- GCN/BACODINE POSITION NOTICE
TITLE: GCN/SWIFT NOTICE
NOTICE_DATE: Sat 31 Aug 13 13:04:34 UT
NOTICE_TYPE: Swift-BAT GRB Position
TRIGGER_NUM: 568849, Seg_Num: 0
GRB_RA: 358.649d {+23h 54m 36s} (J2000),
358.823d {+23h 55m 17s} (current),
358.013d {+23h 52m 03s} (1950)
GRB_DEC: +29.448d {+29d 26' 53"} (J2000),
+29.524d {+29d 31' 27"} (current),
+29.170d {+29d 10' 11"} (1950)
GRB_ERROR: 3.00 [arcmin radius, statistical only]
GRB_INTEN: 2799 [cnts] Image_Peak=167 [image_cnts]
TRIGGER_DUR: 0.512 [sec]
TRIGGER_INDEX: 42 E_range: 25-100 keV
BKG_INTEN: 30238 [cnts]
BKG_TIME: 47045.02 SOD {13:04:05.02} UT
BKG_DUR: 8 [sec]
GRB_DATE: 16535 TJD; 243 DOY; 13/08/31
GRB_TIME: 47056.54 SOD {13:04:16.54} UT
GRB_PHI: 28.72 [deg]
GRB_THETA: 41.65 [deg]
SOLN_STATUS: 0x3
RATE_SIGNIF: 19.39 [sigma]
IMAGE_SIGNIF: 10.54 [sigma]
MERIT_PARAMS: +1 +0 +0 -1 +2 +0 +0 +0 +74 +0
SUN_POSTN: 159.93d {+10h 39m 43s} +8.46d {+08d 27' 41"}
SUN_DIST: 137.88 [deg] Sun_angle= 10.7 [hr] (West of Sun)
MOON_POSTN: 103.25d {+06h 53m 00s} +18.37d {+18d 22' 27"}
MOON_DIST: 92.89 [deg]
MOON_ILLUM: 22 [%]
GAL_COORDS: 108.36,-31.81 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 11.47, 27.34 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS: SWIFT-BAT GRB Coordinates.
COMMENTS: This is a rate trigger.
COMMENTS: A point_source was found.
COMMENTS: This does not match any source in the on-board catalog.
COMMENTS: This does not match any source in the ground catalog.
COMMENTS: This is a GRB.
COMMENTS: This trigger occurred at longitude,latitude = 221.70,-9.14 [deg].
- red DSS finding chart
ps-file
- GCN NOTICE
TITLE: GCN/SWIFT NOTICE
NOTICE_DATE: Sat 31 Aug 13 13:07:06 UT
NOTICE_TYPE: Swift-XRT Position
TRIGGER_NUM: 568849, Seg_Num: 0
GRB_RA: 358.6236d {+23h 54m 29.66s} (J2000),
358.7977d {+23h 55m 11.45s} (current),
357.9877d {+23h 51m 57.04s} (1950)
GRB_DEC: +29.4281d {+29d 25' 41.1"} (J2000),
+29.5042d {+29d 30' 14.9"} (current),
+29.1498d {+29d 08' 59.3"} (1950)
GRB_ERROR: 5.7 [arcsec radius, statistical plus systematic, 90% containment]
GRB_INTEN: 8.87e-10 [erg/cm2/sec]
GRB_SIGNIF: 5.83 [sigma]
IMG_START_DATE: 16535 TJD; 243 DOY; 13/08/31
IMG_START_TIME: 47182.30 SOD {13:06:22.30} UT, 125.8 [sec] since BAT Trigger Time
TAM[0-3]: 327.66 237.20 261.59 243.75
AMPLIFIER: 2
WAVEFORM: 134
SUN_POSTN: 159.93d {+10h 39m 43s} +8.46d {+08d 27' 38"}
SUN_DIST: 137.91 [deg] Sun_angle= 10.7 [hr] (West of Sun)
MOON_POSTN: 103.27d {+06h 53m 05s} +18.37d {+18d 22' 17"}
MOON_DIST: 92.94 [deg]
MOON_ILLUM: 22 [%]
GAL_COORDS: 108.33,-31.82 [deg] galactic lon,lat of the burst
ECL_COORDS: 11.44, 27.33 [deg] ecliptic lon,lat of the burst
COMMENTS: SWIFT-XRT Coordinates.
COMMENTS: The XRT position is 1.78 arcmin from the BAT position.
- GCN NOTICE
TITLE: GCN/SWIFT NOTICE
NOTICE_DATE: Sat 31 Aug 13 13:07:16 UT
NOTICE_TYPE: Swift-XRT Image
TRIGGER_NUM: 568849, Seg_Num: 0
GRB_RA: 358.6236d {+23h 54m 29.6s} (J2000),
358.7977d {+23h 55m 11.4s} (current),
357.9877d {+23h 51m 57.0s} (1950)
GRB_DEC: +29.4281d {+29d 25' 41.1"} (J2000),
+29.5042d {+29d 30' 14.9"} (current),
+29.1498d {+29d 08' 59.3"} (1950)
GRB_ERROR: 5.4 [arcsec, radius, statistical plus systematic]
GRB_INTEN: 34 [cnts]
IMG_START_DATE: 16535 TJD; 243 DOY; 13/08/31
IMG_START_TIME: 47182.30 SOD {13:06:22.30} UT, 125.8 [sec] since BAT Trigger Time
CENTROID_X: 277.87, raw= 278 [pixels]
CENTROID_Y: 316.63, raw= 317 [pixels]
ROLL: 28.29 [deg]
GAIN: 1
MODE: 3, Long Image mode
WAVEFORM: 134
EXPO_TIME: 2.50 [sec]
GRB_POS_XRT_Y: 43.92
GRB_POS_XRT_Z: -60.88
IMAGE_URL: sw00568849000msxps_rw.img
SUN_POSTN: 159.93d {+10h 39m 43s} +8.46d {+08d 27' 38"}
SUN_DIST: 137.91 [deg] Sun_angle= 10.7 [hr] (West of Sun)
MOON_POSTN: 103.27d {+06h 53m 06s} +18.37d {+18d 22' 16"}
MOON_DIST: 92.94 [deg]
MOON_ILLUM: 22 [%]
GAL_COORDS: 108.33,-31.82 [deg] galactic lon,lat of the burst
ECL_COORDS: 11.44, 27.33 [deg] ecliptic lon,lat of the burst
COMMENTS: SWIFT-XRT Image.
- GCN NOTICE
TITLE: GCN/SWIFT NOTICE
NOTICE_DATE: Sat 31 Aug 13 13:07:42 UT
NOTICE_TYPE: Swift-XRT Processed Image
TRIGGER_NUM: 568849, Seg_Num: 0
GRB_RA: 358.6236d {+23h 54m 29.6s} (J2000),
358.7977d {+23h 55m 11.4s} (current),
357.9877d {+23h 51m 57.0s} (1950)
GRB_DEC: +29.4281d {+29d 25' 41.1"} (J2000),
+29.5042d {+29d 30' 14.9"} (current),
+29.1498d {+29d 08' 59.3"} (1950)
GRB_ERROR: 5.4 [arcsec, radius, statistical plus systematic]
GRB_INTEN: 34 [cnts]
IMG_START_DATE: 16535 TJD; 243 DOY; 13/08/31
IMG_START_TIME: 47182.30 SOD {13:06:22.30} UT, 125.8 [sec] since BAT Trigger Time
CENTROID_X: 277.87, raw= 278 [pixels]
CENTROID_Y: 316.63, raw= 317 [pixels]
ROLL: 28.29 [deg]
GAIN: 1
MODE: 3, Long Image mode
WAVEFORM: 134
EXPO_TIME: 2.50 [sec]
GRB_POS_XRT_Y: 43.92
GRB_POS_XRT_Z: -60.88
IMAGE_URL: sw00568849000msxps_rw.img
SUN_POSTN: 159.93d {+10h 39m 44s} +8.46d {+08d 27' 38"}
SUN_DIST: 137.91 [deg] Sun_angle= 10.7 [hr] (West of Sun)
MOON_POSTN: 103.28d {+06h 53m 07s} +18.37d {+18d 22' 15"}
MOON_DIST: 92.94 [deg]
MOON_ILLUM: 22 [%]
GAL_COORDS: 108.33,-31.82 [deg] galactic lon,lat of the burst
ECL_COORDS: 11.44, 27.33 [deg] ecliptic lon,lat of the burst
COMMENTS: SWIFT-XRT Processed Image.
- GCN NOTICE
TITLE: GCN/SWIFT NOTICE
NOTICE_DATE: Sat 31 Aug 13 13:08:09 UT
NOTICE_TYPE: Swift-BAT GRB Lightcurve
TRIGGER_NUM: 568849, Seg_Num: 0
GRB_RA: 358.649d {+23h 54m 36s} (J2000),
358.823d {+23h 55m 17s} (current),
358.013d {+23h 52m 03s} (1950)
GRB_DEC: +29.448d {+29d 26' 53"} (J2000),
+29.524d {+29d 31' 27"} (current),
+29.170d {+29d 10' 11"} (1950)
GRB_DATE: 16535 TJD; 243 DOY; 13/08/31
GRB_TIME: 47056.54 SOD {13:04:16.54} UT
TRIGGER_INDEX: 42
GRB_PHI: 28.72 [deg]
GRB_THETA: 41.65 [deg]
DELTA_TIME: -31.00 [sec]
TRIGGER_DUR: 0.512 [sec]
SOLN_STATUS: 0x3
RATE_SIGNIF: 19.39 [sigma]
IMAGE_SIGNIF: 10.54 [sigma]
LC_URL: sw00568849000msb.lc
SUN_POSTN: 159.93d {+10h 39m 44s} +8.46d {+08d 27' 37"}
SUN_DIST: 137.89 [deg] Sun_angle= 10.7 [hr] (West of Sun)
MOON_POSTN: 103.28d {+06h 53m 08s} +18.37d {+18d 22' 13"}
MOON_DIST: 92.92 [deg]
MOON_ILLUM: 22 [%]
GAL_COORDS: 108.36,-31.81 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 11.47, 27.34 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS: SWIFT-BAT GRB Lightcurve.
COMMENTS:
COMMENTS: The next comments were copied from the BAT_POS Notice:
COMMENTS: This is a rate trigger.
