Gamma-ray Burst 111201A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN Circular #12608
T. Sakamoto (GSFC/UMBC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC), D. M. Palmer (LANL), G. Sato (ISAS), M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU) (i.e. the Swift-BAT team):
Automated BAT ground analysis found a burst that occurred at 14:22:45 UT with a significance of 10.8 sigma (15-200 keV) from the failed event data of trigger #508800. The event is temporary coincident with the Fermi GBM 344442167. The best BAT location is RA, Dec = 190.4854, 32.9935 deg, which is
```
  RA(J2000)  =  12h 41m 56.5s 
  Dec(J2000) = +32d 59' 36.6" 
```
with an uncertainty of 2.1 arcmin, (radius, sys+stat, 90% containment). The partial coding was 32%.
The mask-weighted light curve created from the failed event data (available from 14:22:41 to 14:22:51 UT) shows an increase in the rate ~1 sec after the event data start time. The count rate stays constant until the end of the event data. From the BAT raw light curve, the duration of the event is ~20 sec long.
The spectrum extracted using the full event data is best fit by a simple power-law model. The power law index of the spectrum is 1.6 +- 0.3. The fluence in 15-150 keV band measured from the 10 sec long event data is 4.6 +- 0.8 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from 14:22:46 UT is 1.1 +- 0.3 ph/cm2/sec. All the quoted errors are at the 90% confidence level.
Swift ToO observation of this burst has been scheduled.
GCN Circular #12609
J. A. Kennea (PSU) and T. Sakamoto (GSFC/UMBC) report on behalf of the Swift-XRT team:
We have analysed 3.0 ks of XRT data for the GBM/BAT-detected burst: GRB111201A (Sakamoto et al. et al. GCN Circ. 12608), from 26.5 ks to 32.7 ks after the GBM/BAT trigger. The data are entirely in Photon Counting (PC) mode. An X-ray source is detected within the GBM/BAT error circle. The refined XRT position is RA, Dec = 190.47701, +32.98791 which is equivalent to:
```
RA (J2000): 12 41 54.48
Dec(J2000): +32 59 16.5
```
with an uncertainty of 3.6 arcsec (radius, 90% confidence). This position is 32 arcsec from the BAT position.
A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.3 (+/-0.4). The best-fitting absorption column is 3.6 (+1.7, -1.4) x 10^21 cm^-2, in excess of the Galactic value of 1.3 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 3.7 x 10^-11 (7.3 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
```
Total column:	     3.6 (+1.7, -1.4) x 10^21 cm^-2
Galactic foreground: 1.3 x 10^20 cm^-2
Excess significance: 4.1 sigma
Photon index:	     2.3 (+/-0.4)
```
The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00020188.
This circular is an official product of the Swift-XRT team.
GCN Circular #12610
N.P.M. Kuin (MSSL/UCL) and T. Sakamoto (GSFC/UMBC) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 111201A 26513 s after the BAT trigger (Sakamoto et al., GCN Circ. 12608). No optical afterglow consistent with the XRT position (Kennea and Sakamoto, GCN Circ. 12609) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the initial exposures are:
```
Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white            26513        32667         2746         >22.6
```
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.02 in the direction of the burst (Schlegel et al. 1998)
GCN Circular #12611
K.L. Page (U. Leicester) and T. Sakamoto (GSFC/UMBC) report on behalf of the Swift-XRT team:
Swift performed a second follow-up observation of the GBM/BAT-detected burst, GRB 111201A (Sakamoto et al., GCN Circ. 12608; Kennea & Sakamoto, GCN Circ. 12609), collecting a further 3 ks of data between 92.2 and 97.6 ks after the trigger. This additional observation shows the source to be fading with a power-law decay of alpha = 0.55 (+0.22, -0.20), confirming it is, indeed, the X-ray afterglow of the burst.
This circular is an official product of the Swift-XRT team.
GCN Circular #12623
X.-H. Zhao (YNAO), D. Xu (WIS), J.-R. Mao, J.-M. Bai (YNAO) report:
We observed the field of GRB 111201A (Sakamoto et al., GCN 12608) with the 2.4m Gao-Mei-Gu (GMG) telescope equipped with YFOSC. Observation were carried out in a very poor seeing of ~3.6" and 6x600s R-band images were obtained starting at 21:38:32 UT on 2nd Dec. 2011 (i.e., 31.27hrs after the burst).
We found a faint and apparently extended source on the southern border of the XRT error circle (Kennea et al., GCN 12609) at coordinates
```
RA(J2000)=12:41:54.6
Dec(J2000)=+32:59:12.7
```
with a circle error radius of ~4 arcsec. The source had R~22.7 mag, calibrated with nearby USNO B1 stars.
We thank W.-M. Yi, H.-Y. Gao and F. He for performing these observations.
GCN Circular #12680
V.V. Golovnya (Main Astro Obs, Kyiv) report: We have undertaken the review of the sky area in vicinity of GRB 111201A (J.A.Kennea (PSU) and T.Sakamoto, GCN Circ.12609) on astronegatives, collected in Ukrainian NAS Main astronomical observatory plate archive (1976-1996). All the plates with the possible object appearance are digitized using Microtek ScanMaker 9800XL TMA and Epson Expression 10000XL flatbed scanners and have been placed into Golosiiv Plate Archive database DBGPA with open access to them. The list of plates is given in the table:
```
YYYYMMDD/TimeUT	--Plates--	Exp.	LimMag	Star USNOA2 
19870527/224011	GUA040C000022B	18.2	15.85	1200-06937537
19890205/015711	GUA040C001420	18.0	15.85	1200-06937537
19890504/200715	GUA040C001461A	16.0	15.85	1200-06937537
19900223/003254	GUA040C001582	16.0	16.55	1200-06937256
19930425/205928	GUA040C002202	22.5	15.35	1200-06936881
19930430/205716	GUA040C002205A	18.8	15.85	1200-06937537
Plates-the plate's identifier in GUA040C archive
        of DWA (D/F=400/2000, M=103"/mm) of the Ukrainian NAS 
        Main Astro obs in Kyiv (Marsden's number - 83)[1].
Exp.   - Duration of the maximum exposure (minutes). 
LimMag - Limited V mag, derived in the 18 minutes area around 
       the location given in GCN Circ.12609: 
       RA(J2000): 12h 41m 54.48s, Dec(J2000): +32d 59' 16.5"
Star USNOA2 - Comparison star.
```
The preview images of 6 areas together with the 17x19 min.of arc area from SkyMap can be found in http://gua.db.ukr-vo.org/img/grb/111201A/index.html The images with full resolution are available via e-mail on demand. References:
1.L.Pakuliak DATABASE of GOLOSIIV PLATE ARCHIVE (DBGPA V2.0), http://gua.db.ukr-vo.org

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Jochen Greiner, last update: 14-Dec-2011 [Disclaimer]