THIS FILE CHANGES WITH TIME -- HIT THE RELOAD BUTTON NOW! ///////////////////////////////////////////////////////////////////// GRB 980613 04:51:06 UT SOD=17466 sec TJD=10977 DOY=164 There is no BATSE trigger for this burst. ///////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 99 SUBJECT: GRB980613, BeppoSAX WFC positions DATE: 98/06/13 15:35:21 GMT FROM: SAX Science Operations at IAS/CNR Frascati Luigi Piro and Enrico Costa on behalf of BeppoSAX team report: The GRBM of BeppoSAX was triggered by a GRB (GB980613) on June 13 at 04:51:06 UT. The burst was detected by WFC (n.2). The preliminary WFC position was RA(2000)=154.55 Dec(2000)=71.486 with an error radius of 5'. The refined WFC position is now RA(2000)=154.44 Dec(2000)=71.499 with an error radius of 4'. A BeppoSAX follow up with the NFI is being planned. ///////////////////////////////////////////////////////////////////// Circular No. 6938 Central Bureau for Astronomical Telegrams INTERNATIONAL ASTRONOMICAL UNION Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A. IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions) BMARSDEN@CFA.HARVARD.EDU or DGREEN@CFA.HARVARD.EDU (science) URL http://cfa-www.harvard.edu/iau/cbat.html Phone 617-495-7244/7440/7444 (for emergency use only) GRB 980613 M. J. S. Smith, BeppoSAX Science Operation Center (SOC), Rome, and Space Research Organization of the Netherlands (SRON); R. Ricci, SOC; J. in 't Zand, SRON; M. Feroci, L. Piro, and P. Soffitta, Istituto di Astrofisica Spaziale, CNR, Rome; and N. Masetti and E. Palazzi, Istituto Tecnologie e Studio Radiazioni Extraterrestri, CNR, Bologna, communicate: "A weak gamma-ray burst was observed by the BeppoSAX Gamma Ray Burst Monitor on June 13.20215 UT. The preliminary analysis shows a duration of about 50 s and a peak intensity of 250 counts/s in the energy band 40-700 keV. The burst was also detected in Wide Field Camera (WFC) unit 2 with comparable duration and a peak intensity of about 0.6 +/- 0.1 Crab (2-25 keV). The preliminary position as derived from the WFC image is R.A. = 10h17m44s, Decl. = +71o29'.9 (equinox 2000.0), with an error radius of 4'. A follow-up observation with BeppoSAX narrow-field instruments has been in progress since June 13.56. Observations in all bands are solicited." (C) Copyright 1998 CBAT 1998 June 15 (6938) Daniel W. E. Green ///////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 101 SUBJECT: GRB980613 Near Infra-Red Observations DATE: 98/06/14 05:15:09 GMT FROM: Richard McMahon at Inst.Astonomy, U Cambridge R. G. McMahon, M.G. Beckett, M. Hoenig, G. Gilmore and R. Wyse report, on behalf of the CIRSI GRB team. On June 13th, between UT 21:16 and 22:19, we observed the BeppoSax error box of the Gamma Ray Burst GRB980613 (GCNC#99) in the near-IR, H band with the Isaac Newton Telescope, on LaPalma, using the Cambridge Infra-Red Survey Instrument. Our H band image covers a field of view of 7.8arcmin x 7.8arcmin with spatial resolution of around 1 arcsec. The image is not photometrically calibrated yet. Comparison with the DSS optical image reveals no obvious candidate for a near-IR counterpart to GRB980613. We plan to reobserve the field again on subsequent nights. This image is available, for comparison with future observations, at http://www.ast.cam.ac.uk/~optics/cirsi/grb/. Calibration information will be added in due course. ------------------------------------------------------------------- Richard G. McMahon | Phone(direct) 44-(0)-1223-337519 Institute of Astronomy | (secretary) 1223-337516 University of Cambridge | (switchboard) 1223-337548 Madingley Rd | FAX 1223-337523 Cambridge, CB3 OHA, UK. | mobile 0585-409019 | home 1223-464920 email: rgm@ast.cam.ac.uk | http://www.ast.cam.ac.uk/~rgm ------------------------------------------------------------------- ///////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 102 SUBJECT: GRB 980613 optical/IR obs. DATE: 98/06/14 11:56:29 GMT FROM: Alberto Castro-Tirado at