GRB 080129

S. Immler (CRESST/GSFC/UMD), D. N. Burrows (PSU), M. M. Chester (PSU),
N. Gehrels (NASA/GSFC), S. T. Holland (CRESST/USRA/GSFC),
E. A. Hoversten (PSU), K. L. Page (U Leicester), D. M. Palmer (LANL),
D. Perez (U Leicester), M. Perri (ASDC), M. Stamatikos (NASA/ORAU) and
G. Stratta (ASDC) report on behalf of the Swift Team:

At 06:06:45 UT, the Swift Burst Alert Telescope (BAT) triggered and
located a possible GRB 080129 (trigger=301981). The BAT on-board calculated 
location is RA, Dec 105.280, -7.827 which is 
   RA(J2000) = 07h 01m 07s
   Dec(J2000) = -07d 49' 35"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve for this event appears
to show a duration of about 80 sec with a peak of ~600 counts/sec 
(15-350 keV), at ~30 sec after the trigger although, as is usual
for image triggers, the TDRSS light curve is noisy. 
The location of the source, 1.4 degrees from the Galactic plane
raises the possibility that this is a Galactic transient. 
Further analysis will require the downlinked data from Malindi. 

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.  Swift will slew to this position at about T+3006 s, or 
about 06:56 UT. 

Burst Advocate for this burst is S. Immler (immler 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.)

S. T. Holland (CRESST/USRA/GSFC) reports on behalf of the Swift Team:

      UVOT took a 100 s finding chart exposure of the field of the
possible GRB 080129 (Immler et al., GCN Circ. 7226
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 ) with the white
(160-650 nm) filter starting 3207 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 3-sigma
upper limit at the centre of the BAT position is white ~= 18.5 on the
UVOT photometric system (Poole et al. 2008).  The 8'x8' region for the
list of sources generated on-board covers 100% of the BAT error circle
and contains no uncatalogued sources.  This list of sources is typically
complete to about 18 mag.  This field is 1.42 degrees from the
Galactic place, and no correction has been made for the expected
Galactic extinction corresponding to a reddening of E(B-V) = 1.02.

M. Perri (ASDC), G. Stratta (ASDC) and D.N. Burrows (PSU) report on
behalf of the Swift XRT team:

The Swift XRT began observing the possible GRB 080129 (trigger #301981,
Immler et al., GCN Circ. 7226
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 ) at 07:00:08 UT, about 53 min after the
BAT trigger.

Analysis of prompt downlinked data finds an uncataloged X-ray source
located at RA, Dec 105.2848, -7.8463 which is
   RA(J2000) = 07 01 8.35
   Dec(J2000) = -07 50 46.8
with an uncertainty of 3.3 arcsec (radius, 90% containment). This location
is 71 arcseconds from the BAT on-board position, within the BAT error
circle (Immler et al., GCN Circ 7226
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 ). Further analysis will be
reported in a subsequent circular.

This circular is an official product of the Swift XRT Team.

J. S. Bloom (UC Berkeley) reports on behalf of the larger GRAASP  
collaboration:

"Automatically triggering off of the original GCN/SWIFT_BAT_POSITION  
notice for GRB 080129 (GCN 7226
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 ), we observed the field with Gemini  
South + GMOS in the r-band starting at 06:50:21.4 2008-01-29 in a  
series of 5 dithered exposures of 5 minutes apiece. Consistent with  
the position of the X-ray source (GCN 7228
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 ) we find a point-like  
object at:

     07:01:08.20  -07:50:46.3  (J2000)

(preliminary uncertainty of 300 mas rms relative to 2MASS). We suggest  
that this is the optical afterglow of GRB 080129 but cannot confirm  
variability at this time. More observations are encouraged."

We thank the Gemini Staff for conducting these observations.

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 399 s of overlapping XRT Photon Counting mode and UVOT
V-band data for GRB 080129, 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 = 105.28406, -7.84705 which is equivalent
to:

RA (J2000): 07h 01m 8.17s
Dec (J2000): -07d 50' 49.4"

with an uncertainty of 2.7 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, astro-ph/0708.0986
http://www.swift.ac.uk/xrt_positions/Goad.pdf).

