Gamma-ray Burst 131011A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Fri 11 Oct 13 17:47:59 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      45
TRIGGER_NUM:     403206457
GRB_RA:           41.933d {+02h 47m 44s} (J2000),
                  42.089d {+02h 48m 21s} (current),
                  41.368d {+02h 45m 28s} (1950)
GRB_DEC:         -22.150d {-22d 08' 59"} (J2000),
                 -22.093d {-22d 05' 34"} (current),
                 -22.358d {-22d 21' 28"} (1950)
GRB_ERROR:       19.15 [deg radius, statistical plus systematic]
GRB_INTEN:       99 [cnts/sec]
DATA_SIGNIF:     8.00 [sigma]
INTEG_TIME:      4.096 [sec]
GRB_DATE:        16576 TJD;   284 DOY;   13/10/11
GRB_TIME:        64054.99 SOD {17:47:34.99} UT
GRB_PHI:         161.00 [deg]
GRB_THETA:        55.00 [deg]
DATA_TIME_SCALE: 4.0960 [sec]
HARD_RATIO:      0.47
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      93%  GRB
2nd_MOST_LIKELY:   4%  Generic Transient
DETECTORS:       0,0,0, 0,0,0, 0,1,0, 1,0,0, 0,0,
SUN_POSTN:       197.13d {+13h 08m 32s}   -7.28d {-07d 16' 38"}
SUN_DIST:        141.78 [deg]   Sun_angle= 10.3 [hr] (West of Sun)
MOON_POSTN:      286.49d {+19h 05m 58s}  -17.67d {-17d 39' 54"}
MOON_DIST:       105.51 [deg]
MOON_ILLUM:      48 [%]
GAL_COORDS:      208.67,-63.17 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       31.24,-36.31 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 130.82,-25.07 [deg].

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Fri 11 Oct 13 17:48:08 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      57
TRIGGER_NUM:     403206457
GRB_RA:           24.083d {+01h 36m 20s} (J2000),
                  24.260d {+01h 37m 02s} (current),
                  23.443d {+01h 33m 46s} (1950)
GRB_DEC:          -0.233d {-00d 13' 59"} (J2000),
                  -0.163d {-00d 09' 47"} (current),
                  -0.488d {-00d 29' 16"} (1950)
GRB_ERROR:       9.60 [deg radius, statistical plus systematic]
GRB_INTEN:       211 [cnts/sec]
DATA_SIGNIF:     17.60 [sigma]
INTEG_TIME:      4.096 [sec]
GRB_DATE:        16576 TJD;   284 DOY;   13/10/11
GRB_TIME:        64054.99 SOD {17:47:34.99} UT
GRB_PHI:         175.00 [deg]
GRB_THETA:        80.00 [deg]
DATA_TIME_SCALE: 4.0960 [sec]
HARD_RATIO:      0.68
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      95%  GRB
2nd_MOST_LIKELY:   3%  Generic Transient
DETECTORS:       0,0,0, 0,0,0, 0,1,0, 1,0,0, 0,0,
SUN_POSTN:       197.13d {+13h 08m 32s}   -7.28d {-07d 16' 38"}
SUN_DIST:        169.71 [deg]   Sun_angle= 11.5 [hr] (West of Sun)
MOON_POSTN:      286.49d {+19h 05m 58s}  -17.67d {-17d 39' 53"}
MOON_DIST:        97.35 [deg]
MOON_ILLUM:      48 [%]
GAL_COORDS:      146.62,-61.02 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       22.21, -9.56 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 130.82,-25.07 [deg].