LAEFF-INTA Alberto J. Castro-Tirado (Laboratorio de Astrofisica Espacial y Fisica Fundamental, LAEFF-INTA, Madrid) Javier Gorosabel (LAEFF-INTA) Jochen Greiner (Astrophysikalisches Institut, Potsdam) Dimitra Rigopoulou (Max Planck Institut fur Extraterrestrische Physik, Garching) Dave Clements (IAS, Univ. Paris XI) Marco Barden (MPE Garching) Georg Lamer (University of Southampton) and E. Costa and F. Frontera (on behalf of the BeppoSAX team) Report: We have obtained K'-band images of a 10' x 10' region centred at the BSAX/WFC error box for GRB 980613, with the 3.5-m telescope (+ OMEGA) at the German-Spanish Calar Alto Observatory, on June 13.87-13.92 . R-band and I-band images were also obtained at the 1.23-m telescope on June 13.88-14.00. No variable object, by more than 0.5 mag, is seen when comparing the co-added R-band image with the POSS chart, down to R = 20.5. We notice however, the presence of a point-like object on several IR images, with K' = 17.5 +/- 0.5 (very preliminary). The object is not seen on the R-band image (limiting magnitude R = 22), implying R-K' > 4. Its position is AR(2000) = 10 18 23.15, Dec(2000) = +71 32 18.5 (+/- 1"). Further IR and radio observations are encouraged in order to discern whether this is the true IR counterpart to GRB 980613, resembling that of GRB 980329. ///////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 103 SUBJECT: GRB 980613 new optical/IR observations DATE: 98/06/15 19:53:08 GMT FROM: Alberto Castro-Tirado at LAEFF-INTA GRB 980613. NEW OPTICAL/IR OBSERVATIONS --------------------------------------- Alberto J. Castro-Tirado (Laboratorio de Astrofisica Espacial y Fisica Fundamental, LAEFF-INTA, Madrid) Javier Gorosabel (LAEFF-INTA) Jochen Greiner (Astrophysikalisches Institut, Potsdam) Dimitra Rigopoulou (Max Planck Institut fur Extraterrestrische Physik, Garching) Dave Clements (IAS, Univ. Paris XI) Marco Barden (MPE Garching) Georg Lamer (University of Southampton) Arturo Manchado, Maite Rozas, Victor Sanchez-Bejar, Maria Rosa Zapatero- Osorio (Instituto de Astrofisica de Canarias) and E. Costa and F. Frontera (on behalf of the BeppoSAX team) Report: New images in the K'-band obtained on June 14.87-14.93 at the 3.5-m CAHA telescope (+ OMEGA) indicate that the red object reported by us (GCN 102) is a slow-moving object, probably an asteroid, and therefore unrelated to GRB 980613. One of the K'-band images can be seen at http://laeff.esa.es/~jgu/grb980613.html . I-band images were also taken on June 13.89 and June 14.87 with the IAC-80 telescope at Observatorio del Teide (Canary Islands). No variable object (by more than 0.2 mag) is seen within the BSAX/WFC error box, down to a limiting magnitude of I = 21.5 . ///////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 104 SUBJECT: GRB980613 BeppoSAX-NFI follow up DATE: 98/06/15 23:10:17 GMT FROM: SAX Science Operations at IAS/CNR Frascati GRB980613: follow-up with NFI: Luigi Piro on behalf of the BeppoSAX team report: Two previously unknown X-ray sources have been found in the WFC error circle by the MECS during the follow up observation started 9 hrs after the GRB. Source A is at R.A.(2000)= 10h17m53s Dec.(2000)= +71d27'24" Source B is at R.A.(2000)= 10h18m04s Dec.(2000)= +71d33'30" The error radius is 50". Source B does not show substantial variability. Source A shows a rather strong decay during the observation, and is very likely the X-ray afterglow of GB980613. ///////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 105 SUBJECT: GRB980613 observations from Palomar DATE: 98/06/16 13:01:02 GMT FROM: Steve Odewahn at Caltech S. Odewahn, C. Thomas, S. Djorgovski and S. Kulkarni report that the optical counterpart to GRB980613 detected by BeppoSAX was searched for with the Palomar 60" on Jun15,98 and Jun16,98 (UT). Images were obtained with CCD13 in Gunn gri at an airmass of 1.6 and integration times of (900,600,600) seconds respectively under photometric conditions and seeing measured at 