//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 16425 SUBJECT: Fermi 424934131 / iPTF14cva: Discovery and Redshift of Optical Afterglow DATE: 14/06/20 16:59:04 GMT FROM: Mansi M. Kasliwal at Caltech/Carnegie M. M. Kasliwal (Carnegie Observatories/Princeton), S. B. Cenko (NASA/GSFC), and L. P. Singer (Caltech) report on behalf of the intermediate Palomar Transient Factory (iPTF) collaboration: Fermi GBM reported trigger 424934131 at 2014-06-20 05:15:28.02 UT. Starting 2014-06-20 05:25:25 UT (10 min after trigger), we began our search for optical counterparts using the Palomar 48-inch Oschin telescope (P48). Based on the the ground and final Fermi GBM localizations, we observed 20 fields covering 147 deg^2, with an estimated 59% chance of containing the true location of the event. Sifting through candidate transient sources using image subtraction and standard intermediate Palomar Transient Factory vetting procedures, we detected several optical transients. The fastest fading transient was: iPTF14cva, at the coordinates: RA(J2000) = 18h 47m 29.01s (281.870873 deg) Dec(J2000) = +49d 43' 51.7" (+49.731037 deg) iPTF14cva faded from R=17.6 mag to R=18.8 mag between 05:30 UT to 06:42 UT. We observed iPTF14cva with the Gemini Multi-Object Spectrograph mounted on the 8m Gemini North telescope beginning at 14:00 UT on 2014 June 20 (~ 8.8 hr after the GBM trigger). Two 900 s spectra were obtained, covering the wavelength range from 4000-9300 A. Super-imposed on a relatively flat continuum, we detect a number of strong absorption features, including Mg I, Mg II, Fe II, Al II, Si II, and Si II*, at a common redshift of z = 2.04. The detection of the fine structure Si II* feature, together with the lack of Ly-alpha absorption in the spectrum, imply that this is the redshift of the Fermi GBM GRB. In addition, we detect strong absorption features (Mg II, Fe II) from an intervening system at a redshift of z = 0.88. The diagram http://www.its.caltech.edu/~lsinger/iptf/Fermi424934131.pdf shows the locations of the afterglow and the 20 P48 fields in relation to the Fermi GBM 1- and 2-sigma statistical+systematic contours. We thank the Fermi-GBM team for promptly sharing their detailed localizations with us. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 16426 SUBJECT: GRB 140620A / iPTF14cva: Fermi GBM observations DATE: 14/06/20 18:08:48 GMT FROM: Gerard Fitzpatrick at UCD G. Fitzpatrick (UCD), V. Connaughton (UAH) report on behalf of the Fermi GBM Team: At 05:15:28.02 UT on 20 June 2014, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 140620A, which was observed by the intermediate Palomar Transient Factory beginning 10 minutes after trigger time, and was reported in GCN 16425 (Kasliwal, Cenko, and Singer) as iPTF14cva. The on-ground calculated location, using the GBM trigger data, is RA = 278, DEC = +43 (J2000 degrees, equivalent to 18h 34m, +43d 0.0'), with an uncertainty of 2 degrees (radius, 1-sigma containment, statistical only; there is additionally a systematic error which is currently estimated to be 2 to 3 degrees). The angle from the Fermi LAT boresight is 110 degrees. The GBM light curve consists of a single peak with a duration (T90) of about 46 s (50-300 keV). The time-averaged spectrum from T0-4 s to T0+35 s is adequately fit by a power law function with an exponential high-energy cutoff. The power law index is -1.1 +/- 0.1 and the cutoff energy, parameterized as Epeak, is 77 +/- 5 keV. The event fluence (10-1000 keV) in this time interval is (5.3 +/- 0.2)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+1 s in the 10-1000 keV band is 6.3 +/- 0.4 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 16428 SUBJECT: GRB 140620A: Swift-XRT observations DATE: 14/06/21 14:14:24 GMT FROM: Alessandro Maselli at INAF/IASF Palermo M. De Pasquale (IASF-Palermo) reports on behalf of the Swift-XRT team: We have analysed 3.0 ks of XRT data for the Fermi/GBM-detected burst GRB 140620A (Fitzpatrick et al., GCN circ 16426), from 37.6 ks to 43.9 ks after the Fermi/GBM trigger. The data are entirely in Photon Counting (PC) mode. An X-ray source is detected within the Fermi/GBM error circle at the position of the iPTF transient (Kasliwal et al., GCN circ. 16425). Using 2966 s of PC mode data and 2 UVOT images, we find an enhanced XRT position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 281.87089, +49.73093 which is equivalent to: RA (J2000): 18h 47m 29.01s Dec(J2000): +49d 43' 51.4" with an uncertainty of 2.2 arcsec (radius, 90% confidence). This is 0.4 arcsec from the iPTF position. The late-time light curve (from T0+37.6 ks) is consistent with a constant source of mean