//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19744 SUBJECT: GRB 160801A: Swift detection of a burst DATE: 16/08/01 09:48:44 GMT FROM: Valerio D'Elia at ASDC V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), P.A. Evans (U Leicester), H. A. Krimm (CRESST/GSFC/USRA) and A. Y. Lien (GSFC/UMBC) report on behalf of the Swift Team: At 09:28:30 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 160801A (trigger=706871). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 212.763, +13.499 which is RA(J2000) = 14h 11m 03s Dec(J2000) = +13d 29' 58" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a single-peaked structure with a duration of about 7 sec. The peak count rate was ~2000 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 09:29:57.4 UT, 87.0 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source with an enhanced position: RA, Dec 212.7629, 13.4895 which is equivalent to: RA(J2000) = 14h 11m 03.10s Dec(J2000) = +13d 29' 22.3" with an uncertainty of 2.5 arcseconds (radius, 90% containment). This location is 34 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. We cannot determine whether the source is fading at the present time. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density consistent with the Galactic value of 1.59 x 10^20 cm^-2 (Willingale et al. 2013). UVOT took a finding chart exposure of 150 seconds with the White filter starting 90 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.02. Burst Advocate for this burst is V. D'Elia (delia AT asdc.asi.it). 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.) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19745 SUBJECT: GRB 160801A: MITSuME Okayama upper limits DATE: 16/08/01 14:00:37 GMT FROM: Daisuke Kuroda at OAO/NAOJ D. Kuroda, K. Yanagisawa, Y. Shimizu, H. Toda (OAO, NAOJ), S. Nagayama (NAOJ), M. Yoshida (Hiroshima), K. Ohta (Kyoto) and N. Kawai(Tokyo Tech) report on behalf of MITSuME and OISTER collaboration: We observed the field of GRB 160801A (D'Elia et al., GCNC 19744) with the optical three color (g', Rc and Ic) CCD camera attached to the MITSuME 50cm telescope of Okayama Astrophysical Observatory. The observation started on 2016-08-01 11:06:56 UT (~1.6 h after the burst). We did not find any new point source within the XRT circle (D'Elia et al., GCNC 19744) in all the three bands. Three sigma upper limits of the OT are listed below. We used SDSS-DR8 catalog for flux calibration. #T0+[day] MID-UT T-EXP[sec] g' Rc Ic ----------------------------------------------------- 0.10264 11:56:18 2580.0 >19.1 >19.2 >18.6 ----------------------------------------------------- T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19746 SUBJECT: GRB 160801A: Enhanced Swift-XRT position DATE: 16/08/01 14:22:07 GMT FROM: Phil Evans at U of Leicester M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team. Using 1870 s of XRT Photon Counting mode data and 2 UVOT images for GRB 160801A, 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 = 212.76274, +13.48921 which is equivalent to: RA (J2000): 14h 11m 3.06s Dec (J2000): +13d 29' 21.1" with an uncertainty of 2.0 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. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19749 SUBJECT: GRB 160801A: Swift-BAT refined analysis DATE: 16/08/01 17:43:33 GMT FROM: Hans Krimm at NASA-GSFC J. R. Cummings (GSFC/UMBC), S. D. Barthelmy (GSFC), V. D'Elia (ASDC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team): Using the data set from T-60 to T+243 sec from the recent telemetry downlink, we report further analysis of BAT GRB 160801A (trigger #706871) (D'Elia, et al., GCN Circ. 19744). The BAT ground-calculated position is RA, Dec = 212.763, 13.485 deg which is RA(J2000) = 14h 11m 03.2s Dec(J2000) = +13d 29' 06.5" with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment). The partial coding was 73%. The mask-weighted light curve shows a single peak with ~3 second duration, peaking at T+0. T90 (15-350 keV) is 2.85 +- 