//////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1530 SUBJECT: GRB020903(=H2314): An X-Ray Flash Localized by HETE DATE: 02/09/03 17:12:01 GMT FROM: Don Lamb at U.Chicago G. Ricker, J-L Atteia, N. Kawai, D. Lamb, and S. Woosley on behalf of the HETE Science Team; R. Vanderspek, J. Doty, J. Villasenor, G. Crew, G. Monnelly, N. Butler, T. Cline, J.G. Jernigan, A. Levine, F. Martel, E. Morgan, G. Prigozhin, G. Azzibrouck, J. Braga, R. Manchanda, and G. Pizzichini, on behalf of the HETE Operations and HETE Optical-SXC Teams; C. Graziani, Y. Shirasaki, M. Matsuoka, T. Tamagawa, K. Torii, T. Sakamoto, A. Yoshida, E. Fenimore, M. Galassi, T. Tavenner, and T. Donaghy, on behalf of the HETE WXM Team; M. Boer, J-F Olive, J-P Dezalay, and K. Hurley on behalf of the HETE FREGATE Team; write: At 10:05:37.96 UTC (36337.96 s UT) on 3 Sep 2002, the HETE WXM and SXC instruments detected event H2314, an X-ray flash. The WXM flight localization was correct but was not set out as a GCN Notice because events which trigger only the WXM are currently not sent out, in order not to overwhelm the community with X-ray burst localizations. Ground analysis of the WXM data for the burst produced a refined location, which was reported in a GCN Position Notice at 13:56:24 UT, 231 minutes after the burst. The WXM location can be expressed as a 90% confidence circle that is 16.6 arcminutes in radius and is centered at RA = 22h 49m 25s, Dec = -20o 53' 59" (J2000). Ground analysis of the SXC data for the burst produced a one-dimensional localization, which -- when combined with the WXM localization -- produced a further refinement in the location. This refined location was reported in a GCN Position Notice at 17:00:34 UT, 7 hrs after the burst. The refined location produced by combining the SXC and WXM localizations can be expressed as a 90% confidence quadrilateral that is 4 arcminutes in width and ~31 arcminutes in length, is centered at RA = 22h 49m 01s, Dec = -20o 55' 47" (J2000). and is defined by RA = 22h 48m 48.00 -20o 39' 36.0" RA = 22h 48m 33.60 -20o 42' 36.0" RA = 22h 49m 10.80 -21o 10' 12.0" RA = 22h 49m 30.00 -21o 10' 48.0" In the WXM 2-25 keV band, the burst had a duration of ~3.3 seconds. The WXM localization SNR was ~10. The SXC localization SNR was ~3. Further information (including a light curve) for GRB020903 is provided at the following URL: http://space.mit.edu/HETE/Bursts/ This message is citable. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1531 SUBJECT: XRF 020903, optical observations DATE: 02/09/03 20:02:15 GMT FROM: Alberto Castro-Tirado at Inst.de Astro. de Andalucia XRF 020903, optical observations ------------------------- P. Tristram (Univ. of Auckland) A. J. Castro-Tirado (IAA-CSIC, Granada) J. Gorosabel (IAA-CSIC, Granada) J. M. Castro Cerón (ROA, San Fernando) P. Kilmartin (Mt. John Univ. Observatory) Y. Furuta (Univ. of Nagoya) Ph. Yock (Univ. of Auckland) communicate: "Following the detection of the X-ray flash 020903 by HETE (Ricker et al. GCN Circ. 1530), we have imaged the entire error box with the 0.6-m (+MOA camera) at Mt. John Observatory in a wide B- and wide R-band filters (600-s and 1200-s respectively) starting on Sep 3.5944 UT (i.e. 4.18 hr after the event). Comparison of the frames with the DSS-2 (R-band) reveals no optical transient down to the DSS-2 limiting magnitude." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1533 SUBJECT: XRF 020903: Optical observations DATE: 02/09/04 14:55:51 GMT FROM: Paul Price at RSAA, ANU P.A. Price, B.P. Schmidt (RSAA, ANU) and T.S. Axelrod (Arizona) report: We have observed the error-circle of XRF 020903 (Ricker et al. GCN #1530) with the robotic 50-inch telescope at Mount Stromlo Observatory beginning at Sep 4.42 UT. Observations consisted of 3x300 sec exposures in R_MACHO and cover the entire error circle to a limiting magnitude of approximately R ~ 19.8 mag. We do not identify any source in our images not present on the DSS2 upon visual inspection. Further observations are planned. This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1535 SUBJECT: XRF 020903: Optical observations DATE: 02/09/05 12:55:58 GMT FROM: Vasilij Rumjantsev at CrAO E.Pavlenko (CrAO), V.Rumyantsev (CrAO) and A.Pozanenko (IKI) report: We have imaged of the error box of XRF 020903 (Ricker et al. GCN #1530) with the 0.38-m Cassegrain telescope of Crimean Astrophysical Observatory (field 7x10 arcminutes). We obtained several frames which include the center of error box and partially covered its area on 2002 Sept. 3.9203 (12h after the burst) - 3.9540 UT. We did not identify any afterglow candidate by visual comparison with the DSS2 to a limit approximately R ~ 17.4 mag. Images will by posted shortly in http://grb.rssi.ru/XRF020903. This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1537 SUBJECT: XRF 020903: optical observation at Kyoto DATE: 02/09/06 11:26:27 GMT FROM: Taichi Kato at Kyoto U M. Uemura, R. Ishioka, T. Kato (Kyoto U) and H. Yamaoka (Kyushu U) report on behalf of VSNET-grb collaboration: "We have performed a full analysis of unfiltered CCD images of XRF 020903 (GCN 1530) taken with 25-cm telescope at Kyoto. The observation starts on Sept. 3.595 UT, i.e., 4.2 hours after the flash detection. We imaged the central region of initial XWM error circle, so the coverage of WXM+SXC error box is as rather small as 10%. Our field of view is described in: http://www.rc.kyushu-u.ac.jp/~yamaoka/XRF020903/FOV.gif . It contains the central region of the cluster Abell 2487. A stacked image (30s x 60 exposures), whose limiting magnitude is R ~ 17.5 compared with USNO-A2.0 r mag, revealed no definite new source within our image compared with DSS 2 red image. (Note: XRF 020903 occurred at a location very close to GRB 990527 (GCN 347). The WXM+SXC error box of XRF 020903, however, does not overlap the IPN error box of GRB 990527, as shown in FOV.gif mentioned above.)" This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1554 SUBJECT: XRF 020903: Supernova DATE: 02/09/29 05:12:28 GMT FROM: Alicia Soderberg at Caltech A.M. Soderberg, P.A. Price, D.W. Fox, S.R. Kulkarni, S.G. Djorgovski, E. Berger and F. Harrison, S. Yost (Caltech); M. Hamuy and S. Shectman (OCIW); E. Armstrong, C. Espaillat N. Mirabal and J. Halpern (Columbia); and J. Kemp (Joint Astronomy Center and Columbia) report: We imaged the entire error-box of XRF 020903 with the Palomar 200-inch telescope + Large Format Camera (LFC) on Sep 4.3 UT (epoch 1) and Sep 10.3 UT (epoch 2) in Steidel R-band. Visual comparison of these images with the Digitised Sky Survey and with each other did not reveal any obvious transient. Recently, we undertook a more detailed analysis, namely PSF-matched image subtraction of these two epochs, and found an optical transient (OT) located at coordinates: RA: 22:48:42.34 Dec: -20:46:09.3 J2000 with a bright elliptical galaxy 4 arcsec SE (hereafter G2). The source is also present in images from the MSO 50-inch telescope (GCN #1533) when the second epoch LFC image is subtracted. Upon discovery of the OT, we immediately pursued further observations, thereby obtaining a third epoch of imaging with the MDM 1.3-meter telescope on Sep 28.3 UT in the R-band. Initial photometry demonstrates that the object has re-brightened by ~ 0.3-0.4 mag between epochs 2 and 3. We propose that this optical rebrightening is from an associated supernova, peaking between ~7-24 days after the initial XRF trigger. Spectroscopic observations by M. Hamuy and S. Shectman for the source were also obtained with the Magellan 6.5m telescopes (Baade+LDSS2, Clay+B&C) on Sep 28.1 UT. We detect narrow