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

T. Kruehler, S. Loew, J.Greiner, C.Clemens, A. Kuepcue Yoldas, A. Yoldas
(all MPE Garching) report on behalf of the GROND team:  

We observed the field of GRB 080129 observed by Swift (Immler et al.
2008, GCN#7226
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 ) simultaneously in grizJHK with GROND mounted at the 2.2m
MPI/ESO telescope at La Silla (Chile).
  
Observations started at 06:11 UT, about 4 min after the GRB.
  
We find a point source not present in the Digital Sky Survey images
inside the Swift/XRT error circle of the X-ray afterglow 
(Perri et al. 2008, GCN#7228
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 ; Goad et al. 2008, GCN#7230
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 ).  
  
The coordinates are (+- 0.5 arcsec error):
RA (2000.0) = 07h 01m 08.2s    
Decl. (2000.0) = -07d 50' 47'
consistent with the optical source reported by J. S. Bloom (GCN#7229
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 ).
  
We estimate magnitudes of 22.8 (r), 21.5 (i), 20.6 (z), 18.9 (J), 18.1
(H) and 17.0 (K) calibrated against USNO and 2MASS field stars. These
magnitudes are not corrected for galactic extinction.
  
The source is fading by about 0.5 mag during the first 90 min, suggesting 
it to be the optical/NIR afterglow of GRB 080129.

T. Kruehler, S. Loew, J.Greiner, C.Clemens, A. Kuepcue Yoldas, A. Yoldas
(all MPE Garching) report on behalf of the GROND team:  

We observed the field of GRB 080129 observed by Swift (Immler et al.
2008, GCN#7226
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 ) simultaneously in grizJHK with GROND mounted at the 2.2m
MPI/ESO telescope at La Silla (Chile).
  
Observations started at 06:11 UT, about 4 min after the GRB.
  
We find a point source not present in the Digital Sky Survey images
inside the Swift/XRT error circle of the X-ray afterglow 
(Perri et al. 2008, GCN#7228
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 ; Goad et al. 2008, GCN#7230
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 ).  
  
The coordinates are (+- 0.5 arcsec error):
RA (2000.0) = 07h 01m 08.2s    
Decl. (2000.0) = -07d 50' 47'
consistent with the optical source reported by J. S. Bloom (GCN#7229
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 ).
  
We estimate magnitudes of 22.8 (r), 21.5 (i), 20.6 (z), 18.9 (J), 18.1
(H) and 17.0 (K) calibrated against USNO and 2MASS field stars. These
magnitudes are not corrected for galactic extinction.
  
The source is fading by about 0.5 mag during the first 90 min, suggesting 
it to be the optical/NIR afterglow of GRB 080129.

D. A. Perley and J. S. Bloom (UC Berkeley) report on behalf of the 
GRAASP collaboration:

Preliminary photometry of our first series of r-band observations of the 
candidate afterglow of GRB 080129 (Immler et al., GCN 7226
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 ; Bloom, 7229) 
yields the following magnitudes, calibrated using three DSS stars*:

t=44 min: R = 22.93 +/- 0.06
t=50 min: R = 22.86 +/- 0.05
t=56 min: R = 22.78 +/- 0.04
t=62 min: R = 22.56 +/- 0.04
t=68 min: R = 22.87 +/- 0.05

As these magnitudes are approximately consistent with the value reported 
by Kruehler et al. (GCN 7231
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 /7232) we do not confirm general fading 
behavior of this source over the interval of our observations. 
However, we note that the fourth exposure shows statistically 
significant evidence of a short-lived rebrightening.  While an 
instrumental cause has not been ruled out, given the location in the 
Galactic plane of the source and the very slow fading reported by 
Kruehler et al. (0.5 mag from 4 to ~94 minutes, atypical of extragalactic 
GRBs), it is possible that the GRB may be an analog of GRB 070610 / 
SWIFT J195509.6+261406 (Pagani et al., GCN 6489
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 ; Kasliwal et al. 2007, 
arXiv:0708.0226), which showed extensive short-time scale early-time 
variability above a nearly-constant baseline.  Further observations 
(including rapid-time-series optical observations), and further analysis 
of the X-ray afterglow, are encouraged to further investigate the nature 
of this source.