0.41 sec (estimated error including systematics). The time-averaged spectrum from T-1.34 to T+1.83 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.85 +- 0.22. The fluence in the 15-150 keV band is 1.7 +- 0.3 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T-0.02 sec in the 15-150 keV band is 1.2 +- 0.2 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/706871/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19750 SUBJECT: GRB 160801A: Swift-XRT refined Analysis DATE: 16/08/01 20:11:10 GMT FROM: Phil Evans at U of Leicester A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), D.N. Burrows (PSU), T.G.R. Roegiers (PSU), L.M. McCauley (PSU), B. Mingo (U. Leicester), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester) and V. D'Elia report on behalf of the Swift-XRT team: We have analysed 6.5 ks of XRT data for GRB 160801A (D'Elia et al. GCN Circ. 19744), from 96 s to 19.2 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Goad et al. (GCN Circ. 19746). The light curve can be modelled with a power-law decay with a decay index of alpha=0.94 (+0.13, -0.11). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.1 (+0.6, -0.5). The best-fitting absorption column is 6.0 (+3.9, -2.8) x 10^21 cm^-2, in excess of the Galactic value of 1.6 x 10^20 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.0 x 10^-11 (7.3 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 6.0 (+3.9, -2.8) x 10^21 cm^-2 Galactic foreground: 1.6 x 10^20 cm^-2 Excess significance: 3.5 sigma Photon index: 2.1 (+0.6, -0.5) If the light curve continues to decay with a power-law decay index of 0.94, the count rate at T+24 hours will be 5.8 x 10^-4 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.3 x 10^-14 (4.2 x 10^-14) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00706871. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19753 SUBJECT: GRB 160801A: NOT upper limits DATE: 16/08/02 11:40:16 GMT FROM: Zach Cano at U of Iceland Z. Cano (Univ. Iceland), D. Malesani (DARK/NBI and DTU space), J.-K. Krogager, P. Noterdaeme (IAP) & A. Djupvik (NOT) report on behalf of a larger collaboration: We observed the field of GRB 160801A (D'Elia et al.; GCN Circ. 19744) with the 2.5-m Nordic Optical Telescope equipped with ALFOSC, starting at 21:05 UT on 01 August 2016. We obtained 14 minutes in the z-band and 10 minutes in the r-band. In our co-added images we do not detect any new source(s) within the enhanced XRT error circle (Goad et al.; GCN Circ. 19746) to the following limits: Filter t-t0 (d) magnitude limit (AB) ------------------------------------------- r 0.50 >24.4 z 0.49 >23.1 These upper limits are for an isolated point source in the GRB field, they are calibrated against the SDSS catalogue, and they have not been corrected for foreground extinction. We note the presence of an SDSS object (RA = 14:11:03.21, Dec =+13:29:21.5) just outside the refined XRT error circle. This object is pointlike in our images (0.8" seeing) and its magnitude did not vary within the errors compared to the SDSS archival values. We consider it is unlikely that this object is associated with GRB 160801A. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19755 SUBJECT: GRB 160801A: SAO RAS optical observations DATE: 16/08/02 14:33:46 GMT FROM: Moskvitin Alexander at SAO RAS A. Moskvitin (SAO RAS) and I. Soloviev (Saint-Petersburg Univ.), report on behalf of the larger GRB follow-up team. We observed the field of GRB 160801A (D'Elia et al., GCNC#19744) with Zeiss-1000 - the 1-meter telescope of Special Astrophysical Observatory of Russian Academy of Sciences on August 1, 2016, (18:14:58--20:09:29 UT), T_mid - T0 = 9.73 hours. We have obtained 18 x 300 sec. images in the Rc band under good weather conditions. Within the XRT error circle (Goad et al., GCNC#19746) we did not detect any new objects down to the limiting magnitude R_lim = 23.2. When inspecting SDSS images we found a faint stellar-like source J141103.21+132921.4 located near the enhanced