Gamma-ray Burst 071018

(All information courtesy of the instrument teams.)

Previous IAU Circulars

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Results of Observations

GCN/BACODINE POSITION NOTICE


TITLE:           GCN/SWIFT NOTICE
NOTICE_DATE:     Thu 18 Oct 07 08:44:17 UT
NOTICE_TYPE:     Swift-BAT GRB Position
TRIGGER_NUM:     294645,   Seg_Num: 0
GRB_RA:          164.676d {+10h 58m 42s} (J2000),
                 164.791d {+10h 59m 10s} (current),
                 163.932d {+10h 55m 44s} (1950)
GRB_DEC:         +53.830d {+53d 49' 49"} (J2000),
                 +53.789d {+53d 47' 19"} (current),
                 +54.098d {+54d 05' 54"} (1950)
GRB_ERROR:       3.00 [arcmin radius, statistical only]
GRB_INTEN:       0 [cnts]    Image_Peak=4187 [image_cnts]
TRIGGER_DUR:     376.000 [sec]   (=6.3 [min])
TRIGGER_INDEX:   20000     E_range: 15-50 keV
BKG_INTEN:       0 [cnts]
BKG_TIME:        0.00 SOD {00:00:00.00} UT
BKG_DUR:         0 [sec]
GRB_DATE:        14391 TJD;   291 DOY;   07/10/18
GRB_TIME:        31061.70 SOD {08:37:41.70} UT
GRB_PHI:         -178.50 [deg]
GRB_THETA:        19.90 [deg]
SOLN_STATUS:     0x11
RATE_SIGNIF:     0.00 [sigma]
IMAGE_SIGNIF:    7.55 [sigma]
MERIT_PARAMS:     +0  +1  +0  +7  +1  -2  +0  +0 -32  +1 
SUN_POSTN:       202.78d {+13h 31m 07s}   -9.53d {-09d 31' 40"}
SUN_DIST:         71.00 [deg]   Sun_angle= 2.5 [hr] (West of Sun)
MOON_POSTN:      284.77d {+18h 59m 04s}  -26.83d {-26d 49' 34"}
MOON_DIST:       128.87 [deg]
MOON_ILLUM:      40 [%]
GAL_COORDS:      153.01, 56.21 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      140.80, 42.74 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS:        SWIFT-BAT GRB Coordinates.  
COMMENTS:        This is an image trigger.  (The RATE_SIGNIF & BKG_{INTEN, TIME, DUR} are undefined.)  
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 not a GRB.  
COMMENTS:        This trigger occurred at longitude,latitude = 15.41,18.43 [deg].