COMMENTS: A point_source was found.
COMMENTS: This does not match any source in the on-board catalog.
COMMENTS: This does not match any source in the ground catalog.
COMMENTS: This is a GRB.
COMMENTS: This trigger occurred at longitude,latitude = 221.70,-9.14 [deg].
- GCN NOTICE
TITLE: GCN/SWIFT NOTICE
NOTICE_DATE: Sat 31 Aug 13 13:15:23 UT
NOTICE_TYPE: Swift-UVOT Source List
TRIGGER_NUM: 568849, Seg_Num: 0
POINT_RA: 358.626d {+23h 54m 30s} (J2000)
POINT_DEC: +29.407d {+29d 24' 25"} (J2000)
POINT_ROLL: 28.286d
IMG_START_DATE: 16535 TJD; 243 DOY; 13/08/31
IMG_START_TIME: 47247.42 SOD {13:07:27.42} UT, 190.9 [sec] since BAT Trigger Time
FILTER: 7, U
BKG_MEAN: 0.309
N_STARS: 190
X_OFFSET: 0 [pixels]
Y_OFFSET: 0 [pixels]
X_MAX: 2047 [pixels]
Y_MAX: 2047 [pixels]
DET_THRESH: 5
PHOTO_THRESH: 2
SL_URL: sw00568849000msufc0190.fits
SUN_POSTN: 159.94d {+10h 39m 45s} +8.46d {+08d 27' 31"}
SUN_DIST: 137.94 [deg] Sun_angle= 10.7 [hr] (West of Sun)
MOON_POSTN: 103.34d {+06h 53m 22s} +18.36d {+18d 21' 45"}
MOON_DIST: 93.01 [deg]
MOON_ILLUM: 22 [%]
GAL_COORDS: 108.33,-31.85 [deg] galactic lon,lat of the pointing direction
ECL_COORDS: 11.43, 27.31 [deg] ecliptic lon,lat of the pointing direction
COMMENTS: SWIFT-UVOT Source List.
- GCN NOTICE
TITLE: GCN/SWIFT NOTICE
NOTICE_DATE: Sat 31 Aug 13 13:16:03 UT
NOTICE_TYPE: Swift-UVOT Processed Source List
TRIGGER_NUM: 568849, Seg_Num: 0
POINT_RA: 358.626d {+23h 54m 30s} (J2000)
POINT_DEC: +29.407d {+29d 24' 25"} (J2000)
POINT_ROLL: 28.286d
IMG_START_DATE: 16535 TJD; 243 DOY; 13/08/31
IMG_START_TIME: 47247.42 SOD {13:07:27.42} UT, 190.9 [sec] since BAT Trigger Time
FILTER: 7, U
BKG_MEAN: 0.309
N_STARS: 190
X_OFFSET: 0 [pixels]
Y_OFFSET: 0 [pixels]
X_MAX: 2047 [pixels]
Y_MAX: 2047 [pixels]
DET_THRESH: 5
PHOTO_THRESH: 2
SL_URL: sw00568849000msufc0190.fits
SUN_POSTN: 159.94d {+10h 39m 45s} +8.46d {+08d 27' 30"}
SUN_DIST: 137.94 [deg] Sun_angle= 10.7 [hr] (West of Sun)
MOON_POSTN: 103.35d {+06h 53m 24s} +18.36d {+18d 21' 42"}
MOON_DIST: 93.01 [deg]
MOON_ILLUM: 22 [%]
GAL_COORDS: 108.33,-31.85 [deg] galactic lon,lat of the pointing direction
ECL_COORDS: 11.43, 27.31 [deg] ecliptic lon,lat of the pointing direction
COMMENTS: SWIFT-UVOT Processed Source List.
COMMENTS: All 4 attachments are included.
- GCN NOTICE
TITLE: GCN/SWIFT NOTICE
NOTICE_DATE: Sat 31 Aug 13 13:17:06 UT
NOTICE_TYPE: Swift-UVOT Image
TRIGGER_NUM: 568849, Seg_Num: 0
POINT_RA: 358.626d {+23h 54m 30s} (J2000)
POINT_DEC: +29.407d {+29d 24' 25"} (J2000)
ROLL: 28.286d
IMG_START_DATE: 16535 TJD; 243 DOY; 13/08/31
IMG_START_TIME: 47247.42 SOD {13:07:27.42} UT, 190.9 [sec] since BAT Trigger Time
FILTER: 7, U
EXPOSURE_ID: 399647258
X_OFFSET: 868 [pixels]
Y_OFFSET: 739 [pixels]
WIDTH: 160 [pixels]
HEIGHT: 160 [pixels]
X_GRB_POS: 1028
Y_GRB_POS: 899
BINNING_INDEX: 1
IM_URL: sw00568849000msuni0201.fits
SUN_POSTN: 159.94d {+10h 39m 45s} +8.46d {+08d 27' 29"}
SUN_DIST: 137.94 [deg] Sun_angle= 10.7 [hr] (West of Sun)
MOON_POSTN: 103.36d {+06h 53m 26s} +18.36d {+18d 21' 38"}
MOON_DIST: 93.02 [deg]
MOON_ILLUM: 22 [%]
GAL_COORDS: 108.33,-31.85 [deg] galactic lon,lat of the pointing direction
ECL_COORDS: 11.43, 27.31 [deg] ecliptic lon,lat of the pointing direction
COMMENTS: SWIFT-UVOT Image.
COMMENTS: The GRB Position came from the XRT Position Command.
COMMENTS: The image has 2x2 binning (compression).
- GCN NOTICE
TITLE: GCN/SWIFT NOTICE
NOTICE_DATE: Sat 31 Aug 13 13:17:23 UT
NOTICE_TYPE: Swift-UVOT Processed Image
TRIGGER_NUM: 568849, Seg_Num: 0
POINT_RA: 358.626d {+23h 54m 30s} (J2000)
POINT_DEC: +29.407d {+29d 24' 25"} (J2000)
ROLL: 28.286d
IMG_START_DATE: 16535 TJD; 243 DOY; 13/08/31
IMG_START_TIME: 47247.42 SOD {13:07:27.42} UT, 190.9 [sec] since BAT Trigger Time
FILTER: 7, U
EXPOSURE_ID: 399647258
X_OFFSET: 868 [pixels]
Y_OFFSET: 739 [pixels]
WIDTH: 160 [pixels]
HEIGHT: 160 [pixels]
X_GRB_POS: 1028
Y_GRB_POS: 899
BINNING_INDEX: 1
IM_URL: sw00568849000msuni0201.fits
SUN_POSTN: 159.94d {+10h 39m 45s} +8.46d {+08d 27' 29"}
SUN_DIST: 137.94 [deg] Sun_angle= 10.7 [hr] (West of Sun)
MOON_POSTN: 103.36d {+06h 53m 27s} +18.36d {+18d 21' 37"}
MOON_DIST: 93.02 [deg]
MOON_ILLUM: 22 [%]
GAL_COORDS: 108.33,-31.85 [deg] galactic lon,lat of the pointing direction
ECL_COORDS: 11.43, 27.31 [deg] ecliptic lon,lat of the pointing direction
COMMENTS: SWIFT-UVOT Processed Image.
COMMENTS: The GRB Position came from the XRT Position Command.
COMMENTS: The image has 2x2 binning (compression).
COMMENTS: All 4 attachments are included.
- GCN NOTICE
TITLE: GCN/SWIFT NOTICE
NOTICE_DATE: Sat 31 Aug 13 13:19:17 UT
NOTICE_TYPE: Swift-UVOT Position
TRIGGER_NUM: 568849, Seg_Num: 0
GRB_RA: 358.6245d {+23h 54m 29.88s} (J2000),
358.7986d {+23h 55m 11.66s} (current),
357.9886d {+23h 51m 57.26s} (1950)
GRB_DEC: +29.4295d {+29d 25' 46.2"} (J2000),
+29.5056d {+29d 30' 20.0"} (current),
+29.1512d {+29d 09' 04.3"} (1950)
GRB_ERROR: 0.7 [arcsec radius, statistical only]
GRB_MAG: 14.56 +/- 0.14 [mag]
FILTER: 7, U
IMG_START_DATE: 16535 TJD; 243 DOY; 13/08/31
IMG_START_TIME: 47246.00 SOD {13:07:26.00} UT, 189.5 [sec] since BAT Trigger Time
SUN_POSTN: 159.94d {+10h 39m 45s} +8.46d {+08d 27' 27"}
SUN_DIST: 137.92 [deg] Sun_angle= 10.7 [hr] (West of Sun)
MOON_POSTN: 103.38d {+06h 53m 30s} +18.36d {+18d 21' 29"}
MOON_DIST: 93.03 [deg]
MOON_ILLUM: 22 [%]
GAL_COORDS: 108.33,-31.82 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 11.44, 27.33 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS: SWIFT UVOT Position Notice.
COMMENTS: This Notice was ground-generated -- not flight-generated.
COMMENTS: The UVOT position is 5.4 arcsec from the XRT position.
COMMENTS: Result based on Genie data.
COMMENTS: Notice generated automatically.
- GCN Circular #15139
L. M. Z. Hagen (PSU), M. M. Chester (PSU), J. R. Cummings (NASA/UMBC),
N. Gehrels (NASA/GSFC), D. Grupe (PSU), J. A. Kennea (PSU),
V. Mangano (PSU), F. E. Marshall (NASA/GSFC),
C. J. Mountford (U Leicester), P. T. O'Brien (U Leicester),
D. M. Palmer (LANL), B. Sbarufatti (INAF-OAB/PSU), M. H. Siegel (PSU),
E. Troja (NASA/GSFC/UMCP) and B.-B. Zhang (UAH) report on behalf of
the Swift Team:
At 13:04:16 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 130831A (trigger=568849). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 358.649, +29.448 which is
RA(J2000) = 23h 54m 36s
Dec(J2000) = +29d 26' 53"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a multi-peaked
structure with a duration of about 50 sec. The peak count rate
was ~10000 counts/sec (15-350 keV), at ~2 sec after the trigger.