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Fri 11 Oct 13 17:48:13 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      56
TRIGGER_NUM:     403206457
GRB_RA:           21.920d {+01h 27m 41s} (J2000),
                  22.101d {+01h 28m 24s} (current),
                  21.262d {+01h 25m 03s} (1950)
GRB_DEC:          +9.550d {+09d 33' 00"} (J2000),
                  +9.621d {+09d 37' 16"} (current),
                  +9.291d {+09d 17' 28"} (1950)
GRB_ERROR:       5.25 [deg radius, statistical only]
DATA_SIGNIF:     15.20 [sigma]
DATA_INTERVAL:   2.048 [sec]
GRB_DATE:        16576 TJD;   284 DOY;   13/10/11
GRB_TIME:        64054.99 SOD {17:47:34.99} UT
GRB_PHI:         175.00 [deg]
GRB_THETA:        90.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   4143 (Gnd S/W Version number)
SUN_POSTN:       197.13d {+13h 08m 32s}   -7.28d {-07d 16' 38"}
SUN_DIST:        174.56 [deg]   Sun_angle= 11.7 [hr] (West of Sun)
MOON_POSTN:      286.49d {+19h 05m 58s}  -17.66d {-17d 39' 53"}
MOON_DIST:        98.19 [deg]
MOON_ILLUM:      48 [%]
GAL_COORDS:      137.64,-52.28 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       23.81,  0.33 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Fri 11 Oct 13 17:48:19 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      67
TRIGGER_NUM:     403206457
GRB_RA:           35.800d {+02h 23m 12s} (J2000),
                  35.969d {+02h 23m 53s} (current),
                  35.186d {+02h 20m 45s} (1950)
GRB_DEC:          -9.110d {-09d 06' 35"} (J2000),
                  -9.048d {-09d 02' 51"} (current),
                  -9.337d {-09d 20' 11"} (1950)
GRB_ERROR:       3.37 [deg radius, statistical only]
DATA_SIGNIF:     20.80 [sigma]
DATA_INTERVAL:   4.096 [sec]
GRB_DATE:        16576 TJD;   284 DOY;   13/10/11
GRB_TIME:        64054.99 SOD {17:47:34.99} UT
GRB_PHI:         165.00 [deg]
GRB_THETA:        69.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   4143 (Gnd S/W Version number)
SUN_POSTN:       197.13d {+13h 08m 32s}   -7.28d {-07d 16' 38"}
SUN_DIST:        155.12 [deg]   Sun_angle= 10.7 [hr] (West of Sun)
MOON_POSTN:      286.49d {+19h 05m 59s}  -17.66d {-17d 39' 52"}
MOON_DIST:       105.43 [deg]
MOON_ILLUM:      48 [%]
GAL_COORDS:      177.51,-61.82 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:       30.24,-22.03 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.

GCN Circular #15324
M. M. Kasliwal (Carnegie Observatories/Princeton), L. P. Singer (Caltech) and S. B. Cenko (NASA/GSFC) report on behalf of the intermediate Palomar Transient Factory (iPTF) collaboration:
Starting 2013-10-12 05:26 UT, we imaged about 70 deg^2 in the vicinity of the localization of the Fermi-GBM trigger 403206457 with the Palomar 48-inch Oschin telescope (P48). Sifting through 10,816 candidate variable sources in the GBM error circle using standard iPTF vetting procedures including Palomar 60-inch follow-up, we identify iPTF13dsw as a possible optical afterglow candidate:
```
  RA(J2000)  =  02h 10m 06.38s
  DEC(J2000) = -04d 24' 40.3" 
```
Light Curve: R=19.7mag @ 05:26 UT (P48), R=20.2mag @ 08:07 UT (P60)
iPTF13dsw is 3.4 deg away from the center of the final GBM localization (68% statistical confidence radius of 2.75 deg). Nothing was detected at this location to a limiting magnitude of 20.6 mag on 2013 Sep 25.
At 08:56 UT, we obtained a Gemini-South/GMOS spectrum in twilight. The spectrum is mostly featureless, with no prominent emission or absorption lines between 5100-9300A.
Further observations are encouraged to determine the nature of the source and whether it is related to the Fermi trigger.
GCN Circular #15325
D. Xu, D. Malesani (DARK/NBI), T. Kruehler (ESO), J.P.U. Fynbo (DARK/NBI), P. Jakobsson (U. Iceland) and John Telting (NOT) report on behalf of a larger collaboration:
We observed the location of the candidate optical afterglow (iPTF13dsw; Kasliwal et al., GCN 15324) of the Fermi-GBM trigger 403206457 with the NOT telescope equipped with ALFOSC. We obtained two R-band images with an exposure time of 300 s each starting at 01:32 UT 2013-10-13 in a good seeing of ~0.65".
The candidate afterglow is clearly detected in each image as a point-like source, and we measure an R-band magnitude of R = 21.6 mag assuming R = 18.36 mag for the nearby star at RA = 02:10:07.95, Dec = -04:24:41.7 at a midpoint of 01:35 UT.
Accounting for the different calibration system with respect to the magnitudes given in Kasliwal et al. (GCN 15324), the source has faded by approximately 1.6 magnitudes with respect to the earlier P60 measurement.
Under the assumption that the transient decays as a single power-law, this fading corresponds to a decay index of ~1.6, not untypical of GRB afterglows at the given epoch.
We thank S. B. Cenko for private information about the photometric calibration of the P60 measurement.
GCN Circular #15326
D. Xu (DARK/NBI), C.-M. Zhang, C. Cao, S.-M. Hu (SDU) report:
We observed the location of the candidate optical afterglow (iPTF13dsw; Kasliwal et al., GCN 15324) of the Fermi-GBM trigger 403206457 with the 1m telescope located in Weihai, Shandong, China. We obtained 5x600s R-band frames at a mean time of 2013-10-12 18:01:29 UT (i.e., 24.23 hr after the Fermi-GBM trigger) under some clouds.