XRT error circle. The recalculated magnitude of the object from SDSS images (Epoch = 2003.41) should be R = 20.94 +/- 0.05 (based on the Lupton 2005 equations). In our stacked frame at the edge of the XRT error circle (the offset 2".2) we detected the same source with a brightness of R = 20.9 +/- 0.1. Therefore, we can not detect significant differences between two epochs. This result is in agreement with info reported by Cano et al. (GCNC#19753). Our preliminary photometry is based on the nearby SDSS stars, which magnitudes are converted to the Johnson-Cousins system with the same Lupton 2005 equations. The finding chart based on Zeiss-1000 observations can be found at ftp://ftp.sao.ru/pub/grb/GRB160801A/GRB160801A_z1000.jpg We are grateful to technical staff of SAO RAS for assistance in observations. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19756 SUBJECT: GRB 160801A: Swift/UVOT Upper Limits DATE: 16/08/02 20:48:04 GMT FROM: Mike Siegel at PSU/Swift MOC B. G. Balzer (PSU) and V. D'Elia (ASDC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 160801A 90 s after the BAT trigger (D'Elia et al., GCN Circ. 19744). No optical afterglow consistent with the XRT position (Goad et al. GCN Circ. 19746) 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 first finding chart (FC) exposure and the subsequent summed exposures: Filter T_start(s) T_stop(s) Exp(s) Mag white_FC 90 240 147 >20.50 u_FC 302 552 245 >19.91 white 581 1896 283 >20.94 v 631 1945 155 >18.91 b 557 1871 136 >19.90 u 704 1846 116 >19.48 w1 1455 1474 19 >17.77 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). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19757 SUBJECT: GRB 160801A: TSHAO optical observations DATE: 16/08/02 22:45:50 GMT FROM: Alexei Pozanenko at IKI, Moscow E. Mazaeva (IKI), A. Kusakin (Fesenkov Astrophysical Institute), I. Reva (Fesenkov Astrophysical Institute), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We observed the field of GRB 160801A (D'Elia et al., GCN 19744 ) with Zeiss-1000 (East) 1-m telescope of Tien Shan Astronomical Observatory. We obtained several images in R filter starting on August 01 (UT) 15:10:55. We do not detect any optical source within enhanced XRT error position (Goad et al., GCN 19746). Preliminary photometry of a combined image is following Date UT start t-T0 Filter Exp. OT Err. UL (mid, days) (s) 2016-08-01 15:10:55 0.28422 R 60*120 n/d n/d 22.4 Photometry is based on nearby SDSS DR9 stars SDSS-DR9_id R(Lupton) J141100.70+132838.3 17.993 J141057.03+132833.7 17.684 J141054.86+132751.0 18.338 J141055.05+132937.2 18.545 J141059.52+133105.4 19.518 J141102.35+133019.9 18.384 J141102.64+133004.5 18.354 Our preliminary photometry of the SDSS object (Cano et al., GCN 19753) which is also mentioned by Moskvitin et al. (GCN 19755) is R=21.1+/-0.1 and based on the same nearby SDSS stars. A finding chart can be found in http://grb.rssi.ru/GRB160801A/GRB160801A_TSHAO_160801_2.png //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 19812 SUBJECT: GRB 160801A: 15 GHz upper limits from AMI DATE: 16/08/17 13:56:45 GMT FROM: Kunal Mooley at Oxford U K. P. Mooley, T. D. Staley, R. P. Fender (Oxford), G. E. Anderson (Curtin), T. Cantwell (Manchester), C. Rumsey, D. Titterington, S. Carey, J. Hickish, Y. C. Perrott, N. Razavi-Ghods, P. Scott (Cambridge), K. Grainge, A. Scaife (Manchester) The AMI Large Array robotically triggered on the Swift alert for GRB 160801A (D'Elia et al., GCN 19744) as part of the 4pisky program, and subsequent follow up observations were obtained up to 10 days post-burst. Our observations at 15 GHz on 2016 Aug 02.75, Aug 04.75, and Aug 08.73 (UT) do not reveal any radio source at the XRT location (Goad et al., GCN 19746), with 3sigma upper limits of 147 uJy, 123 uJy, and 126 uJy respectively. We thank the AMI staff for scheduling these observations. The AMI-GRB database is a log of all GRB follow up observations with the AMI, and is available at http://4pisky.org/ami-grb/.