red DSS finding chart ps-file
GCN Circular #6932
H. A. Krimm (GSFC/USRA), S. D. Barthelmy (GSFC), P. T. O'Brien (U Leicester), D. M. Palmer (LANL) and B. Sbarufatti (INAF-IASFPA) report on behalf of the Swift Team:
At 08:37:41 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 071018(?) (trigger=294645). The BAT on-board calculated location is RA, Dec 164.676, +53.830 which is
```
   RA(J2000)  =  10h 58m 42s
   Dec(J2000) = +53d 49' 49"
```
with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). This was a 320-sec long image trigger, so the TDRSS lightcurve does not show any significant signal (as is typical). This location is well off the Galactic plane and does not mach any known sources in SIMBAD. Given that it is a long image trigger, this was automatically classifed as a transient instead of a GRB. We will need the full data set to determine if this is a burst or transient.
Because Swift is in the process of returning to normal operations, automatic slewing to GRBs is currently disabled outside of business hours (US EDT). Therefore, there are no prompt XRT or UVOT observations of this burst.
Burst Advocate for this burst is H. A. Krimm (krimm AT milkyway.gsfc.nasa.gov). 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 #6933
G. Sato (GSFC/ISAS), L. Barbier (GSFC), S. D. Barthelmy (GSFC), J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/UMBC), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. Ukwatta (GWU) (i.e. the Swift-BAT team):
Using the data set from T-239 to T+844 sec from the recent telemetry downlink, we report further analysis of BAT GRB 071018 (trigger #294645) (Krimm, et al., GCN Circ. 69342). The BAT ground-calculated position is RA, Dec = 164.617, 53.857 deg which is
```
    RA(J2000)  = 10h 58m 28.0s
    Dec(J2000) = 53d 51' 26"
```
with an uncertainty of 2.7 arcmin, (radius, sys+stat, 90% containment). The partial coding was 97%.
We confirm that this event has the characteristics of a true gamma-ray burst.
The mask-weighted light curve shows an enlongated multi-peaked structure. The burst location came into the BAT field of view at T-70 sec.and there was an initial peak at T-50 sec, followed by low-level emission from T+20 to T+80, followed by the main emission in several peaks from T+120 sec to T+420 sec. There is also possible emission at later times (~T+600 and ~T+800), although statistics are poorer for this late time since the spacecraft slewed to a new target, moving the burst nearer the edge of the field of view. T90 (15-350 keV) is 376.0 +- 20 sec (estimated error including systematics).
The time-averaged spectrum from T+113.1 to T+417.7 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.63 +- 0.26. The fluence in the 15-150 keV band is 1.0 +- 0.2 x 10^-06 erg/cm2. The 1-sec peak photon flux measured from T+124.18 sec in the 15-150 keV band is 0.2 +- 0.1 ph/cm2/sec. All the quoted errors are at the 90% confidence level.
This burst has several characteristics which are typical of high redshift bursts. Its duration is long (T90 = 376 sec) with relatively few (three) significant peaks. The 1-s peak flux is < 1.0 ph/cm2/s and the power-law photon index (1.65) is < 2.
GCN Circular #6936
L.P. Xin, M. Zhai, Y.L. Qiu, J.Y. Wei, J.Y. Hu, J.S. Deng, X.F Wang and W.K. Zheng on behalf of EAFON report:
We have imaged the field of GRB 071013 ( GCN 6932, GCN 6933) with the TNT 0.8m telescope at Xinglong Observatory started from 19:05:11.203 UT, about 0.435 days after the trager of the burst. A set of 15*600s R-band images were obtained, In our 15*600s combined image, we found two clear new objects at the position RA(J2000) = 10;58:11.3 Dec(J2000)=+53:50:56 and RA(J2000)= 10:58:21.459 Dec(J2000)=+53:51:09.85 within the error region of the BAT ( GCN 6933), based on the USNO-B1.0 with uncertainties of 3" in both coordinates. respectively
After psf photometry , we estimated that the magnitudes of the new two objects were about 21.49+-0.220, 21.46+-0.227 reletive to USNO-B1.0 stars. respectively, with the mean time 0.486 days after the burst
We could not confirm that which one of the two new objects was the OT of the burst or maybe thay were not al all but one of them was possible to be.
We suggest new observations will be going .