The XRT began observing the field at 13:06:22.3 UT, 125.8 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source located at RA, Dec 358.62398,
29.42849 which is equivalent to:
RA(J2000) = 23h 54m 29.76s
Dec(J2000) = +29d 25' 42.6"
with an uncertainty of 3.7 arcseconds (radius, 90% containment). This
location is 105 arcseconds from the BAT onboard position, within the
BAT error circle. This position may be improved as more data are
received; the latest position is available at
http://www.swift.ac.uk/sper.
A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density consistent with the Galactic value of 4.80
x 10^20 cm^-2 (Kalberla et al. 2005).
The initial flux in the 2.5 s image was 8.87e-10 erg cm^-2 s^-1 (0.2-10
keV).
UVOT took a finding chart exposure of 250 seconds with the U filter starting
190 seconds after the BAT trigger. There is a candidate afterglow in the
rapidly available 2.7'x2.7' sub-image at
RA(J2000) = 23:54:29.89 = 358.62453
DEC(J2000) = +29:25:46.2 = 29.42950
with a 90%-confidence error radius of about 0.74 arc sec. This position is 5.8
arc sec. from the center of the XRT error circle. The estimated magnitude is
14.56 with a 1-sigma error of about 0.14. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.04.
Burst Advocate for this burst is L. M. Z. Hagen (lea.zernow.hagen AT gmail.com).
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 #15140
C. Guidorzi (U. Ferrara), A. Melandri (INAF-OAB) on behalf of
a large collaboration report:
The 2-m Faulkes Telescopes North and South automatically began observing
GRB
130831A (Hagen et al. GCN Circ. 15139) on August 31 2013 at 13:09:01 UT
(~4.7 min after the burst trigger).
We clearly detect the fading optical afterglow reported by Swift/UVOT
with R=14.1 +- 0.1 mag at 4.75 minutes since the BAT trigger time,
calibrated against nearby USNOB-1 catalogue stars.
- GCN Circular #15142
D. Xu (DARK/NBI), C. M. Zhang, C. Cao, S. M. Hu (SDU) report:
We observed the field of GRB 130831A (Hagen et al., GCN 15139) using
the 1m telescope located in Weihai, Shandong Province, China, and
2x600s SDSS r'-band frames were obtained.
The optical afterglow is well detected at the UVOT position in each of
the two images with rather fast decaying rate. Following photometry is
calibrated with nearby SDSS stars:
Mag MagErr MeanTime(T-Ttrigger, hr)
14.35 0.04 0.3356
15.66 0.05 0.6575
- GCN Circular #15143
T. Yoshii, K. Ito, Y. Saito, Y. Yano, R. Usui, Y. Tachibana,
S. Kurita, Y. Yatsu, and N. Kawai (Tokyo Tech)
report on behalf of the MITSuME collaboration:
We observed the field of GRB 130831A (L. M. Z. Hagen et al., GCNC 15139) with the
optical three color (g, Rc, and Ic) CCD cameras attached to the MITSuME 50 cm
telescope of Akeno Observatory, Yamanashi, Japan.
And we continue observing .
The observation started on 2013-08-31 13:06:14 UT ( 118 sec after the burst).
And we detected the previously reported afterglow .
But weather condition was not so good.
The measured magnitudes were listed below.
T0+[sec] MID-UT T-EXP[sec] g' Rc Ic
------------------------------------------------------------------------------------------------------------------------------
~118 13:07:41 300 15.40+/-0.23 15.16+/-0.33 analyzing
------------------------------------------------------------------------------------------------------------------------------
(The photon flux were calibrated against GSC2.3 catalog.)
- GCN Circular #15144
A. Cucchiara (UCSC/UCO Lick Observatory), D. Perley (Caltech)
report on behalf of a larger collaboration:
"We observed the afterglow of GRB 130831A (Hagen et al.
GCN 15139, Guidorzi et al. GCN 15140) with the GMOS spectrograph
on Gemini-North, beginning approximately 50 min after the BAT trigger.
We obtained 2x900s exposure spectra under exquisite conditions
using the B600 grism, covering the 3860-6649 Angstrom wavelength range.
In our preliminary analysis we detect MgII2796,2803 doublet and
MgI2853 absorption lines at z=0.4791.
No other strong features are detected in absorption or in emission,
therefore we suggest this as the redshift of GRB 130831A.
We thank the Gemini-N staff, in particular Adam Smith and
Anthony Matulonis, for their support."
- GCN Circular #15145
S. Golenetskii, R.Aptekar, D. Frederiks, V. Pal'shin,
P. Oleynik, M. Ulanov, D. Svinkin, and T. Cline on behalf
of the Konus-Wind team, report:
The long-duration soft-spectrum GRB 130831A
(Swift-BAT trigger 568849: Hagen, et al., GCN 15139)
triggered Konus-Wind at T0=3D47062.044 s UT (13:04:22.044)
The light curve shows a smooth pulse peaked at ~T0+1.6 s
followed by a weaker emission till ~T0+35~s.
The emission is seen up to ~6 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB130831_T47062/
As observed by Konus-Wind, the burst
had a fluence of (7.6 =C2=B1 0.4)x10-6 erg/cm2,
and a 64-ms peak flux, measured from T0+1.600 s,
of (2.5 =C2=B1 0.3)x10-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum (measured from T0 to T0+24.832 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha =3D -1.61 =C2=B1 0.06,
the high energy photon index beta =3D -3.3 =C2=B1 0.3,
the peak energy Ep =3D 55 =C2=B1 4 keV,
chi2 =3D 118/97 dof.
The spectrum at the maximum count rate (measured from T0 to T0+8.448 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha =3D -1.51 =C2=B1 0.10,
the high energy photon index beta =3D -2.8 =C2=B1 0.1,
the peak energy Ep =3D 67 =C2=B1 4 keV,
chi2 =3D 91/96 dof.
Assuming Gemini-North redshift z=3D0.4791 (Cucchiara & Perley, GCN 15144),
and a standard cosmology model with H_0 =3D 70 km/s/Mpc,
Omega_M =3D 0.27, and Omega_Lambda =3D 0.73,
we estimate the following rest-frame parameters of GRB 130831A:
the isotropic energy release E_iso is (4.6 =C2=B1 0.2)x10^51 erg,
the peak luminosity (L_iso)_max is (2.7 =C2=B1 0.3)x10^51 erg/s,
and the rest-frame peak energy Ep,i =3D (81 =C2=B1 6) keV
All the quoted results are preliminary.
- GCN Circular #15146
L. P. Xin, X. H. Han, Y. L. Qiu, J. Y. Wei, J. Wang,
J. S. Deng and C. Wu on behalf of EAFON report:
We began to observe GRB 130831A (Hagen et al. GCN 15139)
with Xinglong 60cm telescope at 15:42:00 (UT),
about 2.7 hours after the burst.
A series of white and R-band images were obtained.
The OT reported by (Hagen et al. GCN 15139, Guidorzi et al. GCN 15140,
Xu et al. GCN 15142; Yoshii et al. GCN 15143, Cucchiara et al. GCN 15144)
was detected in all images. The brightness of this OT was about R=16.6 mag
at 2.7 hours after the burst, calibrated by USNO B1.0 R2 mag.
This message may be cited.
- GCN Circular #15147
P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester)
report on behalf of the Swift-XRT team.
Using 2474 s of XRT Photon Counting mode data and 3 UVOT
images for GRB 130831A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 358.62461, +29.42990 which is equivalent
to:
RA (J2000): 23h 54m 29.91s
Dec (J2000): +29d 25' 47.6"
with an uncertainty of 1.7 arcsec (radius, 90% confidence).
This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).
This circular was automatically generated, and is an official product of the
Swift-XRT team.
- GCN Circular #15148
A. Trotter, J. Haislip, A. LaCluyze, J. Moore, N. Frank, D. Reichart, T.
Berger, H. T. Cromartie, R. Egger, A. Foster, K. Ivarsen, M. Maples, M.
Nysewander, and J. A. Crain report:
Skynet observed the Swift/BAT localization of GRB 130831A (Hagen et al.,
GCN 15139, Swift trigger #568849) with four 17" telescopes of the
newly-commissioned PROMPT array at Siding Spring Observatory, NSW,
Australia. Starting at 2013-08-31, 13:39 UT and continuing until 17:41
UT (t=35.5m-4.65h post-trigger), it took 615 80-s exposures in the BVRI
bands. We detect a bright fading afterglow in all four bands at RA
23:54:29.8, Dec 29:25:46.4 (J2000.0), within the error circle of the
Enhanced Swift-XRT localization (Evans et al., GCN 15147).
A preliminary light curve is at:
http://skynet.unc.edu/grb/grb130831a.png
Magnitudes are in the Vega system, calibrated to 6 APASS stars in the
field, and have not been corrected for the modest expected line-of-sight
Milky Way dust extinction E(B-V)=0.046 (Schlegel et al. 1998).
Skynet observations are ongoing.
- GCN Circular #15150
Simone Leonini, G. Guerrini, P. Rosi and L.M. Tinjaca Ramirez (Montarrent=
i=20
Observatory, Siena, Italy) report:
We observed the optical afterglow of GRB 130831A (Swift trigger 568849, H=
agen=20
et al., GCN Circ. 15139) and slow fading over the four hours span of=20
observations with the automatic 0.53m RC telescope + U47 detector at=20
Montarrenti Observatory (Siena, Italy, IAU code C88).
The observations were started at 2013-08-31 20:18:04 UT (approximately 7
hours=20
post-burst) and continued to 00:29:36 UT on 2013-09-01 stacking 2 unfiltered
CCD exposures of 60s for each run.
The OT was detected in all frames. The resulting time-series are as follows:
2013 Aug 31.84588 UT R=3D18.22 +/- 0.21=20
2013 Aug 31.90427 UT R=3D18.55 +/- 0.21
2013 Aug 31.94019 UT R=3D18.47 +/- 0.22
2013 Aug 31.96977 UT R=3D18.63 +/- 0.23
2013 Aug 31.99955 UT R=3D18.95 +/- 0.22
2013 Sep 01.02056 UT R=3D19.09 +/- 0.21
Magnitudes were obtained using Astrometrica software using USNO-B1 catalo=
gue=20
for positions and photometry. An ensemble between 38 and 66 stars were us=
ed for=20
the magnitude comparison.
The position of the GRB (within the error box given by Swift) is the=20
following:
RA (J2000.0) 23h 54m 29.90s +/-0.13
Decl. (J2000.0) +29=C2=B0 25' 46.8" +/-0.14
The message may be cited.
