GRB 060930

D.Gotz (CEA, Saclay), S.Mereghetti, A.Paizis (IASF-Milano), M.Lazos, 
N.Mowlavi, M. Beck (ISDC, Versoix), and J. Borkowski (CAMK, Torun) on 
behalf of the IBAS Localization Team report:

An X-ray rich GRB lasting about 20 s has been detected by IBAS in 
IBIS/ISGRI data at 09:04:09 UT on September 30, 2006.

The coordinates (J2000)  are:
RA: 304.5363 [degrees], 
DEC: -23.6253

with an uncertainty of 2.5 arcmin (90% c.l.).

The peak flux in the 20-200 keV is 0.3 ph/cmq/s (2.2x10e-8 erg/cmq/s) over 
1 s integration time and the fluence in the same energy range is 2.5x10e-7 
erg/cmq

We note that the faint ROSAT X-ray source 1RXS J201811.2-233536 is 
contained in the error region. Its RASS count rate of 0.03 counts/s 
corresponds to about 2x10e-13 erg/cmq/s

A plot of the light curve will be posted at

http://ibas.mi.iasf.cnr.it/IBAS_Results.html

This message can be cited.

H. Swan (U. Michigan), W. Rujopakarn (U. Arizona), S.A. Yost (U.  
Michigan), E.S. Rykoff (U. Michigan), B. E. Schaefer (Louisiana  
State), report on behalf of the ROTSE collaboration:

ROTSE-IIIa, located at Siding Spring Observatory, Australia, responded
to GRB 060930 (Integral trigger 3503), producing images beginning 6.3
s after the GCN notice time. An automated response took the first
image at 09:05:08.3 UT, 44.1 s after the burst, under fair conditions.
We took 10 5-sec, 10 20-sec and 80 60-sec exposures. These unfiltered
images are calibrated relative to USNO A2.0 (R).

Comparison to the DSS (second epoch) reveals no new sources within the
3-sigma error circle, for both single images and coadding into sets of
10. Individual images have limiting magnitudes ranging from 15.8-17.1;
we set the following specific limits.

start UT       end UT      t_exp(s)   mlim   t_start-tGRB(s)  Coadd?
--------------------------------------------------------------------
09:05:08.3   09:05:13.3         5     15.8           44.1       N
09:05:08.3   09:07:44.3       156     17.1           44.1       Y

M.Zhai, L.P. Xin, Y.L. Qiu, J.Y. Wei, J.Y. Hu, J.S. Deng
Y. Urata and W.K. Zheng on behalf of EAFON report:

We have imaged the field of GRB 060930 with the TNT 0.8m telescope
at Xinglong Observatory.Observations started about 2.74 hours after the 
burst under bad condition (cloudy and high airmass). in our combined
 6*10 minutesR band image, we do not detect any new source  down to
 ~17.25 with mean time 3.55 hours after the burst derived from  USNO A2.0

This message may be cited.

C. Guidorzi (Univ Bicocca & INAF-OAB), D. Bersier (Liverpool JMU),
C.G. Mundell, I.A. Steele, A. Melandri, A. Gomboc
(University of Ljubljana), R.J. Smith, A. Monfardini, D. Carter,
S. Kobayashi, M. Bode (Liverpool JMU), E. Rol, P. O'Brien,
N. Bannister (Leicester) report:

"The 2m Faulkes Telescope South (Siding Spring, Australia) automatically
reacted to the INTEGRAL burst GRB 060930 (Gotz et al., GCN Circ. 5665
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 )
and began observing 1.98 minutes after the burst trigger time.

From a stacked 6x10s R-band image (from 1.98 min to 4.97 min after the
burst) with a FOV of 4.75' x 4.75' centred on the first INTEGRAL error
circle (RA=20:17:58; Dec=-23:38:16, J2000) we do not detect any
object not present on the DSS, down to R~19.5 (calibrated with the
USNOB catalogue). Furthermore we do not detect any variable object
down to the same limit."

A. de Ugarte Postigo, M. Jelinek, A.J. Castro-Tirado,  
J.Gorosabel (IAA-CSIC Granada), N. Pinilla-Alonso (TNG La Palma)
J. de Le��n Cruz (IAC Tenerife), J. Licandro (ING-IAC)

on behalf of a larger collaboration report:

We have observed the field of the GRB 060930 detected by INTEGRAL 
(Gotz et al., GCN 5665
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 ) with the 3.5m Telescopio Nazionale Galileo 
(+NICS) at La Palma in the JHK bands on 30 Sep 2006 (from 20:30 to 
20:51 UT) and revisited the field in H band on 1 Oct 2006 (from 
20:37 to 20:51 UT; i.e. 11.5 hr and 35.5 hr respectively after the 
onset of the gamma-ray event).

The NICS frames cover the central 80% of the INTEGRAL/IBIS error 
box (2.5' radius). We detect a variable, stationary object at the 
following coordinates (J2000):

RA = 20:18:11.51, Dec = -23:37:19.6

with an astrometric error of 0.5".

In the first epoch the source is detected in all 3 bands and has 
an H band magnitude of ~18.2. In the second H band epoch it has 
faded by about 1 magnitude. This would imply a decay index of 
alpha -0.9 +/- 0.2 .

For this object we obtain (Js-K)=1.10+/-0.22, consistent with the
near-IR colour expected for a GRB afterglow (Gorosabel et al. 2002, 
A&A, 384, 11).

A finding chart is available at:

http://www.iaa.es/~deugarte/GRBs/060930/grb060930.gif

This message is quotable.

A. de Ugarte Postigo, M. Jelinek, A.J. Castro-Tirado,
J. Gorosabel (IAA-CSIC Granada)

on behalf of a larger collaboration report:

"We have reobserved the field of GRB 060930 (GCNC 5665)
on a third epoch. This time we obtained frames with the
3.5m Calar Alto telescope in the H-band on Oct. 5.81 UT.
The magnitude of the suspected afterglow candidate that
we reported in GCNC 5682 is consistent with the one measured
on the first epoch and we believe that the data taken on
the second epoch (Oct 1.86 UT) were severely affected due
to the presence of the Moon four degrees away.

We thus conclude that the object reported in GCNC 5682
is not the near-IR afterglow to GRB 060930. A search for
variability of the faintest near-IR sources within the INTEGRAL
error box is under way.

We acknowledge Heather F. Swan for also independently
pointing out this to us by means of AEOS data."

H. Swan (U. Michigan), C. Akerlof (U. Michigan), M. Skinner (AMOS 
Observatory, Boeing LTS), report on behalf of the MARGE collaboration:

The AEOS Burst Camera (ABC) began imaging GRB060930 (GCN 5665
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 ) Sept 30 
09:15:47.3 UTC, ~11 minutes after the GRB was detected, obtaining ~ 2 
hrs of images of the error box. We coadded 10s images into sets of
20. Comparison of these images with images taken on Oct 5th, 2006
reveals no optical counterpart within the 2.5 arc minute error radius.
We have a 3 sigma limiting magnitude of 21.0 for our coadded images.

[GCN OPS NOTE(19oct06): Per author's request, the Subject line was corrected
to the 060930 burst.]