GRB150818A

This page lists all entries on GRB150818A in GRBweb

Summary IPN Swift GCN 18152 GCN 18154 GCN 18155 GCN 18157 GCN 18159 GCN 18161 GCN 18162 GCN 18164 GCN 18166 GCN 18171 GCN 18174 GCN 18175 GCN 18177 GCN 18179 GCN 18182 GCN 18189 GCN 18198 GCN 18205 GCN 18213 GCN 18244

Summary table
Variable Value Source
T0 11:36:32 UTC GCN_circulars,Swift Det
ra 230.3560° Swift
decl 68.3425° Swift
pos_error 8.54e-05° Swift
T90 123.3 s Swift
T90_start 11:36:32 UTC Swift
fluence 4.10e-06 erg/cm² Swift
redshift 0.2820
T100 123.3 s
GBM_located False
mjd 57252.48370370371 GCN_circulars,Swift Det
IPN table
GRB_name GRB150818A
ra 230.4458°
decl 68.3500°
pos_error 5.00e-02°
redshift 0.2820
Swift table
GRB_name GRB150818A
t_trigger 11:36:32 UTC
ra 230.3560°
decl 68.3425°
pos_error 8.54e-05°
T90 123.3 s
fluence 4.10e-06 erg/cm²
redshift 0.2820
GCN 18152 table
GRB_name GRB150818A
GCN_number 18152
Detection_method Swift Det
t_trigger 11:36:32 UTC
ra 230.4460°
decl 68.3420°
Circular_text TITLE: GCN CIRCULAR NUMBER: 18152 SUBJECT: GRB 150818A: Swift detection of a burst DATE: 15/08/18 11:53:55 GMT FROM: Kim Page at U.of Leicester V. D'Elia (ASDC), A. A. Breeveld (UCL-MSSL), P. A. Evans (U Leicester), N. Gehrels (NASA/GSFC), L. Izzo (URoma/ICRA), F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester) and B. Sbarufatti (INAF-OAB/PSU) report on behalf of the Swift Team: At 11:36:32 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 150818A (trigger=652603). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 230.446, +68.342 which is RA(J2000) = 15h 21m 47s Dec(J2000) = +68d 20' 32" 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 50 sec. The peak count rate was ~1990 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 11:37:57.3 UT, 84.5 seconds after the BAT trigger. XRT found a bright, uncatalogued X-ray source located at RA, Dec 230.3621, 68.3446 which is equivalent to: RA(J2000) = +15h 21m 26.90s Dec(J2000) = +68d 20' 40.6" with an uncertainty of 6.1 arcseconds (radius, 90% containment). This location is 111 arcseconds from the BAT onboard position, within the BAT error circle. No event data are yet available to determine the column density using X-ray spectroscopy. UVOT took a finding chart exposure of 28 seconds with the White filter starting 94 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image processing failed because of no aspect solution is available. Results from the list of sources generated on-board are not available at this time. 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.)
GCN 18154 table
GRB_name GRB150818A
GCN_number 18154
Detection_method Other
ra 230.3621°
decl 68.3446°
Circular_text TITLE: GCN CIRCULAR NUMBER: 18154 SUBJECT: GRB 150818A: Planned XMM-Newton observation DATE: 15/08/18 13:44:25 GMT FROM: Norbert Schartel at XMM-Newton/ESA XMM-Newton will observe GRB 150818A at location (RA=15h 21m 26.9s, DEC=68d 20' 40.5", J2000), starting at 18:15:45 UT, on August 18, 2015, for an exposure of 22400 seconds. This message and any attachments are intended for the use of the addressee or addressees only. The unauthorised disclosure, use, dissemination or copying (either in whole or in part) of its content is not permitted. If you received this message in error, please notify the sender and delete it from your system. Emails can be altered and their integrity cannot be guaranteed by the sender. Please consider the environment before printing this email.