- GCN Circular #15151
B. Sbarufatti (INAF-OAB/PSU), V. Mangano (PSU), M.C. Stroh (PSU), D.N.
Burrows (PSU), C. Pagani (U. Leicester), A.P. Beardmore (U. Leicester),
P.A. Evans (U. Leicester), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC) and
L.M.Z. Hagen report on behalf of the Swift-XRT team:
We have analysed 6.2 ks of XRT data for GRB 130831A (Hagen et al. GCN
Circ. 15139), from 115 s to 23.9 ks after the BAT trigger. The data
comprise 73 s in Windowed Timing (WT) mode (the first 10 s were taken
while Swift was slewing) with the remainder in Photon Counting (PC)
mode. The enhanced XRT position for this burst was given by Evans et
al. (GCN. Circ 15147).
The light curve can be modelled with a series of power-law decays. The
initial decay index is alpha=3.0 (+0.4, -0.6). At T+239 s the decay
flattens to an alpha of -0.1 (+0.3, -0.6) before breaking again at
T+783 s to a final decay with index alpha=1.09 (+0.09, -0.07).
A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.53 (+0.12, -0.11). The
best-fitting absorption column is consistent with the Galactic value
of 4.8 x 10^20 cm^-2 (Kalberla et al. 2005). The PC mode spectrum has a
photon index of 1.78 (+0.12, -0.08) and a best-fitting absorption
column of 5.2 (+2.8, -0.4) x 10^20 cm^-2. The counts to observed
(unabsorbed) 0.3-10 keV flux conversion factor deduced from this
spectrum is 3.9 x 10^-11 (4.4 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 5.2 (+2.8, -0.4) x 10^20 cm^-2
Galactic foreground: 4.8 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index: 1.78 (+0.12, -0.08)
If the light curve continues to decay with a power-law decay index of
1.09, the count rate at T+24 hours will be 0.024 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 9.5 x
10^-13 (1.1 x 10^-12) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00568849.
This circular is an official product of the Swift-XRT team.
- GCN Circular #15152
G. Masi (Ceccano, Italy) and F. Nocentini (Frosinone, Italy) report:
On Sept 1.0599 2013 UT, we imaged the field around GRB 130831A (GCN 15139)
remotely using the the 0.43m-f/6.8 robotic unit part of the Virtual
Telescope robotic facility in Italy, about 12 hours after the burst.
The source is visible on 300 seconds unfiltered CCD images
following coordinates (J2000.0):
R.A. = 23 54 29.89
Decl. +29 25 46.6
We also performed photometry, assuming R-mags from UCAC-4 for the stars in the
field, getting an estimate for the magnitude of 19.1 (CR).
Observations are ongoing.
- GCN Circular #15153
L. Izzo and L. D'Avino report:
We have observed the optical afterglow of GRB 130831A using a 0.32m =
f/9.3 Ritchey-Chretien telescope of the iTelescope network, at Siding =
Spring =96 Australia.
We have detected the afterglow in the R and V, but not in the B band. =
After an ensemble photometry, using nearby SDSS stars, and correction =
from SDSS to V and R filters, we have obtained the following =
magnitudes:
R =3D 15.58 +- 0.09 (78 min post-trigger =96 240s exposure)
V =3D 16.89 +- 0.09 (92 min post-trigger =96 180 s exposure)
The R-composite image can be seen at
http://blacksabburst.files.wordpress.com/2013/08/r_median.png
- GCN Circular #15155
S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL),
N. Gehrels (GSFC), L. M. Z. Hagen (PSU),
H. A. Krimm (GSFC/USRA), A. Y. Lien (NASA/GSFC/ORAU),
C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Sakamoto (AGU), G. Sato (ISAS), M. Stamatikos (OSU),
J. Tueller (GSFC), T. N. Ukwatta (MSU)
(i.e. the Swift-BAT team):
Using the data set from T-61 to T+243 sec from the
recent telemetry downlink, we report further analysis
of BAT GRB 130831A (trigger #568849) (Hagen, et al.,
GCN Circ. 130831A). The BAT ground-calculated position is
RA, Dec = 358.635, 29.431 deg which is
RA(J2000) = 23h 54m 32.4s
Dec(J2000) = +29d 25' 51.4"
with an uncertainty of 1.0 arcmin, (radius, sys+stat,
90% containment). The partial coding was 28%.
BAT mask-weighted light curve shows a bright peak
starting from ~T-1 sec peaking around T+3 sec
and ending at ~T+12 sec. Two more very weak
emission can be seen around T+20 sec and T+32 sec.
T90 (15-350 keV) is 32.5 +- 2.5 sec
(estimated error including systematics).
The time-averaged spectrum from T-1.86 to T+41.38 sec
is best fit by a simple power-law model. The power
law index of the time-averaged spectrum is 1.93 +- 0.05.
The fluence in the 15-150 keV band is
6.5 +- 0.2 x 10^-06 erg/cm2. The 1-sec peak photon
flux measured from T+2.30 sec in the 15-150 keV band
is 13.6 +- 0.6 ph/cm2/sec. All the quoted errors are
at the 90% confidence level.
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/568849/BA/
- GCN Circular #15156
Veli-Pekka Hentunen, Markku Nissinen, Harri Vilokki and Tuomo Salmi
(Taurus Hill Observatory, Varkaus, Finland) report:
We have detected GRB 130831A optical afterglow at Taurus Hill Observatory
A95 (Varkaus, Finland). We used 0.35m C-14 OTA telescope (f =3910 mm),
NextGen 0.5X, Paramount ME and SBIG ST-8XME CCD camera.
The observation was started 6.65 hours after the Swift trigger. Six unfiltered
images with 600 sec exposure time were made.
The afterglow was detected at following position RA 23 54 29.7 and
DEC +29 25 46.6.
The following magnitude was obtained from the observation using NOMAD1
1194-0619856 (R=16.240) as the comparison:
Tmid(h)+T0 Filter Exp. time Mag Mag err.
7.218 unfiltered 6x600 18.01CR 0.08
A png preview of the observation showing the position of the afterglow is
available at this URL:
www.kassiopeia.net/wp-content/uploads/2013/09/GR130831A_comparison.png
- GCN Circular #15159
B. A. Zauderer, T. Laskar , and E. Berger (Harvard) report on behalf of the
CARMA Key Project, "A Millimeter View of the Transient Universe" and a
larger collaboration:
"We observed the position of the optically bright GRB 130831A
(Hagen et al. GCN 15139; Xu et al. GCN 15142) with the Combined Array for
Research in Millimeter Astronomy (CARMA) beginning 2013 September 1.30
(dt = 0.76 d). At a mean frequency of 90 GHz, in marginal weather
conditions,
we obtain a 3-sigma upper limit of 0.78 mJy. We thank the CARMA observers
and staff for their support."
- GCN Circular #15161
E. Sonbas (Adiyaman Univ.), U. Temiz (Cukurova Univ.), T. Guver (Sabanci
Univ.), Z. Eker (Akdeniz Univ.), S. Kaynar (TUG), E. Gogus (Sabanci Univ.),
H. Kirbiyik (TUG) report on behalf of a larger collaboration
We observed the field of Swift GRB 130831A (Hagen et al. GCN#15139)
with the 1.0 meter T100 telescope (TUBITAK National Observatory,
Antalya - Turkey), starting August, 31; 18:27:23 UT (~ 5.4 hours after
the trigger). Observations were carried out in the R filter under moderate
weather conditions. We detected a new source in 300 s R band
image at a position that is consistent with Swift/UVOT (Hagen et al.
GCN#15139)
Using USNO-B1 star USNO-B1 1193-0589854 (RA= 23:54:29.226, Dec=
+29:23:08.41) in the field, the magnitude of the OT were estimated as;
t-t0 (hr) exp.(s) filt mag err (+/-)
5.38 300 R 17.98 0.034
5.48 300 R 17.99 0.035
Further observations using the same filter are ongoing.
We are grateful to the TUBITAK National Observatory staff for promptly
scheduling the observations and their technical support.
- GCN Circular #15162
T. Laskar, A. Zauderer, and E. Berger (Harvard) report:
"We observed the position of GRB 130831A (Hagen et al; GCN 15139) with
the VLA beginning on 2013 September 1.19 UT (0.64 days after the burst). No
significant radio emission is detected at the enhanced Swift-XRT position
or the optical position, to a three-sigma upper limit of 38 uJy at 5.8 GHz
and 71 uJy at 21.8 GHz."
- GCN Circular #15164
A. Trotter, J. Haislip, D. Reichart, A. LaCluyze, J. Moore, N. Frank, V.
Hoette, D. Harper, R. Kron, K. Cudworth, E. Struble, R. Russell, T.
Berger, H. T. Cromartie, R. Egger, A. Foster, K. Ivarsen, M. Maples, M.
Nysewander, and J. A. Crain report:
Skynet continued observing the Swift-XRT localization of GRB 130831A
(Hagen et al., GCN 15139, Swift trigger 568849) with the four 17"
telescopes of the PROMPT array at Siding Spring Observatory, NSW,
Australia, four 16" telescopes of the PROMPT array at Cerro Tololo,
Chile, and the 41" telescope of Yerkes Observatory in Wisconsin, USA.
Starting at 2013-08-31, 13:39 UT and continuing until 2013-09-01, 17:40
UT (t=35.5m-28.2h post-trigger), Skynet took a total of 2,227 exposures
of 60-160s in the BVRI (PROMPT) and g'i' bands (Yerkes). As we reported
in Trotter et al. (GCN 15148), we detect a bright fading afterglow in
all bands at RA 23:54:29.8, Dec 29:25:46.4 (J2000.0), within the error
circle of the Enhanced Swift-XRT localization (Evans et al., GCN 15147).
We continue to detect a fading afterglow in stacked images, with R~20
mag at t~15h, and R~20.6 mag at t~25h.
A preliminary light curve that includes our first-day PROMPT-CTIO and
Yerkes data, and our second-day PROMPT-SSO data is at:
http://skynet.unc.edu/grb/grb130831a_2.png
BVRI magnitudes are in the Vega system, and g'i' magnitudes are in the
AB system, calibrated to 3 APASS stars in the field. Photometry has not
been corrected for the modest expected line-of-sight Milky Way dust
extinction E(B-V)=0.046 (Schlegel et al. 1998).