1.0" fwhm. Images and details of observations are given in: http://astro.caltech.edu/~sco/sco1/research/grb/grb980613.html The faintest source shown in our map at r=20.96 (object 6 in Fig1) is detected at better than 5-sigma. No such source (r<21) has been found to vary in the MECS error box with delta mag greater than 0.5 mags in the period from Jun15,98 to Jun1698 (UT). In Figure 2 of our web page we show the Jun15 and Jun16 (UT) 600 second r images from the Palomar 60" with the latest position and errorbox from the L. Piro (MECS). The 8' diameter error box is centered on 10:17:45.6 +71:29:56.0 (J2000). The Jun16 image is shifted into the coordinate system of the Jun15 image. We also show for comparison the corresponding DSS field. A more thorough photometric analysis of the our images will be reported following the completion of our Palomar observing run (Jun18,98). [GCN Operator's Note: This circular was received at 10:44 UT, but due to a computer network problem at GSFC its distribution was delayed until now. GSFC and GCN apologize for the delay.] ///////////////////////////////////////////////////////////////////// Circular No. 6939 Central Bureau for Astronomical Telegrams INTERNATIONAL ASTRONOMICAL UNION Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A. IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions) BMARSDEN@CFA.HARVARD.EDU or DGREEN@CFA.HARVARD.EDU (science) URL http://cfa-www.harvard.edu/iau/cbat.html Phone 617-495-7244/7440/7444 (for emergency use only) GRB 980613 E. Costa, Istituto di Astrofisica Spaziale, CNR, Rome; L. A. Antonelli, Osservatorio Astronomico di Roma and BeppoSAX, Rome; C. De Libero, G. Spoliti, M. Celidonio, A. Tesseri, and M. R. Daniele, BeppoSAX, Rome; J. in 't Zand, Space Research Organization Netherlands, Utrecht; and F. Frontera, Istituto Tecnologie e Studio Radiazioni Extraterrestri, CNR, Bologna, report: "The error circle of GRB 980613 (IAUC 6938) was observed with the BeppoSAX Narrow Field Instruments from June 13.5618 (9 hr after the burst) to 14.6771 UT. Two previously unknown sources have been detected by the Medium Energy Concentrator Spectrometer (MECS) within the circle during this follow-up observation. One source, 1SAX J1018.1+7133, is located at R.A. = 10h18m04s, Decl. = +71o33'30" (equinox 2000.0; error radius 50"), and the other source, 1SAX J1017.9+7127, is located at R.A. = 10h17m53s, Decl. = +71o27'24". 1SAX J1018.1+7133 has an average count rate of 0.0036 +/- 0.0004 counts/s in the two MECS units, corresponding to a flux of (1.9 +/- 0.2) x 10E-13 erg cmE-2 sE-1. This source does not show substantial variability. 1SAX J1017.9+7127 has an average count rate of 0.0016 +/- 0.0004 counts/s in the two MECS units, corresponding to a flux of (1.1 +/- 0.3) x 10E-13 erg cmE-2 sE-1. In the first 7000 s, the average count rate is about 3 times this value; due to this fading behavior, the source is likely to be the x-ray afterglow of GRB 980613." (C) Copyright 1998 CBAT 1998 June 16 (6939) Daniel W. E. Green ///////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 106 SUBJECT: GRB980613 Optical Observations DATE: 98/06/16 23:16:03 GMT FROM: Jules Halpern at Columbia U. J. Halpern, R. Fesen, E. Costa, & L. Piro report on behalf of the MDM Observatory GRB followup team and the BeppoSAX team: We obtained I-band images of the BeppoSAX WFC error circle of GRB 980613 (Smith et al. IAUC 6938) using the MDM Observatory 2.4m telescope beginning on June 14.17 and June 15.17 UT. No variations at the 0.3 mag level were detected in the error circle of the fading MECS X-ray source "A" (GCN #104) to a limiting magnitude of I=22.3. Conditions were photometric and seeing of 0.9 arcsec was obtained. Total exposure times were 3000 s and 3600 s, respectively, on the first and second nights. We also obtained 2000 s of R-band exposure beginning on June 14.19 UT. Photometric calibration of stars in both colors can be made available if needed. We also note that this field