GCN 18155 table
GRB_name GRB150818A
GCN_number 18155
Detection_method Swift-UVOT Other
ra 230.3562°
decl 68.3428°
Circular_text TITLE: GCN CIRCULAR NUMBER: 18155 SUBJECT: GRB 150818A: Swift/UVOT candidate afterglow DATE: 15/08/18 14:59:35 GMT FROM: Frank Marshall at GSFC F. E. Marshall (NASA/GSFC) and V. D'Elia (ASDC) report on behalf of the Swift/UVOT team: UVOT took a finding chart exposure of 28 seconds with the White filter starting 94 seconds after the BAT trigger on GRB 150818A. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at RA(J2000) = 15:21:25.48 = 230.35616 DEC(J2000) = 68:20:34.0 = 68.34278 with a 90%-confidence error radius of about 1.0 arc sec. This position is 10 arcseconds from the center of the XRT error circle (D'Elia et al. GCN Circ. 18152). The estimated magnitude is 19.5 with a 1-sigma error of about 0.2. No correction has been made for extinction.
GCN 18157 table
GRB_name GRB150818A
GCN_number 18157
Detection_method Swift-BAT Det
ra 230.3400°
decl 68.3420°
Circular_text TITLE: GCN CIRCULAR NUMBER: 18157 SUBJECT: GRB 150818A: Swift-BAT refined analysis DATE: 15/08/18 17:25:59 GMT FROM: Scott Barthelmy at NASA/GSFC D. M. Palmer (LANL), S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC), V. D'Elia (ASDC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), T. Sakamoto (AGU), M. Stamatikos (OSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team): Using the data set from T-61 to T+242 sec from the recent telemetry downlinks, we report further analysis of BAT GRB 150818A (trigger #652603) (D'Elia, et al., GCN Circ. 18152). The BAT ground-calculated position is RA, Dec = 230.340, 68.342 deg, which is RA(J2000) = 15h 21m 21.7s Dec(J2000) = +68d 20' 31.5" with an uncertainty of 1.1 arcmin, (radius, sys+stat, 90% containment). The partial coding was 36%. The mask-weighted light curves shows two overlapping peaks starting at ~T-25 sec, peaking at ~T+1 sec, and ending at ~T+180 sec. T90 (15-350 keV) is 123.3 +- 31.3 sec (estimated error including systematics). The time-averaged spectrum from T-11.18 to T+165.12 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.96 +- 0.09. The fluence in the 15-150 keV band is 4.1 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T-0.88 sec in the 15-150 keV band is 2.4 +- 0.3 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/652603/BA/
GCN 18159 table
GRB_name GRB150818A
GCN_number 18159
Detection_method Swift-XRT Det
ra 230.3560°
decl 68.3420°
Circular_text TITLE: GCN CIRCULAR NUMBER: 18159 SUBJECT: GRB 150818A: Enhanced Swift-XRT position DATE: 15/08/18 18:09:34 GMT FROM: Phil Evans at U of Leicester A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) report on behalf of the Swift-XRT team. Using 2975 s of XRT Photon Counting mode data and 7 UVOT images for GRB 150818A, 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 = 230.35595, +68.34204 which is equivalent to: RA (J2000): 15h 21m 25.43s Dec (J2000): +68d 20' 31.4" 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 18161 table
GRB_name GRB150818A
GCN_number 18161
Detection_method Swift-UVOT Det
ra 230.3560°
decl 68.3425°
Circular_text TITLE: GCN CIRCULAR NUMBER: 18161 SUBJECT: GRB 150818A: Swift/UVOT Detection DATE: 15/08/18 20:39:33 GMT FROM: Marissa McCaule at PSU L. M. McCauley (PSU), L. M. Z. Hagen (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 150818A 94 s after the BAT trigger (D'Elia et al., GCN Circ. 18152). A source consistent with the XRT position (Beardmore et al. GCN Circ. 18159) is detected in the initial UVOT exposures. The preliminary UVOT position is: RA (J2000) = 15:21:25.43 = 230.35594 (deg.) Dec (J2000) = +68:20:33.0 = 68.34251 (deg.) with an estimated uncertainty of 0.66 arc sec. (radius, 90% confidence). Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white_fc 94 121 27 19.39+-0.25 white 3414 4790 344 19.92+-0.17 white 10222 10826 590 19.68+-0.07 v 3572 5201 393 >19.36 b 4385 4585 196 >20.16 b 5821 10217 927 20.56+-0.33 u 4180 4379 196 >19.66 u 5616 5816 196 19.63+-0.25 uvw1 3976 4175 195 18.78+-0.20 uvw1 5411 5611 196 18.95+-0.20 uvm2 3776 3976 192 18.81+-0.23 uvm2 5206 5406 196 18.89+-0.24 uvw2 4796 4996 196 18.90+-0.19 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.02 in the direction of the burst (Schlegel et al. 1998).