Skynet observations are ongoing.
- GCN Circular #15165
Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), Willia=
m
H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB)=
,
J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UCSC),
Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC)=
,
Jos=E9 A. de Diego (UNAM), Leonid Georgiev (UNAM), Jes=FAs Gonz=E1lez (UN=
AM),
Carlos Rom=E1n-Z=FA=F1iga (UNAM), Neil Gehrels (GSFC), and Harvey Moseley=
(GSFC)
report:
We observed the field of GRB 130831A (Hagen, et al., GCN 15139) with the
Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the
1.5m Harold Johnson Telescope at the Observatorio Astron=F3mico Nacional
on
Sierra San Pedro M=E1rtir from 2013/09 1.16 to 2013/09 1.49 UTC (14.65 to
22.73 hours after the BAT trigger), obtaining a total of 5.16 hours
exposure in the r' and i' bands and 2.09 hours exposure in the Z, Y, J, and
H bands.
For a source within the Swift-XRT error circle (Evans et al., GCN 15147),
in comparison with SDSS DR9 and 2MASS, we obtain the following detections:
r' 20.64 +/- 0.03
i' 20.38 +/- 0.03
Z 20.20 +/- 0.07
Y 19.69 +/- 0.07
J 19.87 +/- 0.09
H 19.88 +/- 0.14
These magnitudes are in the AB system and not corrected for Galactic
extinction in the direction of the GRB.
We thank the staff of the Observatorio Astron=F3mico Nacional in San
Pedro M=E1rtir.
- GCN Circular #15166
G. Masi (Ceccano, Italy) and F. Nocentini (Frosinone, Italy)
report:
On Sept 1.9197 2013 UT, we imaged the field around GRB
130831A (GCN 15139)
remotely using the the 0.43m-f/6.8 robotic unit part of the
Virtual
Telescope robotic facility in Italy, about 33 hours after
the burst.
We co-added 12, 300-seconds unfiltered CCD images and
detected the afterglow at the same position we gave in GCN
15152.
We performed photometry, assuming R-mags from UCAC-4 for the
stars in the
field, getting an estimate for the magnitude of 20.7 (CR).
- GCN Circular #15167
Simone Leonini, G. Guerrini, P. Rosi and L.M. Tinjaca Ramirez (Montarrenti
Observatory, Siena, Italy) report:
We continue to observe and detect the fading optical afterglow of GRB 130831A
(Swift trigger 568849, Hagen et al., GCN Circ. 15139) with the automatic 0.53m
RC
telescope + U47 detector at Montarrenti Observatory (Siena, Italy, IAU code
C88).
We stacked 4 unfiltered CCD exposures of 60s each and we detect the very faint
OT at the same position previously measured (GCN 15150) obtaining the
following
photometry at t~34h :
2013 Sep. 01.95733 UT R=20.46 +/- 0.24
Magnitudes were obtained using Astrometrica software using USNO-B1 catalogue
for positions and photometry. An ensemble of 66 stars were used for the
magnitude
comparison.
- GCN Circular #15168
M. M. Chester (PSU) and L.M.Z. Hagen (PSU) report on behalf of the
Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 130831A
(Hagen et al., GCN Circ. 15139) 191 seconds after the BAT trigger.
A source consistent with the enhanced XRT position (Evans et al.,
GCN Circ. 15147) is detected in the initial UVOT exposures.
Preliminary detections and 3-sigma upper limits using the UVOT
photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373)
for the first finding chart (FC) exposures and subsequent exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
v 498 818 58 14.4 +/- 0.1
v 10802 11709 885 18.0 +/- 0.1
v 46801 47000 196 > 18.9
b 448 767 58 14.9 +/- 0.1
b 23522 23925 393 19.2 +/- 0.2
b 40193 41100 885 20.1 +/- 0.2
u_FC 191 441 246 14.6 +/- 0.1
u 572 742 39 13.9 +/- 0.1
u 16594 23517 1645 18.3 +/- 0.1
w1 548 849 40 13.9 +/- 0.1
w1 15688 16588 886 18.1 +/- 0.1
m2 673 843 39 13.6 +/- 0.1
m2 11714 12387 663 17.5 +/- 0.1
w2 474 494 19 14.8 +/- 0.1
w2 9896 10796 886 17.5 +/- 0.1
w2 41107 46795 1009 19.3 +/- 0.2
The magnitudes in the table are not corrected for the Galactic
extinction due to the reddening of E(B-V) = 0.04 in the direction
of the burst (Schlegel et al. 1998).
- GCN Circular #15174
I.A. Smith (Rice U.), R.P.J. Tilanus (Leiden Observatory), N.R. Tanvir
(U. of Leicester), D.A. Frail (NRAO) report:
We observed the location of GRB 130831A (Hagen et al., GCN Circ.
15139) using the SCUBA-2 sub-millimeter continuum camera on the
James Clerk Maxwell Telescope. The observation started at 14:13 UT
on 2013-08-31, corresponding to 69 minutes after the burst trigger.
Exposures totaling 2.0 hours were made in good weather conditions.
No source was detected, with a preliminary RMS of 1.4 mJy/beam at
850 microns and 13.7 mJy/beam at 450 microns.
We thank Callie McNew for the prompt support of these observations.
- GCN Circular #15179
Alan M. Watson (UNAM), Owen Littlejohns (ASU), Nat Butler (ASU),
Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G.
Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB), J. Xavier
Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UCSC),
Eleonora Troja (GSFC), Enrico Ramirez-Ruiz (UCSC), Jos=E9 A. de
Diego (UNAM), Leonid Georgiev (UNAM), Jes=FAs Gonz=E1lez (UNAM),
Carlos Rom=E1n-Z=FA=F1iga (UNAM), Neil Gehrels (GSFC), and Harvey
Moseley (GSFC) report:
We again observed the field of GRB 130831A (Hagen, et al., GCN 15139) wit=
h
the Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on
the 1.5m Harold Johnson Telescope at the Observatorio Astron=F3mico Nacio=
nal
on Sierra San Pedro M=E1rtir from 2013/09 4.32 to 2013/09 4.34 UTC (90.60
to 91.04 hours after the BAT trigger), obtaining a total of 0.36 hours
exposure in the r' and i' bands and 0.15 hours exposure in the Z,
Y, J, and H bands.
For a source within the Swift-XRT error circle (Evans et al., GCN 15147),
in comparison with SDSS DR9 and 2MASS, we obtain the following upper limi=
ts
(3-sigma):
r' > 22.84
i' > 22.94
Z > 20.76
Y > 20.23
J > 20.09
H > 19.49
In comparison with earlier RATIR observations (Butler et al., GCN 15165)
the source has faded by 2.2 magnitudes in the r' band and 2.6 magnitudes
in the i' band. This implies a power-law decay steeper than t^-1.7. The
upper limits obtained in the Z, Y, J, and H bands are also consistent wit=
h
such a steep decay index. These magnitudes are in the AB system and not
corrected for Galactic extinction in the direction of the GRB.
We thank the staff of the Observatorio Astron=F3mico Nacional in San Pedro
M=E1rtir.
- GCN Circular #15185
A. Volnova (IKI), A. Matkin (UAFO, ISON), A. Stepura (UAFO, ISON), I.
Molotov (KIAM), A. Pozanenko (IKI) report on behalf of larger GRB
follow-up collaboration:
We observed the afterglow (Hagen et al., GCN 15139; Guidorzi et al.,
GCN 15140) of the Swift GRB 130831A (Hagen et al., GCN 15139) with
SANTEL-650 (0.65m) and VT-50 (0.5m) telescopes of UAFO/ISON-Ussuriysk
observatory starting on Aug. 31 (UT) 13:14:32, i.e. 10.3 minutes
after burst trigger. We took unfiltered images of 120s and 30s
exposures ending observations at (UT) 19:20:53.
In each initial frames we clearly detect afterglow. A preliminary
photometry of the afterglow in the initial frames are following
T_start T0+ Filter, Exposure, OT, OT_err
(UT) (mid, d) (s)
2013-08-31T13:14:32 0.00782 none 120 13.86 0.02
2013-08-31T13:l6:40 0.00931 none 120 13.75 0.02
2013-08-31T13:18:49 0.01080 none 120 13.78 0.02
The photometry is based on reference stars SDSS-DR9, (R mag,
transformation by Lupton 2005)
N SDSS id R(Lupton)errR
1 J235443.71+292539.3 13.491 0.016
2 J235438.60+292547.3 14.136 0.015
3 J235423.64+292452.8 17.120 0.016
- GCN Circular #15186
A. Volnova (IKI), N. Minikulov (Institute of Astrophysics), M.Gulyamov
(Institute of Astrophysics), I. Molotov (KIAM), A. Pozanenko (IKI)
report on behalf of larger GRB follow-up collaboration:
We observed the afterglow (Hagen et al., GCN 15139; Guidorzi et al.,
GCN 15140) of the Swift GRB 130831A (Hagen et al., GCN 15139) with
AZT-8 (0.7m) telescope of Gissar observatory in R filter starting on
Aug. 31 (UT) 17:47:54. A preliminary photometry of combined image is
based on SDSS DR9 stars
T_start T0+ Filter, Exposure, OT, OT_err
(UT) (mid, d) (s)
2013-08-31T17:47:54 0.21932 R 57x60 18.28 0.04
Reference stars SDSS-DR9, (R mag, transformation by Lupton 2005)
N SDSS id R(Lupton)errR
1 J235443.71+292539.3 13.491 0.016
2 J235438.60+292547.3 14.136 0.015
3 J235423.64+292452.8 17.120 0.016
- GCN Circular #15188
A. Volnova (IKI), V. Linkov (ISON), K. Polyakov (ISON), D. Ivanov
(ISON), I. Molotov (KIAM), A. Pozanenko (IKI) report on behalf of
larger GRB follow-up collaboration:
We observed the afterglow (Hagen et al., GCN 15139; Guidorzi et al.,
GCN 15140) of the Swift GRB 130831A (Hagen et al., GCN 15139) with
SANTEL-400AN telescope of ISON-Kislovodsk observatory starting on
Aug. 31 (UT) 19:12:30. We took several unfiltered images. Preliminary
photometry of combined images is following
T_start T0+ Filter, Exposure, OT, OT_err
(UT) (mid, d) (s)
2013-08-31T19:12:30 0.26113 none 840 18.32 0.08
2013-08-31T19:28:20 0.27212 none 840 18.44 0.10
2013-08-31T19:47:24 0.29470 none 1760 18.47 0.13
The photometry is based on reference stars SDSS-DR9, (R mag,
transformation by Lupton 2005)
