Gamma-ray Burst 100909A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN Circular #11260
S.Mereghetti, A.Paizis (IASF- Milano), D.Gotz (CEA-Saclay), E. Bozzo, C. Ricci, M. Beck (ISDC, Versoix), and J. Borkowski (CAMK, Torun) on behalf of the IBAS Localization Team report:
a gamma ray burst lasting about 60 s has been detected by IBAS in the IBIS/ISGRI data at 09:04 U.T. on September 9th. The detection significance was slightly below the threshold for automatic alert delivery.
Its refined coordinates (J2000) are:
```
 RA:  73.9506 [degrees]
 DEC: 54.6544 [degrees]
```
with an uncertainty of 2 arcmin (90% c.l.).
A preliminary analysis gives a 20-200 keV fluence of about 10e-6 erg/cmsq.
A plot of the light curve will be posted at
http://ibas.iasf-milano.inaf.it/IBAS_Results.html
This message can be cited.

GCN/BACODINE POSITION NOTICE

TITLE:          GCN/INTEGRAL NOTICE
NOTICE_DATE:    Thu 09 Sep 10 10:41:09 UT
NOTICE_TYPE:    INTEGRAL Offline
TRIGGER_NUM:    6060,   Sub_Num: 0
GRB_RA:          73.9505d {+04h 55m 48s} (J2000),
                 74.1681d {+04h 56m 40s} (current),
                 72.9342d {+04h 51m 44s} (1950)
GRB_DEC:        +54.6544d {+54d 39' 16"} (J2000),
                +54.6707d {+54d 40' 15"} (current),
                +54.5750d {+54d 34' 30"} (1950)
GRB_ERROR:      2.00 [arcmin, radius, statistical only]
GRB_INTEN:      7.71 [sigma]
GRB_TIME:       32693.94 SOD {09:04:53.94} UT
GRB_DATE:       15448 TJD;   252 DOY;   10/09/09
SC_RA:           92.32 [deg] (J2000)
SC_DEC:          54.65 [deg] (J2000)
SUN_POSTN:      167.71d {+11h 10m 51s}   +5.27d {+05d 16' 11"}
SUN_DIST:        87.75 [deg]   Sun_angle= 6.2 [hr] (West of Sun)
MOON_POSTN:     178.84d {+11h 55m 22s}   -4.88d {-04d 52' 46"}
MOON_DIST:      102.44 [deg]
GAL_COORDS:     153.62,  7.07 [deg] galactic lon,lat of the burst
ECL_COORDS:      79.15, 31.82 [deg] ecliptic lon,lat of the burst
COMMENTS:       INTEGRAL GRB Coordinates.  
COMMENTS:       possible GRB below automatic threshold

red DSS finding chart ps-file

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 09 Sep 10 13:05:56 UT
NOTICE_TYPE:     Swift-XRT Position
TRIGGER_NUM:     20147,   Seg_Num: 1
GRB_RA:           73.9483d {+04h 55m 47.59s} (J2000),
                  74.1660d {+04h 56m 39.83s} (current),
                  72.9320d {+04h 51m 43.68s} (1950)
GRB_DEC:         +54.6570d {+54d 39' 25.1"} (J2000),
                 +54.6733d {+54d 40' 24.0"} (current),
                 +54.5776d {+54d 34' 39.5"} (1950)
GRB_ERROR:       4.9 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  15448 TJD;   252 DOY;   10/09/09
IMG_START_TIME:  44388.00 SOD {12:19:48.00} UT,   11748.0 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       167.80d {+11h 11m 13s}   +5.23d {+05d 13' 54"}
SUN_DIST:         87.83 [deg]   Sun_angle= 6.2 [hr] (West of Sun)
MOON_POSTN:      180.23d {+12h 00m 55s}   -5.50d {-05d 30' 09"}
MOON_DIST:       103.74 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:      153.61,  7.07 [deg] galactic lon,lat of the burst
ECL_COORDS:       79.15, 31.82 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        This Notice is generated as a result of an uploaded TOO -- this is not a normal BAT-detected burst.  
COMMENTS:        And the IMG_START_DATE/TIME fields are the current epoch -- not the original detection.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        TAM values, flux and significance fields are not valid.  
COMMENTS:        This position was automatically generated on the ground using  
COMMENTS:        Photon Counting data telemetered via TDRSS (SPER data).  
COMMENTS:        See http://www.swift.ac.uk/sper/docs.php for details.  
COMMENTS:        The probability that this is a serendipitous source in the