More detailed analysis is on going!
The message my be cited
GCN Circular #6937
I am sorry to correct the title of the GCN 6936 to be the GRB 071018: Possible OT from Xinglong TNT Observation
GCN Circular #6938
L.P. Xin, M. Zhai, Y.L. Qiu, J.Y. Wei, J.Y. Hu, J.S. Deng, X.F Wang and W.K. Zheng on behalf of EAFON report:
We are sorry to make you in trouble ! It was GRB 071018 but not GRB 071013
GCN Circular #6939
L.P. Xin, M. Zhai, Y.L. Qiu, J.Y. Wei, J.Y. Hu, J.S. Deng, X.F Wang and W.K. Zheng on behalf of EAFON report:
We are sorry to make you in trouble !
In the GCN 6936, what we observed was GRB 071018 but not GRB 071013
GCN Circular #6940
L.P. Xin, M. Zhai, Y.L. Qiu, J.Y. Wei, J.Y. Hu, J.S. Deng, X.F Wang and W.K. Zheng on behalf of EAFON report:
We are sorry to make you in trouble !
In the GCN 6936, what we observed was GRB 071018 but not GRB 071013
GCN Circular #6941
P. Chandra (UVA/NRAO) and D. A. Frail (NRAO) report on behalf of the Caltech-NRAO-Carnegie GRB Collaboration:
"We observed the Swift burst GRB 0701018 (GCN#6932) using the VLA at a frequency of 8.46 GHz and starting at 12.38 UT on Oct 19, 2007. We do not detect any radio emission within BAT error box (GCN#6933). We also do not detect any radio emission at the positions of the two new sources found by the TNT 0.8m telescope at Xinglong Observatory (GCN#6936). The map noise is 31 uJy.
The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc."
GCN Circular #6943
A.P. Beardmore, K.L. Page, P.A. Evans, R.L.C. Starling, J.P. Osborne (U. Leicester) and H.A Krimm (GSFC/USRA) report on behalf of the Swift-XRT team:
The Swift-XRT began observing the field of the BAT GRB 071018 (trigger #294645) at 2007-10-19T00:36, 57 ks after the trigger. A photon counting mode image containing an exposure time of 4.0 ks reveals two faint uncatalogued sources:
Source 1 is at RA, Dec (J2000) = 164.51244, 53.82275, which is
```
RA(J2000)  =  10 58 02.99
Dec(J2000) = +53 49 21.9
```
with an estimated uncertainty of 6.4 arcsec (radius, 90 percent confidence). This is 4.25 arcmin away from the refined BAT position of Sato et al. (GCN 6933), but outside the quoted BAT 2.7 arcmin 90 percent error circle. Its estimated count rate is (3.2+/-0.9)e-3 count s^-1.
Source 2 is at RA, Dec (J2000) = 164.58083, 53.82383, which is
```
RA(J2000)  =  10 58 19.40
Dec(J2000) = +53 49 25.8
```
with an estimated uncertainty of 7.9 arcsec (radius, 90 percent confidence). This is 2.37 arcmin away from the refined BAT position and within its error circle. Its estimated count rate is (2.0+/-0.8)e-3 count s^-1.
At this stage we cannot tell whether either source is fading and therefore associated with the GRB. Further observations are planned by Swift over the weekend.
This circular is an official product of the Swift-XRT team.
GCN Circular #6944
Adria C. Updike, Brian Donehew, Paul Jay Searcy, Ernest Garrison, and=20 Dieter H. Hartmann report (on behalf of the Clemson GRB Follow-Up Team):
We observed the field of GRB 071018 (GCN 6932, Krimm et al.) beginning=20 1.05 days after the trigger under good weather conditions. We obtained=20 69 minutes of R-band images at high airmass.
Upon comparison to the sources identified by Xin et al. (GCN 6936), we=20 find a magnitude of 20.5 =B1 0.15 for OT candidate #1. We note that this= =20 is brighter than the magnitude reported by Xin et al. half a day=20 earlier, so this may indeed be a variable source.=20
We also note a source in SDSS images at the location of GCN 6936 OT=20 candidate #2.
At the locations of the XRT error circles (GCN 6943, Beardmore et al.),=20 we detect no new sources down to a limiting magnitude of 20.8 in the R=20 band.
Calibration to the USNO B1.0 catalog was done relative to 10 field stars.
We would like to thank Liping Xin for providing a finder chart and=20 additional information on their observations. We also acknowledge the=20 help of Kenneth Rumstay (Valdosta U).
This message may be cited.
GCN Circular #6947
J. Gorosabel (IAA-CSIC Granada), A. de Ugarte Postigo (ESO Santiago), M. Jel=EDnek (IAA-CSIC), M. Vuckovic (Katholieke Universiteit Leuven), E. Rubio-Herrera, P. van Ham, F. van Weerdenburg, P. van Oers (Univ. of Amsterdam) and A. J. Castro-Tirado (IAA-CSIC) report:
