
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 , the OT has faded
with a temporal decay index of alpha~2.3.

H. Mikuz on behalf of PIKA observing program at Crni Vrh Observatory
reports:

We imaged the field of GRB 061110B (SWIFT trigger 238174) with the
60 cm robotic telescope at Crni Vrh Observatory, Slovenia.

Due to the object low altitude (16 degrees) and presence of some cirrus
clouds, only three 90 second exposures in R filter were secured,
starting 44 s after the trigger was received. Exposure start times (in
UT) are 22:09:46, 22:15:19 and 22:20:52.

No variable object was detected down to a limiting R magnitude 17.2
on single 90 s exposures, nor on three 90 s co-added exposures with
R limiting magnitude 17.8. Magnitudes were estimated with the nearby
USNO A2 stars.

J.P.U. Fynbo, D. Malesani, C.C. Thoene (NBI-DARK), P.M. Vreeswijk (ESO), 
J. Hjorth (NBI-DARK), C. Henriksen (NOT and DARK), report on behalf of a 
larger collaboration:

We observed the afterglow of GRB 061110B (Fox et al., GCN 5800
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 , Melandri 
et al., GCN 5804
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 ) with the ESO-VLT UT2 equipped with FORS1. Observations 
started on 2006 Nov 11.018 UT (2.45 hr after the GRB), and two spectra 
lasting 30 minutes each were acquired with the grism 300V.

 From the analysis of the first spectrum, we clearly see a strong DLA 
through at lambda ~ 5390 AA. From this feature, as well from OI+SiII, 
CII and SiIV, we measure a redshift of z = 3.44.

We acknowledge kind assistance from the ESO staff, in particular Stan 
Stefl and Chris Lidman.

[GCN OPS NOTE(11nov06): Per author's request, the typo in the Subject-line
was changed from "061011B" to "061110B".]

M. Stamatikos (GSFC/ORAU), L. Barbier (GSFC), S. D. Barthelmy (GSFC),
J. Cummings (GSFC/UMBC), E. Fenimore (LANL), D. Fox (PSU),
N. Gehrels (GSFC), D. Hullinger (BYU-Idaho), H. Krimm (GSFC/USRA),
C. Markwardt (GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC),
T. Sakamoto (GSFC/ORAU), G. Sato (GSFC/ISAS), J. Tueller (GSFC)
on behalf of the Swift-BAT team:
 
Using the data set from T-119 to T+183 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 061110B (trigger #238174)
(Fox, et al., GCN Circ. 5800
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 ).  The BAT ground-calculated position
is RA,Dec = 323.916, 6.870 deg {21h 35m 39.8s, 6d 52' 12.2"} (J2000)
+- 1.7 arcmin, (radius, sys+stat, 90% containment).  The partial coding
was 100%.
 
The mask-weighted lightcurve has several peaks starting at ~T-18 sec 
out to ~T+38 sec.  There is ongoing low-level emission out to at least
T+172 sec at which time the spacecraft slewed to a planned target and
the burst location slewed out of the BAT FOV.  T90 (15-350 keV) is
is at least 128 +- 5 sec (estimated error including systematics).
 
The time-averaged spectrum from T-16.5 to T+127.9 is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.03 +- 0.16.  The lower limit to the fluence in the 15-150 keV band
is 1.3 +- 0.1 x 10^-6 erg/cm2.  The 1-sec peak photon flux measured
from T+3.26 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 GCN Notices for this burst were delayed (~10 min) because this trigger
occurred during a Malindi downlink pass, during which the TDRSS data stream
is buffered on-board the spacecraft.
-

D. Grupe, D.B. Fox, J. Racusin, J. Kennea, report on behalf of the Swift 
XRT team:

We have analyzed the first three orbits of Swift XRT data of GRB 061110B.
The X-ray position was determined from the XRT image using the new 
teldef file:

Ra(2000)   =  21 35 40.42
Dec(2000)  = +06 52 34.0

with an 4.2" error (90% confidence). This position is 2" away from the initial
position given by Kennea et al. (GCN 5805
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 ) and 0.1" away from the optical
position reported by Melandri et al. (GCN 5804
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 ).


The X-ray light curve can be fitted by a single power law decay slope
alpha=1.35+/0.10. The flux a 4ks after the burst was 2.4e-12 ergs/s/cm2. Our
prediction for the flux at 24h after the burst is 4.5e-14 ergs/s/cm2, or 
9e-4 XRT counts/s.

The spectral analysis shows a typical GRB afterglow spectrum with a power law
photon index Gamma=1.9+/-0.4. The absorption column density in consistent with
the Galactic value (4.83e20 cm-2).

[GCN OPS NOTE(11nov06): Per author's request, the Galactic NH was changed
from 4.83e21 to 4.83e20.  We thank A.Kann for pointing this out.]

P. Schady (UCL-MSSL), D.B. Fox (PSU) report on behalf of the
Swift/UVOT team:

The Swift/UVOT began observing the field of GRB 061110b at 22:49:14 on 
2006-11-10 UT, ~50 minutes after the BAT trigger (Fox et al., GCN 5800
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 ). 
No new source was detected within the XRT error circle (Grupe et al., GCN 
5811
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 ) or at the afterglow position reported by Melandri et al. (GCN 5804
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 ) 
in coadded images in any filter down to the following 3-sigma magnitude 
upper limits:

Filter  T_mid (s)    Exp. (s) 3-sigma UL
------------------------------------------------
V       12256           1438    20.14
B       19296           2815    21.57
U       18864           2164    21.08
UVW1    18288           1928    20.58
UVM2    18192           1279    20.61
UVW2    13376           1737    20.99
White   15952           2494	21.03
------------------------------------------------

T_mid is the mid time of the coadded exposure with respect to the BAT trigger. 
These upper limits are not corrected for Galactic extinction E(B-V) = 0.04.

A. C. Updike, B. C. Donehew, S. D. Brittain, D. H. Hartmann, and A. L.
Homewood (Clemson University) report on behalf of the Clemson GRB
Follow-up team:

We observed GRB 061110B using the Kitt Peak 2.1m telescope and FLAMINGOS. 
Observations began in the J band 3 hours and 32 minutes after the burst
trigger (238174), and consisted of 34 x 120s images.

We detect no new sources at the position noted by A. Melandri (GCN 5804
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 )
or within the XRT error box.  Our limiting J-band magnitude (with respect
to the 2MASS catalog) was 18.4 +/- .2 magnitudes.

The Clemson University GRB Response Site can be found at:
http://people.clemson.edu/~kgarime/burst/index.php

This message may be cited.

[GCN OPS NOTE(13nov06): Per author's request, "B. Donahue" was changed
to "B. C. Donehew".]