GCN 18162 table
GRB_name GRB150818A
GCN_number 18162
Detection_method Swift-XRT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 18162 SUBJECT: GRB 150818A: Swift-XRT refined Analysis DATE: 15/08/18 23:54:04 GMT FROM: Phil Evans at U of Leicester P.A. Evans (U. Leicester), B.P. Gompertz (U. Leicester), A. D'ai (INAF-IASFPA), A. Maselli (INAF-IASFPA), L.M. McCauley (PSU), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), J.P. Osborne (U. Leicester) and V. D'Elia report on behalf of the Swift-XRT team: We have analysed 6.4 ks of XRT data for GRB 150818A (D'Elia et al. GCN Circ. 18152), from 74 s to 21.7 ks after the BAT trigger. The data comprise 34 s in Windowed Timing (WT) mode (the first 9 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 Beardmore et al. (GCN Circ. 18159). The late-time light curve (from T0+3.5 ks) can be modelled with a power-law decay with a decay index of alpha=. A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 2.59 (+0.11, -0.10). The best-fitting absorption column is 2.33 (+0.28, -0.27) x 10^21 cm^-2, in excess of the Galactic value of 2.5 x 10^20 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 1.96 (+0.30, -0.27) and a best-fitting absorption column of 7.6 (+7.6, -5.1) x 10^20 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.3 x 10^-11 (3.9 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 7.6 (+7.6, -5.1) x 10^20 cm^-2 Galactic foreground: 2.5 x 10^20 cm^-2 Excess significance: <1.6 sigma Photon index: 1.96 (+0.30, -0.27) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00652603. This circular is an official product of the Swift-XRT team.
GCN 18164 table
GRB_name GRB150818A
GCN_number 18164
Detection_method Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 18164 SUBJECT: GRB150818A: NOT imaging DATE: 15/08/19 01:04:40 GMT FROM: Steve Schulze at U of Iceland S. Schulze (PUC, MAS), J. P. U. Fynbo (DARK, NBI), T. Kruehler (MPE), D. Malesani, (DARK/NBI), I. V. Rasmussen, J. L. Marcher, L. L. Thomson (NBI), A. Djupvik (NOT), B. Milvang-Jensen (DARK/NBI) and P. Jakobsson (U Iceland) report on behalf a larger collaboration: We observed the field of GRB 150818A (D'Elia et al., GCN 18152) with the Nordic Optical Telescope (NOT) equipped with ALFOSC. We obtained a 180 s and a 3x300 s image in R band. Observations started at 21:34 UT on August 18 (i.e. 9.62 hr after the burst). We clearly detect the source reported in Marshall et al. (GCN 18155) and McCauley et al. (GCN 18161). We measure R=20.86 +/- 0.08 mag calibrated against several USNO stars. This value is not corrected for foreground extinction. Given the lack of evidence for variability (McCauley et al., GCN 18161), the association of this object with GRB 150818A remains unclear.
GCN 18166 table
GRB_name GRB150818A
GCN_number 18166
Detection_method correction
Circular_text TITLE: GCN CIRCULAR NUMBER: 18166 SUBJECT: GRB 150818A: Swift-XRT update, correction to GCN 18162 DATE: 15/08/19 07:17:42 GMT FROM: Phil Evans at U of Leicester P.A. Evans (U, Leicester) reports on behalf of the Swift-XRT team: Due to a computer error, the light curve decay index was missing in GCN 18162. At the present time, we have analysed 7.6 ks of XRT data for GRB 150818A (D'Elia et al. GCN Circ. 18152), from 74 s to 44.1 ks after the BAT trigger. The XRT light curve can be modelled as a broken power-law, with an initial decay index of 2.36 (+0.08, -0.06), a break at T0 + 3600 (+/-500) s, and a subsequent shallow decay of 0.66 (+0.16, -0.15). If the decay continues at alpha=0.66, the predicted count-rate at T0+24 hrs is 8.9e-3 ct/sec, which corresponds to an observed (unabsorbed) 0.3-10 keV flux of 2.97e-13 (3.56e-13) erg/cm^2/s. This circular is an official product of the Swift-XRT team.
