//////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4775 SUBJECT: GRB 060218: Swift-BAT detection of a possible burst DATE: 06/02/18 04:28:55 GMT FROM: Scott Barthelmy at NASA/GSFC G. Cusumano (IASF-Pa INAF), S. Barthelmy (GSFC), N. Gehrels (GSFC), S. Hunsberger (PSU), S. Immler (GSFC), F. Marshall (GSFC), D. Palmer (LANL), T. Sakamoto (GSFC/ORAU) on behalf of the Swift team: At 03:34:30 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 060218 (trigger=191157). Swift slewed immediately to the burst. The BAT on-board calculated location is RA,Dec 50.404, +16.866 deg {03h 21m 37s, +16d 51' 58"} (J2000) with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The TDRSS lightcurve shows nothing, which is consistent and common for an image trigger. The XRT began taking data at 03:37:04 UT, 153 seconds after the BAT trigger. The XRT on-board centroid algorithm did not find a source in the image and no prompt position is available. We are waiting for down-linked data to detect and determine a position for the source. The UVOT began taking data 152 seconds after the BAT trigger. There is an indication of an afterglow candidate at RA,Dec 03h 21m 39.8s,+16d 52' 06" +/- 1 arcsec with an estimated B magnitude of 19.4. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4776 SUBJECT: Subject: GRB 060218: Swift XRT Position DATE: 06/02/18 10:49:54 GMT FROM: Giancarlo Cusumano at INAF-IASFA J. A. Kennea, D. N. Burrows (PSU), G. Cusumano (INAF-Pa), and G. Tagliaferri (INAF-OAB) report on behalf of the Swift XRT team: The Swift XRT observed the position of GRB 060218 (Cusumano et al., GCN 4775) beginning at 03:37:04 UT, 153 s after the BAT trigger. The on-board centroiding algorithm did not find a source. Ground-processing of the data was delayed, but we have now partially analyzed data from the first two orbits, using Level 0 data from the MOC. The XRT was in Windowed Timing mode for the entire first orbit and therefore no position is available from that orbit. The XRT switched into PC mode during the second orbit, during which we clearly detect a bright, fading point source located at: RA(J2000): 03h 21m 39.7s Dec(J2000): 16d 52' 01.33" We estimate the uncertainty to be about 5 arcseconds (90% confidence radius). This position lies 39 arcseconds from the BAT position reported in GCN 4775. A full analysis of the XRT data will follow. This circular is an official product of the Swift XRT Team. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4777 SUBJECT: GRB060218 : SDSS pre-burst observations DATE: 06/02/18 11:27:26 GMT FROM: Richard J. Cool at U.of AZ/Steward Obs Richard J. Cool (Arizona), Daniel J. Eisenstein (Arizona), David W. Hogg (NYU), Michael R. Blanton (NYU), David J. Schlegel (LBNL), J. Brinkmann (APO), Donald P. Schneider (PSU), and Daniel E. Vanden Berk (PSU) report: The Sloan Digital Sky Survey (SDSS) imaged the field of burst GRB060218 prior to the burst. As these data should be useful as a pre-burst comparison and for calibrating photometry, we are supplying the images and photometry measurements for this GRB field to the community. Data from the SDSS, including 5 FITS images, 3 JPGS, and 3 files of photometry and astrometry, are being placed at http://mizar.as.arizona.edu/~grb/public/GRB060218 We supply FITS images in each of the 5 SDSS bands of a 8'x8' region centered on the GRB position (ra=50.4154 (03:21:39.7), dec=16.8670 (16:52:01.3); GCN 4776), as well as 3 gri color-composite JPGs (with different stretches). The units in the FITS images are nanomaggies per pixel. A pixel is 0.396 arcsec on a side. A nanomaggie is a flux-density unit equal to 10^-9 of a magnitude 0 source or, to the extent that SDSS is an AB system, 3.631e-6 Jy. The FITS images have WCS astrometric information. In the file GRB060218_sdss.calstar.dat, we report photometry and astrometry of 308 bright stars (r<20.5) within 15' of the burst location. The magnitudes presented in this file are asinh magnitudes as are standard in the SDSS (Lupton 1999, AJ, 118, 1406). Beware that some of these stars are not well-detected in the u-band; use the errors and object flags to monitor data quality. In the files GRB060218_sdss.objects_flux.dat and GRB060218_sdss.objects_magnitudes.dat, we report photometry of 947 objects detected within 6' of the GRB position. We have removed saturated objects and objects with model magnitudes fainter than 23.0 in the r-band. The fluxes listed in GRB060218_sdss.objects_flux.dat are in nanomaggies while the magnitudes listed in GRB060218_sdss.objects_magnitudes.dat are asinh magnitudes. All quantities reported are standard SDSS photometry, meaning that they are very close to AB zeropoints and magnitudes are quoted in asinh magnitudes. Photometric zeropoints are known to about 2% rms. None of the photometry is corrected for dust extinction. The Schlegel, Finkbeiner, and Davis (1998) predictions for this region are A_U=0.749 mag, A_g=0.551 mag, A_r = 0.400 mag, A_i=0.303 mag, and A_z=0.215 mag. There are currently no objects within 6 arcminutes of the GRB position in the SDSS spectroscopic database. SDSS astrometry is generally better than 0.1 arcsecond per coordinate. Users requiring high precision astrometry should take note that the SDSS astrometric system can differ from other systems such as those used in other notices; we have not checked the offsets in this region. More detailed information pertaining to our SDSS GRB releases can be found in our initial data release paper (Cool et al. 2006, astro-ph/0601218). See the SDSS DR4 documentation for more details: http://www.sdss.org/dr4. These data have been reduced using a slightly different pipeline than that used for SDSS public data releases. We cannot guarantee that the values here will exactly match those in the data release in which these data are included. In particular, we expect the photometric calibrations to differ by of order 0.01 mag. This note may be cited, but please also cite the SDSS data release paper, Adelman-McCarthy et al. (2006, ApJS, in press, astro-ph/0507711), when using the data or referring to the technical documentation. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4779 SUBJECT: Further UVOT Observations of the Candidate Optical Afterglow for GRB 060218 DATE: 06/02/18 17:01:28 GMT FROM: Frank Marshall at GSFC F. Marshall (GSFC), S. Immler (GSFC/USRA) and G. Cusumano (IASF-Pa INAF) report on behalf of the Swift team: The UVOT source reported by Cusumano et al. (GCN 4775) is detected in all four UVOT finding chart exposures ranging from 153s to 1036s from the burst trigger as shown in the table below. There is marginal evidence for brightening in the V filter. The revised source position is 03:21:39.71 +16:52:02.6 (J2000) with an estimated 1-sigma error of about 1.0". This position is within the XRT error circle (Kennea et al. GCN 4776). We note the existence of a source in the USNO-B1 catalog at 03:21:39.69 +16:52:02.2 with a B2 magnitude of 20.67 and an R2 magnitude of 20.3. Further UVOT observations are underway to search for fading of this afterglow candidate. T_start Exposure Filter Mag Mag. Range (1-sigma) 153 200 V 19.6 19.1 - 20.3 359 155 B 19.4 19.2 - 19.6 830 127 B 19.3 19.1 - 19.5 1036 148 V 18.4 18.2 - 18.6 //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4780 SUBJECT: Preliminary refined analysis of the Swift-BAT trigger 191157 DATE: 06/02/18 21:12:56 GMT FROM: Scott Barthelmy at NASA/GSFC L. Barbier (GSFC), S. Barthelmy (GSFC), J. Cummings (GSFC/NRC), G. Cusumano (IASF-Pa INAF), E. Fenimore (LANL), N. Gehrels (GSFC), D. Hullinger (GSFC/UMD), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/NRC), G. Sato (ISAS), J. Tueller (GSFC) on behalf of the Swift-BAT team: Using a partial data set from T-60 to T+116 sec from the recent telemetry downlink, we report further analysis of BAT GRB 060218 (trigger #191157) (Cusumano, et al., GCN 4775). The BAT ground-calculated position is RA,Dec = 50.380,+16.904 deg {03h 21m 31.1s, 16d 54' 14.8"} (J2000) +- 2.6 arcmin, (radius, sys+stat, 90% containment). The partial coding was 88%. The mask-weighted lightcurve is weak and flat from T-60 to T+120 sec (all the data we have so far). Nothing can be said about T90. Since there is obvious emission prior to T-60 and after T+116, we are not quoting the usual spectral fit values at this time. We note that Swift completed a Pre-Planned Slew 8 sec prior to the beginning of the image trigger integration which resulted in trigger 191157, and therefore BAT was unable to trigger prior to this slew on this source. We also note that all the emission is in the 15-50 keV band. There is also a detection at this location at the same flux level at T+900 sec. And there is a possible 5.6-sigma detection at the same location on Jan 17, 2006 (a month earlier). While we can rule out that this is a chance fluctuation, it does call into question the GRB nature of the event (trigger 191157). At this stage in the analysis, it is equally likely that this trigger is a GRB or hard x-ray transient. We expect the full data set by Feb 20, and so will be able make a better assessment. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4781 SUBJECT: GRB060218: Swift/XRT refined position of a possible burst DATE: 06/02/18 23:18:46 GMT FROM: Giancarlo Cusumano at INAF-IASFA G. Cusumano (IASF-Pa INAF), A. Moretti (INAF-OAB), G. Tagliaferri (INAF-OAB), J. Kennea (PSU) and D. Burrows (PSU), report on behalf of the Swift/XRT Team: We have performed a preliminary analysis of Swift/XRT ground-linked data associated to the possible burst GRB060218 (trigger=191157; Cusumano et al., GCN 4775, Kennea et al. 4776). We confirm the presence of a bright X-ray source at the following location: RA(J2000): 3h 21m 39.9s Dec(J2000): 16d 52m 03.7s with an estimated uncertainty of 7 arcseconds (90% containment). Note that this position lies 3.7" from the previous XRT position (GCN 4775), 3' from the BAT position reported in GCN 4780 and 2.9" from the UVOT position. A full analysis of the XRT data will follow. This circular is an official product of the Swift XRT Team. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4782 SUBJECT: GRB 060218A: ROTSE-III Possible Optical Flare DATE: 06/02/19 02:51:12 GMT FROM: Robert Quimby at U of Texas/ROTSE R. Quimby (U Texas), B. E. Schaefer (Louisiana State), H. Swan (U Mich), report on behalf of the ROTSE collaboration: ROTSE-IIIb, located at the McDonald Observatory, Texas, responded to Swift trigger 191157 (possible GRB 060218A; Cusumano et al. GCN 4775; Barbier et al. GCN 4780). The first image was taken at 03:36:07.9 UT, 97.0 s after the burst (5.9 s after the GCN notice time). We detect a source coincident with the refined UVOT position reported by Marshall et al. (GCN 4779). Intermittent clouds reduced the overall data quality, and after 80 minutes the clouds rendered the images unusable. We set the following magnitude limits and detection calibrated relative to the USNO-B1.0 R2 magnitudes: tstart(s) tend(s) exp(s) mag emag limmag -------------------------------------------------------------- 96.98 130.61 25 --- -- 15.68 217.71 472.78 180 --- -- 17.60 482.43 681.24 180 --- -- 18.55 690.49 1027.40 300 18.09 0.11 19.00 1036.55 1789.28 660 --- -- 18.44 1868.39 4780.74 1680 --- -- 16.91 These magnitudes show that the optical source was significantly brighter for a ~5-minute interval starting ~12-minutes after the burst than either before or after this interval, as is consistent with the two UVOT V-band magnitudes reported by Marshall et al. (GCN 4779). //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4783 SUBJECT: GRB 060218: Pre-burst detection of a possible host galaxy DATE: 06/02/19 02:55:07 GMT FROM: Nestor Mirabal at U Michigan N. Mirabal (U. Michigan) reports: "Analysis of the SDSS pre-burst observations of the GRB 060218 field (Cool et al. GCN #4777) reveals an extended object at 03h21m39.68s +16:52:01.66 (J2000). Given the proximity of this object to the reported XRT and UVOT positions for a candidate afterglow (Cusumano et al. GCN #4775, Marshall et al. GCN #4779), this should be considered a potential host galaxy of a low-redshift GRB. Further multiwavelength observations are encouraged to confirm the reality of this trigger (Barbier et al. GCN #4780), and its possible association with this nearby galaxy. I acknowledge useful conversations with Richard Cool." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4784 SUBJECT: GRB 060218: MDM Observations DATE: 06/02/19 04:26:33 GMT FROM: Nestor Mirabal at U Michigan N. Mirabal (U. Michigan) reports on behalf of the MDM Observatory GRB follow-up team: "I observed the candidate optical afterglow of Swift GRB 060218 detected by the Swift UVOT (Cusumano et al. GCN #4775, Marshall et al. GCN #4779, Quimby et al. GCN #4782) with the MDM 2.4m telescope and RETROCAM imager under partly cloudy conditions. Calibration with SDSS pre-burst observations (Cool et al. GCN #4777) yields r = 17.55 +/- 0.1 on Feb. 19.1438 UT for the OT. This is brighter than the pre-burst observations and confirms it as the OT of GRB 060218." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4785 SUBJECT: Brightening of the Optical Counterpart of the Possible GRB 060218 DATE: 06/02/19 06:07:32 GMT FROM: Frank Marshall at GSFC F. Marshall (GSFC), S. Immler (GSFC/USRA) and G. Cusumano (IASF-Pa INAF) report on behalf of the Swift team: Continuing UVOT observations of the possible GRB 060218 show that the candidate optical afterglow reported by Cusumano et al. (GCN 4775) and Marshall et al. (GCN 4779) has brightened by a factor of about 5 in the 10 hours since the BAT trigger. Consequently, this source is unlikely to be the optical afterglow of a GRB. This brightening, the extended emission detected with BAT, and the possible BAT detection a month earlier (Barbier et al. GCN 4780) suggest that the UVOT source is the optical counterpart of a hard X-ray transient. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4786 SUBJECT: GRB060218: Swift/XRT Team preliminary analysis of the possible burst DATE: 06/02/19 13:54:11 GMT FROM: Giancarlo Cusumano at INAF-IASFA Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 8bit G. Cusumano (IASF-Pa INAF), A. Moretti (INAF-OAB), G. Tagliaferri (INAF-OAB), J. Kennea (PSU) and D. Burrows (PSU), report on behalf of the Swift/XRT Team: We analised the first 14 orbits of data (the first orbit is fully in Windowed Timing (WT) mode, the second is in WT mode for the first 84 seconds, the rest of the data are all in Photon Counting (PC) mode). The following refined position for the X-ray afterglow was determined: RA(J2000) = 03h 21m 39.7s Dec(J2000) = +16d 52' 01.8" with an estimated uncertainty of 3.6 arcsec (90% containment). This is 3.0 arcmin from the BAT position reported in GCN 4780, 3.4 arcsec from the XRT position given in GCN 4781 and 0.8 arcsec from the UVOT source given in GCN 4779. The WT light curve starts 159 s after the BAT trigger with a count rate that rises from about 40 counts/s up to about 110 counts/s. The peak occurs around 990 s after the trigger, then the count rate decays and at 2770 s after the trigger, when the first observation orbit ends, the count rate is about 50 counts/s. At the beginning of the second orbit (5944 s post-trigger) the count rate has faded to a value of about 1.1 cts/s and decays very fast. The light curve after the first orbit is modelled by a broken power law characterized by a decay index of 6.38 ± 0.05 up to 9250 ± 270 s post trigger, followed by an intensity decrease with a decay index of 1.15+/- 0.15. The light curve can be seen at http://www.merate.mi.astro.it/~moretti/lc_060218.gif The spectrum obtained for the first orbit of data (159 - 2770 s post-trigger) can be fitted with a power-law of photon index Gamma = 1.82 ± 0.01, with an absorbing column density of (1.9 ± 0.01)e21 cm^-2 in excess of the Galactic column of 1.1e21 cm^-2. Over this time span, the mean 0.2-10 keV observed (unabsorbed) flux is 3.6e-9 (5.6e-9) erg cm^-2 s^-1. The spectrum obtained in the following orbits can be fitted with a power-law of photon index Gamma = 3.3 ± 0.2, with an excess of absorbing column density of (3.2 ± 0.4)e21 cm^-2. The mean 0.2-10 keV observed (unabsorbed) flux is 1.5e-12 (1.4e-11) erg cm^-2 s^-1. If the burst continues to decay at the current rate we estimate an XRT count rate of 2.5e-3 counts/s at T+48hr, which corresponds to an unabsorbed 0.2-10 keV flux of 7.6e-13 erg cm^-2 s^-1. The long, slow flux increase and gradual decrease are unlike any previous GRB prompt or afterglow emission seen by the XRT. Combined with the unusual spectral evolution, this suggests that this source may be an X-ray transient rather than a GRB. This circular is an official product of the Swift XRT Team. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4787 SUBJECT: Oddball GRB 060218, transient or GRB? DATE: 06/02/19 21:49:58 GMT FROM: Neil Gehrels at GSFC N. Gehrels (NASA-GSFC) on behalf of the Swift team: We point out that GRB 060218 (Cusumano et al. GCN 4775) is a strange event. It has - a gamma-ray light curve that is flat and a soft spectrum (Barbier et al. GCN 4780) - an X-ray light curve with a long, slow rise and gradual decline (Cusumano et al. GCN 4786) - an optical light curve with brightening after 10 hours (Marshall et al. GCN 4785). These characteristics are unlike previous GRBs. It has properties that are also atypical of a transient: - it is far off the galactic plane (b = -32.9 deg) and far away from the bulge (l = 166.9 deg) - there is a possible association (Mirabel GCN 4783) with a galaxy in the SDSS pre-burst field (Cool et al. GCN 4777). Further observations are warranted. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4790 SUBJECT: GRB 060218: optical/nIR observations at La Palma DATE: 06/02/20 01:59:46 GMT FROM: Alberto Castro-Tirado at Inst.de Astro. de Andalucia A. de Ugarte Postigo, A. J. Castro-Tirado, S. B. Pandey (IAA-CSIC, Granada), D. Barrado- Navascués, A. Bayo, B. Montesinos (LAEFF-INTA, Madrid), K. Mishra (ARIES, Nainital),and S. Dehaes (Inst. voor Sterrenkunde, K.U. Leuven), on behalf of a larger collaboration report: "Following the detection by SWIFT of "GRB" 060218 (Cusumano et al. GCN Circ. 4770, Gehrels et al. GCN Circ. 4787) we have obtained UBVRIJHK images with the 1.2m Mercator (+MEROPE) and 3.5m TNG (+NICS) telescopes at La Palma (Canary Islands), starting on Feb 19.85 UT (i.e. 40.8 hr after the event). We detect a near-IR counterpart to the hard energy source on a stacked 150s image in the K'-band with K about 17 (with respect to 2MASS catalogue). Astrometry against USNO-A2.0 yields RA(2000) = 03 21 39.71, Dec(2000) = +16 52 02.1 (+/-0.5"). This position is fully consistent with the optical counterpart proposed by Cusumano et al. (op. cit.) and Marshall et al. (GCN Circ. 4779) and with the faint object reported by Mirabal (GCN Circ. 4783) on the SDSS archival data (Cool et al. GCN Circ. 4777). However, we do not find evidence of underlying extended emission in our K'-band frame (0".7 seeing). Together with the fact that the colour index of the source is J-K = 0, unlike GRB afterglow colours (see fig. 2 of Gorosabel et al. 2002, A&A 384, 11), it clearly favours a high-energy transient in our Galaxy." This Circular might be cited. [GCN OPS NOTE(20feb06): Per author's request, A. Bayo was added to the author list.] //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4792 SUBJECT: GRB 060218: MDM Redshift DATE: 06/02/20 03:32:23 GMT FROM: Jules Halpern at Columbia U. N. Mirabal (U. Michigan) and J. P. Halpern (Columbia U.) report on behalf of the MDM Observatory GRB follow-up team: "We obtained a low-resolution spectrum of the optical afterglow and host galaxy of GRB 060218 using the MDM 2.4m telescope and Boller & Chivens (CCDS) Spectrograph on Feb. 20 02:20 UT. Strong, narrow emission lines of H-beta, [O III] 4959,5007, and H-alpha at z=0.0331 are seen, superposed on a blue continuum, which is still much brighter than the SDSS pre-burst magnitudes. The line ratios are typical of a high-excitation starburst. This confirms the low-redshift, extragalactic nature of this unusual GRB. This message may be cited." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4794 SUBJECT: GRB060218: Radio Afterglow Discovery DATE: 06/02/20 04:24:40 GMT FROM: Alicia Soderberg at Caltech Alicia M. Soderberg (Caltech) and Dale A. Frail (NRAO) report on behalf of a large collaboration: "We observed the field of GRB 060218 (GCN 4775) with the Very Large Array at 8.46 GHz on February 20.0 UT. We detect a source coincident with the optical afterglow candidate (GCN 4779) and host galaxy (GCN 4783). Further observations are planned." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4800 SUBJECT: GRB060218: UV Detection and Light Curves DATE: 06/02/21 01:17:18 GMT FROM: Frank Marshall at GSFC F. Marshall (GSFC), P. Brown (PSU), S. Immler (GSFC/USRA), and G. Cusumano (IASF-Pa INAF) report on behalf of the Swift team: The optical counterpart of the unusual GRB 060218 (Cusumano et al. (GCN 4775), Marshall et al. (GCN 4779)) is detected in all 6 of the Swift/UVOT broad-band filters (V, B, U, UVW1, UVM2, UVW2). The filters collectively cover the wavelength range from 180 to 560 nm. The light curves for all the filters have similar shapes. The emission steadily brightens by 1 to 2 magnitudes from the first detection about 150 s. after the burst trigger, peaks in a broad plateau about 10 hours after the trigger, and then slowly declines for at least the next 20 hours. Peak magnitudes are 17.8, 17.7, 16.3, 16.2, 16.1, and 16.0 for the V, B, U, UVW1, UVM2, and UWW2 filters respectively. UVOT observations are continuing. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4802 SUBJECT: GRB 060218: Optical Observations at Xinglong Obs. DATE: 06/02/21 15:17:57 GMT FROM: Yulei Qiu at Nat.Astro.Obs.of China W.K. Zheng, M.Zai, Y.L. Qiu, J.Y. Wei,J.Y. Hu and J.S Deng reports on behalf of the Xinglong GRB follow-up team report: "We observed the optical counterpart of the GRB 20060218 (Cusumano et al. (GCN 4775)) with the 0.8m and the 1m telescopes at Xinglong Observatory, National Astronomical Observatories, Chinese Academy of Sciences. We began observations in R band 7.1953 hours after the trigger. Preliminary analyses show the object has a R magnitude of 17.79 0.1 on Feb 18.4522 UT and 18.25 0.1 on Feb 20.4471 UT (reference stars from USNO-A2.0), which is brighter than the pre-burst counterpart observed by SDSS(GCN 4777). Further analysis is under processing." This message may be cited //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4803 SUBJECT: GRB060218: VLT spectroscopy DATE: 06/02/21 16:59:19 GMT FROM: Nicola Masetti at INAF-IASF,Bologna N. Masetti, E. Palazzi (INAF-IASF, Bologna), E. Pian (INAF, OA Trieste) and F. Patat (ESO), on behalf of the GRACE collaboration, report: "On 2006 February 21.051 UT we acquired a 30-min spectrum of the optical transient associated with the possible GRB060218 (Cusumano et al., GCN 4775) with VLT-Antu equipped with FORS2 and low resolution grating 300V+GG435. We confirm the presence of narrow nebular lines at redshift z = 0.033 (Mirabal & Halpern, GCN 4792). We also note that the spectral continuum shows an overall shape which resembles that of supernova 1997ef around maximum (Iwamoto et al., 2000, ApJ, 534, 660). This may suggest that, if this object is a SN associated with GRB060218, it is either rapidly evolving or it exploded days before the GRB. We acknowledge the assistance of the ESO-Paranal staff. This message may be cited." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4804 SUBJECT: GRB060218: Optical Spectroscopy of GRB-SN DATE: 06/02/21 19:11:20 GMT FROM: Alicia Soderberg at Caltech A. M. Soderberg (Caltech), E. Berger (Carnegie), and B. P. Schmidt (ANU) report on behalf of a larger collaboration: "We obtained an optical spectrum of the afterglow of GRB 060218 (GCN 4775) with GMOS on the Gemini-south telescope starting on 2006 Feb 21.024 UT, for a total of 1800 sec. We confirm the presence of narrow emission lines at z=0.033 (GCNs 4792,4803), as well as the presence of broad absorption features similar to those seen in SN1998bw and other broad-lined Type Ibc supernovae (GCN 4803). A plot of our spectrum is available at: http://www.ociw.edu/~eberger/grb060218_gemini.ps Further observations are planned." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4805 SUBJECT: GRB 060218: Likely an underluminous GRB DATE: 06/02/21 19:13:26 GMT FROM: John Nousek at Penn State U/Swift J. Nousek (PSU), G. Cusumano (IASF-Pa INAF), A. Moretti (INAF-OAB), G. Tagliaferri (INAF-OAB), S. Campana (INAF-OAB), J. Kennea (PSU), D. Burrows (PSU), P. Roming (PSU), D. VandenBerk (PSU), P. Brown (PSU), N. Gehrels (GSFC), S. Barthelmy (GSFC), F. Marshall(GSFC), P. Boyd (GSFC), T. Sakamoto (GSFC), J. Osborne (U. Leicester), P. O'Brien (U. Leicester), G. Chincarini (Univ. Milano-Bicocca), B. Zhang (UNLV) and M. de Pasquale (MSSL) report on behalf of the Swift Team: The Swift team now believes that GRB 060218 is most likely an underluminous GRB. This view is supported by the remarkably long duration of the prompt emission seen by all three Swift instruments and the probable association with a low-z (z=0.033) galaxy (Mirabel GCN 4783; Masetti et al GCN 4803). Although there are unusual aspects to this event (cf. Gehrels GCN 4787), the high galactic latitude seems to make a Galactic X-ray transient origin unlikely. Moreover, the extremely rapid X-ray decay after T+3000 seconds (3 orders of magnitude in an hour), followed by a slow power law decay in time (alpha = 1.2), looks very much like a normal GRB XRT lightcurve. We also draw attention to the chromatic nature of the Swift light curves. The BAT emission peaked substantially earlier than the XRT emission, which preceded the UVOT emission peak. Although the low luminosity inferred from the low-z might suggest a highly off-axis viewing angle for this burst, an off-axis burst should show achromatic emission variation, which is not seen here (see predictions by Kumar, P. & Granot, J. 2003, ApJ, 591, 1075, for example.) The burst continues to be bright in the UVOT, (V= 18.29 +/- 0.07 at 21:29 UT on 20 Feb 2006), so we suggest additional follow-up observations that might confirm signatures of a host supernova or other evidence that might clarify the nature of this highly unusual GRB. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4806 SUBJECT: GRB 060218: Further refined analysis of the Swift-BAT burst DATE: 06/02/21 19:17:31 GMT FROM: Scott Barthelmy at NASA/GSFC S. Barthelmy (GSFC), J. Cummings (GSFC/NRC), T. Sakamoto (GSFC/NRC), C. Markwardt (GSFC/UMD), N. Gehrels (GSFC) on behalf of the Swift-BAT team: Using the data set from T-50 to T+2000 sec from telemetry downlinks, we report further analysis of BAT GRB 060218 (trigger #191157) (Cusumano, et al., GCN 4745; Barbier, et al., GCN 4780; Gehrels, GCN 4787). The BAT ground-calculated position is RA,Dec = 50.379,+16.904 deg {3h 21m 30.9s, 16d 54' 14.2"} (J2000) +- 2.6 arcmin, (radius, sys+stat, 90% containment). The partial coding was 88%. Extending the mask-weighted lightcurve beyond T+120 sec (GCN 4780), it continues the weak, flat, soft emission out to T+280 sec. This flux is 0.06 +- 0.02 counts/cm2/sec in the 15-50 keV band. At T+290 sec there is a 10-sec wide spike which is spectrally harder than the flat emission (all the emission is in the 25-100 keV band). Starting at ~T+200 the lightcurve starts an approximately linear increase to a peak flux of 0.1 counts/cm2/sec (15-100 keV), and then begins a roughly exponential decay out to at least T+2000 sec. We note that this is a very long event. It is among the very longest of GRBs. At this point, using BAT results alone, we can not rule out a non-GRB nature for this event. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4807 SUBJECT: GRB 060218: spectroscopic observations DATE: 06/02/21 19:21:07 GMT FROM: Daniele Malesani at SISSA-ISAS,Trieste,Italy D. Fugazza, P. D'Avanzo (INAF/OABr), D. Malesani (SISSA/ISAS), M. Della Valle (INAF/OAA), N. Masetti, E. Palazzi (INAF/IASF Bo), E. Pian (INAF/OATs), L.A. Antonelli, V. D'Elia, F. Fiore, S. Piranomonte, L. Stella (INAF/OAR), S. Campana, G. Chincarini, S. Covino, G. Tagliaferri (INAF/OABr), L. Di Fabrizio (INAF/TNG) report: We observed the optical counterpart of GRB 060218 (Moretti et al., GCN 4775; Marshall et al., GCN 4779; Quimby et al., GCN 4782) with the 3.6m TNG telescope located at the Canary Islands. Spectroscopy in the range 4000-8000 AA reveals a blue continuum with prominent star-forming emission features (Mirabal & Halpern, GCN 4792; Masetti et al., GCN 4803). A weak, broad bump is seen at ~5000 A, which is consistent with the peak of a broad-lined SN like SN\1998bw (see also Masetti et al., GCN 4803; Soderberg et al., GCN 4804). The overall observed shape would imply a roughly equal contribution from the afterglow and the SN. This message can be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4808 SUBJECT: GRB 060218: Decline in r-band flux DATE: 06/02/21 22:58:14 GMT FROM: Edo Berger at Carnegie Obs E. Berger (Carnegie), B. P. Schmidt (ANU), and A. M. Soderberg (Caltech) report on behalf of a larger collaboration: "As part of our spectroscopic observations with GMOS on Gemini-south (GCN 4804) we obtained a single 30-sec r-band image of the field on 2006, Feb 21.01 UT. Calibration against 9 nearby stars from SDSS (GCN 4777) yields r = 17.92+/-0.12 mag for the afterglow+SN+host. Subtracting off the contribution of the host (r = 19.93+/-0.03; GCN 4777) we find that the afterglow+SN faded by 0.43+/-0.22 mag compared to the measurement by Mirabal (GCN 4784). This corresponds to a decay rate of -0.4+/-0.2, which is relatively shallow compared to typical optical afterglows, and furthermore indicates a turnover in the flux evolution following the initial period of brightening in the B,V bands observed with UVOT (GCN 4800)." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4809 SUBJECT: GRB 060218: emergence of the underlying SN spectrum DATE: 06/02/22 01:06:34 GMT FROM: Alberto Castro-Tirado at Inst.de Astro. de Andalucia T. A. Fatkhullin, V.V. Vlasyuk, V. V. Sokolov, A. V. Moiseev (SAO-RAS Nizhnij Arkhyz), S. Guziy and A. J. Castro-Tirado (IAA-CSIC Granada), on behalf of a larger collaboration, report: "We have obtained optical spectroscopy of the GRB 060218 optical counterpart (Cusumano et al. GCNC 4775) with the 6.0m BTA telescope of SAO-RAS in Zelenchuk, equipped with SCORPIO. First epoch spectroscopy in the 3500-7500 A range was obtained on Feb 20.65 UT, confirming z = 0.033 (Mirabal and Halpern GCNC 4792). Second epoch data was gathered on Feb 21.65 UT. Comparison between the two datasets clearly reveals continuum variations that we interpret as the emergence of the underlying type-Ic SN spectrum, strengthening the SN-GRB 060218 relationship first suggested by Masetti et al. (GCNC 4803). In particular, an "emission peak" at ~4500 A is showing up, possibly as a result of the blending of the Fe lines redward of this feature, giving rise to a broad absorption trough, as it was seen in the type Ic SNe 1997ef (Iwamoto et al. 2000, ApJ 534, 660) and 2002ap (Foley et al. 2003, PASP 115, 1220). Further spectroscopic observations are encouraged." [GCN OPS NOTE(22feb06): Per author's request, the 2nd author was added.] //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4810 SUBJECT: GRB 060218: rebrightening DATE: 06/02/22 03:48:28 GMT FROM: Daniele Malesani at SISSA-ISAS,Trieste,Italy P. D'Avanzo (INAF/OABr), D. Malesani (SISSA/ISAS), M. Della Valle (INAF/OAA), D. Fugazza (INAF/OABr), N. Masetti, E. Palazzi (INAF/IASF Bo), E. Pian (INAF/OATs), L.A. Antonelli, V. D'Elia, F. Fiore, S. Piranomonte, L. Stella (INAF/OAR), S. Campana, G. Chincarini, S. Covino, G. Tagliaferri (INAF/OABr), L. Di Fabrizio (INAF/TNG), report: We observed again the optical counterpart of GRB 060218 (Moretti et al. GCN 4775; Marshall et al., GCN 4779) with the TNG telescope. Comparison between our previous photometry (taken on Feb 20.85 UT) and the new observations (Feb 21.84 UT) reveals a rebrightening by 0.20+-0.05 mag in both the V and R filters. Following the earlier decay (e.g. Marshall et al., GCN 4800; Berger et al., GCN 4808), this behaviour may mark the emergence of the underlying SN 2006aj already suggested on spectroscopic grounds (Masetti et al., GCN 4803; Soderberg et al., IAUC 8674; Fugazza et al., GCN 4807, CBET 410; Mirabal et al., CBET 409; Fatkhullin et al., GCN 4809). The rebrightening may also suggest that the SN is still before its maximum. This message can be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4816 SUBJECT: GRB060218: Optical brightening in V and R DATE: 06/02/23 10:35:09 GMT FROM: Andreas O. Jaunsen at ITA Jan-Erik Ovaldsen (ITA), Dong Xu (DARK, NBI), Josefine H. Selj (ITA), Andreas O. Jaunsen (ITA), Chloe Feron, Christina Thoene, Johan P. U. Fynbo, and Jens Hjorth (DARK, NBI) report: From observations of GRB060218/SN 2006aj (Cusumano et al., GCN #4775) with DFOSC on the Danish 1.5m telescope at La Silla/ESO we find that the optical afterglow + SN 2006aj has brightened by 0.2 (+/- 0.01) mag in R and 0.1 (+/- 0.02) mag in V from Feb 20.03 UT to Feb 21.03 UT. An optical brightening is in line with the notion that the underlying SN 2006aj has still to reach its maximum, as noted in previous reports. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4812 SUBJECT: Spectral properties of GRB060218/SN2006aj DATE: 06/02/23 02:09:54 GMT FROM: Elena Pian at ITESRE-CNR,Bologna Paolo A. Mazzali (MPA, INAF-Ts) and Elena Pian (INAF-Ts) report: inspection of the VLT-FORS2 spectrum of GRB060218/SN2006aj taken on 21 Feb 2006 (Masetti et al. 2006, GCN 4803), i.e. ~3 days after the GRB event, indicates that the observed features are similar to those of the energetic type Ic SN 2002ap at a comparable epoch (Mazzali et al. 2002, Ap. J. 572, L21, Fig. 2). In particular, broad absorptions near 4800 Ang and 5800 Ang can be identified as due to FeII and SiII lines, respectively. This suggests that the SN and the GRB occurred within ~1 day of one another. The observed luminosity of the optical counterpart of GRB060218 is larger than that of SN2002ap at the same epoch, and is consistent with the luminosity of SN1998bw. If an afterglow is still present, we estimate that it does not contribute for more than 25% of the total flux. If it has a power-law shape, this is not bluer than nu^{-2}. Although spectroscopy of SN1998bw did not begin until day 8 (Galama et al. 1998, Nature 395, 670), and therefore a direct comparison is not yet possible, it is likely that SN2006aj will evolve to resemble SN1998bw. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4817 SUBJECT: GRB 060218/SN 2006aj: optical observations DATE: 06/02/23 10:37:29 GMT FROM: Daniele Malesani at SISSA-ISAS,Trieste,Italy D. Malesani (SISSA/ISAS), P. D'Avanzo (INAF/OABr), M. Della Valle (INAF/OAA), L.A. Antonelli, V. D'Elia, F. Fiore, S. Piranomonte, L. Stella (INAF/OAR), S. Campana, G. Chincarini, S. Covino, G. Tagliaferri (INAF/OABr), N. Masetti, E. Palazzi (INAF/IASF Bo), E. Pian (INAF/OATs), M. Pedani (INAF/TNG) report: We observed the optical counterpart of GRB 060218 (Cusumano et al., GCN 4775, 4781; Marshall et al., GCN 4800) with the TNG telescope under good observing conditions. Comparison of the new data with our earlier photometry (D'Avanzo et al., GCN 4810) reveals further brightening of the source between Feb 21.85 and Feb 22.86 UT. This is consistent with the underlying supernova being in the rise phase (Masetti et al., GCN 4803; Soderberg et al., IAUC 8674; Fugazza et al., GCN 4807, CBET 410; Mirabal et al., CBET 409; Fatkhullin et al., GCN 4809; Mazzali & Pian, GCN 4812). This message can be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4818 SUBJECT: Correction to GCN 4816 on GRB060218 DATE: 06/02/23 11:32:27 GMT FROM: Andreas O. Jaunsen at ESO Jan-Erik Ovaldsen (ITA) et al. report: Due to a typo the time of the brightening event was incorrectly reported in GCN 4816. The text should read: "From observations of GRB060218/SN 2006aj (Cusumano et al., GCN #4775) with DFOSC on the Danish 1.5m telescope at La Silla/ESO we find that the optical afterglow + SN 2006aj has brightened by 0.2 (+/- 0.01) mag in R and 0.1 (+/- 0.02) mag in V from Feb 21.03 UT to Feb 22.03 UT. An optical brightening is in line with the notion that the underlying SN 2006aj has still to reach its maximum, as noted in previous reports." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4819 SUBJECT: GRB 060218: rebrightening DATE: 06/02/23 17:24:47 GMT FROM: Daniele Fargion at Phys.Dept, Rome Univ1,It The very recent GRB 060218 long burst, brightening, decline and rebrightening are puzzling, but consistent with a model for GRB (and later on for SGR), made by precessing spinning and blazing gamma collimated Jets (solid angle about 10^-8 sr). See ref. below. The GRB is associated to a blazing Jet whose peak power is like a Supernova one (but apparent as GRB power). In a very small near-by cosmic volumes as GRB 060218 at z=0.0331 or GRB980425 at z=0.008, it is quite off-axis (a few degree). The off-axis geometry increase the probability to be found and reduce its apparent luminosity (underluminous GRB). The spinning-precessing jet lead to inner fast variability, rebrightenings and while shining away, the smooth GRB decay. In analogy, but at much lower power and therefore at nearer distances later on, comparable and longeve X-Jet-pulsars are blazing as SGR. The persistent precessing jet offer multi optical rebrightening and-or permits un-correlation with earlier SN. Hadron material around the SN make the GRB event a possible TeV source observable by Milagro or ARGO,Hess and MAGIC, an UHECR source in Auger and Hires,a UHE neutrino source for AMANDA and Baikal (see DF and M.G. Nuovo Cim. 28 C.N 4-5.p.813-816. astro-ph/0505150). The GRB maybe obsevable by its PeVs Glashow neutrino while inducing air-showers at horizons or EeV Tau air-showers below the MAGIC horizons (see astro-ph/0511597). In conclusion: The presence (but even the already absence) in near days of a complete SN rise combined with multi-bumps (optical and-or radio rebrightening) will stand for a definitive long live (but decaying) precessing Jet, blazing within an earlier SN shell. Its possible late Jet blaze has been and it maybe observed in future X flare again (if shining online to us). On the contrary the rise of an unique dramatic SN bump a few days later the observed brightening and rebrightening of the GRB, will be the clear hint that GRB-SN explosion maybe preceeded by a persistent SGR Jet activity whose culmination ends into a the catastrophic SN-GRB most powerfull beamed event. This scenario may be still marginally coexisting with previous one , if a Jet activity may trigger the star collapse and survive the SN explosion. see D.F. ATEL # 31; by DF, 15 Jul 1998; "On the nature of GRB-SGRs blazing jets" in Astron. Astrophys. Suppl. Ser. 138, 507-508; and or more recent astro-ph/0501403 in D.F. Chin.J.Astron.Astrophys.3,3 (2003) 472-482. This message may be cited Daniele Fargion E_mail: daniele.fargion@roma1.infn.it Phone: +390649914287 Fax: +39064957697 ---------------------------------------------- //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4822 SUBJECT: GRB 060218/SN 2006aj: Swift-BAT fluence and peak flux DATE: 06/02/23 21:19:22 GMT FROM: Takanori Sakamoto at NASA/GSFC T. Sakamoto (GSFC/ORAU), L. Barbier (GSFC), S. Barthelmy (GSFC), J. Cummings (GSFC/ORAU), E. Fenimore (LANL), N. Gehrels (GSFC), D. Hullinger (UMD), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC), G. Sato (ISAS), J. Tueller (GSFC), on behalf of the Swift-BAT team: We report further analysis of BAT GRB 060218/SN 2006aj (trigger #191157) (Cusumano, et al., GCN 4775, Barbier, et al., GCN 4780, Nousek, et al., GCN 4805). The time-averaged spectrum from T-8 to T+2732 is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.5 +- 0.1. The fluence in the 15-150 keV band is 6.8 +- 0.4 x 10^-6 erg/cm2. The peak energy flux in 1.6 sec time interval starting from T+455.2 sec in the 15-150 keV band is 2.0 +- 1.1 x 10^-8 erg/cm2/sec. Using the redshift of z=0.033 (Soderberg, et al., GCN 4804), the isotropic equivalent energy, Eiso, is 1.9 +- 0.1 x 10^49 erg, and the peak luminosity, Liso, is 6 +- 3 x 10^46 erg/s in 15.5 keV - 154.8 keV at the GRB rest frame. This Eiso is comparable to that of the one of the softest X-ray flash XRF 020903 observed by HETE-2 (Sakamoto et al., ApJ, 602, 875, Soderberg et al., ApJ, 606, 994). The Liso is comparable to that of GRB 980425/SN 1998bw (Galama et al., Nature, 395, 670). Note that the BAT Eiso and Liso of GRB 060218 are not bolometric values due to its narrow energy band. All the quoted errors are at the 90% confidence level. We use Omega_M = 0.3, Omega_lamda = 0.7, and H0 = 65 in the calculation of the luminosity distance. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4828 SUBJECT: GRB 060218: Refined analysis of the radio afterglow DATE: 06/02/24 23:31:34 GMT FROM: Dale A. Frail at NRAO Alicia M. Soderberg (Caltech) and Dale A. Frail (NRAO) report on behalf of a larger collaboration: "Using additional data we have been able to obtain a flux calibration of the radio afterglow detected with the VLA on February 20.01 UT (GCN 4794). At 8.46 GHz the peak flux density was 453 +/- 77 microJy at a position (epoch J2000) of R.A.=03:21:39.683, dec.+16:52:01.82, with conservative errors of +/-0.06 arcsec. Further observations are planned. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4830 SUBJECT: GRB 060218/SN 2006aj: RBO optical observations DATE: 06/02/25 07:56:19 GMT FROM: Chris Rodgers at U of Wyoming C. Rodgers (U of Wyoming), D. Allen (U of Wyoming), Marc Herman (U of Wyoming), R. Rodgers (ACSD#1), R. Canterna (U of Wyoming) report on behalf of the Red Buttes Observatory (0.6m) GRB Team as part of the FUN GRB Collaboration. We responded to the rebrightening of GRB 060218/SN 2006aj at the position reported by Kennea et al. (GCN 4776) at 2006/02/25 01:47:07 UT. We took 10 minute exposures in BVRI over 4 different epochs. The data are presented below in magnitudes with a S/N > 14.0. Each of the BRI magnitudes were obtained using the USNO B1.0 catalog, and the V magntudes were determined from Cool et al. (GCN 4777) SDSS g and r data by using Smith et al. (2002) transformation equations. B V R I UT (B) 18.140 17.116 17.240 16.369 01:47:07 18.134 17.294 17.214 16.248 02:46:14 18.188 17.312 17.243 16.301 03:46:55 18.054 17.288 17.212 16.128 04:30:42 This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4831 SUBJECT: GRB 060218/SN 2006aj: WIRO optical observations DATE: 06/02/25 09:00:04 GMT FROM: Chris Rodgers at U of Wyoming C. Rodgers, D. Allen, B. Barlow, C. Garcia, M. Pierce, R. Canterna (U of Wyoming) report on behalf of the Wyoming Infra-Red Observatory (2.3m) GRB Team as part of the FUN GRB Collaboration. GRB 060218/SN 2006aj was observed at the postion reported by Kennea et al. (GCN 4776) at 2006/02/25 02:03:49 UT in Johnson B. The following B magnitudes were determined using the USNO B1.0 catalog with a S/N ~ 180. B (mag) B err (mag) UT 18.250 0.007 02:03:49 18.281 0.006 02:09:48 18.276 0.006 02:33:12 18.295 0.006 02:51:45 18.282 0.007 02:57:13 18.259 0.006 03:14:08 18.245 0.006 03:19:32 18.293 0.011 04:52:09 18.245 0.010 04:57:32 This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4832 SUBJECT: GRB 060218 : Radio upper limits from GMRT DATE: 06/02/25 10:42:05 GMT FROM: Atish Kamble at Raman Research Inst Atish Kamble (Raman Research Institute [RRI], Bangalore, India), C. H. Ishwara Chandra (NCRA, Pune, India) and D. Bhattacharya (RRI) report on behalf of a larger GRB collaboration : The Giant Meterwave Radio Telescope (GMRT), India observed the field of GRB 060218 (GCN 4775, GCN 4776, GCN 4779) on 20 Feb. 2006 (between 14.0 UT to 17.0 UT) at 1280 MHz using a bandwidth of 32 MHz. We do not detect any source coincident with the position of optical afterglow (GCN 4779). The 3-sigma upper limit achieved is ~ 0.45 mJy. We thank GMRT and the National Centre for Radio Astrophysics (NCRA) staff. This TOO was done under the GMRT Director's Discretionary Time. GMRT is run by NCRA-TIFR, Pune (INDIA). This messege may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4833 SUBJECT: GRB 060218/SN 2006aj: REM optical and near-infrared observations DATE: 06/02/25 16:53:52 GMT FROM: Daniele Malesani at SISSA-ISAS,Trieste,Italy S. Covino, D. Malesani, E. Molinari, G. Chincarini, F.M. Zerbi, V. Testa, G. Tosti, F. Vitali, L.A. Antonelli, P. Conconi, G. Cutispoto, G. Malaspina, L. Nicastro, E. Palazzi, E. Meurs, P. Goldoni, on behalf of the REM/ROSS team, report: We imaged the field of GRB 060218 (Cusumano et al., GCNs 4775, 4781) with the robotic 60-cm REM telescope located at La Silla, Chile. Observations were performed on 2006 Feb 25 from 00:16 to 00:30 UT under mediocre conditions just after the La Silla sunset with the R and J filters. REM is equipped with the REMIR near-infrared camera (10x10 arcmin^2 FoV, JHK filters) and the ROSS optical spectrograph/imager (10x10 arcmin^2 FoV, VRI filters and AMICI prism). The optical counterpart (Cusumano et al., GCN 4775; Marshall et al., GCN 4779; Mirabal et al., GCN 4784) was detected in both bands with magnitudes: R = 17.05 +- 0.17 J = 16.90 +- 0.20 Calibration was based on the SDSS and 2MASS catalogs for the optical and near-infrared observations, respectively. This message is citeable. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4834 SUBJECT: GRB 060218/SN 2006aj: ABT observations DATE: 06/02/25 17:40:22 GMT FROM: Klaas Wiersema at GRACE/U of Amsterdam K. Wiersema (University of Amsterdam) and F. Nieuwenhout report on behalf of the AWSV "Metius" ABT collaboration: "We observed GRB060218/SN 2006aj (Cusumano et al., GCN 4775) with the amateur 0.25m ABT telescope, from Alkmaar, The Netherlands, under moderate observing conditions. Starting from Feb 24 17:58 UT, a series of 1 minute exposures in V band were acquired, ending at 18:38 UT. 28 exposures were combined. The object is detected and we measure V = 17.37 +/- 0.21, using SDSS g' and r' data from Cool et al. (GCN 4777) and the transformation equations by Smith et al. (2002). We like to point out the suitability of this supernova for intensive amateur follow-up. The ABT telescope is an internet-controlled 0.25m telescope located in Alkmaar, The Netherlands, built and operated by members of local amateur astronomy club "Metius". This detection of GRB060218/SN 2006aj is the first reported detection of an optical GRB afterglow/SN from Dutch soil. We acknowledge the assistance of E. Rol and R. Wijers in making the ABT GRB follow-up program possible." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4838 SUBJECT: GRB 060218/SN 2006aj: K-380 optical observations DATE: 06/02/27 12:07:53 GMT FROM: Sergei Guziy at IAA Elena Pavlenko(CrAO, Crimea), Alex Shlyapnikov (CrAO,Crimea), Sergey Guziy (IAA-CSIC, Granada) , on behalf of a larger collaboration, report: "We imaged the field of GRB 060218 (Cusumano et al., GCNs 4775, 4781) with the K-380 Cassegrain telescope of the Crimean Astrophysical Observatory. Observations of the afterglow have been carried out on 2006 Feb 20 - Feb 23. A series of 2-minute exposures in R(Johnson) band were acquired. Calibration was based on the SDSS catalog. On Feb 20 19:18 - 20:00 UT for 20 combined images, afterglow has magnitude R = 18.00 +/- 0.06 and displayed the brightening of 0.15 mag/day. Further observations are planned." This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4840 SUBJECT: GRB 060218 : GMRT observation [Correction and Improvement] DATE: 06/02/27 16:41:08 GMT FROM: Atish Kamble at Raman Research Inst Atish Kamble (Raman Research Institute [RRI], Bangalore, India), C. H. Ishwara Chandra (NCRA, Pune, India) and D. Bhattacharya (RRI) report on behalf of a larger GRB collaboration : The date of GMRT observation of GRB 060218 reported in GCN 4832 has a typo. The correct date of observation was 21 Feb 2006 and not 20 Feb 2006. Our apologies for the inconvenience it might have caused. With further analysis of the data (same observation) we could improve the upper limits on the radio afterglow flux of GRB 060218. We now put a 3 sigma upper limit of ~ 0.3 mJy. This messege may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4842 SUBJECT: GRB060218/SN 2006aj: optical observation DATE: 06/02/28 10:44:29 GMT FROM: Alexei Pozanenko at IKI, Moscow E. Pavlenko, Yu. Efimov, A. Shlyapnikov, V.Rumyantsev (CrAO), A.Pozanenko (IKI) on behalf of a larger collaboration report: We observed GRB 060218/SN 2006aj (Cusumano et al. GCN 4775) with CrAO Shajn 2.6m telescope on Feb. 23. A series of BVRI 30 s exposures were taken starting (UT) 19:27. Using SDSS pre-burst observations (Cool et al. GCN 4777) we estimate brightness of the optical afterglow + SN in R: Mid time, exp., R mag (UT) (s) Feb.23 19:32 8x30 s 17.40 +/- 0.01 Feb.23 19:58 8x30 s 17.41 +/- 0.01 The values is compatible with the brightening rate ~0.2 per day between Feb. 20 and Feb. 23 reported earlier (Ovaldsen et al, GCN 4818, Pavlenko et al, GCN 4838). //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4843 SUBJECT: GRB060218/SN 2006aj: optical observation in V DATE: 06/02/28 10:49:31 GMT FROM: Alexei Pozanenko at IKI, Moscow M. Andreev (Institute of Astronomy), E. Pavlenko (CrAO), A. Pozanenko (IKI) on behalf of larger GRB follow up collaboration report: We observed GRB 060218/SN 2006aj (Cusumano et al. GCN 4775) in V-band with the 60 cm telescope of peak Terskol observatory on Feb. 22 and Feb. 23. A series of 60 s exposures were taken in both epochs. Using SDSS pre-burst observations (Cool et al. GCN 4777) we estimate brightness of the optical afterglow + SN: Mid time, exp., V mag (UT) (s) Feb.22 17:08 147x60 s 18.00 +/- 0.01 Feb.23 18:20 12x60 s 17.82 +/- 0.03 The brightening rate in V between Feb. 22 and Feb. 23 is 0.16m per day. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4845 SUBJECT: GRB060218: R-band CCD photmetry DATE: 06/02/28 11:19:33 GMT FROM: Rudolf Novak at N.Copernicus Obs/Czech Rep R. Novak (N. Copernicus Observatory in Brno, Czech Republic), report: We have observed filed of GRB060218 (sn 2006aj) for 133 min during night 24./25.2.2006 with the 40cmreflector at N. Copernicus Observatory equipped with ST-7 CCD (R band filter) camera. we have detected source as R aprox. 18mag close to the limit of the combined dframe beacuse of very bad weather conditions (high altitude clouds, wind). More precise photometry may be available in future. This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4846 SUBJECT: GRB060218: Ep,i - Eiso correlation DATE: 06/03/01 16:43:33 GMT FROM: Cristiano Guidorzi at ARI,Liverpool JMU L. Amati (INAF-IASF Bologna), F. Frontera (Ferrara University and INAF-IASF Bologna), C. Guidorzi (Liverpool JM University) and E. Montanari (Ferrara University) report: "Based on the photon index measured by Swift/BAT (2.5+/-0.1 in 15-150 keV, Sakamoto et al., GCN #4822) and Swift/XRT during the prompt emission (1.82+/-0.01 in 0.2-10 keV, Cusumano et al., GCN #4786), it can be inferred that the intrinsic peak energy Ep,i of GRB060218/SN2006aj (at the suggested redshift z=0.03) is < 10 keV and lies probably towards the low energy bound of XRT (i.e. a few keV at most). This information, when combined with the Eiso (1-10000 keV) value of about (5 - 8)x10^(49) erg, as derived on the basis of the preliminary BAT and XRT (first orbit) fluxes and spectra, shows that GRB060218 is likely consistent with the Ep,i - Eiso (Amati) correlation. This behaviour, if confirmed by more refined analysis, is at odds with that of GRB980425/SN1998bw and of the other possibly sub-energetic event GRB031203/SN2003lw, which showed Ep,i and Eiso values completely inconsistent with the correlation (see e.g. Amati, 2006, astro-ph/0601553 for a discussion). Given that one of the most popular explanations of the inconsistency of GRB980425 and GRB031203 with the Ep,i-Eiso correlation is that they were 'normal' GRBs seen at very high off-axis angles (e.g. Yamazaki, Yonetoku & Nakamura, 2003, ApJ 594 L79 , Ramirez-Ruiz et al., 2005, ApJ, 625 L91), this evidence shows that GRB060218 may not be an off-axis event, as also suggested by Nousek et al. (GGN #4805) based on the 'chromatic' behaviour of afterglow light curves measured by Swift." This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4847 SUBJECT: GRB 060218: RTT150 optical observations DATE: 06/03/02 19:13:25 GMT FROM: Rodion Burenin at IKI, Moscow R. Burenin, A. Mescheryakov, M. Pavlinsky, R. Sunyaev (IKI), I. Khamitov, Z. Aslan (TUG), U. Kiziloglu (METU), E. Gogus (Sabanci Uni.), I. Bikmaev, N. Sakhibullin (KSU/AST) report: We observed GRB 060218/SN 2006aj (Cusumano et al., GCN 4775) with Russian-Turkish 1.5-m telescope (RTT150, Bakirlitepe, TUBITAK National Observatory, Turkey) over 3 nights in BVRI. The magnitudes of the object are: Time (UT) B V R I Feb 21.84 18.49 - 17.82 17.53 Feb 22.75 18.20 17.80 17.62 17.40 Feb 25.75 17.98 17.57 17.30 16.89 The photometry is preliminary and is based on our observations of Landolt stars in these and previous nights. This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4853 SUBJECT: GRB060218: analysis of the XMM-Newton observation DATE: 06/03/06 19:28:13 GMT FROM: Andrea De Luca at IASF-CNR,Milano Andrea De Luca (INAF/IASF, Milano) on behalf of a larger collaboration reports: We have analyzed the XMM-Newton observation of the field of GRB060218, discovered by Swift/BAT on 2006, February 18 at 03:34:30 UT (GCN4775, Cusumano et al.) The XMM-Newton observation started on 2006, February 20 at 17:21:45 UT (~61.8 hours after the GRB trigger) and lasted for 14 ks. The observation is affected by a high particle background, which hampers a detailed temporal and spectral analysis of the faint X-ray afterglow. We report here on data collected by the EPIC/pn camera. spanning the time range 223.9-234.9 ks after the trigger. The afterglow of GRB060218 is detected at the following coordinates: RA(J2000): 03h 21m 39.63s, Dec(J2000): 16d 52' 03.4" with an uncertainty of 1.2 arcsec (1sigma), fully consistent with the coordinates of the optical (GCN4779, Marshall et al.) and radio (GCN4828, Soderberg & Frail) afterglow, as well as with the Swift/XRT position (GCN4786, Cusumano et al.). Extracting source events from a circle of 10 arcsec radius (containing ~50% of the total counts) the pn time-averaged, background-subtracted count rate in the 0.5-8 keV range is of 0.017+/-0.002 cts/s. No significant fading of the X-ray flux is detected along the XMM-Newton observation. The time-integrated X-ray spectrum is well fit (reduced chi2=0.98, 14 d.o.f.) by a steep power law absorbed by the Galactic column (NH=1.1e21 cm^-2, Dickey & Lockman, 1990), with a photon index Gamma=3.3+/-0.6 (90% conf. level for a single parameter). The observed flux (0.5-10 keV) is of 5.7x10^-14 erg cm^-2 s^-1, corresponding to an unabsorbed flux of 8.4x10^-14 erg cm^-2 s^-1. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4863 SUBJECT: GRB 060218/SN 2006aj, high resolution spectra DATE: 06/03/12 15:05:08 GMT FROM: Sylvio Klose at TLS Tautenburg E. W. Guenther, S. Klose, Thueringer Landessternwarte Tautenburg, P. Vreeswijk, University of Chile/ESO, E. Pian, INAF-OA Trieste, and J. Greiner, MPE Garching, on behalf of the GRACE collaboration report: ESO's VLT-Kueyen (UT 2) observed SN 2006aj (GRB 060218) around the time of maximum light on March 3/4, 2006. Observations were performed using the Ultraviolet and Visual Echelle Spectrograph (UVES) at a spectral resolution of 46 000. The signal-to-noise ratio of the spectrum (2100 sec exposure time) is about 30 per resolution element, which is sufficient to measure the equivalent width (EW) of the Na I D lines along the line of sight. For the Na I D2 component (lambda 5889.95) produced in our Galaxy we find EW = (0.321 +/- 0.008) Angstrom. Using the empirical relation between the equivalent width of the 5889.95 line and the interstellar reddening (Munari & Zwitter A&A 318, 269, 1997), this corresponds to a Galactic reddening of E(B-V) = (0.127 +/- 0.005) mag. Assuming a ratio of total-to-selective extinction of R_V = 3.1, we obtain a Galactic visual extinction along the line of sight of A_V = (0.39 +/- 0.02) mag. This is slightly less than what follows from the COBE maps (Schlegel, Finkbeiner, & Davis 1998). In the GRB host galaxy we identify two redshift systems at a heliocentric velocity of 10008.1 km/s and 10032.3 km/s (Na I D2) with the following equivalent widths in the observer frame: system I: EW(D2) = (0.084 +/- 0.008) Angstrom, system II: EW(D2) = (0.072 +/- 0.008) Angstrom. Assuming that the aforementioned empirical relation is also representative for the interstellar medium in the GRB host galaxy, and correcting EW for a factor of 1/(1+z) for the host frame, we arrive at a combined reddening of E(B-V) = (0.042 +/- 0.003) mag. If again R_V = 3.1, we obtain a host extinction along the line of sight of A_V = (0.13 +/- 0.01) mag. We finally note that the tiny error bars should not be overinterpreted. They just include the measurement errors but not the systematic error of the method itself, which we cannot quantify. We thank the ESO staff, in particular Dominique Naef, for performing the observations and Alain Smette, ESO, for valuable comments. This message may be quoted. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4866 SUBJECT: GRB060218: SARA Observations of SN2006aj DATE: 06/03/12 23:37:38 GMT FROM: Autumn Homewood at Clemson U A.L. Homewood, C.A. Riddle, K.V. Garimella, M.R. Troutman, D.H. Hartmann (Clemson University) and G.D. Henson (ETSU) report on behalf of the Clemson GRB Follow-Up Team: We have imaged the field of GRB060218 (GCN 4775, 4776) beginning approximately 4 days after the trigger notice with the SARA 0.9-m at Kitt Peak, under good weather conditions. We obtained 9 300-seconds exposures in V filter and 7 300-second exposures in B filter. We detect the supernova in each exposure and have carried out the following data analysis: Observations in V began at UT Feb. 22.0923958 and ended at 22.1539931. We observe magnitudes ranging from V=17.3 to 17.7 +/- 0.2 mag during that time period. Similiarly, observations in B began at UT Feb. 22.096088 and ended at 22.1504167. We observed magnitudes ranging from B=18.2 to 18.7 +/-0.2 mag. These values correspond to single 300-second exposures, and quoted errors are 1-sigma. Further analyses of observations from additional nights are in progress. The Clemson Unversity GRB Response Site may be found at: http://people.clemson.edu/~kgarime/burst/index.php The SARA Homepage can be found at: http://saraobservatory.org This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4898 SUBJECT: GRB060218: Refined photometric calibration of comparison stars DATE: 06/03/20 20:19:10 GMT FROM: Malcolm Hicken at Harvard/Physics Malcolm Hicken (CFA), Maryam Modjaz (CFA), Peter Challis (CFA), Robert Kirshner (CFA), Jose Luis Prieto (OSU), Krzystof Stanek (OSU) and Richard Cool (Arizona) report: The CFA Supernova Group obtained UBVRr'i' photometry of 9 comparison stars in the field of GRB060218/SN2006aj on March 4, 2006 UT. Data was taken using the FLWO 1.2m telescope at Mt. Hopkins, Arizona. We present our V-band light curve in Modjaz, et. al. (2006), astro-ph/0603377, submitted to ApJL. A finding chart, coordinates and photometry can be found at the following website: http://cfa-www.harvard.edu/oir/Research/supernova/sn2006aj_compstars.html It should be noted that our V magnitudes are approximately 0.27 mag fainter than those derived in GCN 4777 by Cool, et. al. at http://mizar.as.arizona.edu/~grb/public/GRB060218. There is also an offset in the other bands. In investigating this photometric offset, Richard Cool has discovered calibration offsets between the two SDSS photometric reductions of this field indicating possible non-photometric conditions or other calibration problems in the SDSS photometry. The problem is being investigated to ensure data with suspicious photometric quality will be flagged as such in future SDSS GRB releases. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4899 SUBJECT: GRB 060218/SN 2006aj, LNA optical observation DATE: 06/03/21 00:14:36 GMT FROM: Antonio Pereyra at IAG-U.Sao Paulo A. Pereyra and A. M. Magalhães (IAG, Univ. of São Paulo) report: We obtained optical imaging of GRB 060218/SN 2006aj (Cusumano et al., GCN 4775) on 2006/March 3.958 (UT) using the IAG-USP 60cm telescope at the Laboratório Nacional de Astrofísica (LNA), Brazil. The observation was made under poor sky conditions and through high airmass (>2). A 90-second exposure in the I filter yielded I = (17.06 +/- 0.10) mag. The zero point calibration was obtained using comparison stars in the GRB field from Hicken et al. (GCN 4898) and Modjaz et al. (astro-ph/0603377). This message can be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4900 SUBJECT: GRB060218/SN2006aj: optical observations DATE: 06/03/22 00:45:36 GMT FROM: Alexei Pozanenko at IKI, Moscow D. Sharapov (MAO, and NOT, La Palma), A. Pozanenko (IKI), and M. Ibrahimov (MAO) on behalf of larger GRB follow up collaboration report: We have observed GRB060218/SN 2006aj (Cusumano et al. GCN 4775) with Maidanak 1.5m telescope in BVR on Feb.27, Mar.08, and in BR bands with NOT/StanCam on Mar.15. The following photometry is based on Modjaz, et. al. (2006, astro-ph/0603377) calibration and the same reference stars in each epochs: Mid time (UT), B, V, R Feb.27.63 18.08 (.01) 17.40 (.01) 17.21 (.01) Mar.08.66 18.98 (.02) 17.83 (.02) 17.39 (.01) Mar.15.86 19.66 (.03) - 17.84 (.02) Only measurement errors are presented. The photometry is preliminary, reduction and observations are continuing. Our observations confirm a maximum of the light curve (Modjaz, et. al. 2006, astro-ph/0603377) between Feb.27 and Mar.08. It is also evident gradual reddening of the SN. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4929 SUBJECT: GRB060218, optical observations DATE: 06/03/27 16:57:54 GMT FROM: Adalberto Piccioni at Astronomy, Bologna U. F. Terra, (Second University of Roma "Tor Vergata"), D. Nanni (INAF/OAR and Second University of Roma "Tor Vergata"), G. Greco, C. Bartolini, A. Guarnieri, A. Piccioni (Bologna University), R. Gualandi, A. De Blasi (INAF Bologna) and G. Pizzichini (INAF/IASF Bologna) report: We observed the OT of GRB 060218/SN 2006aj (Cusumano et al. GCN 4775) in the V and R bands with the 152 cm Loiano telescope equipped with the BFOSC camera system. Observations were carried out on 2006 Mar 7 and 11 under poor observing conditions (seeing=2.7-3.2 arcsec). Using the comparison stars reported by Hicken et al. (GCN 4898), we find the following magnitudes, in agreement with those given by other authors, e.g. Sollerman et al., astro-ph/0603495 and Pian et al., astro-ph/0603530: Mean UT.........filter.....Exptime(s)....... magnitude Mar 07.7506 ......Rc...........300..........17.31+/-0.06 Mar 07.7633.......Rc......... 1200..........17.36+/-0.03 Mar 07.7779.......V...........1200..........17.76+/-0.04 Mar 11.7865.......V............300..........18.15+/-0.08 Mar 11.7962.......V...........1200..........18.11+/-0.06 Mar 11.8123.......Rc..........1200..........17.63+/-0.04 Mar 11.8302.......Rc..........1200..........17.60+/-0.04 One of our images is posted in our public directory from where it can be retrieved by sftp using: hostname: ermione.bo.astro.it username: publicGRB password: GRB_bo. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4932 SUBJECT: GRB 060218SN 2006aj: optical observations at Rozhen Observatory DATE: 06/03/28 13:01:08 GMT FROM: Evgeni Semkov at Inst.of Astronomy,Bulgaria E. Semkov (IA, BAS) on behalf of the BAS/CNRS collaboration report: We observed the afterglow of GRB 060218 (Cusumano et al., GCN 4775; Marshall et al., GCN 4800) with the 2m RCC telescope at the National Astronomical Observatory Rozhen (Bulgaria) on Mar. 21 and 26. The calibration was made using comparison stars from Hicken et al. (GCN 4898) and Modjaz et al. (astro-ph/0603377). Observations were made under good atmospheric conditions through a standard Johnson-Cousins set of filters. The optical counterpart was detected at the following magnitudes: Date, UT(R), I, R, V Mar 21 18:45 17.921 (0.062) 18.340 (0.027) 18.589 (0.026) Mar 26 18:00 18.106 (0.057) 18.429 (0.022) 18.916 (0.024) This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 5358 SUBJECT: GRB 060218 (SN 2006aj): IR afterglow detection six months after the DATE: 06/07/25 11:53:01 GMT FROM: Evgeni Semkov at Inst.of Astronomy,Bulgaria E. Semkov (IA, BAS) on behalf of the BAS/CNRS collaboration report: We observed the afterglow of GRB 060218 (SN 2006aj) six months after the burst. Observations were made with the 2m RCC telescope at the National Astronomical Observatory Rozhen (Bulgaria) on July 24 (UT=01h). The calibration was made using comparison stars from Hicken et al. (GCN 4898) and Modjaz et al. (astro-ph/0603377). Observations were made under good atmospheric conditions, but through high airmass (>2.5). A standard Johnson-Cousins set of filters was used. The optical counterpart was detected at the following magnitudes: I=19.53 (+/-0.07), R=19.97 (+/-0.09) This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 5376 SUBJECT: GRB 060218 / SN 2006aj Nebular Spectrum DATE: 06/08/01 03:39:43 GMT FROM: Ryan Foley at UC Berkeley Spectroscopic Detection of the Late Nebular Phase of SN 2006aj (associated with GRB 060218) R. J. Foley, J. S. Bloom, D. A. Perley, and N. R. Butler (UC Berkeley) report: "We obtained 2x600 sec spectra of GRB 060218 / SN 2006aj (GCN 4775) on 20060726 UT, 153 rest-frame days past the GRB trigger, with Keck I (+ LRIS). The spectrum shows prominent nebular emission lines attributed to [O I] 6300, 6364, Na D, and the Ca II IR triplet. The spectrum resembles the nebular spectrum of GRB 980425 / SN 1998bw at a similar epoch. With a redshift of z = 0.033 (Mirabal & Halpern, GCN 4792), this is the most distant GRB-SN with a observed nebular spectrum. The [O I] line has a velocity width of 10700 km/s, which is quantitatively similar to SN 1998bw 157 rest-frame days past the GRB trigger. The line has one strong peak, with a slight shoulder, attributed to [O I] 6364. There is no obvious asymmetry in this spectrum, consistent with the models of Mazzali et al. (2005, Science, 308, 1284). Further spectroscopic observations are encouraged. A comparison of our spectrum of GRB 060218 / SN 2006aj to a spectrum of GRB 980425 / SN 1998bw can be found at http://astro.berkeley.edu/~rfoley/foley_etal-grb060218.jpg