N SDSS id R(Lupton)errR
1 J235443.71+292539.3 13.491 0.016
2 J235438.60+292547.3 14.136 0.015
3 J235423.64+292452.8 17.120 0.016
- GCN Circular #15189
A. Volnova (IKI), Yu. Krugly (IA KhNU), I. Slyusarev (IA KhNU), I.
Molotov (KIAM), A. Pozanenko (IKI) report on behalf of larger GRB
follow-up collaboration:
We observed the afterglow (Hagen et al., GCN 15139; Guidorzi et al.,
GCN 15140) of the Swift GRB 130831A (Hagen et al., GCN 15139) with
AZT-8 (0.7m) telescope of Institute of Astronomy, Kharkiv National
University in R filter starting on Sep. 01 (UT) 19:37:49. A preliminary
photometry of combined images is based on SDSS DR9 stars
T_start T0+ Filter, Exposure, OT, OT_err
(UT) (mid, d) (s)
2013-09-01T19:37:49 1.29474 R 28x120 21.26 0.07
Reference stars SDSS-DR9, (R mag, transformation by Lupton 2005)
N SDSS id R(Lupton)errR
1 J235443.71+292539.3 13.491 0.016
2 J235438.60+292547.3 14.136 0.015
3 J235423.64+292452.8 17.120 0.016
- GCN Circular #15190
A. Pozanenko (IKI), A. Volnova (IKI), B. Hafizov (UBAI), O. Burhonov
(UBAI) report on behalf of larger GRB follow-up collaboration:
We observed the afterglow (Hagen et al., GCN 15139; Guidorzi et al.,
GCN 15140) of the Swift GRB 130831A (Hagen et al., GCN 15139) with
AZT-22 telescope equipped with SNUCAM of Maidanak observatory in R
filter. A preliminary photometry of combined images is based on SDSS
stars (see at the bottom):
T_start T0+ Filter, Exposure, OT
(UT) (mid, d) (s)
2013-09-02T13:58:23 2.0410 R 1x600 22.20 +/- 0.10
2013-09-04T18:47:13 4.2555 R 5x600 22.53 +/- 0.07
2013-09-05T18:57:03 5.2658 R 6x600 22.90 +/- 0.07
A preliminary lc of the afterglow GRB 130831A based on our GCNs ##15185,
15186, 15188, 15189 and reported in this circular can be found in
http://grb.rssi.ru/GRB130831A/grb130831A_lc_preliminary.PNG
A power-law decay of the lc between 0.1 days and 2 days after trigger is
-1.68 +/- 0.06 and marginally consistent with power-law decay reported
by Watson (GCN 15179).
Reference stars
N SDSS id R(Lupton)errR
1 J235443.71+292539.3 13.491 0.016
2 J235438.60+292547.3 14.136 0.015
3 J235423.64+292452.8 17.120 0.016
- GCN Circular #15237
A. Pozanenko (IKI), A. Volnova (IKI), B. Hafizov (UBAI), O. Burhonov
(UBAI) report on behalf of larger GRB follow-up collaboration:
We continue observation of the afterglow (Hagen et al., GCN 15139;
Guidorzi et al., GCN 15140) of the Swift GRB 130831A (Hagen et al., GCN
15139) with AZT-22 telescope equipped with SNUCAM at Maidanak
observatory. A preliminary photometry of combined images obtained on
Sep. 16 is following:
T_start T0+ Filter, Exposure, OT
(UT) (mid, d) (s)
2013-09-16T19:00:13 16.28 R 14x300 22.77 +/- 0.07
The photometry is based on SDSS stars (see GCN 15190).
This is brighter than we obtained on Sep. 9 (23.11 +/- 0.06) and on
Sep. 15 (22.87 +/- 0.08). We suggest the observed re-brightening is an
emerging Supernova associated with GRB 130831A.
A preliminary lc of the afterglow+SN of GRB 130831A can be found in
http://grb.rssi.ru/GRB130831A/grb130831A_lc_preliminary.PNG
- GCN Circular #15242
FROM: Nat Butler at Az State U
William H. Lee (UNAM), Alan M. Watson (UNAM), Nat Butler (ASU), Alexander
Kutyrev (GSFC), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB=
),
J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UCSC),
Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC)=
,
Jos=E9 A. de Diego (UNAM), Leonid Georgiev (UNAM), Jes=FAs Gonz=E1lez (UN=
AM),
Carlos Rom=E1n-Z=FA=F1iga (UNAM), Neil Gehrels (GSFC), and Harvey Moseley=
(GSFC)
report:
We again observed the field of GRB 130831A (Hagen, et al., GCN 15139) wit=
h
the Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on
the 1.5m Harold Johnson Telescope at the Observatorio Astron=F3mico Nacional
on Sierra San Pedro M=E1rtir from 2013/09 22.11 to 2013/09 22.31 UTC (21.57
to 21.77 days after the BAT trigger), obtaining a total of 6.40 hours
exposure in the r and i bands and 2.60 hours exposure in the Z, Y, J, and
H
bands.
For a source within the Swift-XRT error circle (Evans et al., GCN 15147),
in comparison with SDSS DR9 and 2MASS, we obtain the following detections
and upper limits (3-sigma):
r 23.02 +/- 0.14
i 22.78 +/- 0.13
Z > 22.87
Y > 22.35
J 21.62 +/- 0.19
H > 21.75
These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB. The flux levels are consistent
with our prior upper limits measured 4 days after the GRB (Butler et al.,
GCN 15179) and with the measurements reported by Pozanenko et al. (GCN
15237), confirming a flattening of the afterglow light curve.
We thank the staff of the Observatorio Astron=F3mico Nacional in San Pedro
M=E1rtir.
- GCN Circular #15244
G. Khorunzhev, R. Burenin, M. Pavlinsky, R. Sunyaev (IKI),
I. Bikmaev, N. Sakhibullin (KFU/AST),
I. Khamitov, H. Kirbiyik (TUG)
report:
The optical afterglow of GRB 130831A (GCN 15139, D. Palmer) was
observed with 1.5-m Russian-Turkish Telescope RTT150 at Bakyrlytepe
(TUBITAK National Observatory, Turkey). The observation started at
2013-09-01 00:42:03 UT, appr. 12 hours after the burst.
Two images each with exposure 300 seconds were obtained in R-band:
1. UT = 00:42:03.678; t-t0 = 11.630h; m_R = 19.57 +- 0.02
2. UT = 00:48:35.373; t-t0 = 11.739h; m_R = 19.62 +- 0.03
Images are calibrated using stars proposed by Pozanenko et al. (GCN
15190). The magnitudes are not corrected for the Galactic extinction.
- GCN Circular #15274
William H. Lee (UNAM), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), Nat
Butler (ASU), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB),
J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UCSC),
Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC),
Jos=E9 A. de Diego (UNAM), Leonid Georgiev (UNAM), Jes=FAs Gonz=E1lez (UNAM),
Carlos Rom=E1n-Z=FA=F1iga (UNAM), Neil Gehrels (GSFC), and Harvey Moseley
(GSFC)
report:
We observed the field of GRB 130831A (Hagen, et al., GCN 15139) with the
Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the
1.5m Harold Johnson Telescope at the Observatorio Astron=F3mico Nacional
on
Sierra San Pedro M=E1rtir from 2013/09 30.12 to 2013/09 30.49 UTC (29.58
to
29.94 days after the BAT trigger), obtaining a total of 6.27 hours exposure
in the r and i bands and 2.65 hours exposure in the Z, Y, J, and H bands.
For a source within the Swift-XRT error circle (Evans et al., GCN 15147),
in comparison with 2MASS, we obtain the following detections and upper
limits (3-sigma):
r 23.84 +/- 0.18
i 23.23 +/- 0.15
Z > 23.04
Y > 22.53
J > 22.37
H > 21.72
These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB. The source has faded relative to
our last measurement (t~21.5 days; Lee et al., GCN 15242) by about 0.8
magnitudes in r and J and 0.5 magnitudes in i. Our measurements (see,
also, Watson et al., GCN 15179; Butler et al., GCN 15165) are consistent
with a bump or re-brightening in the lightcurve at t~10 days (see,
Pozanenko et al., GCN 15237), followed by continued fading.
We thank the staff of the Observatorio Astron=F3mico Nacional in San Pedro
M=E1rtir.
- GCN Circular #15320
S. Klose, A. Nicuesa Guelbenzu (both TLS Tautenburg), T. Kruehler (ESO),
J. Greiner, D. A. Kann, A. Rau (all MPE Garching), F. Olivares E. (UNAB,
MCSS, Chile), and S. Schulze (PUC, MCSS, Chile), on behalf of a larger
collaboration report:
We observed the optical transient following GRB 130831A (e.g., Hagen et
al. 2013, GCN 15139; Guidorzi et al. 2013, GCN 15140; Xu et al. 2013, GCN
15142; Yoshii et al. 2013, GCN 15143) with VLT/FORS2 equipped with the
300V grism on Sep 29 and Sep 30, 2013, between 28.5 and 29.5 days after
the burst under excellent sky conditions with mean seeing around 0.6". The
total exposure time of the spectrum was 1.53 hr and covers the spectral
range between approximately 440 and 920 nm.
In the combined spectrum, we detect the optical emission over the full
spectral range. The spectrum peaks at about 800 nm and shows broad
absorption features, very much reminiscent of the spectrum of, e.g., GRB
031203 / SN 2003lw (z=0.1055; Malesani et al. 2004, ApJ 609, L5), and the
recent GRB 120714B / SN 2012eb (z=0.40; Klose et al. 2012, GCN 13613), GRB
130215A / SN 2013ez (z=0.597; de Ugarte Postigo et al., GCN 14303), GRB
130427A / SN 2013cq (z=0.34; Xu et al. 2013, ApJ 776, 98), and GRB 130702
/ SN 2013dx (z=0.145; Schulze et al. 2013, GCN 14994), all obtained around
SN maximum light.