---

*Calibration stars are:

ra            dec            R2
07:01:10.5033 -07:50:24.020  17.130
07:01:07.7333 -07:51:24.620  17.040
07:01:04.7193 -07:50:46.690  17.310

[GCN OPS NOTE(29jan08): Per author's request, the "Greiner" citation was changed
to "Kruehler".]

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

We imaged the field of GRB 080129 detected by SWIFT
(trigger 301981) with the TAROT robotic telescope (D=25cm)
located at the European Southern Observatory,
La Silla observatory, Chile.

The observations started 352.7s after the GRB trigger
(270.9s after the notice). The elevation of the field decreased from
from 42 degrees above horizon and weather conditions
were good.

The date of trigger : t0 = 2008-01-29T06:06:45.216

The fiirst image is 90.0s exposure in tracking mode.
We do not detect any OT with a limiting magnitude of:
t0+352.7s to t0+442.7s : R > 16.4

We co-added a series of exposures:
t0+448.5s to t0+1039.0s : R > 18.3

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

N.B. Galactic coordinates are lon=220.9983 lat= -1.4244
and the galactic extinction in R band is about 9 magnitudes
estimated from D. Schlegel et al. 1998ApJ...500..525S.

This message may be cited.

S. D. Barthelmy (GSFC), J. Cummings (GSFC/UMBC), E. Fenimore (LANL),
N. Gehrels (GSFC), S. Immler (CRESST/GSFC/UMD), H. Krimm (GSFC/USRA),
C. Markwardt (GSFC/UMD), D. Palmer (LANL), T. Sakamoto (GSFC/UMBC),
G. Sato (GSFC/ISAS), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC),
T. Ukwatta (GWU)
(i.e. the Swift-BAT team):
 
Using the data set from T-239 to T+963 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 080129 (trigger #301981)
(Immler, et al., GCN Circ. 7226
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 ).  The BAT ground-calculated position is
RA, Dec = 105.297, -7.840 deg which is 
   RA(J2000)  = 07h 01m 11.2s 
   Dec(J2000) = -7d 50' 24" 
with an uncertainty of 2.4 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 46%.
 
The mask-weighted light curve shows a single broad peak starting at ~T-20 sec,
peaking at ~T+20, and ending at ~T+50.  T90 (15-350 keV) is 48 +- 10 sec
(estimated error including systematics).
 
The time-averaged spectrum from T-15.0 to T+49.0 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.34 +- 0.26.  The fluence in the 15-150 keV band is 8.9 +- 1.4 x 10^-07 erg/cm2.
The 1-sec peak photon flux measured from T+24.50 sec in the 15-150 keV band
is 0.2 +- 0.1 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level. 

The majority of the indicators say this is a GRB, but at this time
we can not rule out a galactic source explanation for this trigger.
 
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/301981/BA/

M.Cwiok, W.Dominik, G.Kasprowicz, A.Majcher, A.Majczyna,
K.Malek, L.Mankiewicz, M.Molak, K.Nawrocki, L.W.Piotrowski,
D.Rybka, M.Sokolowski, J.Uzycki, G.Wrochna, A.F.Zarnecki
on behalf of "Pi of the Sky" collaboration http://grb.fuw.edu.pl

"Pi of the Sky" apparatus located at Las Campanas Observatory
imaged the region of GRB 080129 from 6:09:21 UT,
i.e. 155s after the GRB (74s after the trigger),
with 10s exposures (IR-cut filter only).
No new object has been detected within the XRT error box.

Limiting magnitude for 10s exposures is >11.8 mag.
The limit for 20 coadded images is >12.5 mag.