emission lines from an underlying host galaxy (hereafter G1) are (Halpha, Hbeta, Hgamma, [O III], [Ne III], [O II]) at a mean redshift of z = 0.25 +/- 0.01. Subtraction of the emission lines reveals a continuum that is consistent with a SN-like transient near maximum. In particular, the spectrum reveals deficit of emission at rest wavelengths < 4000A, as would be expected from a SN. Spectra of G2 (R ~ 17 mag) reveal it to be an elliptical galaxy at z = 0.23 and therefore is not associated with the optical transient. If the OT is indeed associated with XRF020903, it is the first known optical afterglow of an XRF, and may be the most nearby cosmological high energy transient known yet. Parenthetically we note that microlensing from G2 may result in sharp variations of the light curve (see Garnavich, Loeb and Stanek, 2000). We encourage further monitoring of this OT/SN. A web page summarizing the discovery and subsequent observations can be found at: http://www.astro.caltech.edu/~ams/XrF.html This message may be cited. [GCN OPS NOTE (29Sep02): Three names were added to the author list.] //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1555 SUBJECT: Radio Observations of XRF 020903: The Missing Link DATE: 02/09/29 06:22:30 GMT FROM: Edo Berger at Caltech E. Berger, S. R. Kulkarni, D. A. Frail, A. Soderberg, P. A. Price, D. W. Fox, F. A. Harrison, and S. Yost report on behalf of the larger Caltech-NRAO-CARA GRB collaboration: Following the discovery of the optical transient of GRB 020903 (GCN #1530) by Soderberg et al. (GCN #1554), we observed the position of the OT with the VLA on Sep. 27.22 UT. We detect a bright radio source at the position of the OT, with a flux of 1.1 mJy at 8.46 GHz. The source is not detected in the NRAO VLA Sky Survey (NVSS; Condon et al. 1998, AJ, 115, 1693) above their flux limit of 1 mJy at 1.4 GHz. Observations undertaken today (Sep. 29.11 UT) show that the source is fading with a flux of 0.7 mJy at 8.46 GHz. The variable radio counterpart lends supports to the identification of the optical transient (OT) reported by Soderberg et al. as the afterglow of XRF 020903. Unlike the optical emission, the radio emission is dominated by the afterglow. The isotropic, prompt energy release of XRF 020903 (using the redshift of z=0.25, GCN #1554, and a rough estimate of the fluence detected by WXM; see the HETE-2 web page: http://space.mit.edu/HETE/Bursts/GRB020903/) is well below those of typical cosmological GRBs but higher than that of GRB 980425. Therefore, the energy in relativistic ejecta of XRF 020903 is intermediate between that of SN1998bw, about 10^49 erg, as inferred from the radio emission (Kulkarni et al. 1998, Nature, 395, 663), and that of typical cosmological GRBs. Finally, the ratio of energy in the relativistic ejecta to the energy in the SN of XRF 020903 is well below those of cosmological GRBs (typically 1-10), but higher than SN1998bw (~0.01). These arguments suggest that XRF 020903 is a "transition" object -- a link between GRB 980425 and comsological GRBs. Scaling the ratio of radio to X-ray luminosity of SN1998bw to XRF 020903, we predict detectable X-ray emission on this timescale, which may be an additional robust indicator of the relativistic energy in the ejecta. See http://www.astro.caltech.edu/~ams/XrF.html for a full discussion. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1556 SUBJECT: XRF 020903: Archival Optical Images DATE: 02/09/29 19:46:04 GMT FROM: Edo Berger at Caltech A. Gal-Yam (Tel Aviv University) reports: "We have extracted from the USNO plate archive (http://ftp.nofs.navy.mil/data/fchpix/) two blue plates, covering the location of the variable object possibly connected with XRF 020903, reported by Soderberg et al (GCN 1554). Inspecting these plates we find the following: 1) A plate obtained on UT 1977.6 reveals an object, coincident with the variable source reported by Soderberg et al. The B-band magnitude of this object appears to be about one magnitude fainter than that of the nearby galaxy noted as "G2" by these authors. 