GCN NOTICE

TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 09 Sep 10 13:18:52 UT
NOTICE_TYPE:     Swift-XRT Position UPDATE
TRIGGER_NUM:     20147,   Seg_Num: 1
GRB_RA:           73.9491d {+04h 55m 47.78s} (J2000),
                  74.1668d {+04h 56m 40.02s} (current),
                  72.9328d {+04h 51m 43.87s} (1950)
GRB_DEC:         +54.6578d {+54d 39' 28.0"} (J2000),
                 +54.6741d {+54d 40' 26.9"} (current),
                 +54.5785d {+54d 34' 42.4"} (1950)
GRB_ERROR:       4.7 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN:       1.00e-10 [erg/cm2/sec]
GRB_SIGNIF:      10.00 [sigma]
IMG_START_DATE:  15448 TJD;   252 DOY;   10/09/09
IMG_START_TIME:  44388.00 SOD {12:19:48.00} UT,   11748.0 [sec] since BAT Trigger Time
TAM[0-3]:        100.00 100.00 100.00 100.00
AMPLIFIER:       1
WAVEFORM:        31
SUN_POSTN:       167.81d {+11h 11m 15s}   +5.23d {+05d 13' 42"}
SUN_DIST:         87.84 [deg]   Sun_angle= 6.2 [hr] (West of Sun)
MOON_POSTN:      180.35d {+12h 01m 25s}   -5.56d {-05d 33' 29"}
MOON_DIST:       103.85 [deg]
MOON_ILLUM:      2 [%]
GAL_COORDS:      153.61,  7.07 [deg] galactic lon,lat of the burst
ECL_COORDS:       79.15, 31.82 [deg] ecliptic lon,lat of the burst
COMMENTS:        SWIFT-XRT Coordinates.  
COMMENTS:        This Notice is generated as a result of an uploaded TOO -- this is not a normal BAT-detected burst.  
COMMENTS:        And the IMG_START_DATE/TIME fields are the current epoch -- not the original detection.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        This is an Update Notice -- the RA,Dec values herein supersede the previous XRT_POS Notice.  
COMMENTS:        TAM values, flux and significance fields are not valid.  
COMMENTS:        This position was automatically generated on the ground using  
COMMENTS:        Photon Counting data telemetered via TDRSS (SPER data).  
COMMENTS:        See http://www.swift.ac.uk/sper/docs.php for details.  
COMMENTS:        The probability that this is a serendipitous source in the  
COMMENTS:        SPER window is 15% < P(seren) < 100%.