We conclude that we have spectroscopically discovered the appearence of a
broad-line SN following GRB 130831A at z=0.4791 (Cucchiara et al. 2013,
GCN 15144), confirming the conclusion of Pozanenko et al. (GCN 15237)
based on the optical light curve.
- GCN Circular #15321
William H. Lee (UNAM), Nat Butler (ASU), Alan M. Watson (UNAM),
Alexander Kutyrev (GSFC), Michael G. Richer (UNAM), Chris Klein (UCB),
Ori Fox (UCB), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino
Cucchiara (UCSC), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico
Ramirez-Ruiz (UCSC), Jos=E9 A. de Diego (UNAM), Leonid Georgiev (UNAM),
Jes=FAs Gonz=E1lez (UNAM), Carlos Rom=E1n-Z=FA=F1iga (UNAM), Neil Gehrels
(GSFC),
and Harvey Moseley (GSFC) report:
We observed the field of GRB 130831A (Hagen, et al., GCN 15139) with the
Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the
1.5m Harold Johnson Telescope at the Observatorio Astron=F3mico Nacional
on
Sierra San Pedro M=E1rtir from 2013/10 9.10 to 2013/10 9.47 UTC (925.41
to 934.19 hours after the BAT trigger), obtaining a total of 6.08 hours
exposure in the r and i bands and 2.61 hours exposure in the Z,
Y, J, and H bands.
For a source within the Swift-XRT error circle, in comparison with 2MASS,
we
obtain the following upper limits (3-sigma):
r > 24.14
i > 23.63
Z > 22.94
Y > 22.45
J > 22.23
H > 21.74
These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.
As compared with our previous RATIR observations (Lee et al., GCN 15274)
we
confirm the fading in r and i by at least 0.3 and 0.4 and magnitudes, respectively.
The upper limits in Z, Y, J, and H are also consistent with fading.
Overall our measurements (Butler et al. GCN 15165, Watson et al. GCN 15179,
Lee et al., GCN 15242, 15274) are consistent with the re-brightening due to
a SN, as reported by Pozanenko et al. (GCN 15237) and spectroscopically by
Klose et al. (GCN 15320), and fading.
We thank the staff of the Observatorio Astron=F3mico Nacional in San Pedro
M=E1rtir.
- 1509.09234 from 1 Oct 15
M. De Pasquale et al.: The central engine of GRB 130831A and the energy breakdown of a relativistic explosion
Gamma-ray bursts (GRBs) are the most luminous explosions in the universe, yet the nature and physical properties of their energy sources are
far from understood. Very important clues, however, can be inferred by studying the afterglows of these events. We present optical and X-ray
observations of GRB 130831A obtained by Swift, Chandra, Skynet, RATIR, Maidanak, ISON, NOT, LT and GTC. This burst shows a steep drop in the
X-ray light-curve at $\simeq 10^5$ s after the trigger, with a power-law decay index of $\alpha \sim 6$. Such a rare behaviour cannot be
explained by the standard forward shock (FS) model and indicates that the emission, up to the fast decay at $10^5$ s, must be of "internal
origin", produced by a dissipation process within an ultrarelativistic outflow. We propose that the source of such an outflow, which must
produce the X-ray flux for $\simeq 1$ day in the cosmological rest frame, is a newly born magnetar or black hole. After the drop, the faint
X-ray afterglow continues with a much shallower decay. The optical emission, on the other hand, shows no break across the X-ray steep decrease,
and the late-time decays of both the X-ray and optical are consistent. Using both the X-ray and optical data, we show that the emission after
$\simeq 10^5$ s can be explained well by the FS model. We model our data to derive the kinetic energy of the ejecta and thus measure the
efficiency of the central engine of a GRB with emission of internal origin visible for a long time. Furthermore, we break down the energy
budget of this GRB into the prompt emission, the late internal dissipation, the kinetic energy of the relativistic ejecta, and compare it with
the energy of the associated supernova, SN 2013fu.
- GCN Circular #18673
E.Gorbovskoy, V. Lipunov, N.Tyurina, V.Kornilov,
P.Balanutsa, A.Kuznetsov, D.Kuvshinov
Lomonosov Moscow State University, Sternberg Astronomical Institute
K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk
Irkutsk State University
After this observation night there was no electricity at the
Tunka observatory for a few days . Therefore, the data were not immediately available. We
forgot to check the follow-up after power is restored and rediscovered
this source as optical transient during the data reprocessing of the
present time.
MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru)
located in Tunka was pointed to the GRB130831A 58 sec after trigger
time at 2013-08-31 13:05:14 UT. On our second (20s exposure 120 sec after
trigger) set we
found 1 optical transient within SWIFT error-box (ra=23 54 36 dec=+29 27
00 r=0.05) brighter then 15.1.
T-Tmid Date Time Expt. Ra Dec Mag
-------|-----------|----------|-------|-----------------|-----------------|-------
130 2013-08-31 13:06:16 20 23h 54m 29.82s +29d 25m 47.1s 14.34
The 5-sigma upper limit has been about 15.1mag
The automatic reduction data are below:
date time coord2000 Exp. Polaroid mag err
UT s
2013-08-31 13:05:13 - - 10 P/ >15.4
2013-08-31 13:05:14 - - 10 P\ >15.5
2013-08-31 13:06:14.969 23h 54m 29.77s +29d 25m 46s.5 20 P/ 14.19 0.13
2013-08-31 13:06:16.09 23h 54m 29.82s +29d 25m 47s.1 20 P\ 14.34 0.15
2013-08-31 13:07:37.707 23h 54m 29.94s +29d 25m 46s.6 40 P 13.70 0.07
2013-08-31 13:07:38.411 23h 54m 29.89s , +29d 25m 46s.3 40 P 14.08 0.08
2013-08-31 13:09:21.157 23h 54m 29.87s , +29d 25m 46s.5 60 P 13.96 0.06
2013-08-31 13:09:22.329 23h 54m 29.86s , +29d 25m 46s.3 60 P 14.17 0.06
2013-08-31 13:11:11.731 23h 54m 29.87s , +29d 25m 46s.8 80 P 13.96 0.05
2013-08-31 13:11:12.656 23h 54m 29.87s , +29d 25m 46s.4 80 P 14.05 0.04
2013-08-31 13:13:26.831 23h 54m 29.87s , +29d 25m 46s.4 110 P 13.14 0.02
2013-08-31 13:13:26.904 23h 54m 29.87s , +29d 25m 46s.7 110 P 13.23 0.01
2013-08-31 13:16:22.741 23h 54m 29.88s , +29d 25m 46s.4 140 P 12.76 0.01
2013-08-31 13:16:23.769 23h 54m 29.89s , +29d 25m 46s.7 140 P 12.79 0.01
2013-08-31 13:19:48.725 23h 54m 29.88s , +29d 25m 46s.5 180 P 13.10 0.01
2013-08-31 13:19:49.319 23h 54m 29.89s , +29d 25m 46s.6 180 P 13.03 0.01
2013-08-31 13:23:42.166 23h 54m 29.89s , +29d 25m 46s.6 180 P 13.44 0.01
2013-08-31 13:23:43.007 23h 54m 29.89s , +29d 25m 46s.6 180 P 13.40 0.01
2013-08-31 13:27:40.436 23h 54m 29.90s , +29d 25m 46s.5 180 P 13.80 0.01
2013-08-31 13:27:41.309 23h 54m 29.89s , +29d 25m 46s.7 180 P 13.79 0.01
2013-08-31 13:31:39.264 23h 54m 29.88s , +29d 25m 46s.7 180 P 14.08 0.02
2013-08-31 13:31:39.957 23h 54m 29.88s , +29d 25m 46s.8 180 P 14.12 0.01
2013-08-31 13:36:03.651 23h 54m 29.89s , +29d 25m 46s.4 180 P 14.44 0.02
2013-08-31 13:36:04.486 23h 54m 29.89s , +29d 25m 46s.5 180 P 14.51 0.02
2013-08-31 13:39:59.065 23h 54m 29.88s , +29d 25m 46s.6 180 P 14.55 0.02
2013-08-31 13:39:59.918 23h 54m 29.89s , +29d 25m 46s.7 180 P 14.53 0.02
2013-08-31 13:44:00.574 23h 54m 29.89s , +29d 25m 46s.7 180 P 14.72 0.02
2013-08-31 13:44:01.425 23h 54m 29.89s , +29d 25m 46s.6 180 P 14.78 0.03
2013-08-31 13:48:10.668 23h 54m 29.91s , +29d 25m 46s.5 180 P 14.94 0.03
2013-08-31 13:48:11.488 23h 54m 29.87s , +29d 25m 46s.5 180 P 14.95 0.02
2013-08-31 13:52:19.736 23h 54m 29.89s , +29d 25m 46s.3 180 P 14.97 0.03
2013-08-31 13:52:20.267 23h 54m 29.88s , +29d 25m 46s.3 180 P 14.99 0.03
2013-08-31 13:56:25.283 23h 54m 29.89s , +29d 25m 46s.7 180 P 15.11 0.03
2013-08-31 13:56:25.394 23h 54m 29.88s , +29d 25m 46s.6 180 P 15.05 0.03
2013-08-31 14:00:30.776 23h 54m 29.88s , +29d 25m 46s.7 180 P 15.16 0.03