GCN 18171 table
GRB_name GRB150818A
GCN_number 18171
Detection_method MITSuME
Circular_text TITLE: GCN CIRCULAR NUMBER: 18171 SUBJECT: GRB 150818A: MITSuME Akeno optical upper limits DATE: 15/08/19 12:38:55 GMT FROM: Taketoshi Yoshii at Tokyo Tech T.Fujiwara, T. Yoshii, Y. Saito, Y. Tachibana, H. Ohuchi, Y. Yano, S. Kurita, Y.Ono, S.Harita,Y.Muraki, Y. Yatsu, and N. Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration: We searched for the optical counterpart of GRB 150818A (V. D'Elia et al. GCN Circular #18152) with the optical three color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50 cm telescope of Akeno Observatory, Yamanashi, Japan. The observation started on 2015-08-18 11:54:53 UT (~18 min after the burst). We did not find any new point source within XRT circle in all three bands. We obtained following limits for the magnitudes. T0+[sec] MID-UT T-EXP[sec] g' Rc Ic --------------------------------------------------------------------------------------- 1101 11:59:46 540 >19.4 >19.4 > 18.5 --------------------------------------------------------------------------------------- T0+ : Elapsed time after the burst T-EXP: Total Exposure time We used GSC2.3 catalog for flux calibration
GCN 18174 table
GRB_name GRB150818A
GCN_number 18174
Detection_method MITSuME
Circular_text TITLE: GCN CIRCULAR NUMBER: 18174 SUBJECT: GRB 150818A: MITSuME Ishigakijima upper limits DATE: 15/08/19 14:55:43 GMT FROM: Daisuke Kuroda at OAO/NAOJ D. Kuroda (OAO, NAOJ), H. Hanayama, T. Miyaji, J. Watanabe (IAO, NAOJ), K. Yanagisawa (OAO, NAOJ), S.Nagayama (NAOJ), M. Yoshida (Hiroshima), K. Ohta (Kyoto) and N. Kawai(Tokyo Tech) report on behalf of the MITSuME and OISTER collaboration: We observed the field of GRB 150818A (D'Elia et al., GCNC 18152) with the optical three color (g', Rc and Ic) CCD camera attached to the Murikabushi 1m telescope of Ishigakijima Astronomical Observatory. The observation started on 2015-08-18 13:09:10 UT (~1.5h after the burst). We could not detect the previously reported afterglow (Marshall and D'Elia, GCNC 18155; McCauley et al., GCNC 18161; Schulze et al., GCNC 18164) in all the three bands. Three sigma upper limits of the OT are listed below. We used GSC2.3 catalog for flux calibration. #T0+[day] MID-UT T-EXP[sec] g' Rc Ic ----------------------------------------------------- 0.11943 14:28:30 6180.0 >19.4 >19.7 >19.5 ----------------------------------------------------- T0+ : Elapsed time after the burst [day] T-EXP: Total Exposure time [sec]
GCN 18175 table
GRB_name GRB150818A
GCN_number 18175
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 18175 SUBJECT: GRB 150818A: Mondy optical observations DATE: 15/08/19 16:25:12 GMT FROM: Alexei Pozanenko at IKI, Moscow E. Mazaeva (IKI), E. Klunko (ISTP), A. Volnova (IKI), I. Korobtsev (ISTP), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We observed the field of Swift GRB 150818A (D'Elia et al., GCNC 18152) with AZT-33IK telescope of Sayan observatory (Mondy) starting on Aug., 18 (UT) 15:07:42. We obtained several images in R-filter of 120 s exposure. The source previously mentioned (McCauley et al., GCN 18161; Schulze et al., GCN 18164) is clearly visible. Coordinates of the source are (J2000) 15:21:25.56 +68:20:32.0 with uncertainty of 0.3 arcsec in both coordinates. Preliminary photometry of the source is following Date UT start t-T0 Filter Exp. OT Err. (mid, days) (s) 2015-08-18 15:07:42 0.16843 R 31*120 20.25 0.08 Photometry is based on USNO-B1.0 stars: USNO-B.1_id R2 1583-0162302 16.65 1583-0162268 17.48 1583-0162214 16.71 1583-0162248 19.43 We can suggest the source as shallow fading afterglow because the source is significantly faded between our observations (R=20.25+/-0.08 at 4 hrs after burst trigger) and NOT observations at 9.62 hrs (Schulze et al., GCN 18164).