count rate 1.2e-01 ct/sec. A power-law fit formally gives an index of -0.1 (+2.4, -1.3). Further observations might be needed to confirm that this source is the X-ray afterglow of 140620A. A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.04 (+0.26, -0.24). The best-fitting absorption column is 1.4 (+0.7, -0.6) x 10^21 cm^-2, in excess of the Galactic value of 5.2 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 3.3 x 10^-11 (4.3 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 1.4 (+0.7, -0.6) x 10^21 cm^-2 Galactic foreground: 5.2 x 10^20 cm^-2 Excess significance: 2.3 sigma Photon index: 2.04 (+0.26, -0.24) If the light curve continues to evolve with a power-law index of -0.1, the count rate at T+24 hours will be 0.13 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.3 x 10^-12 (5.6 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/00020387. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 16432 SUBJECT: GRB 140620A: Swift/UVOT Detection DATE: 14/06/21 21:43:23 GMT FROM: Mike Siegel at PSU/Swift MOC M. H. Siegel (PSU) and M. De Pasquale (IASF-Palermo) report on behalf of the Swift/UVOT team: The Swift/UVOT observed the field of the Fermi/GBM-detected burst GRB 140620A beginning 37.6 ks after the trigger (Fitzpatrick et al., GCN circ 16426). We confirm the fading optical transient reported by iPTF (Kasliwal et al., GCN circ 16425) at a position of: RA (J2000) = 18:47:29.00 = 281.87082 (deg.) Dec (J2000) = 49:43:51.0 = 49.73085 (deg.) with an uncertainty of 0.3 arcsec (radius, 90% confidence). This is 0.7 arcsec from the iPTF position. Preliminary detections using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) are given in the following table: Filter T_start(ks) T_stop(ks) Exp(s) Mag u 37.6 43.9 1718 19.78+-0.10 u 124.0 125.3 1251 20.38+-0.18 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.06 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 16440 SUBJECT: GRB 140620A / iPTF14cva: Konkoly optical observations DATE: 14/06/22 23:56:29 GMT FROM: Janos Kelemen at Konkoly Obs/Hungary J. Kelemen (kelemen at konkoly.hu) on behalf of the GRB OT observing program at the Konkoly Observatory. Starting on the evening of 21/06/2014 UT we observed the field of GRB 140620A (Fermi GBM reported trigger 424934131 at 2014-06-20 05:15:28.02 UT) 150898 sec. after the burst, using a 60/90/180 cm Schmidt telescope located at the Mountain Station of the Konkoly Observatory . On the coadded R images (total exp.time 900 sec) we easily detected the OT at the position reported by M. M. Kasliwal et al. (GCN 16425) Based on the nearby UCAC-4 stars we provide 21.9 +/- 0.15 magnitude in the R band for the OT. time from GRB. exp filter Mag. ------------------------------------------------ 150898 s. 900 s R 21.9 +/-0.15 ------------------------------------------------ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 16453 SUBJECT: GRB 140620A / iPTF14cva: TShAO optical observations DATE: 14/06/24 23:39:18 GMT FROM: Alexei Pozanenko at IKI, Moscow A. Volnova (IKI), W. Mundrzyjewski (Fesenkov Astrophysical Institute), A. Kusakin (Fesenkov Astrophysical Institute), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We observed the optical candiadate iPTF14cva (Kasliwal et al., GCN 16425) of Fermi GRB 140620A (Fermi trig. # 424934131) (Fitzpatrick et al., GCN 16426) with Zeiss-1000 (East) 1m telescope of Tien Shan Astronomical Observatory on June, 20 starting (UT) 21:22:56. We took several images in R-filter. We clearly detected optical transient (Siegel et al., GCN 16432; Kelemen GCN 16440) in a stacked image. Details of the photometry are following: date UT start t-T0 Filter Exp. OT (mid, days) (s) 2014-06-20 21:22:56 0.68914 R 20*120 20.37 +/- 0.09 The photometry is based on star USNO-B1.0 1397-0294956 (RA 18:47:28.76 Dec +49:43:44.5) assuming R=16.35. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 16455 SUBJECT: Further Swift/XRT observations of GRB140620A/iPTFcva DATE: 14/06/25 14:41:52 GMT FROM: Massimiliano de Pasquale at IASF-Palermo M. De Pasquale (INAF-Palermo) reports on behalf of the Swift team: Analyzing XRT data of the X-ray source at the position of the iPTF14cva transient (De Pasquale, GCN Circ. 16428) from 37.6 to 367.3 ks after the trigger, we found that this source is fading with a decay slope of 1.32 (+0.18, -0.15). We therefore confirm that this source is the X-ray afterglow of the GRB associated with this transient. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00020387. This circular is an official product of the Swift-XRT team. I.A.S.F. INAF Mailing System Outgoing mail is certified Virus Free. Checked by Kaspersky anti-virus system