2) Comparison of the 1977 plate with the (much poorer) POSSI blue plate obtained on 1954.6 may suggest a variation of the flux ratio between the source coincident with the Soderberg et al. variable, and the galaxy G2, with G2 being brighter on the 1977 plate, but possibly fainter than the source reported by Soderberg et al., in 1954. This may hint that this source was variable in the past. We stress, however, that the 1954 data are quite poor, so past variability can not be ascertained at this stage. GIF Cutouts from both plates, showing the area around the Soderberg et al. variable, can be obtained from ftp://wise3.tau.ac.il/pub/avishay/xrf. These can be compared with the Palomar data shown by Soderberg at http://www.astro.caltech.edu/~ams/XrF.html. The source detected on the 1977 plate may be hard to interpret as a possible "host" galaxy for the Soderberg et al. transient, even if we disregard its possible past variability. Soderberg et al. report that this source is not detected on POSSII red plates, and estimate a magnitude of R=22 from their OT+SN+host model. This fact can be reconciled with the 1977 B-band data, showing this object only about 1 magnitude fainter than G2 (which has R=17 mag), if this object has a very blue B-R color. However, this appears to be in contradiction with the Magellan spectrum presented by Soderberg et al., which is flat, or possibly even red, in B-R. An alternative explanation fitting both the archival analysis and the entire data set presented by Soderberg et al. and Berger et al (GCN 1555) is that this source is a variable radio-loud AGN. We have recently shown (Gal-Yam et al. 2002, PASP, 114, 587) that such objects can appear to be very similar to optical transients associated with GRBs. Further inspection of archival data, as well as further observations (B-band especially), can distinguish between an OT+SN model, and an AGN, according to their variability properties. If an AGN, the source discovered by Soderberg et al. may still be related to XRF 020903. However, in that case, a SN component no longer seems to be required. Until this issue is clarified, we urge some caution in interpreting the Soderberg et al. data set as evidence for a connection between XRF 020903 and a SN. This work has made use of the USNOFS Image and Catalogue Archive operated by the United States Naval Observatory, Flagstaff Station (http://www.nofs.navy.mil/data/fchpix/)." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1557 SUBJECT: XRF 020903: R band observations DATE: 02/09/29 21:36:32 GMT FROM: Andrew S. Fruchter at STScI A. Fruchter, L. Strolger, B. Mobasher, J. Rhoads, A. Levan, I. Burud (STScI), A. Becker (Lucent) report for a larger collaboration: We observed the field of XRF 020903 on both September 3.1 and 9.1 (UT) using the Mosaic imager on the CTIO 4-m telescope. Images were taken in B, R and I on the first night and in only R on the second. An image subtraction performed shortly after the second night showed no variability consistent with that expected of a GRB/XRF. In light of the report of the possible discovery of a counterpart to this object (GCN 1554) we have re-examined our data. We find that the object cited as the possible counterpart declined by approximately 0.2 mags in R between our two epochs. Unfortunately, we do not have a reliable absolute calibration of the field at this moment. We expect that a better calibration and more complete analysis will be available on a relatively short timescale. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1558 SUBJECT: GRB 020903: correction to GCN 1557 DATE: 02/09/29 21:52:35 GMT FROM: Andrew S. Fruchter at STScI The date of the first observations of GRB 020903 on the CTIO 4-m reported in GCN 1557 should have read "September 4.1". //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1560 SUBJECT: XRF 020903: VRI observations DATE: 02/09/30 19:52:42 GMT FROM: Daniele Malesani at Brera Astro. Obs. M. Stefanon, S. Covino, D. Malesani (INAF, Merate Obs., Milan, I), N. Masetti (IASF/CNR, Bologna, I.), G. Temporin (Inst. fur Astr. Innsbruck, A), and S. Desidera (Padova Astr. Obs., I), on behalf of a larger Italian collaboration, communicate: We observed the variable source in the field of XRF 020903 (Ricker et al., GCN 1530; Soderberg et al, GCN 1554) on 29.9 UT, with the 182cm telescope at Cima Ekar-Asiago, near Padova (Italy). The object was at high airmass. We find the following magnitudes with respect to the USNO stars (1) and (2) reported in the finding chart of Soderberg et al. (see http://www.astro.caltech.edu/~ams/XrF.html ): Filter UT OT - (1) OT - (2) -------------------------------------- V 29.923 4.20+-0.09 2.82+-0.09 R 29.931 2.63+-0.01 1.34+-0.01 I 29.937 4.50+-0.13 5.85+-0.13 In the I-band image (300 s exposure), the object is barely visible. Using the USNO R-magnitudes for the stars 1 (R = 16.0) and 2 (R = 17.1), we find R = 18.55 +- 0.2 @29.931 UT (26.5 days after XRF), where the error is mainly due to calibration. More accurate photometry will be distributed when available. Our data suggest further brightening between 28.3 and 29.9 UT, with respect to the value found in Soderberg et al. web page. With present data, we cannot say if the varying source is a rising supernova or a variable radio-loud AGN, as suggested by Gal-Yam (GCN 1556). Further observations are planned this night. This message is citeable. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1561 SUBJECT: XRF 020903: Correction to GCN 1560 DATE: 02/09/30 21:32:57 GMT FROM: Daniele Malesani at Brera Astro. Obs. M. Stefanon, S. Covino, D. Malesani (INAF, Merate Obs., Milan, I), N. Masetti (IASF/CNR, Bologna, I.), G. Temporin (Inst. fur Astr. Innsbruck, A), and S. Desidera (Padova Astr. Obs., I), on behalf of a larger Italian collaboration, communicate: We have found that the star named (2) in our previous circular (GCN 1560) was actually saturated in our images. We hence removed it from our analysis. Here is the whole correct text. We observed the variable source in the field of XRF 020903 (Ricker et al., GCN 1530; Soderberg et al, GCN 1554) on 29.9 UT, with the 182cm telescope at Cima Ekar-Asiago, near Padova (Italy). The object was at high airmass. We find the following magnitudes for the suspect afterglow (AG) with respect to the USNO star (1) reported in the finding chart of Soderberg et al. (see http://www.astro.caltech.edu/~ams/XrF.html ): Filter UT Exposure AG - (1) ------------------------------------ V 29.923 600 sec 4.20+-0.09 R 29.931 600 sec 2.63+-0.01 I 29.937 300 sec 4.50+-0.13 In the I-band image, the object is barely visible. Using the USNO R-magnitude for the reference star (1), R = 16.0 (star 2 is saturated), we find R = 18.63 +- 0.2 @29.931 UT (26.5 days after XRF), where the error is mainly due to calibration. More accurate photometry will be distributed when available. Our data suggest further brightening between 28.3 and 29.9 UT, with respect to the value found in Soderberg et al. web page. With present data, we cannot say if the varying source is a rising supernova or a variable radio-loud AGN, as suggested by Gal-Yam (GCN 1556). Further observations are planned tonight. This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1562 SUBJECT: GRB 020903: Optical observations at RIKEN DATE: 02/10/01 11:18:09 GMT FROM: Ken ichi Torii at RIKEN K. Torii (RIKEN) and H. Yamaoka (Kyushu