GCN 18177 table
GRB_name GRB150818A
GCN_number 18177
Detection_method Swift-BAT Det
redshift 0.2820
Circular_text TITLE: GCN CIRCULAR NUMBER: 18177 SUBJECT: GRB 150818A: 10.4m GTC spectroscopy and host galaxy DATE: 15/08/19 22:15:53 GMT FROM: Alberto Castro-Tirado at Inst.de Astro. de Andalucia R. Sanchez-Ramirez (UPV/EHU, IAA-CSIC), J. Gorosabel (+, UPV/EHU, IAA-CSIC), D. Perez-Ramirez (+, Univ. de Jaen), S. Jeong (IAA-CSIC, SKKU), A. J. Castro-Tirado (IAA-CSIC, ISA-UMA), F. J. Aceituno, R. Cunniffe, P. Ferrero, Y. Hu, S. R. Oates, J. C. Tello, B.-B. Zhang (IAA-CSIC), M. Jelinek (ASU-CAS), S. Guziy (Nikolaev Univ.), V. Sokolov (SAO-RAS), J.M. Castro Ceron (ESAC), J. Cepa (IAC), A. Garcia (GRANTECAN) and R. Scarpa (IAC, GRANTECAN), report: Following the detection of GRB 150818A by Swift/BAT (D Elia et al. 2015, GCNC 18152), we have obtained an optical spectrum (2 x 900s) with the 10.4m GTC telescope (+OSIRIS) in La Palma (Spain), starting on Aug 18, 22:05 UT (i.e. 10.5 hr postburst), covering the 3700-7800 A wavelength range. The slit included the position of the proposed optical afterglow (Marshall and D Elia, GCNC 18155; Schulze et al., GCNC 18164; Mazaeva et al. GCNC 18175). At the position of the optical afterglow, we see no obvious absorption features with the continuum extending from 3700 to 7800 A. However we clearly detect emission lines of [OII] 3727A, H-beta and [OIII] 4960A,5008A, all at a common redshift z = 0.282. Indeed a diffuse object seems to be adjacent (within 1 to the west) to the optical afterglow in the acquisition image (under 0.7 seeing), which could be the host galaxy at the above mentioned redshift. Further spectroscopy and monitoring at all wavelengths is encouraged to search for the emergence of the underlying supernova component in the next weeks.
GCN 18179 table
GRB_name GRB150818A
GCN_number 18179
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 18179 SUBJECT: GRB 150818A: Continued NOT monitoring - afterglow confirmation DATE: 15/08/20 10:59:44 GMT FROM: Steve Schulze at U of Iceland S. Schulze (PUC, MAS), J. P. U. Fynbo, D. Malesani (DARK/NBI), R. Tuma, S. Dinh, M. Homann, M. Munoz (NBI) and P. Jakobsson (U. Iceland) report on behalf a larger collaboration: We observed the field of GRB 150818A (D'Elia et al., GCN 18152) with the Nordic Optical Telescope (NOT) equipped with ALFOSC. We obtained a 300-s image in R band. Observations started at 21:03 UT on August 19 (i.e. 1.39 days after the burst). We clearly detect the source reported in Marshall et al. (GCN 18155), McCauley et al. (GCN 18161), Schulze et al. (GCN 18164) and Mazaeva et al. (GCN 18175). We measure R=21.18 +/- 0.05 calibrated against several USNO stars. The optical transient faded by 0.3 mag compared to Schulze et al. (GCN 18164) in agreement with Mazaeva et al. (GCN 18175) who also found evidence for a shallow decay. Sanchez-Ramirez (GCN 18177) hinted that the host is possibly detected in GTC image. A significant host contribution would explain the shallow decay. [GCN OPS NOTE(20aug15): Per author's request, the 18177 id_num for the S-R reference was added.]
