Gamma-ray Burst 110206A

(All information courtesy of the instrument teams.)

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Results of Observations

GCN/BACODINE POSITION NOTICE

TITLE:          GCN/INTEGRAL NOTICE
NOTICE_DATE:    Sun 06 Feb 11 18:08:32 UT
NOTICE_TYPE:    INTEGRAL Wakeup
TRIGGER_NUM:    6133,   Sub_Num: 1
GRB_RA:          92.3708d {+06h 09m 29s} (J2000),
                 92.4111d {+06h 09m 39s} (current),
                 92.1891d {+06h 08m 45s} (1950)
GRB_DEC:        -58.7771d {-58d 46' 37"} (J2000),
                -58.7797d {-58d 46' 46"} (current),
                -58.7660d {-58d 45' 57"} (1950)
GRB_ERROR:      3.30 [arcmin, radius, statistical only]
GRB_INTEN:      8.03 [sigma]
GRB_TIME:       65298.07 SOD {18:08:18.07} UT
GRB_DATE:       15598 TJD;    37 DOY;   11/02/06
SC_RA:           81.27 [deg] (J2000)
SC_DEC:         -71.52 [deg] (J2000)
SUN_POSTN:      320.05d {+21h 20m 11s}  -15.56d {-15d 33' 25"}
SUN_DIST:        96.15 [deg]   Sun_angle= -8.8 [hr] (East of Sun)
MOON_POSTN:     355.87d {+23h 43m 28s}   +3.79d {+03d 47' 07"}
MOON_DIST:       96.63 [deg]
GAL_COORDS:     267.56,-28.29 [deg] galactic lon,lat of the burst
ECL_COORDS:      99.02,-82.14 [deg] ecliptic lon,lat of the burst
COMMENTS:       INTEGRAL GRB Coordinates.  
COMMENTS:       Possibly real GRB event

red DSS finding chart ps-file

GCN NOTICE

TITLE:          GCN/INTEGRAL NOTICE
NOTICE_DATE:    Sun 06 Feb 11 18:11:31 UT
NOTICE_TYPE:    INTEGRAL Refined
TRIGGER_NUM:    6133,   Sub_Num: 2
GRB_RA:          92.3501d {+06h 09m 24s} (J2000),
                 92.3904d {+06h 09m 34s} (current),
                 92.1686d {+06h 08m 40s} (1950)
GRB_DEC:        -58.7876d {-58d 47' 15"} (J2000),
                -58.7902d {-58d 47' 24"} (current),
                -58.7767d {-58d 46' 35"} (1950)
GRB_ERROR:      3.15 [arcmin, radius, statistical only]
GRB_INTEN:      8.98 [sigma]
GRB_TIME:       65307.52 SOD {18:08:27.52} UT
GRB_DATE:       15598 TJD;    37 DOY;   11/02/06
SC_RA:           81.27 [deg] (J2000)
SC_DEC:         -71.52 [deg] (J2000)
SUN_POSTN:      320.05d {+21h 20m 11s}  -15.56d {-15d 33' 23"}
SUN_DIST:        96.13 [deg]   Sun_angle= -8.8 [hr] (East of Sun)
MOON_POSTN:     355.89d {+23h 43m 34s}   +3.80d {+03d 47' 42"}
MOON_DIST:       96.61 [deg]
GAL_COORDS:     267.57,-28.30 [deg] galactic lon,lat of the burst
ECL_COORDS:      98.95,-82.15 [deg] ecliptic lon,lat of the burst
COMMENTS:       INTEGRAL GRB Coordinates.  
COMMENTS:       Possibly real GRB event

GCN NOTICE

TITLE:          GCN/INTEGRAL NOTICE
NOTICE_DATE:    Sun 06 Feb 11 19:01:17 UT
NOTICE_TYPE:    INTEGRAL Offline
TRIGGER_NUM:    6133,   Sub_Num: 3
GRB_RA:          92.3553d {+06h 09m 25s} (J2000),
                 92.3955d {+06h 09m 35s} (current),
                 92.1741d {+06h 08m 42s} (1950)
GRB_DEC:        -58.8073d {-58d 48' 25"} (J2000),
                -58.8099d {-58d 48' 35"} (current),
                -58.7963d {-58d 47' 46"} (1950)
GRB_ERROR:      2.00 [arcmin, radius, statistical only]
GRB_INTEN:      8.98 [sigma]
GRB_TIME:       65307.52 SOD {18:08:27.52} UT
GRB_DATE:       15598 TJD;    37 DOY;   11/02/06
SC_RA:           81.27 [deg] (J2000)
SC_DEC:         -71.52 [deg] (J2000)
SUN_POSTN:      320.08d {+21h 20m 20s}  -15.55d {-15d 32' 45"}
SUN_DIST:        96.12 [deg]   Sun_angle= -8.8 [hr] (East of Sun)
MOON_POSTN:     356.27d {+23h 45m 04s}   +3.96d {+03d 57' 36"}
MOON_DIST:       96.56 [deg]
GAL_COORDS:     267.60,-28.30 [deg] galactic lon,lat of the burst
ECL_COORDS:      98.99,-82.17 [deg] ecliptic lon,lat of the burst
COMMENTS:       INTEGRAL GRB Coordinates.  
COMMENTS:       refined_coordinates_after_offline_analysis