GCN Circular #11261
M. H. Siegel (PSU), S. D. Barthelmy (GSFC), M. M. Chester (PSU), P. A. Evans (U Leicester), J. M. Gelbord (PSU), J. A. Kennea (PSU), K. L. Page (U Leicester) and R. L. C. Starling (U Leicester) report on behalf of the Swift Team:
Swift began a target of opportunity observation of GRB 100909A on September 9, 2010 at 12:18 UT, approximately 3.2 hours after the burst was detected by INTEGRAL. Swift data for these observations utilize Target ID 20147.
The XRT began observing the field at 12:19:37.4 UT, 11.7 ks after the INTEGRAL trigger. In 1.8 ks of promptly downlinked data there is a faint source, detected at the 3.2-sigma level at: RA, Dec= 73.94797, +54.65798 which is equivalent to:
```
RA (J2000) : 04h 55m 47.51s
Dec (J2000): +54d 39' 28.7''
```
with an estimated uncertainty of 6 arcsec (radius, 90% confidence).
UVOT took a finding chart exposure of 150 seconds with the White filter starting 11687 seconds after the INTEGRAL trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 44% of the INTEGRAL error circle and 100% of the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. The coverage of the INTEGRAL and XRT error circles by the 8'x8' region for the list of sources generated on-board is uncertain because the large number of sources filled the available telemetry. No correction has been made for the expected extinction corresponding to E(B-V) of 0.51.
Burst Advocate for this burst is M. H. Siegel (siegel AT astro.psu.edu). 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.)
GCN Circular #11263
XMM-Newton will observe GRB 100909A at location (RA=4h 55m 48s, DEC=+54d 39' 15", J2000), starting at 04:30 UT, on September 10, 2010, for an exposure of 31000 seconds.
GCN Circular #11264
B. E. Schaefer (Louisiana State) reports on behalf of the ROTSE collaboration:
ROTSE-IIIb, located at McDonald Observatory, Texas, responded to GRB 100909A (INTEGRAL trigger 6060; Mereghetti et al., GCN 11260), producing images beginning 6.4 s after the GCN notice time. An automated response took the first image at 10:41:45.5 UT, 5811.6 s after the burst. For the first 20 minutes the conditions were partly cloudy with occassional holes, but after 11:02 UT the sky became clear and excellent. We took 10 5-sec, 10 20-sec and 116 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 INTEGRAL/IBIS error circle, for both single images and coadding into sets of 10. The Swift XRT team reports that a faint X-ray source is visible at 12:19 UT (Siegel et al. 2010, GCN 11261), and we have also closely examined this error circle, again finding no variable star or object of interest. The Swift XRT position is not crowded, although there is one fairly faint star in it. Individual images have limiting magnitudes ranging from 12.8-17.6; we set the following specific limits.
```
start UT       end UT      t_exp(s)   mlim   t_start-tGRB(s)  Coadd?
--------------------------------------------------------------------
10:44:07.5   10:45:25.7        78     15.7         5953.6       Y
11:02:58.7   11:07:40.0       281     18.5         7084.8       Y
```
GCN Circular #11265
C. Guidorzi (U. Ferrara), Z. Cano, D. Bersier (LJMU), P. O'Brien (U. Leicester) report on behalf of a large collaboration:
The Faulkes Telescope North automatically began observing INTEGRAL GRB 100909A (Mereghetti et al. GCN Circ. 11260) on September 09, 10:42:34 UT, 1.6 hours from the GRB trigger time. Within the Swift-XRT error circle (Siegel et al. GCN Circ. 11261) we identify an uncatalogued, possibly fading object at the following position:
```
RA(J2000.0):  04:55:47.86
Dec(J2000.0): +54:39:32.1
```
with the following magnitudes:
```
Mid Time from      Exposure      Filter     Magnitude
GRB (hours)          (s)
-------------------------------------------------------
2.07                540            R        21.6 +- 0.2
2.16                520            i        20.6 +- 0.1
5.05               1200            R        22.1 +- 0.2
-------------------------------------------------------
```
Calibration was done against the nearby USNOB-1 star RA,DEC=04:55:49.14, +54:39:42.66, assuming R2=16.82, I=16.06. We note that the uncatalogued source lies 3" from a USNOB-1 object with R2=18.54.
GCN Circular #11268
J. M. Gelbord (PSU) and M. H. Siegel (PSU) report on behalf of the Swift-XRT team:
We have analysed 7.7 ks of XRT data for GRB 100909A (Mereghetti et al., GCN Circ. 11260; Siegel et al., GCN Circ. 11261), from 11.8 ks to 25.8 ks after the Integral trigger. The data are entirely in Photon Counting (PC) mode. Using 1953 s of PC mode data and 1 UVOT images, we find an enhanced XRT position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 73.94760, +54.65970 which is equivalent to:
```
RA (J2000): 04 55 47.42
Dec(J2000): +54 39 34.8
```
with an uncertainty of 5.4 arcsec (radius, 90% confidence).
The X-ray light curve appears to be fading, although we note that the evidence is limited by the small number of counts in the XRT data (approximately 60 counts spread over three orbits). When modelled with a power-law decay, the best-fitting decay index is alpha=1.2 (+1.1, -1.0).
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.5 (+0.8, -0.7). The best- fitting absorption column is 4.8 (+3.4, -2.6) x 10^21 cm^-2, consistent with the Galactic value of 2.8 x 10^21 cm^-2 (Kalberla et al. 2005). The time-averaged 0.3-10 keV flux observed (unabsorbed) is 2.8 x 10^-13 (7.1 x 10^-13) erg cm^-2 s^-1. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.4 x 10^-11 (1.1 x 10^-10) erg cm^-2 count^-1.
If the light curve continues to decay with a power-law decay index of 1.2, the count rate at T+24 hours will be 1.1 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.2 x 10^-14 (1.2 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/00020147.
This circular is an official product of the Swift-XRT team.
GCN Circular #11269
Martin Jelinek, Javier Gorosabel (IAA-CSIC) and Sergio Simon (IAC-ULL) report on behalf of a larger colaboration:
"We observed the optical afterglow of GRB100909A (Mereghetti et al. GCNC11260; Siegel et al. GCNC11261; Guidorzi et al. GCNC 11265) with the 2.56m Nordic Optical Telescope equipped with ALFOSC, starting on September 10 at 4:30 UT (i.e. 19.4h after the burst).
A preliminary analysis of the 600-s R-band exposure shows the proposed afterglow with magnitude R~23.2 in respect to the R2=18.54 object mentioned by Guidorzi et al. (GCNC11265). This implies a decay rate alpha~1.6, and confirms the fading nature of the object.
This message may be cited."
GCN Circular #11272
M. De Pasquale (MSSL-UCL) and M. H. Siegel (PSU) report, on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 100909A 11747 s after the INTEGRAL trigger (Mereghetti et `al.,GCN Circ. 11260). Data summed from the first and second orbits do not reveal a source at the enhanced position of the X-ray afterglow (Gelbold et al., GCN Circ. 11268).
The 3-sigma upper limits f are reported below:
```
FILTER T_start(s) T_stop    Exposure   Mag/3UL
========================================================
wh      11747     25861     1809       >21.9
v       14755     18362      894       >20.21
b       11906     44659     1770       >21.48
u       33619     34527      885       >20.84
w1      19275     20040      752       >20.39
w2      13732     14301      561       >20.33
=======================================================
```
The above magnitudes are not corrected for the strong Galactic extinction corresponding to a reddening of E_{B-V} = 0.51 (Schlegel et al., 1998, ApJS, 500, 525). The photometry is on the UVOT photometric system described in Poole et al. (2008, MNRAS, 383, 627).
GCN Circular #11273
D. Kuroda (OAO, NAOJ), H. Hanayama, T. Miyaji, J. Watanabe (IAO, NAOJ), K. Yanagisawa (OAO, NAOJ), M. Yoshida (Hiroshima), K. Ohta (Kyoto) and N. Kawai(Tokyo Tech) report on behalf of the MITSuME collaboration:
We observed the field of GRB 100909A (Mereghetti et al., GCN 11260) with the optical three color (g', Rc and Ic) CCD camera attached to the Murikabushi 1m telescope of Ishigakijima Astronomical Observatory.
The observation started on 10 16:05:58 UT (~1.3 days after the INTEGRAL trigger). We could not detect the previously reported afterglow (Siegel et al., GCNC 11261; Guidorzi et al., GCN 11265; Gelbord and Siegel, GCN 11268; Jelinek et al., GCN 11269) in all the three bands.
Three sigma upper limits of the OT are listed below. We used GSC2.3 catalog for flux calibration.
```
T0+[day]   MID-UT   T-EXP[sec]    g'     Rc     Ic
------------------------------------------------------
1.31686    16:41:10   960.0     >21.3  >20.9  >20.0
------------------------------------------------------
T0+ : Elapsed time after the burst [day]
T-EXP: Total Exposure time [sec]
```

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Jochen Greiner, last update: 09-Sep-2010 [Disclaimer]