2013-08-31 14:00:31.465 23h 54m 29.88s , +29d 25m 46s.6 180 P 15.13 0.03
2013-08-31 14:04:35.057 23h 54m 29.88s , +29d 25m 46s.5 180 P 15.18 0.03
2013-08-31 14:04:37.274 23h 54m 29.90s , +29d 25m 46s.8 180 P 15.10 0.03
2013-08-31 14:08:42.051 23h 54m 29.88s , +29d 25m 46s.6 180 P 15.18 0.03
2013-08-31 14:08:42.358 23h 54m 29.89s , +29d 25m 46s.8 180 P 15.18 0.03
2013-08-31 14:13:16.808 23h 54m 29.88s , +29d 25m 46s.5 180 P 15.16 0.03
2013-08-31 14:13:17.534 23h 54m 29.87s , +29d 25m 46s.6 180 P 15.19 0.03
2013-08-31 14:17:26.33 23h 54m 29.88s , +29d 25m 46s.6 180 P 15.22 0.03
2013-08-31 14:17:26.78 23h 54m 29.89s , +29d 25m 46s.7 180 P 15.16 0.03
2013-08-31 14:21:33.6 23h 54m 29.87s , +29d 25m 46s.4 180 P 15.33 0.03
2013-08-31 14:21:34.446 23h 54m 29.89s , +29d 25m 46s.6 180 P 15.27 0.03
2013-08-31 14:26:01.003 23h 54m 29.90s , +29d 25m 46s.7 180 P 15.37 0.03
2013-08-31 14:26:01.882 23h 54m 29.89s , +29d 25m 46s.5 180 P 15.30 0.03
2013-08-31 14:29:49.129 23h 54m 29.89s , +29d 25m 46s.7 180 P 15.45 0.03
2013-08-31 14:29:50.359 23h 54m 29.87s , +29d 25m 46s.7 180 P 15.39 0.03
2013-08-31 14:33:42.843 23h 54m 29.90s , +29d 25m 46s.4 180 P 15.47 0.03
2013-08-31 14:33:43.028 23h 54m 29.89s , +29d 25m 47s.0 180 P 15.46 0.04
2013-08-31 14:37:43.134 23h 54m 29.87s , +29d 25m 46s.4 180 P 15.52 0.04
2013-08-31 14:37:44.1 23h 54m 29.87s , +29d 25m 46s.6 180 P 15.42 0.04
2013-08-31 14:41:37.936 23h 54m 29.90s , +29d 25m 46s.5 180 P 15.66 0.04
2013-08-31 14:41:40.554 23h 54m 29.90s , +29d 25m 46s.5 180 P 15.57 0.04
2013-08-31 14:45:27.386 23h 54m 29.89s , +29d 25m 46s.4 180 P 15.71 0.04
2013-08-31 14:45:28.83 23h 54m 29.92s , +29d 25m 46s.7 180 P 15.54 0.04
2013-08-31 14:49:23.464 23h 54m 29.88s , +29d 25m 46s.6 180 P 15.70 0.04
2013-08-31 14:49:24.934 23h 54m 29.89s , +29d 25m 46s.6 180 P 15.58 0.04
2013-08-31 14:53:18.194 23h 54m 29.88s , +29d 25m 46s.4 180 P 15.66 0.04
2013-08-31 14:53:18.686 23h 54m 29.90s , +29d 25m 46s.8 180 P 15.58 0.04
2013-08-31 14:57:36.995 23h 54m 29.87s , +29d 25m 46s.3 180 P 15.76 0.04
2013-08-31 14:57:37.418 23h 54m 29.90s , +29d 25m 46s.6 180 P 15.63 0.04
2013-08-31 15:01:42.896 23h 54m 29.91s , +29d 25m 46s.3 180 P 15.88 0.05
2013-08-31 15:01:43.521 23h 54m 29.92s , +29d 25m 46s.6 180 P 15.69 0.04
2013-08-31 15:05:42.207 23h 54m 29.88s , +29d 25m 46s.6 180 P 15.95 0.04
2013-08-31 15:05:43.764 23h 54m 29.89s , +29d 25m 46s.7 180 P 15.75 0.04
2013-08-31 15:09:53.777 23h 54m 29.89s , +29d 25m 46s.4 180 P 15.93 0.05
2013-08-31 15:09:54.9 23h 54m 29.90s , +29d 25m 46s.5 180 P 15.84 0.05
2013-08-31 15:14:14.225 23h 54m 29.90s , +29d 25m 46s.5 180 P 16.04 0.05
2013-08-31 15:14:14.636 23h 54m 29.88s , +29d 25m 46s.5 180 P 15.90 0.05
2013-08-31 15:18:32.515 23h 54m 29.88s , +29d 25m 46s.4 180 P 15.98 0.05
2013-08-31 15:18:32.972 23h 54m 29.62s , +29d 25m 46s.7 180 P 16.80 0.08
2013-08-31 15:22:42.728 23h 54m 29.86s , +29d 25m 46s.4 180 P 16.13 0.05
2013-08-31 15:22:43.005 23h 54m 29.72s , +29d 25m 47s.5 180 P 16.50 0.08
2013-08-31 15:27:06.639 23h 54m 29.88s , +29d 25m 46s.1 180 P 16.23 0.06
2013-08-31 15:27:07.166 23h 54m 29.90s , +29d 25m 46s.6 180 P 15.99 0.06
2013-08-31 15:31:14.164 23h 54m 29.89s , +29d 25m 46s.5 180 P 16.32 0.06
2013-08-31 15:31:14.663 23h 54m 29.89s , +29d 25m 47s.1 180 P 16.06 0.06
2013-08-31 15:35:08.964 23h 54m 29.87s , +29d 25m 46s.4 180 P 16.39 0.07
2013-08-31 15:35:10.803 23h 54m 29.97s , +29d 25m 49s.0 180 P 16.83 0.10
2013-08-31 15:39:37.457 23h 54m 29.89s , +29d 25m 46s.7 180 P 16.47 0.07
2013-08-31 15:39:38.229 23h 54m 29.84s , +29d 25m 48s.1 180 P 16.73 0.10
2013-08-31 15:43:50.963 23h 54m 29.89s , +29d 25m 46s.6 180 P 16.51 0.07
2013-08-31 15:43:51.628 23h 54m 29.68s , +29d 25m 46s.2 180 P 17.30 0.14
2013-08-31 15:47:41.439 23h 54m 29.92s , +29d 25m 46s.8 180 P 16.41 0.08
2013-08-31 15:47:41.868 23h 54m 29.70s , +29d 25m 46s.3 180 P 16.70 0.10
2013-08-31 15:51:28.744 23h 54m 29.89s , +29d 25m 46s.7 180 P 16.57 0.08
2013-08-31 15:51:29.974 23h 54m 29.69s , +29d 25m 45s.8 180 P 16.99 0.12
2013-08-31 15:55:28.935 23h 54m 29.91s , +29d 25m 46s.6 180 P 16.68 0.11
2013-08-31 15:55:29.91 23h 54m 29.92s , +29d 25m 46s.6 180 P 16.36 0.10
2013-08-31 15:59:32.081 23h 54m 29.88s , +29d 25m 46s.5 180 P 16.78 0.09
2013-08-31 15:59:32.882 23h 54m 29.77s , +29d 25m 45s.2 180 P 16.75 0.10
2013-08-31 16:03:45.019 23h 54m 29.89s , +29d 25m 46s.2 180 P 16.71 0.09
2013-08-31 16:03:45.878 23h 54m 29.73s , +29d 25m 49s.2 180 P 16.98 0.13
2013-08-31 16:03:45.878 23h 54m 29.67s , +29d 25m 45s.0 180 P 17.21 0.14
2013-08-31 16:07:40.752 23h 54m 29.87s , +29d 25m 46s.7 180 P 16.68 0.10
2013-08-31 16:07:40.756 23h 54m 29.85s , +29d 25m 46s.9 180 P 16.53 0.11
2013-08-31 16:11:45.003 23h 54m 29.89s , +29d 25m 46s.5 180 P 16.65 0.09
2013-08-31 16:11:46.074 23h 54m 29.68s , +29d 25m 47s.0 180 P 16.51 0.11
2013-08-31 16:16:04.472 23h 54m 29.89s , +29d 25m 46s.2 180 P 16.90 0.11
2013-08-31 16:16:05.21 23h 54m 29.71s , +29d 25m 46s.2 180 P 17.15 0.14
2013-08-31 16:20:16.552 23h 54m 29.88s , +29d 25m 46s.4 180 P 16.71 0.09
2013-08-31 16:20:16.892 23h 54m 29.90s , +29d 25m 47s.3 180 P 16.63 0.12
2013-08-31 16:24:28.011 23h 54m 29.92s , +29d 25m 46s.2 180 P 16.74 0.12
2013-08-31 16:24:28.419 23h 54m 29.64s , +29d 25m 46s.9 180 P 17.97 0.22
2013-08-31 16:28:38.273 23h 54m 29.91s , +29d 25m 46s.3 180 P 16.75 0.11
2013-08-31 16:28:39.181 23h 54m 29.66s , +29d 25m 47s.7 180 P 17.10 0.16
2013-08-31 16:32:35.03 23h 54m 29.88s , +29d 25m 46s.4 180 P 17.03 0.12
2013-08-31 16:36:41.311 23h 54m 29.91s , +29d 25m 46s.9 180 P 16.88 0.13
2013-08-31 16:36:41.982 23h 54m 29.90s , +29d 25m 45s.2 180 P 16.91 0.14
2013-08-31 16:40:40.333 23h 54m 29.85s , +29d 25m 46s.5 180 P 17.07 0.15
2013-08-31 16:40:40.788 23h 54m 29.80s , +29d 25m 46s.5 180 P 18.57 0.32
The automatic light curve is available at
http://observ.pereplet.ru/images/GRB130831A.jpg
The message may be cited.
- 1604.04817 from 19 Apr 16
Q. Zhang et al.: Modeling the Multi-Band Afterglow of GRB 130831A: Evidence for a Spinning-Down Magnetar Dominated by Gravitational Wave Losses?
The X-ray afterglow of GRB 130831A shows an "internal plateau" with a decay slope of $\sim$ 0.8, followed by a steep drop at around $10^5$ s
with a slope of $\sim$ 6. After the drop, the X-ray afterglow continues with a much shallower decay. The optical afterglow exhibits two
segments of plateaus separated by a luminous optical flare, followed by a normal decay with a slope basically consistent with that of the
late-time X-ray afterglow. The decay of the internal X-ray plateau is much steeper than what we expect in the simplest magnetar model. We
propose a scenario in which the magnetar undergoes gravitational-wave-driven r-mode instability, and the spin-down is dominated by
gravitational wave losses up to the end of the steep plateau, so that such a relatively steep plateau can be interpreted as the internal
emission of the magnetar wind and the sharp drop can be produced when the magnetar collapses into a black hole. This scenario also predicts an
initial X-ray plateau lasting for hundreds of seconds with an approximately constant flux which is compatible with observation. Assuming that
the magnetar wind has a negligible contribution in the optical band, we interpret the optical afterglow as the forward shock emission by
invoking the energy injection from a continuously refreshed shock following the prompt emission phase. It is shown that our model can basically
describe the temporal evolution of the multi-band afterglow of GRB 130831A.
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