Univ.) report: The entire WXM error circle of XRF 020903 (Ricker, et al. GCN 1530) was observed at RIKEN with the 0.25-m reflector equipped with unfiltered cooled CCD AP6E. The observation started at 2002 September 3.6479 UT (5.23 hours after the burst trigger) and 20-s exposures were repeated. The first 168 frames, obtained between 3.6479 and 3.6965 UT, have been stacked and inspected for the variable source (hereafter VS) found by Soderberg, et al. (GCN 1554). In our image (4".2/pixel) a spatially unresolvable source is detected at (R.A., Dec.) = (22:48:42.37, -20:46:13.0) (J2000). The position is derived by using 12 comparison stars from UCAC1 and the fitting error is 0".3 in both coordinates. This position is closer to the galaxy G2 (as tabulated in USNO-A2.0) rather than to the VS. We also find that the flux for the spatially unresolved G2+VS was 2.0+/-0.2 mag fainter than the star 1 in the finding chart of Soderberg et al. (GCN 1554), which is consistent with the magnitude difference (G2 - star 1 = +2.17) in GSC-2.2.1 F magnitude. These results, both astrometrically and photometrically, show that the VS was much fainter than the galaxy G2 during our observation. ========== //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1563 SUBJECT: XRF020903: TNG and Asiago photometry DATE: 02/10/03 08:43:21 GMT FROM: Stefano Covino at Brera Astronomical Observatory Covino S., Malesani D., Ghisellini G., Stefanon M., Tavecchio F. (INAF-OAB), Covone G., Fugazza D. (INAF-TNG), Di Paola A., Israel G.L. (INAF-OAR), Mannucci F. (IRA-CNR), Masetti N. (IASF-CNR), Pian E. ((INAF-OAT), on behalf of a larger Italian collaboration, report: We observed the varying source (VS) in the field of XRF 020903 (Ricker et al., GCN 1530; Soderberg et al., GCN 1554) on Oct 1.9 UT, with the Italian 3.5m TNG telescope, using BVRI filters. Seeing conditions were moderate (about 1.5 arcsec) and airmass about 1.6. Magnitudes were derived by PSF fitting photometry. One standard star field was also observed under clear (but not photometric) conditions; therefore a small zeropoint offset is still possible. The magnitudes for the VS are the following: Filter UT Magnitude ----------------------------- B 1.941 21.87 +- 0.06 V 1.932 21.14 +- 0.04 R 1.916 20.60 +- 0.09 I 1.919 20.29 +- 0.07 For comparison, we also report the magnitudes of some nearby USNO stars; U0675_37142330 is named "star 1" in Soderberg et al. finding chart. U0675_37143953 U0675_37141960 U0675_37142330 ---------------------------------------------- B 18.54 +- 0.02 19.51 +- 0.02 17.14 +- 0.01 V 17.77 +- 0.01 19.02 +- 0.01 16.40 +- 0.01 R 17.21 +- 0.04 18.63 +- 0.04 15.92 +- 0.03 I 16.81 +- 0.03 18.36 +- 0.03 15.58 +- 0.03 Based on the photometry performed at the TNG, we re-analyzed data obtained on Sep., 29.9 UT with the Asiago telescope (GCN 1561). Seeing conditions were mediocre (about 2 arcsec) and airmass about 2. Magnitudes were again derived by PSF fitting photometry. We report the following results for the VS: Filter UT Magnitude ----------------------------- V 29.923 20.94 +- 0.12 R 29.931 20.42 +- 0.10 I 29.937 19.98 +- 0.13 The source has simultaneously faded by about 0.2 mag in all V, R and I bands between Sep 29.9 and Oct 1.9. Comparing with the R-band measurement by Soderberg et al. on Sep 28.3, the source appears fainter by more than 1 magnitude. A color-color diagram, together with a BVRI spectrum and a light curve are shown at the web page: http://www.merate.mi.astro.it/~malesani/XRF020903 . The values reported here supersede those in our GCN 1561, that were based on a misidentification of the reference star. We apologize for any inconvenience this may have caused. Detailed analsys of these data is still in progress, and more observations will be performed in the next few