"Following the detection of GRB 071018 by SWIFT (Krim et al. GCNC 6932) we have obtained R & I-band observations with the 1.2m Mercator telescope at Observatorio del Roque de los Muchachos in La Palma. The frames were obtained starting on 19.2916 Oct (i.e. 22.4 hr after the BAT trigger). The result of the Mercator Telescope follow-up observation, referred to the two optical sources reported by Lin et al. (GCNC 6936) and the two XRT sources reported by Beardmore et al. (GCNC 6943) is the following one:
The optical source # 1 at RA(J2000) =3D 10:58:11.3 Dec(J2000)=3D +53:50:5= 6 is well detected in our R & I-band frames with R =3D 20.6 +/- 0.4 based on the photometry given in the USNO-B1.0 catalogue. This is consistent with the value reported by SARA (Updike et al. GCNC 6944) about 3 hours later. We note that there is no "quiescent" counterpart to this object in the SDSS but the lack of an X-ray counterpart argues against this variable object being the optical afterglow.
The location of the optical source # 2 at RA(J2000)=3D 10:58:21.459 Dec(J2000)=3D +53:51:09.85 is covered in our images and we do not see any object at this position with a limiting magnitude of R ~ 22.0 (besides the one present in the SDSS).
The location of the XRT source # 1 at RA(J2000) =3D 10 58 02.99 Dec(J2000) =3D +53 49 21.9 is covered in our images and we do not see any object at this position with a limiting magnitude of R ~ 22.0.
The XRT source # 2, outside the refined BAT error box (Sato et al. GCNC 6933), is also outside the field of view of the Mercator frames.
Further observations are encouraged."
GCN Circular #6965
L.P. Xin, M. Zhai, Y.L. Qiu, J.Y. Wei, J.Y. Hu, J.S. Deng, J. Wang, Y. Urata and W.K. Zheng on behalf of EAFON report:
We observed the field of GRB071018 (Krim et al. GCN 6932) with the TNT 0.8m telescope at Xinglong Observatory for the 2nd epoch, Observation was started from 19:12:25 UT, 19th Oct. 1.494 days after the burst. A series of R-band images were obtained. In our 14*600s combined images we can still find the two sources of our last observation (Xin et al. GCN 6936).
The estimated bringhtness of the source #1 and #2 (Xin et al. GCN6936) derieved from USNO-B1.0 R2 magnitude were R=20.67+-0.318 and R=20.72+-0.36 respectively. The magnitude of source #1 was consistent with the value reported by SARA (Updike et al. GCN 6944) and Mercator (Alberto Castro-Tirado, GCN6947). but bringter than the value of our last observation (Xin et al. GCN6936), So the source #1 only maybe a avariable source as reported (Adria, GCN 6944), and the source $2 also might not be the OT of the burst.
At the locations of the XRT error circles of source 1 and source 2 (GCN 6943, Beardmore et al.), We found no new optical source to the 3sigma limit magnitude R=21.2 .
We also checked the combined image (Xin et al. GCN6936) obtained on 18th Oct, No new source was found at the location of XRT source 2 to 3-sigma limit magnitude R=21.5. The location of XRT source 1 was outside the field of view of the combined image.
This massage may be cited.
GCN Report 96.1
GCN_Report 96.1 has been posted: http://gcn.gsfc.nasa.gov/reports/report_96_1.pdf by H.A. Krimm at CRESST/NASA/GSFC/USRA titled: "Swift Observations of GRB 071018"
GCN Circular #7009
H.A. Krimm (CRESST/GSFC/USRA), J. R. Cummings (CRESST/GSFC/UMBC), A.P. Beardmore (U. Leicester)report on behalf of the Swift-BAT team:
In further analysis of GRB 071018 (Krimm et al, GCN 6932), when we use a time interval of T+20 to T+470 and an energy interval of 14 to 100 keV, we get a higher significance detection with a position:
```
RA, dec =  164.685, +53.822 deg, which is
RA(J2000) = 10h 58m 44.4s
dec(J2000) = 53d 49' 18"
```
with an uncertainty of 2.1 arcmin, (radius, sys+stat, 90% containment).
We note that this new error circle is inconsistent with any of the sources found in the XRT (Beardmore et al, GCN 6943) or optical (Xin et al, GCN 6936). However, XRT source #5 (Krimm et al, GCN Report 96.1) at RA, dec = 164.7216, +53.8140 deg, is within the new error circle.
GCN Report 96.2
GCN_Report 96.2 has been posted: http://gcn.gsfc.nasa.gov/reports/report_96_2.pdf by H.A. Krimm at CRESST/NASA/GSFC/USRA titled: "Final Swift Observations of GRB 071018"

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