W. Li and A. V. Filippenko, University of California, Berkeley, on behalf
of the KAIT GRB team, report:

We imaged the field of GRB 080129 detected by Swift (trigger 301981;
Immler et al. GCN 7226
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 ) with the robotic 0.76-m Katzman Automatic Imaging
Telescope (KAIT) at Lick Observatory. The automatic sequence was not 
executed due to poor weather, but a manual sequence was observed remotely.
In total, 14 x 20 s  unfiltered observations were observed. Our first 20 s
image started at 6:11:31 UT, 286 s after the GRB trigger. We did not detect 
the optical/NIR afterglow candidate reported by Bloom (GCN 7229
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 ) and
Kruehler et al. (GCN 7231
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 ) to a limiting magnitude of 17.9 (calibrated to 
USNO B1). A 200 s co-added image with the middle exposure time at 643 s 
after the GRB trigger did not detect the afterglow candidate to a limiting
magnitude of 20.0. 

This message may be cited.

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G. Stratta (ASDC), M. Perri (ASDC) and D. N. Burrows (PSU)
report on behalf of the Swift-XRT team:

The Swift-XRT began observing GRB 080129 (trigger=301981) on
2008-01-29 at 07:00:17 UT, 53 minutes after the BAT trigger
(Immler et al., GCN Circ. 7226
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 ).

Using 2045 s of overlapping XRT Photon Counting mode and UVOT
v-band data for GRB 080129, we find a refined astrometrically
corrected X-ray position (using the XRT-UVOT alignment and
matching UVOT field sources to the USNO-B1 catalogue):
RA, Dec =  105.284125, -7.846722 which is equivalent to:

RA (J2000): 07h 01m 8.19s
Dec (J2000): -07d 50' 48.2"

with an uncertainty of 2.0 arcsec (radius, 90% confidence).
This is 1.2 arcsec away from the previous position derived from the
XRT and UVOT data reported in Goad et al. (GCN Circ. 7230
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 ),
51 arcsec from the refined BAT position of Barthelmy et al.
(GCN Circ. 7235
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 ) and 1.9 arcsec from the Gemini South position
(GCN Circ. 7229
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 ).

The X-ray light curve from T + 3.2 ks to T + 85.8 ks can be
fitted by a broken power law model (chi2 of 39 for 28 degrees
of freedom) with a temporal break at about T + 15.5 ks and
decay indices alpha1 = 0.6 +/- 0.1 and alpha2 = 1.5 +/- 0.1
before and after the break, respectively.

The 0.3-10 keV spectrum from T + 3.2 ks to T + 32.2 ks
is well fit by an absorbed power law
(reduced chi2 of 1.02, with 20 degrees of freedom).
The best fit photon index is 2.0 +/- 0.1, with an hydrogen column
density of (2 +/- 1)e21 cm^-2, in addition to the Galactic column along
the line of sight of 6.3e21 cm^-2 (Kalberla et al. 2005).
The observed (unabsorbed) flux in the 0.3-10 keV band is
4.2e-12 (8.5e-12) erg cm^-2 s^-1.

The timing and spectral behaviors are completely consistent
with those of a typical GRB X-ray afterglow,
removing any uncertainty about the nature of this burst.

The predicted XRT count rate 48 hours after the trigger is 1.6e-3
count s^-1, which corresponds to an observed 0.3-10.0 keV flux of
1.3e-12 ergs cm^-2 s^-1.