days. This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1571 SUBJECT: XRF020903, BVRI field photometry DATE: 02/10/04 22:32:34 GMT FROM: Arne A. Henden at USNO/USRA A. Henden (USRA/USNO) reports on behalf of the USNO GRB team: We have acquired BVRcIc all-sky photometry for a 20x20 arcmin field centered at the variable object coordinates for XRF020903 (Ricker et al. GCN 1530; Soderberg et al. GCN 1554) with the USNOFS 1.0-m telescope on one photometric night. Stars brighter than V=14.0 are saturated and should be used with care. We have placed the photometric data on our anonymous ftp site: ftp://ftp.nofs.navy.mil/pub/outgoing/aah/grb/xrf020903.dat The astrometry in this file is based on linear plate solutions with respect to UCAC2. The external errors are less than 100mas. While the night was photometric, the XRF field is towards our southern horizon and so there is a higher risk of zeropoint errors. We estimate the present zeropoint errors to be about 0.03mag. We will be extending this calibration with additional nights to ensure against a systematic zeropoint error. You should check the dates on the .dat file prior to final publication to get the latest photometry. In particular, the two stars marked on Soderberg et al. finding chart have the following position and magnitudes: RA (J2000) DEC V B-V V-R R-I Star 1 22:48:36.05 -20:44:34.8 16.381 0.789 0.455 0.399 Star 2 22:48:53.48 -20:43:23.1 14.743 0.466 0.304 0.313 These values match closely those given in Covino et al. (GCN 1563). Calibration of the GRB021004 field will occur around October 9 UT. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1609 SUBJECT: XRF 020903 spectrum DATE: 02/10/09 06:51:57 GMT FROM: Ryan Chornock at UC Berkeley R. Chornock and A. V. Filippenko, University of California, Berkeley, report that an optical spectrum (range 300-940 nm) of the proposed optical transient (OT) associated with XRF 020903 (GCN 1554) was obtained with the Low Resolution Imaging Spectrometer on the Keck-I 10-m telescope on Oct. 8 UT. Our spectrum is similar to that obtained by Hamuy & Shectman (GCN 1554), revealing a rich set of narrow emission lines associated with the host galaxy. The host is clearly a low-metallicity, high-excitation starburst galaxy, with high [O III]/H-beta and low [N II]/H-alpha intensity ratios; [Ne III] is also visible. The shape of the underlying continuum suggests the presence of an older population of stars as well. While we cannot yet rule out a contribution from an optical supernova (rather than some other type of OT), at this time there is little if any direct spectroscopic evidence for supernova features. Specifically, the deficit at rest wavelengths below 4000A (mentioned in GCN 1554) is consistent with a population of old to intermediate-age stars. This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1631 SUBJECT: XRF 020903: flattening of the optical light curve. DATE: 02/10/13 09:51:48 GMT FROM: Javier Gorosabel at LAEFF-INTA, Madrid J. Gorosabel (IAA-CSIC), J. Hjorth, H. Pedersen, B.L. Jensen (Univ of Copenhagen), J.P.U. Fynbo (Univ. of Aarhus), M. Andersen (AIP Potsdam), J.M. Castro Cerón (ROA, San Fernando), A.J. Castro-Tirado (IAA-CSIC) report: We have imaged the transient source present in the field of XRF 020903 (GCN 1530, GCN 1554) with the 1.54-m Danish Telescope around Oct 10.2 UT, yielding the following preliminary BVR-band magnitudes: B = 21.89 +/- 0.15 V = 21.07 +/- 0.12 R = 20.54 +/- 0.12 The observations we carried out with a mean seeing of 1". The zeropoint is based on the calibration given in GCN 1571. These magnitudes agree with the ones measured on Oct 1.9 UT for the transient source (GCN 1563). The source seems slightly elongated in the North-East direction at can be seen in at: http://www.dsri.dk/~jgu/grb020903/FCs/grb020903.R1.gif http://www.dsri.dk/~jgu/grb020903/FCs/grb020903.R2.gif Thus, our measurements are consistent with i) a flattening of the light curve due to an underlying host or ii) with a transitory plateau phase spanning at least 8.3 days (from Oct 1.9 to Oct 10.2 UT). The elongated appearance of the object supports the first hypothesis (i). A combination of both effects could be also possible. Further observations are planned. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 1761 SUBJECT: XRF 020903 : HST observations DATE: 02/12/17 18:59:13 GMT FROM: Andrew Levan at U.of Leicester Andrew Levan (U. Leicester/STScI), Andrew Fruchter, Lou Strolger, Ingunn Burud and James Rhoads (STScI) report for the GOSH collaboration. The candidate optical transient for XRF 020903 (Soderberg et al, GCN 1554) was imaged with HST/ACS in F606W on 3rd Dec 2002. 4 dithered exposures were obtained with a total exposure time of 1840s. The candidate appears to be within an irregular galaxy, with four (possibly interacting) components. Astrometry with images obtained with the CTIO 4-m telescope and Mosaic imager on Sept 4th and 9th 2002 (Fruchter et al, GCN 1558) shows that the transient source is located at a position coincident with the peak of the most western of these compact knots (with a positional accuracy of approximately ~0."1). The knot has an F606W AB magnitude of 22.6 and a FWHM of ~0."14, greater than the PSF of ACS. Hence the source is resolved at this resolution, indicating that an AGN does not dominate the optical light from this object. The galaxy, named G2 by Soderberg et al, (GCN 1554) is clearly an interacting system. However, as noted by Soderberg et al the redshift difference (z=0.23 for G2 and z=0.25 for the host of the candidate OT) indicate that the systems are not associated. Using a 1" aperture the magnitude of the entire system in F606W is approximately R=21, roughly consistent with the late time magnitudes determined by Gorosabel et al (GCN 1631). Observations taken at a later date will allow a search for further variability in this source. Images of the host galaxy, and surrounding field can be found at http://www.stsci.edu/~fruchter/GRB/020903 //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2761 SUBJECT: XRF 020903: Observations of the Host Galaxy DATE: 04/10/04 16:16:04 GMT FROM: Sabrina Savage at U of Wyoming We observed XRF 020903 with the CTIO 0.9-inch 32, 35, and 37 days after the burst and with the USNO 1.0-meter 32 and 60 days after the burst. We find no evidence for a rebrightening at these times. Zero points for the g' and r' filters used for the CTIO 0.9-meter images were taken from Smith, J. A. et al., 2003, AJ,126, 2037 (Table 3). UBVRI standard star magnitudes were taken from Henden, A. 2002, GCN 1571. Due to poor seeing at USNO and the close proximity of the galaxy complexes, a subtraction routine was performed with limited success on the galaxies labeled G2 + G3 in Soderberg, A. M. et al., 2004, ApJ, 606, 994 (Figure 1) to determine the magnitude of the OT. Within the errors, the magnitude of the OT does not change between one and two months post-burst and is thus taken as the magnitude of the G1 complex (Soderberg et al. 2004). The CTIO images yield average magnitudes of g' = 21.30 +/- 0.07 mag and r' = 20.18 +/- 0.14 mag. The USNO images yield average magnitudes of R ~ 21 mag and I ~ 20.4 mag. These results are very consistent with prior authors regarding the underlying host galaxy; however, the subtraction routine may be a source of systematic error. This message can be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2762 SUBJECT: XRF 020903: Observations of the Host Galaxy (authors) DATE: 04/10/04 16:32:13 GMT FROM: Sabrina Savage at U of Wyoming Authors for GCN 2761: S. Savage, R. Canterna, A. Smith, A. Henden, D. Reichart, M. Nyeswander, FUN GRB group