was observed by the ROSAT PSPC for 7300 s on 1993 May 11, and that an X-ray source was detected at the position (J2000) 10h18m2.4s, +71d33'47.6", consistent with that of MECS source "B" (GCN #104). Its PSPC count rate is 0.020+/-0.001. No source was detected by ROSAT at the position of MECS source "A", which supports its identification as the afterglow of GRB 980613. ///////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 108 SUBJECT: GRB 980613 optical observations DATE: 98/06/18 14:37:20 GMT FROM: Alan Diercks at U.Washington A. Diercks, E.W. Deutsch, C. Stubbs (U. of Washington); P.M. Vreeswijk, T.J. Galama (U. of Amsterdam); J. van Paradijs (U. of Amsterdam; U. of Alabama in Huntsville); C. Robinson, and C. Kouveliotou (USRA at MSFC-NASA) report: We observed the BeppoSAX error box of GRB 980613 on June 14.35 UT and June 15.35 UT in Kron-Cousins I with the APO 3.5m telescope. Conditions were mostly clear with ~2.0 arcsec seeing. Photometry on a 30 min series of I-band (Kron-Cousins) images centered around June 14.35 UT (28 hr after the burst) yields the following preliminary magnitudes and relative uncertainties for several reference stars: ID I mag Rel Err RA (J2000) DEC -- ----- ------ ------------------------ 1 17.28 0.02 10 17 47.48 +71 27 0.6 2 18.74 0.02 10 17 54.83 +71 27 40.2 3 18.70 0.03 10 18 6.55 +71 27 5.1 4 18.58 0.02 10 17 55.29 +71 28 16.5 5 18.25 0.02 10 17 41.45 +71 28 9.3 Absolute calibration is based on a single observation of the PG 2213-006 standard field (Landolt 1992) and a previously determined airmass correction for this filter and instrument. The uncertainty in the absolute calibration is 0.1 mag. The limiting magnitude (SNR~5) for the combined images for each of the June 14.35 and 15.35 epochs is I~22.0. We find no object at the position of the slow moving K~17.5 detection reported by Castro-Tirado(GCN #102,#103). The error circle was also observed with the 1m JKT telescope in Harris I on June 13.97 for 1600s and June 14.96 for 420s. Conditions were clear with ~2.0 arcsec seeing. Difference imaging between the June 13.97 UT JKT data and the June 14.35 UT APO data reveals no point sources which varied by more than the flux equivalent of I = 20.6 mags between the two images. Similar analysis on June 14.35 UT and June 15.35 UT APO data gives an upper limit of 21.5 mags to any such flux differences. An image of the field is posted at: http://www.astro.washington.edu/deutsch/grb/grb980613/ This note can be cited. ///////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 109 SUBJECT: GRB 980613 Optical Observations DATE: 98/06/18 16:18:04 GMT FROM: Jens Hjorth at NORDITA GRB 980613 Optical Observations J. Hjorth, M. I. Andersen, H. Pedersen, A. O. Jaunsen on behalf of the NOT GRB team and E. Costa & E. Palazzi on behalf of the SAX GRB team report: On June 13.9 UT and June 17.9 UT we obtained R band images (600 sec each, seeing FWHM=0.7") of the BeppoSAX error circle of GRB 980613 (Piro & Costa, GCN #99) with the 2.5-m Nordic Optical Telescope. We have discovered a faint point source in our June 13.9 image which is not detected in our June 17.9 image (which reaches a similar limiting magnitude). The source is located at (+- 0.5"): RA(J2000) = 10 17 57.64 Dec(J2000) = +71 27 26.4 Preliminary photometry (Cousins R) of the source yields: June 13.8897 UT: R = 22.9+-0.2 June 17.9088 UT: R > 24.0 (formal 10-sigma limit) These numbers assume R=19.11 for USNO catalogue entry U1575-03105992 located at RA(J2000)=10 17 54.83, Dec(2000)=+71 27 39.8, consistent with the photometry of the isolated star 4_r of Odewahn et al. (GCN #105) (assuming r-R=0.35). The location of the source is consistent with the BeppoSAX WFC error circle of GRB 980613 (GCN #99) and the BeppoSAX MECS error circle for source A (Piro, GCN #104; Costa et al., IAUC 6939). The photometry is consistent with previously reported upper limits for optically variable objects in the field (R > 20.5 on June 13.9, Castro-Tirado