No optical source is detected at the iPTF location in the stacked image down to a limiting magnitude of R > ~20.0 mag, calibrated with the nearby SDSS field.
GCN Circular #15327
D. A. Perley (Caltech), S. B. Cenko (GSFC), and M. M. Kasliwal (Carnegie Observatories/Princeton) report:
We imaged PTF13dsw, the possible optical counterpart to Fermi trigger 403206457 (Kasliwal et al., GCN 15324) with the Palomar 60-inch telescope starting at 05:16:19 UT in i, r, and g filters. Five exposures of 180 seconds each were acquired per filter.
Calibrating to USNO B1.0 stars in the field, photometry of the candidate gives an approximate magnitude of R = 21.2 (+/- 0.2) in a stack of 15 minutes of r-band imaging at midpoint UT 05:40. As also noted by Malesani et al. (GCN 15325) the continued, significant fading relative to the previous night is consistent with that of a GRB afterglow and strengthens the association of this source with the Fermi trigger.
GCN Circular #15328
V. Sudilovsky, M. Tanga, and J. Greiner (all MPE Garching) report on behalf of the GROND team:
We observed the field of GRB 131011A (Kasliwal et al., GCN #15324) simultaneously in g'r'i'z'JHKs with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m MPG telescope at La Silla Observatory (Chile).
Observations started at 03:30 UT on 13 October 2013. They were performed at an average seeing of 1.3" and at and average airmass of 1.2. We find the afterglow candidate reported by Kasliwal et al.
Based on the first 1500 sec g'r'i'z' and 1200 sec JHK exposure, we estimate preliminary magnitudes (all in AB) of
```
g' = 21.9 +- 0.1 mag
r' = 21.7 +- 0.1 mag,
i' = 21.5 +- 0.1 mag,
z' = 21.3 +- 0.1 mag,
J  = 21.1 +- 0.1 mag,
H  = 20.5 +- 0.2 mag,
K  = 20.2 +- 0.4 mag,
```
Magnitudes are calibrated against nearby SDSS (griz) and 2MASS (JHK) stars, and are not corrected for the Galactic foreground extinction corresponding to a reddening of E_(B-V)=3D 0.02 mag in the direction of the burst (Schlegel et al. 1998).
GCN Circular #15329
K.L. Page (U. Leicester) reports on behalf of the Swift-XRT team:
We have analysed 4.9 ks of XRT data for the candidate afterglow iPTF 13dsw (Kasliwal, Singer & Cenko, GCN Circ. 15324; Xu et al., GCN Circ. 15325; GCN Circ. 15326; Perley, Cenko & Kasliwal, GCN Circ. 15327; Sudilovsky, Tanga, & Greiner, GCN Circ. 15328), obtained on October 12, between 17:06 and 20:54 (starting approximately 24 hours after Fermi Trigger 403206457). A faint X-ray source consistent with the iPTF 13dsw position is detected: RA, Dec = 32.5255, -4.4117, which is equivalent to
```
RA(J2000)  =  02h 10m 06.11s
Dec(J2000) = -04d 24' 42.1" 
```
with an uncertainty of 4.1 arcsec (radius, 90% confidence). Currently the source has a 0.3-10 keV count rate in the Swift-XRT of (5.9 +0.9/-0.8)e-3 count s^-1. We cannot determine at the present time whether the source is fading.
Given the small number of detected X-ray photons, any spectral analysis is uncertain. However, the spectrum can be suitably approximated by a power-law with Gamma = 1.5 +0.6/-0.7, absorbed by the Galactic NH in this direction of 1.85e20 cm^-2. The observed (unabsorbed) flux is 2.9e-13 (3.0e-13) erg cm^-2 s^-1.
This circular is an official product of the Swift-XRT team.
GCN Circular #15330
A. Rau (MPE Garching), T. Kruehler (ESO), J. Greiner (MPE Garching) report for the GROND team:
We observed the optical afterglow candidate iPTF13dsw of the Fermi-GBM trigger 403206457 (Kasliwal et al. 2013, GCN 15324; Xu et al. 2013, GCN 15325; Perley et al. 2013, GCN 15327; Sudilovsky et al. 2013, GCN 15328) using ESO/VLT UT3 equipped with the X-shooter spectrograph. The observations started on 2013-10-13 at 03:59 UT. A total exposure of 5x900 s was obtained, covering the spectral range from ~3000 AA to ~24000 AA.