GCN Circular #11654
S.Mereghetti, A.Paizis (IASF-Milano), D.Gotz (CEA-Saclay), J. Borkowski (CAMK, Torun), E. Bozzo, C.Ferrigno, M. Beck (ISDC, Versoix), on behalf of the IBAS Localization Team report:
a gamma ray burst lasting about 20 s has been detected by IBAS in the IBIS/ISGRI data at 18:08:05 UT of February 6.
Its refined coordinates (J2000) are:
```
  RA:  92.35535  [degrees]
  DEC: -58.8075  [degrees]
```
with an uncertainty of 2 arcmin (90% c.l.).
A preliminary analysis gives a 20-200 keV peak flux of about 1 ph/cm2 s (1 s integration time)
A plot of the light curve will be posted at http://ibas.iasf-milano.inaf.it/IBAS_Results.html
GCN Circular #11656
Klotz A. (CESR-OMP), Gendre B. (ASDC), Lass-Bourez M. (UWA) Boer M. (OHP-OAMP), Atteia J.L. (LATT-OMP) report:
We imaged the field of GRB 110206A detected by INTEGRAL (trigger 6088, Mereghetti et al. 2011 GCNC 11654) with the TAROT robotic telescope (D=25cm) located at the European Southern Observatory, La Silla observatory, Chile.
The observations started 6.3h after the GRB trigger (beginning of the night). The elevation of the field increased from 57 degrees above horizon and weather conditions were good.
We co-added a series of exposures t0+6.3h to t0+7.3h : R > 19.3
Magnitudes were estimated with the nearby USNO-B1 stars and are not corrected for galactic dust extinction.
N.B. Galactic coordinates are lon=267.5629 lat=-28.2892 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.
GCN Circular #11657
P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:
We have analysed 4.2 ks of XRT data for the INTEGRAL-detected GRB 110206A (Mereghetti et al. et al. GCN Circ. 11654), from 26.9 ks to 34.9 ks after the INTEGRAL trigger. The data are entirely in Photon Counting (PC) mode. Inside the INTEGRAL error circle we find a single, uncatalogued X-ray source. Using 2309 s of PC mode data and 2 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 = 92.33400, -58.80700 which is equivalent to:
```
RA (J2000): 06h 09m 20.17s
Dec(J2000): -58d 48' 25.3"
```
with an uncertainty of 1.9 arcsec (radius, 90% confidence). The light curve is consistent with a constant source of mean count rate 6.8e-02 ct/sec: a power-law fit gives an index of 0.0 (+/-1.1). Given the brightness of the source (which is more than 3-sigma above the Rosat All Sky Survey detection limit), and the large uncertainty on the decay index, we propose this source as the probable afterglow of GRB 110206A, however further observations are needed to confirm this.
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.12 (+0.27, -0.30). The best-fitting absorption column is 9.5 (+4.5, -6.4) x 10^20 cm^-2, consistent with the Galactic value of 3.1 x 10^20 cm^-2 (Kalberla et al. 2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.6 x 10^-11 (4.7 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     9.5 (+4.5, -6.4) x 10^20 cm^-2
Galactic foreground: 3.1 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index:	     2.12 (+0.27, -0.30)
```
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00020156.
This circular is an official product of the Swift-XRT team.
GCN Circular #11662
E. A. Hoversten (PSU) and P. A. Evans (U. Leicester) report on behalf of the Swift UVOT team:
We have analyzed Swift UVOT observations of the INTEGRAL-detected GRB 110206A (Mereghetti et al. et al. GCN Circ. 11654). UVOT observations began 26.9 ks after the INTEGRAL trigger. The UVOT data reveal a faint new source that does not appear in archival MAST DSS images. The refined UVOT position of the new source is:
```
      RA (J2000)  06:09:20.14  =  92.33392 (deg)
     Dec (J2000) -58:48:25.3   =  -58.80703 (deg)
```
with an estimated uncertainty of 0.8 arcsec (radius, 90% confidence, statistical + systematic). This position is within 0.2 arcseconds of the enhanced XRT position (Evans, GCN Circ. 11657) which is well within the measurement errors.
The source is detected in the uvw1, u, and b filters, while an upper limit was found in uvm2. The observed magnitudes and 3-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
=============================================================
b        28761       29253       480   21.00 +/- 0.37
u        27847       34952      1044   20.56 +/- 0.24
uvw1     26941       34783      1771   20.36 +/- 0.26
uvm2     32977       33876       885      > 20.61
```