GCN 18182 table
GRB_name GRB150818A
GCN_number 18182
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 18182 SUBJECT: GRB 150818A: Mondy optical observations DATE: 15/08/20 17:24:54 GMT FROM: Alexei Pozanenko at IKI, Moscow E. Mazaeva (IKI), E. Klunko (ISTP), A. Volnova (IKI), I. Korobtsev (ISTP), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We continue observations of the of Swift GRB 150818A (D'Elia et al., GCNC 18152) with AZT-33IK telescope of Sayan observatory (Mondy). We obtained several images in R-filter starting on Aug., 19 (UT) 15:33:10. The optical transient (Marshall et al., GCN 18155; McCauley et al., GCN 18161; Schulze et al., GCN 18164; Mazaeva et al., GCN 18175) is clearly visible. Preliminary photometry of the optical transient is following Date UT start t-T0 Filter Exp. OT Err. (mid, days) (s) 2015-08-19 15:33:10 1.18517 R 30*120 21.0 0.1 Photometry is based on USNO-B1.0 stars referenced in (Mazaeva et al., GCN 18175)
GCN 18189 table
GRB_name GRB150818A
GCN_number 18189
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 18189 SUBJECT: GRB 150818A: continued Mondy optical observations DATE: 15/08/21 15:39:24 GMT FROM: Alexei Pozanenko at IKI, Moscow E. Mazaeva (IKI), E. Klunko (ISTP), A. Volnova (IKI), I. Korobtsev (ISTP), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We continue observations of the of Swift GRB 150818A (D'Elia et al., GCNC 18152) with AZT-33IK telescope of Sayan observatory (Mondy). We obtained several images in R-filter starting on Aug., 20 (UT) 16:54:32. The optical transient (Marshall et al., GCN 18155; McCauley et al., GCN 18161; Schulze et al., GCN 18164; Mazaeva et al., GCN 18175) is clearly visible. Preliminary photometry of the optical transient is following Date UT start t-T0 Filter Exp. OT Err. (mid, days) (s) 2015-08-20 16:54:32 2.23334 R 15*120 21.15 0.09 Photometry is based on USNO-B1.0 stars referenced in (Mazaeva et al., GCN 18175). The continued shallow decay mentioned in Schulze et al. (GCN 18179) indeed can be explained by underlying host galaxy (Sanchez-Ramirez et al., GCN 18177).
GCN 18198 table
GRB_name GRB150818A
GCN_number 18198
Detection_method Konus-Wind Det
redshift 0.2820
Circular_text TITLE: GCN CIRCULAR NUMBER: 18198 SUBJECT: Konus-Wind observation of GRB 150818A DATE: 15/08/24 09:58:14 GMT FROM: Dmitry Svinkin at Ioffe Institute S. Golenetskii, R.Aptekar, D. Frederiks, V. Pal'shin, P. Oleynik, M. Ulanov, D. Svinkin, A. Tsvetkova, A.Lysenko, A. Kozlova, and T. Cline on behalf of the Konus-Wind team, report: The long-duration GRB 150818A (Swift-BAT trigger #652603: D'Elia, et al., GCN Circ. 18152; Palmer, et al., GCN Circ. 18157) was detected by Konus-Wind in the waiting mode. The burst light curve shows a single pulse with a total duration of about 47 s. As observed by Konus-Wind, the burst had a fluence of 5.3(-0.6,+0.7)x10^-6 erg/cm2 and a 2.944-s peak flux, measured from ~T0(BAT)-3.3 s, of 1.8(-0.3,+0.4)x10^-7 erg/cm2/s (both in the 20 - 1000 keV energy range). Modeling the K-W 3-channel time-integrated spectrum (from T0(BAT)-6.2 s to T0(BAT)+40.9 s) by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) yields alpha = -1.4(-0.2,+0.6) and Ep = 100 (-18,+29) keV. The K-W light curve of this burst is available at http://www.ioffe.ru/LEA/GRBs/GRB150818A/ Assuming the redshift z=0.282 (Sanchez-Ramirez, et al., GCN 18177) and a standard cosmology model with H_0 = 70 km/s/Mpc, Omega_M = 0.27, and Omega_Lambda = 0.73, we estimate the following rest-frame parameters: the isotropic energy release E_iso is ~1.0x10^51 erg, the peak luminosity L_iso is ~3.6x10^49 erg/s, and the rest-frame peak energy of the time-integrated spectrum, Ep,i, is ~128 keV. All the quoted errors are at 1 sigma confidence level. All the quoted values are preliminary.