et al., GCN #102; I>21.5 on June 13.9, Castro-Tirado et al., GCN #103; r>21.0 on June 16.0, Odewahn et al., GCN #105; I>22.3 on June 14.2, Halpern et al., GCN #106, I>20.6 on June 14.0 and I>21.5 on June 14.4, Diercks et al., GCN #108). Given the consistency with the BeppoSAX error circles of GRB 980613 and the rapidly fading nature of the source we suggest that the detected object is the optical afterglow of GRB 980613. Finding charts and updates of these preliminary results will be posted at http://www.nordita.dk/~jens/grb980613/ This report may be cited. ///////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 112 SUBJECT: GRB 980613: BATSE Observations DATE: 98/06/19 01:46:59 GMT FROM: R Marc Kippen at BATSE/UAH/MSFC GRB 980613: BATSE Observations P. Woods, R. M. Kippen (University of Alabama in Huntsville) & V. Connaughton (NRC & NASA/MSFC) report on behalf of the BATSE GRB team: On June 13.20215 UT, BATSE detected a gamma-ray burst coincident with GRB 980613 (IAUC 6938). The event did not activate the on-board BATSE trigger because it was not sufficiently intense to override a large solar flare (trigger number 6821) that occurred ~33 minutes earlier. The GRB consisted of a single pulse lasting about 20 s with little resolvable structure on the 1 second time-scale. Its peak flux (50-300 keV; integrated over 1 s) and fluence (>20 keV) are 0.63 (-/+ 0.05) photons cmE-2 sE-1 and 1.71 (-/+ 0.25) x 10E-6 erg cmE-2, respectively. This ranks it near the middle of the BATSE burst flux/fluence distribution. The average spectral hardness of the burst, as estimated by the ratio of 100-300 keV counts to those in the 50-100 keV range, is H32 = 0.93 (-/+ 0.12), which is also average for events of this duration. The BATSE location is consistent with those measured by BeppoSAX. This message is citeable. ///////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 114 SUBJECT: GRB980613, Detection of the probable host galaxy DATE: 98/06/19 07:24:37 GMT FROM: George Djorgovski at Caltech/Palomar GRB 980613: Detection of the probable host galaxy S. G. Djorgovski, S. R. Kulkarni, S. C. Odewahn (Caltech), and H. Ebeling (IfA, Univ. of Hawaii), report on behalf of the Caltech GRB collaboration: Images of the field of GRB 980613 were obtained by H. Ebeling at the Keck-II telescope on UT 1998 June 16.3, in the R band. We detect a galaxy coincident to within 0.5 arcsec with the optical transient (OT) reported by Hjorth et al. (GCN circ. 109). The galaxy may include a faint, unresolved source, which may be the faded OT. The preliminary total magnitude of the object at the epoch of our observations, assuming the zero-point given by Hjorth et al. (R = 19.1 for their star 1, which is identical to star 2 of Diercks et al., GCN circ. 108), is R ~ 23.3, which is consistent with the conservative upper limits reported by Hjorth et al. for their June 17 image. We propose that this is the host galaxy of GRB 980613. Further analysis of these data is in progress. Images will be posted at: http://astro.caltech.edu/~george/grb/grb980613.html This message can be cited. ///////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 117 SUBJECT: GRB 980613: Optical transient and its host galaxy DATE: 98/06/19 23:23:44 GMT FROM: George Djorgovski at Caltech/Palomar [GCN Operator's Note: This is a redistribution of GCN 117 to correct a typo in the original distribution. See full explanation below.] GRB 980613: Optical transient and its host galaxy S. G. Djorgovski, S. R. Kulkarni, and S. C. Odewahn (Caltech), and H. Ebeling (IfA, Hawaii) report on behalf of the Caltech GRB collaboration: Further analysis of the Keck images of the field of GRB 980613 (see GCN 114), calibrated with the Palomar 60-inch images (see GCN 105) gives the following results: We resolve the image of the optical transient (OT) found by Hjorth et al. (GCN 109) from its host galaxy, which extends up to 1.5 - 2 arcsec from the point source (the OT) in approximate PA ~ 70 