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

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G. Stratta (ASDC), M. Perri (ASDC) and D. N. Burrows (PSU) <br>report on behalf of the Swift-XRT team:<br>&nbsp;<br>The Swift-XRT began observing GRB 080129 (trigger=301981) on <br>2008-01-29 at 07:00:17 UT, 53 minutes after the BAT trigger&nbsp; <br>
(Immler et al., GCN Circ. 7226
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 ). <br><br>Using 2045 s of overlapping XRT Photon Counting mode and UVOT<br>v-band data for GRB 080129, we find a refined astrometrically <br>corrected X-ray position (using the XRT-UVOT alignment and <br>
matching UVOT field sources to the USNO-B1 catalogue): <br>RA, Dec =&nbsp; 105.284125, -7.846722 which is equivalent to:<br><br>RA (J2000): 07h 01m 8.19s<br>Dec (J2000): -07d 50&#39; 48.2&quot;<br><br>with an uncertainty of 2.0 arcsec (radius, 90% confidence).<br>
This is 1.2 arcsec away from the previous position derived from the <br>XRT and UVOT data reported in Goad et al. (GCN Circ. 7230
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 ),&nbsp; <br>51 arcsec from the refined BAT position of Barthelmy et al. <br>(GCN Circ. 7235
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 ) and 1.9 arcsec from the Gemini South position <br>
(GCN Circ. 7229
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 ).<br><br>The X-ray light curve from T + 3.2 ks to T + 85.8 ks can be <br>fitted by a broken power law model (chi2 of 39 for 28 degrees <br>of freedom) with a temporal break at about T + 15.5 ks and <br>decay indices alpha1 = 0.6 +/- 0.1 and alpha2 = 1.5 +/- 0.1 <br>
before and after the break, respectively. <br><br>The 0.3-10 keV spectrum from T + 3.2 ks to T + 32.2 ks <br>is well fit by an absorbed power law <br>(reduced chi2 of 1.02, with 20 degrees of freedom). <br>The best fit photon index is 2.0 +/- 0.1, with an hydrogen column <br>
density of (2 +/- 1)e21 cm^-2, in addition to the Galactic column along <br>the line of sight of 6.3e21 cm^-2 (Kalberla et al. 2005). <br>The observed (unabsorbed) flux in the 0.3-10 keV band is <br>4.2e-12 (8.5e-12) erg cm^-2 s^-1. <br>
<br>The timing and spectral behaviors are completely consistent <br>with those of a typical GRB X-ray afterglow, <br>removing any uncertainty about the nature of this burst.<br><br>The predicted XRT count rate 48 hours after the trigger is 1.6e-3 <br>
count s^-1, which corresponds to an observed 0.3-10.0 keV flux of <br>1.3e-12 ergs cm^-2 s^-1.<br><br>This circular is an official product of the Swift-XRT team.<br><br clear="all"><br><br>

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A. de Ugarte Postigo (ESO, Santiago), D. Diaz Fraile, F. Aceituno, E. 
Rodr�guez,
A.J. Castro-Tirado, J. Gorosabel, M. Jelinek (IAA-CSIC, Granada) and
A. Pozanenko (IKI, Moscow)
report on behalf of a larger collaboration:

We have observed GRB 080129 (Immler et al. GCN 7226
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 ) with the 1.5m OSN 
telescope
at Sierra Nevada Observatory (Granda, Spain). The observations consist 
of a series of
625x19s exposures in I-band, and range from 29.8614 Jan 2008 to 30.0166 
Jan 2008 UT
(0.607-0.762 days after the burst). We do not detect any source in the 
individual frames down
to an average limiting magnitude I < 20.3. However, the combined frame 
does show the
source identified by Bloom et al. (GCN 7229
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 ) at I ~ 22.1.
A finding chart can be seen at:
http://www.iaa.es/~deugarte/GRBs/080129/080129_OSN_fc.jpg

This message may be cited.

[GCN OPS NOTE(31jan08): Per author's request, M. Jelinek was added
to the author list.]

S. T. Holland (CRESST/GSFC/USRA) and S. Immler (CRESST/UMCP/GSFC)
report on the behalf of the Swift UVOT team:

        The Swift/UVOT observed the field of GRB 080129 starting 3188 s
after the BAT trigger (Immler et al. 2007, GCN Circ. 7226
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 ).  We do not
find any source, in any of the UVOT observations, at the location of
the Gemini-South source (Bloom, 2007 GCN Circ. 7229
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 ).

        The 3-sigma upper limits for detecting a source at this
location in the co-added images are:


Filter    T_start   T_stop    Exp(s)    Mag (3-sigma upper limit)
-----------------------------------------------------------------
    v         3188   21,457      2023    21.3
    b         4134   28,152      2164    22.2
    u         3929   27,239      1278    21.5
  uvw1        3724   32,166      1182    21.3
  uvm2        3519   22,362      1279    21.2
  uvw2        4545   17,372      1920    21.7
white        3207   28,940      2856    23.1
-----------------------------------------------------------------

This burst occurred 1.43 degrees from the Galactic plane, so the
Galactic reddening along the line of sight is highly uncertain.  The
values quoted above are not corrected for Galactic extinction.  All
photometry is on the UVOT flight system described in Poole et al.  
(2008).