GCN 18205 table
GRB_name GRB150818A
GCN_number 18205
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 18205 SUBJECT: GRB 150818A: possible SN rise in light curve of Mondy observations DATE: 15/08/27 16:54:50 GMT FROM: Alexei Pozanenko at IKI, Moscow E. Mazaeva (IKI), E. Klunko (ISTP), A. Volnova (IKI), I. Korobtsev (ISTP), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We continue observations of the Swift GRB 150818A (D'Elia et al., GCN 18152) with AZT-33IK telescope of Sayan observatory (Mondy). We imaged optical transient (Marshall et al., GCN 18155; McCauley et al., GCN 18161; Schulze et al., GCN 18164; Mazaeva et al., GCN 18175) in R-filter on Aug., 21, 22, 23, and 26. The optical transient is clearly visible in each epochs. Preliminary light curve of the optical transient can be found in http://grb.rssi.ru/GRB150818A/GRB150818A_R_lc.png (Photometry is based on USNO-B1.0 stars referenced in (Mazaeva et al., GCN 18175). One can suggest that steady re-brightening of the optical transient is related to a Supernova associated with nearby GRB 150818A (z = 0.282, Sanchez-Ramirez et al., GCN 18177). We encourage observation for spectroscopic SN-confirmation.
GCN 18213 table
GRB_name GRB150818A
GCN_number 18213
Detection_method Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 18213 SUBJECT: GRB 150818A: Spectroscopic confirmation of the SN from GTC DATE: 15/08/31 17:49:21 GMT FROM: Antonio de Ugarte Postigo at IAA-CSIC A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), Z. Cano (U. Iceland), D. A. Perley (DARK/NBI), S. Schulze (PUC, MAS), D. Xu (NAOC/CAS), R. Sanchez-Ramirez (IAA-CSIC), D. Malesani (DARK/NBI), G. Lombardi (GRANTECAN, IAC, ULL), and A. Garcia (GRANTECAN), R. Scarpa (GRANTECAN) report on behalf of a larger collaboration: We observed the counterpart of GRB 150818A (D'Elia et al. GCN 18152; Marshall et al. GCN 18155; McCauley et al. GCN 18161; Mazaeva et al. GCN 18175; Sanchez-Ramirez et al. GCN 18177; Mazaeva et al. GCN 18182, GCN 18189, GCN 18205; Schulze et al. GCN 18179) with the 10.4 m GTC telescope (+OSIRIS) on the 29th August 2015 (11.4 days after the burst). The observation consisted of 3x900 s spectroscopy using the R1000B grism (3700-7800 AA coverage with a resolution of ~1000) plus g-, r- and i-band imaging. We detect a point-like source at the location of the afterglow superposed on top of an extended source. The combined spectrum shows broad features typical of a broad-lined Type Ic SN near maximum light, thus confirming the detection of a rising supernova proposed by Mazaeva et al. (GCN 18205). The spectrum also shows narrow emission features of [OII], [OIII] and H-beta at z=0.282 (Sanchez-Ramirez et al. GCN 18177).
GCN 18244 table
GRB_name GRB150818A
GCN_number 18244
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 18244 SUBJECT: GRB 150818A: TSHAO and SAO RAS optical observations DATE: 15/09/07 09:29:09 GMT FROM: Alexei Pozanenko at IKI, Moscow E. Mazaeva (IKI), A. Moskvitin (SAO RAS), I. Reva (Fesenkov Astrophysical Institute), A. Kusakin (Fesenkov Astrophysical Institute), A. Volnova (IKI), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We are continuing observations the field of Swift GRB 150818A (D'Elia et al., GCNC 18152) with Zeiss-1000 1-m telescope of Tien Shan Astronomical Observatory and Zeiss-1000, 1-m telescope of SAO RAS. The optical transient (Marshall et al. GCN 18155; McCauley et al. GCN 18161; Mazaeva et al. GCN 18175; Sanchez-Ramirez et al. GCN 18177; Mazaeva et al. GCN 18182, GCN 18189, GCN 18205; Schulze et al. GCN 18179) is clearly visible on combined images in each epochs. The updated light curve of Supernova (de Ugarte Postigo et al. GCN 18213; Mazaeva et al. GCN 18205) + host galaxy (Sanchez-Ramirez et al., GCN 18177; de Ugarte Postigo et al. GCN 18213) can be found in http://grb.rssi.ru/GRB150818A/GRB150818A_R_lc.png The evident maximum of SN brightness (in Rc-filter) was on ~ Sep. 1-2, and the brightness of SN+host galaxy was R ~ 21.1 +/- 0.1 on Sep. 6 (UT) 18:00. We are grateful to V.P. Goranskiy for assistance in SAO RAS observations.