deg. Magnitudes of stars 1-5 from Diercks et al., GCN 108, in the Gunn r band are: ARC star 1 r = 18.45 RA = 10 17 47.559 DEC = +71 27 00.75 ARC star 2 r = 19.59 RA = 10 17 54.828 DEC = +71 27 39.81 ARC star 3 r = 20.82 ARC star 4 r = 20.07 ARC star 5 r = 19.51 RA = 10 17 41.456 DEC = +71 28 09.11 The positions given are from the USNO A1.0 catalog where available (J2000). ARC star 2 is identical to star 1 from Hjorth et al. (GCN 109). In this system, the integrated magnitude of the optical transient (OT) plus its apparent host galaxy is: r = 24.15 +- 0.3. The total flux is divided approximately equally between the two. Assuming the mean zero-point offset = 0.4, this implies the magnitude for the OT at this epoch (June 16.30 UT) of R = 24.5 +- 0.5 (and the same for the host galaxy). Using the measurement of R = 22.9 +- 0.2 on June 13.9 UT from Hjorth et al., the implied power-law decay slope is -1.0, which is perfectly normal for GRB afterglows. Images are now posted at: http://astro.caltech.edu/~george/grb/grb980613.html This message can be cited. [GCN Operator's Note: D. Djorgovski, et al., points out that there was a typo in their original submission to GCN Circular 117. The text above is the corrected version. The original quoted the "... its apparent host galaxy is: r = 25.15 +- 0.3", when it should have said "... its apparent host galaxy is: r = 24.15 +- 0.3." This second distribution has been given the same serial number. The archive files on the GCN web site have been corrected.] ///////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 118 SUBJECT: GRB980613, optical observations DATE: 98/06/22 15:26:21 GMT FROM: Vladimir Sokolov at SAO RAS V. Sokolov, S. Zharikov on behalf of the SAO-RAS GRB follow-up team and L. Piro, E. Costa, L. Nicastro and E. Palazzi on behalf of the SAX GRB team report: On Jun. 20.858 we obtained Rc band images with the 6-m BTA telescope of SAO-RAS. We detected the source reported by Hjorth et al. (GCN #109). Conditions were not photometric with seeing of 3.0 arcsec. The total observing time was 3600 s with 600 s per exposure. For photometric calibration we used star 1 from Hjorth et al. (GCN #109) and star 4_r from Odewahn et al. (GCN #105) (assuming r-R=0.35). Preliminary photometry (Cousins R) of the source yields: June 20.858 UT: Rc = 23.17+/-0.08 This result is not consistent with the upper limit of June 17.9088 UT: R > 24.0 (formal 10-sigma limit) from Hjorth et al. (GCN #109). Finding charts and updates of these preliminary results will be posted at http://www.sao.ru/~zhar/home/GRB/980613.html This message can be cited. ///////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 119 SUBJECT: GRB 980613 Near-IR observations DATE: 98/06/23 20:36:15 GMT FROM: Jeff Goldader at STScI J. Goldader (STScI), M. Beasley (U. Colorado), M. Hanson (Steward Observatory, U. Arizona), and P. Conti (U. Colorado) report: We imaged part of the initial 8 arcminute diameter error circle of GRB 980613 (Piro & Costa, GCN 99) at K (2.2 micron) using ONIS on the KPNO 4m telescope. Our observations covered approximately (RA=10h 18m 23.90s, DEC=+71d 28' 25") through (RA=10h 17m 29.10s, DEC=+71d 31' 25"), and also (RA=10h 17m 26.24s, DEC=+71d 28' 25") through (RA=10h 16m 54.30s, DEC=+71d 31' 25") (J2000.0), and were made between 1998 June 14.22 and 14.26 UT. No objects not present on the DSS were observed, to a limiting point-source magnitude of K=18.0 +/- 0.2 (3 sigma, estimated by spreading flux evenly over a 4x4 pixel box) in seeing of ~0.7 arcsec FWHM. The fields observed fall north of, and do not include, the positions of the fading X-ray source 1SAX J1017.9+7127 (Costa et al., IAUC 6939; Piro et al., GCN 104) and the possibly associated optical transient reported by Hjorth et al. (GCN 109). This report may be cited. ///////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 134 SUBJECT: GRB980613 Optical Observations DATE: 98/07/07 18:13:02 GMT FROM: Jules Halpern at Columbia U. J. P. Halpern (Columbia), and R. Fesen (Dartmouth) report on behalf of the MDM Observatory GRB follow-up team that the optical afterglow of GRB 980613 discovered by Hjorth et al. (GCN #109) is also present and variable on MDM images at a level just below the limit of I = 22.3 previously quoted by us in GCN #106. Our J2000 position of the OT is (+/- 0.6"): RA = 10 17 57.82 Dec = +71 27 25.5 Measured magnitudes (at mean epoch) and 1-sigma statistical errors are: R = 22.96 +/- 0.09 (June 14.24 UT) I = 22.53 +/- 0.09 (June 14.20 UT) I = 22.83 +/- 0.15 (June 15.19 UT) Actual errors are larger, limited by systematic effects of fringing in the I band. Photometry was calibrated using Landolt standards. Our magnitudes of the five reference stars measured by Diercks et al. (GCN #108) are given in the following table, and are in agreement with their values, as well as those of Djorgovski et al. (GCN #117). Quoted uncertainties are 1-sigma statistical. Coordinates are measured with respect to the USNO A1.0 reference system. Star RA(2000) Dec(2000) R I -------------------------------------------------------------------- 1 10 17 47.52 +71 26 59.9 17.91 +/- 0.01 17.34 +/- 0.01 2 10 17 54.87 +71 27 39.8 19.20 +/- 0.01 18.76 +/- 0.01 3 10 18 06.61 +71 27 04.7 20.02 +/- 0.05 18.72 +/- 0.01 4 10 17 55.31 +71 28 16.3 19.54 +/- 0.02 18.61 +/- 0.01 5 10 17 41.44 +71 28 08.9 18.70 +/- 0.01 18.31 +/- 0.01 -------------------------------------------------------------------- Our measurement of R = 22.96 for the OT on June 14.24 is similar to that of Hjorth et al. (R = 22.9 +/- 0.2 on June 13.89), which may be consistent with a plateau in the first 24 hours after the burst, or perhaps just an effect of the large error bars. Our R-band measurement combined with the later detection by Djorgovski et al. (R = 24.5 +/- 0.5 on June 16.30) implies a power-law decay slope of 1.3. Our images are posted at http://cba.phys.columbia.edu/grb/980613/ This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 189 SUBJECT: GRB 980613: Spectroscopy of the host galaxy DATE: 99/01/03 22:18:24 GMT FROM: George Djorgovski at Caltech/Palomar GRB 980613: Spectroscopy of the host galaxy S. G. Djorgovski, S. R. Kulkarni, J. S. Bloom (Caltech), D. Frail (NRAO), F. Chaffee and R. Goodrich (CARA/WMKO), on behalf of the Caltech-NRAO-CARA GRB collaboration, report: We obtained spectra of the host galaxy of GRB 980613 (see GCN Circ. 114 and 117) at the Keck-I telescope, on 17 Dec 1998 UT. The reduced spectrum shows a single strong emission line at 7814 Angstroms, which we interpret as the [O II] 3727 line at z = 1.0964 +- 0.0003, a probable 4000-A break just to the red of it, and a very blue, featureless continuum blueward of the line. Other plausible spectroscopic identifications of this line (e.g., Ly alpha, Balmer lines, [O III], etc.) would predict appearance of other strong emission lines or continuum breaks, which are clearly not seen in our data. We thus consider our redshift interpretation to be secure. The spectrum is typical of star forming galaxies at comparable redshifts. Both the continuum and the line emission are clearly extended. The images of the galaxy (which is coincident with the OT discovered by Hjorth et al., 1998, GCN Circ. 109), show a patchy or asymmetric morphology, suggestive of an interacting system. In what follows, we assume the Galactic foreground extinction A(V) = 0.27 mag from Schlegel et al. (1998, ApJ 500, 525), and a simple Friedman model cosmology with H_0 = 65 km/s/Mpc, Omega_0 = 0.2, and Lambda_0 = 0. At this redshift, the luminosity distance is 2.256e28 cm. The extinction-corrected spectroscopic magnitudes of the host are: B = 24.4, V = 24.1, and R = 23.85 mag, with the zero-point uncertain by at least 0.2 mag. This is in an excellent agreement with the R-band magnitude in a comparable aperture, derived from direct images obtained at the Keck-II telescope on 28 Nov 1998 UT, and consistent with our earlier estimate (GCN Circ. 