In the spectrum, we identify several very weak absorption features which we interpret as absorption from FeII, MgII and MgI at a common redshift of z = 1.874. This redshift is consistent with flux being detected down to ~3200 AA, and a broad absorption feature around 3400 AA corresponding to Lyman\alpha. The combined evidence of fading, powerlaw slope SED and redshift suggests iPTF13dsw to be the optical afterglow of GRB 131011A.
We thank the Paranal staff for expert support, in particular Andrea Mehner, Christophe Martayan, Julio Navarrete, Felipe Gaete, L. Schmidtobreick, and A. Smette.
GCN Circular #15331
P. Jenke (UAH) reports on behalf of the Fermi GBM Team:
At 17:47:34.99 UT on October 11 2013, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 131011A (trigger 403206457/131011741). A candidate optical afterglow was found by iPTF (Kasliwal et al. 2013, GCN 15324) using the GBM on-ground location. Additional follow-ups confirmed that the optical source has faded (Xu et al. 2013, GCN 15325) and has a redshift of z = 1.874 (Rau et al. 2013, GCN 15330). A weak X-ray source consistent with the optical afterglow was detected by the Swift XRT (Page et al. 2013, GCN 15329).
The angle of the burst direction to the Fermi LAT boresight is 74 degrees.
The GBM light curve consists of one main peak and a small post burst with a combined duration (T90) of about 77 s (50-300 keV). The time-averaged spectrum from T0-3 s to T0+25s is well fit by a Band function with Epeak of 220 +/- 30 keV. Alpha = -0.79 +/- 0.08 and Beta = -2.0 +/- 0.1.
The event fluence (10-1000 keV) in this time interval is (6.60 +/- 0.03)E-05 erg/cm^2. The 1.0-sec peak photon flux measured starting from T0+4.3 s in the 10-1000 keV band is 4.3 +/- 0.4 ph/s/cm^2.
The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."
GCN Circular #15341
A. Volnova (IKI), R. Inasaridze (AAO), G. Inasaridze (AAO), V. Zhuzhunadze (AAO), Yu. Krugly (IA KhNU), I. Molotov (KIAM), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration:
We observed the optical afterglow (Kasliwal et al. 2013, GCN 15324; Xu et al. 2013, GCN 15325; Perley et al. 2013, GCN 15327; Sudilovsky et al. 2013, GCN 15328) of Fermi trigger 403206457 / GRB 131011A (Jenke, GCN 15331) with AS-32 (0.7m) telescope of Abastumani Observatory on Oct. 12 starting (UT) 22.32. We obtained several unfiltered images of 120 s exposure. The optical afterglow is clearly visible in a stacked image in coordinates (J2000) RA= 02 10 06.32 Dec= -04 24 40.5 (uncertainty of 0.33 arcseconds on both axes) which is coincide with position reported by Kasliwal et al. (GCN 15324).
The photometry of combined image against nearby SDSS stars reported by Xu et al. (GCN 15325), R magnitude, transformed by Lupton gri -> R transformation is following:
```
Date        T_start     t-t0,      exp,    OT
             (UT)        mid, d     s
2013-10-12  22:32:33    1.2218     26x120  21.33 +/- 0.09
```
A finding chart can be found at http://grb.rssi.ru/GRB131011A/GRB131011A_AS32.png
GCN Circular #15343
L. M. Z. Hagen (PSU) and K. L. Page (U. Leicester) report on behalf of the Swift/UVOT team:
The Swift/UVOT began observations of the field of GRB 131011A starting 83.9 ks after the Fermi trigger 403206457 (Kasliwal et al., GCN 15324). No optical afterglow consistent with the PTF position 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

w2           83920    97601         4896         >22.10
```
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 #15395
P. Hancock (Curtin University/CAASTRO), T. Murphy, B. Gaensler, M. Bell, D. Burlon (University of Sydney/CAASTRO), A. de Ugarte Postigo (IAA-CSIC, DARK/NBI)
We observed GRB131011A (GCN 15324) with the Australia Telescope Compact Array at 34GHz for 55 minutes centered on 11:20UT Oct-17-2013 in poor weather.
We detect no radio source at the optical location of the GRB and place a 3sigma upper limit of 120uJy on the flux of an afterglow.
These observations were obtained as part of ATCA project C2689. We thank the observatory staff for their support and scheduling the observations. The Australia Telescope is funded by the Commonwealth of Australia for operation as a National Facility managed by CSIRO.
GCN Report 456.1
GCN_Report 456.1 has been posted: http://gcn.gsfc.nasa.gov/reports/report_456_1.pdf by K.L. Page at U. Leicester titled: "Swift Observations of GRB 131011A"

Back to JG's homepage

Jochen Greiner, last update: 26-Apr-2014 [Disclaimer]