The values quoted above are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.05 in the direction of the burst (Schlegel et al. 1998).
GCN Circular #11665
J. Elliott, R. Filgas, T. Kruehler and J. Greiner (all MPE Garching), report on behalf of the GROND team:
GROND observed the field of the INTEGRAL GRB 110206 (Mereghetti et al., GCN# 11654) starting at 00:33 UT on 2011-02-07, which is 6.42 hours after the trigger. In total, 1.7 hours of imaging was obtained simultaneously in g'r'i'z'JHK. Within the enhanced XRT error circle (Evans, GCN #11657), we detect a single point source at
```
RA (J2000): 06:09:20.04
Decl (J2000): -58:48:24.9
```
with typical uncertainties of 0.5" in each coordinate. These coordinates are consistent with the source detected by UVOT (Hoversten & Evans, GCN# 11662). At a midtime of 6.7 hours after the trigger we measure a preliminary AB magnitude of r' = 21.2 +/- 0.1 based on the GROND zeropoint. The source is detected in all GROND filters, which implies a redshift constraint of z < 4.
Within the observational errors, no variability is evident in the timeframe of the GROND observations, and hence we cannot claim the association of the source with GRB 110206A at the current stage.
GCN Circular #11668
B. E. Cobb (GWU) reports:
Using the ANDICAM instrument on the 1.3m telescope at CTIO, we obtained optical/IR imaging of the error region of GRB 110206A (GCN 11654, Mereghetti et al.) with a mid-exposure time of 6.8 hours post-burst (2011-02-07 00:57:41 UT). Total summed exposure times amounted to 36 minutes in I and 30 minutes in J.
The source which is the possible optical afterglow of GRB 110206A (GCN 11662, Hoversten et al. and GCN 11665, Elliott et al.) is detected in our optical image. Preliminary comparison to Landolt standards stars in I and 2MASS stars in J indicates the following I-band magnitude and J-band 3-sigma upper limit for this source:
```
time post-burst       I mag             J 3-sigma limit
6.8 hours               20.6+/-0.1      >18.8
```
Our data do not allow for a test of variability at this time, so we cannot confirm that this source is the optical afterglow of GRB 110206A.
GCN Circular #11669
J. Elliott, R. Filgas and J. Greiner (all MPE Garching), report on behalf of the GROND team:
GROND observed the field of INTEGRAL GRB 110206A (Mereghetti et al., GCN #11654) again starting at 01:10 UT on 2011-02-08, which is 24.62 hours after the first epoch. In total 8 minutes of imaging was obtained simultaneously in g'r'i'z'JHK.
The candidate (GCN 11662, Hoversten et al., GCN 11665, Elliott et al. and GCN 11668, Cobb et al.) has been seen to have decayed by 1.2 magnitudes suggesting that it is the afterglow of GRB110206A
We measure a preliminary magnitude of the second epoch of r' = 22.4 +/- 0.1 based on the GROND zeropoint.
GCN Circular #11675
B. E. Cobb (GWU) reports:
Using the ANDICAM instrument on the 1.3m telescope at CTIO, we obtained optical/IR imaging of the error region of GRB 110206A (GCN 11654, Mereghetti et al.) with a mid-exposure time of 34.2 hours post-burst (2011-02-08 04:22 UT). Total summed exposure times amounted to 36 minutes in I and 30 minutes in J.
In agreement with Elliott et al. (GCN 11669), we observe that the candidate optical afterglow of GRB 110206A (GCN 11662, Hoversten et al. and GCN 11665, Elliott et al.) has decayed significantly from our previous observations (GCN 11668), indicating that this is the optical afterglow of GRB 110206A. Preliminary comparison to Landolt standard stars indicates the following magnitude for the optical afterglow:
```
time post-burst       I mag
 6.8 hours             20.6+/-0.1
34.2 hours             21.6+/-0.2
```
This indicates that the decay rate of the burst between ~7 and 34 hours post burst is alpha ~ 0.6 (where afterglow flux is proportional to t^-alpha).
GCN Circular #11686
P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:
Swift performed a second epoch observation of the INTEGRAL GRB 110206A (Mereghetti et al. GCN Circ. 11654), collecting 4.8 ks of data from T0+253 ks to T0+277 ks. The X-ray source reported by Evans et al. (GCN Circ. 11657) has clearly faded, confirming that this is the afterglow. The decay can be modelled as a single power-law decay with an index of 1.1 (+0.2, -0.1).
This circular is an official product of the Swift-XRT team.

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Jochen Greiner, last update: 10-Feb-2011 [Disclaimer]