117). From the BATSE fluence of 1.71e-6 erg/cm2 (Woods et al. 1998, GCN Circ. 112) the implied isotropic gamma-ray energy of the burst was 5.2e51 erg. The extinction-corrected [O II] line flux is 4.4e-17 erg/cm2/s, giving the line luminosity of 2.8e41 erg/s. The implied unobscured SFR, using the conversion from Kennicutt (1998, ARAA 36) is 3.9 Msun/yr. The observed, extinction-corrected monochromatic flux at the rest wavelength of 2800 A is 0.9 microJy, corresponding to the restframe power of 2.76e28 erg/s/Hz. The implied unobscured SFR, using the estimator from Madau et al. (1998, ApJ 498, 106) is 3.5 Msun/yr, in an excellent agreement with the [O II] line estimate, although both may be uncertain by as much as 20-50%. This agreement suggests that the host galaxy as a whole is not heavily obscured. We note that this SFR is rather moderate, despite the very blue color of the host galaxy. Further observations and analysis are in progress. This report may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 777 SUBJECT: HST/STIS observations of the chaotic environment of GRB 980613 DATE: 00/08/21 20:31:38 GMT FROM: Stephen Holland at IFA, U of Aarhus HST/STIS observations of the chaotic environment of GRB 980613 Stephen Holland, Bjarne Thomsen (University of Aarhus), Jens Hjorth, Johan Fynbo (University of Copenhagen), Michael Andersen (University of Oulu), Gunnlaugur Bjornsson (University of Iceland), Andreas Jaunsen (ESO), Priya Natarajan (University of Cambridge, & Yale), and Nial Tanvir (University of Hertfordshire) We have used the Space Telescope Imaging Spectrograph (STIS) on the Hubble Space Telescope to image the environment where GRB 980613 occurred. We obtained 5851 seconds of STIS/CCD images with the 50CCD (clear) aperture and 5936 seconds of images with the F28X50LP (long pass) aperture. This data was taken as part of the Survey of the Host Galaxies of Gamma-Ray Bursts (Holland et al., GCN 698) approximately 799 days after the burst. Combined images are now available at "http://www.ifa.au.dk/~hst/grb_hosts/data/index.html". A comparison with ground-based R-band images of the optical afterglow associated with GRB 980613, taken with from the Nordic Optical Telescope (NOT) (Hjorth et al., GCN 109) suggests that the GRB occurred at X = 1023.95 +/- 1.52, Y = 1068.73 +/- 0.96 on the drizzled 50CCD image. The quoted uncertainties are the uncertainties in the transformation between the NOT and STIS images. They do not reflect the uncertainty in the position of the optical afterglow in the NOT images due to the GRB being superimposed on a fragmented, extended structure (object A in Djorgovski et al., astro-ph/0008029). This systematic uncertainty means that the position of the optical afterglow may be consistent with the position of a blue, compact source at the southeast end of the A complex. This source has a full-width at half-maximum of 0.13 arcsec (the resolution of the drizzled STIS images is 0.089 arcsec), and AB magnitudes of CL = 26.3 +/- 0.1 and LP = 26.2 +/- 0.1 in an aperture of radius 0.25 arcsec. An image of the complex structure where GRB 980613 occurred is available at "http://www.ifa.au.dk/~hst/grb_hosts/data/grb980613cd.gif". There are several extended objects within a few arcseconds of the GRB (Djorgovski et al., astro-ph/0008029). These objects have a wide range of colours, significant substructure, and some of them appear to have extended tails that may be due to tidal interactions. The total diameter of the chaotic environment around GRB 980613 is approximately eight arcseconds. If we assume that all of the structure lies at the same redshift (z = 1.0969, Djorgovski et al., astro-ph/008029), and adopt a cosmology with H0 = 70, Omega_matter = 0.3, and Omega_lambda = 0.7, then this corresponds to a diameter of approximately 65 proper kpc. The total light in this region is CL = 23.0 +/- 0.1, LP = 22.9 +/- 0.2. A detailed analysis of this data is in progress (Hjorth et al., in preparation).