//////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2640 SUBJECT: GRB 040812: a long GRB detected by INTEGRAL DATE: 04/08/12 06:52:50 GMT FROM: Diego Gotz at IASF-CNR D. Gotz, S. Mereghetti (IASF, Milano), N. Mowlavi, M. Beck, J.Borkowsk (ISDC) on behalf of the IBAS Localization Team report: A 20 s long GRB has been detected with the INTEGRAL Burst Alert System (IBAS) on August 12 at 06:01:50 UT. The GRB has been detected with IBIS/ISGRI in the 15-200 keV band (IBAS Alert # 1901) Its coordinates (J2000) are: R.A. 16h 26m 05s Dec. -44deg 42' 32'' with an uncertainty of 2 arcmin (90% c.l. radius) The preliminary peak flux in the 20-200 keV range is about 0.6 photons/cmsq/s (5E-8 erg/cmsq/s) (1 s integration time). A preliminary spectral analysis inidcates that this event is X-ray rich. This message can be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2642 SUBJECT: GRB040812, optical/IR observations DATE: 04/08/13 18:06:44 GMT FROM: Charles Bailyn at Yale/Astro B. E. Cobb and C. D. Bailyn (Yale), part of the larger SMARTS consortium, report: Using the ANDICAM instrument on the 1.3m telescope at CTIO, we obtained optical/IR imaging of the error region of GRB 040812 (Gotz et al. GCN 2640) beginning ~18.4 hours post-burst (2004-08-13 00:25 UT). Optical imaging in B,V,R and I has a field of view of 6'x6' and, therefore, covers the entire GRB error circle. IR imaging in J, H, K and Y has a smaller field of view and covers a region totalling 3 square arcminutes in the middle of the quoted error region. Several dithered images were obtained in each filter, with total summed exposure times of 180s in each of BRIYJK and 120s in each of H and V. Preliminary visual comparison of the optical images to the SDSS and the IR images to 2MASS frames does not reveal any new sources to the limit of the comparison frames. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2643 SUBJECT: GRB 040812: radio observations DATE: 04/08/14 22:27:47 GMT FROM: Alicia Soderberg at Caltech A. M. Soderberg (Caltech) reports on behalf of a larger Caltech/NRAO/Carnegie collaboration: "We have observed the error box of GRB 040812 (GCN 2640) with the Very Large Array on 2004 August 14.15 UT (t ~ 2 days since burst). At 8.5 GHz we detect a 0.45 mJy source at location: RA: 16:26:08.5 Dec: -44:41:04.0 (J2000) with a positional uncertainty of 8 arcsec (radius). The source is also detected at 4.9 GHz with a flux density of 0.79 mJy giving a spectral index of beta ~ -1 between the two observing bands. This spectral index is inconsistent with those measured for early radio afterglows. No other sources are detected within the error box with a 2 sigma detection limit of 0.14 and 0.16 mJy at 4.9 and 8.5 GHz, respectively. Further observations are planned." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2644 SUBJECT: GRB 040812: Keck and LCO observations DATE: 04/08/14 22:43:57 GMT FROM: Edo Berger at Caltech E. Berger (Carnegie Observatories), D.B. Fox, S.R. Kulkarni (Caltech), Wojtek Krzeminski and Mario Hamuy (Las Campanas Observatory, Carnegie) report on behalf of a larger collaboration: "We imaged the 2-arcmin error circle of GRB 040812 (GCN #2640) with the Low-Resolution Imaging Spectrometer on the Keck-I telescope 47 and 104 minutes after the burst, and with the Du Pont 2.5-m telescope at Las Campanas Observatory (LCO) 1.75 days after the burst. All observations were taken in the I-band (Galactic extinction, A_I~2.3 mag). Within the 8-arcsec radius error cirle of the VLA source detected by Soderberg (GCN #2643) we find several sources, but none exhibit significant variability either between the two Keck epochs or between the Keck and LCO observations. Visual comparison of the two Keck epochs do not reveal the presence of a strongly fading source within the entire 2-arcmin INTEGRAL error circle." This message may be cited //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2645 SUBJECT: GRB 040812: Keck and LCO optical observations DATE: 04/08/14 22:59:59 GMT FROM: Edo Berger at Caltech E. Berger (Carnegie Observatories), D.B. Fox, S.R. Kulkarni (Caltech), Wojtek Krzeminski and Mario Hamuy (Las Campanas Observatory, Carnegie) report on behalf of a larger collaboration: "We imaged the 2-arcmin error circle of GRB 040812 (GCN #2640) with the Low-Resolution Imaging Spectrometer on the Keck-I telescope 47 and 104 minutes after the burst, and with the Du Pont 2.5-m telescope at Las Campanas Observatory (LCO) 1.75 days after the burst. All observations were taken in the I-band (Galactic extinction, A_I~2.3 mag). Within the 8-arcsec radius error cirle of the VLA source detected by Soderberg (GCN #2643) we find several sources, but none exhibit significant variability either between the two Keck epochs or between the Keck and LCO observations. Visual comparison of the two Keck epochs do not reveal the presence of a strongly fading source within the entire 2-arcmin INTEGRAL error circle." This message may be cited //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2648 SUBJECT: CXO observation of GRB 040812 DATE: 04/08/18 15:27:41 GMT FROM: Peter Woods at UAH/MSFC S. Patel (USRA/NSSTC), C. Kouveliotou (NASA/MSFC,NSSTC), S. Mereghetti, D. Gotz (IASF-Milano), N. Lund, J. Chenevez (Danish Space Research Institute), P. Ubertini (IASF-Rome), E. van den Heuvel (University of Amsterdam), K. Hurley (UCB), report on behalf of a larger Integral team: We observed with Chandra/ACIS-S the error box of the Integral GRB 040812 (Gotz et al. 2004, GCN 2640). The observation started at 2004-08-17 7:08:22 UT, approximately 5 days after the trigger, and lasted for 10 ks. We find 4 sources above SNR=2.6 within a 2' radius (90% c.l.) centered at the refined Integral/IBIS location (RA=246.50, DEC=-44.70). No. RA Dec Counts* SNR 1 16 26 0.47 -44 41 22.6 9 2.8 2 16 26 2.25 -44 43 49.4 57 6.9 3 16 26 6.48 -44 43 20.8 10 2.9 4 16 26 8.44 -44 41 25.2 33 5.0 *0.5-8.0 keV band Within the Jem-X error region centered at RA=16:25:55.0, Dec=-44:42:40 (1.7' preliminary error radius) which is consistent with the IBIS location, we detect no source above SNR=2.6. Our source detection method found 3 sources above SNR=1.7 in this region as given below. These sources become more significant when we increase the search energy band to 0.1-10 keV. No. RA Dec Counts* SNR 5 16 25 54.65 -44 42 49.4 6 1.9 6 16 25 58.73 -44 41 47.0 4 1.9 7 16 26 1.21 -44 42 46.6 4 1.9 *0.5-8.0 keV band All coordinates are given in J2000. None of these sources exhibits significant variability within the 10ks observation. No X-ray source was found at the position of the radio source reported by Soderberg et al (2004, GCN 2643). At this point we cannot identify any of these sources as the counterpart of GRB040812, and we strongly encourage searches for optical variability. Another planned 10 ks Chandra DDT observation may reveal the GRB counterpart. We are grateful to the Chandra Science Data Center for processing the data rapidly and in particular to Harvey Tananbaum and Andrea Prestwich for approving this DDT observation. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2649 SUBJECT: XRF040812: possible afterglow DATE: 04/08/18 15:57:39 GMT FROM: Sergio Campana at INAF-OAB S. Campana and A. Moretti (INAF-Osservatorio di Brera) report: "We analyzed the Chandra ACIS-S data of the XRF040812 (Gotz et al. 2004, GCN 2640) region. We carried out spectral analysis of the second source (CXOJ162602.3-444349) in the Patel et al. (2004, GCN 2648), the only one with a sizable number of counts. The source is extremely hard with a photon index of 0.1+\-0.6 (90% confidence level), fixing the column density to the Galactic value of 5.3x10^21 cm-2. Leaving free the column density the error on the photon index increases to 0.1_(-1.0)^(+1.5). This hard photon index is typical of GRB X-ray afterglows. The unabsorbed 0.5-10 keV source flux is 2.53E-13 erg cm-2 s-1. The following Chandra observation (August 22, 2004) will allow to assess the afterglow nature of CXOJ162608.4-444125." We acknowledge the extraordinary effort by the CXC in providing rapid processing of this challenging data-set, thereby enabling this report. This message can be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2650 SUBJECT: GRB 040812: Optical counterparts of CXO sources DATE: 04/08/18 17:45:40 GMT FROM: Edo Berger at Caltech E. Berger (Carnegie Observatories) reports on behalf of a larger collaboration: "We inspected the positions of Chandra sources CXO 1-7 (GCN #2648), detected in the error circle of GRB 040812 (GCN #2640), in our Keck LRIS and Las Campanas Du Pont 2.5-m I-band images (GCN #2645): CXO# RA Dec Counterpart? --------------------------------------------------- 1 16 26 00.47 -44 41 22.6 star 2 16 26 02.25 -44 43 49.4 ---- * 3 16 26 06.48 -44 43 20.8 star 4 16 26 08.44 -44 41 25.2 none ** 5 16 25 54.65 -44 42 49.4 star/galaxy 6 16 25 58.73 -44 41 47.0 star/galaxy 7 16 26 1.21 -44 42 46.6 star * CXO-2 is located about 20" away from a very bright star, and this position is saturated in all of our images ** CXO-4 is located about 2" away from a galaxy/star In addition, none of the optical counterparts (excluding CXO-2) exhibit any significant variability either between the two Keck epochs (taken 47 and 104 minutes after the burst) or between the Keck and LCO observations (taken 1.75 days after the burst)." //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2651 SUBJECT: XRF 040812: optical observation at VLT DATE: 04/08/18 20:19:37 GMT FROM: Daniele Malesani at SISSA-ISAS,Trieste,Italy P. D'Avanzo, A. Cucchiara, G. Tagliaferri, D. Malesani, D. Fugazza, S. Covino, S. Campana, on behalf of a larger collaboration, report We observed the field of XRF 040812 (Gotz et al. GCN 2640) with the ESO-VLT on Aug 12.9795 UT (~17.5 hours after the GRB) and Aug 13.9844 UT (~41.5 hours after the GRB). Observations were performed in the I-band, under good observing conditions. Ten 1-minute exposures were taken in both nights. The seeing was 1.1" on Aug 12 and 0.8" on Aug 13. We estimate the limiting magnitude to be I ~ 24. To avoid saturation from the bright star close to the center of the field, we had to place on occulting bar, which hides 9% of the error box. We briefly report about the Chandra X-ray sources (Patel et al. GCN 1648). Source #1, #3 and #7 are visible in the DSS, as well as in our images. Source #2 (see also Campana & Moretti, GCN 1649) is not detected in the DSS and, moreover, in our images it is falling just behind the occulting bar. Source #4 is close (~1.5"), but not coincident, with a faint source in the VLT images, not visible in the DSS. Source #5, #6 are visible in our images but not in the DSS. None of the counterparts of the Chandra sources shows any significant variability. Moreover we don't have evidence of candidates in the whole Integral error-box (Gotz et al. GCN 2640), in particular at the radio position (Soderberg GCN 2643). PSF-matched photometry was performed with DAOPHOT and image subtraction with ISIS. We thank the ESO staff at Paranal for carefully performing the observations. This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2653 SUBJECT: XRF040812: GMRT observations DATE: 04/08/24 10:48:05 GMT FROM: D. Bhattacharya at Raman Research Inst. C.H. Ishwara Chandra and A.P. Rao (National Centre for Radio Astrophysics, Pune, India), L. Resmi and D. Bhattacharya (Raman Research Institute, Bangalore, India) report: We imaged the XRF040812 field at 1280 MHz on Aug 16, 2004 using the Giant Metrewave Radio Telescope. The following previously uncatalogued sources were detected within a 15' field of view centered at the position of the VLA source reported by Soderberg et al (2004, GCN 2643). No. RA (J2000) Dec (J2000) flux (mJy) 1. 16 26 08.404 -44 41 27.2 0.8 2. 16 26 15.674 -44 43 56.2 2.5 3. 16 26 13.025 -44 47 08.8 1.9 4. 16 26 08.795 -44 47 46.0 1.0 5. 16 26 09.448 -44 47 51.0 1.9 Typical astrometric uncertainties in the above coordinates are expected to be better than an arcsec, but ionospheric refraction due to low elevation could introduce a systematic shift up to 2 arc sec. All sources except no. 5 are point sources. Source no. 5 shows extended emission. We note that source no. 1 in the above list is within 2 arc sec of source no. 4 in the list of Chandra sources reported by Patel et al (2004, GCN 2648), and could be coincident with it. No detectable emission was found at the location of the VLA source (GCN 2643). At present we are unable to determine the extent of variability, if any, of the above sources. This message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2655 SUBJECT: GRB 040812: Second epoch CXO Observations DATE: 04/08/25 01:53:25 GMT FROM: Chryssa Kouveliotou at MSFC S. Patel (USRA/NSSTC), C. Kouveliotou (NASA/MSFC,NSSTC), S. Mereghetti, D. Gotz (IASF-Milano), N. Lund, J. Chenevez (Danish Space Research Institute), P. Ubertini (IASF-Rome), A. Levan (U. Leicester), E. van den Heuvel (University of Amsterdam), K. Hurley (UCB), report on behalf of a larger Integral team: We observed with Chandra/ACIS-S the error box of the Integral GRB 040812 (Gotz et al. 2004, GCN 2640) for a second time starting on 2004-08-22 9:55 UT, approximately 10 days after the trigger for 10 ks. We have compared the sources reported in our earlier GCN on the first CXO observation (Patel et al., 2004, GCN 2648) with the second CXO image, applying a SNR>2 selection threshold. The results are shown in the Table below. No. RA Dec Counts(1)* SNR Counts(2) SNR 1 16 26 0.47 -44 41 22.6 9 2.8 -- -- 2 16 26 2.25 -44 43 49.4 57 6.9 38 5.4 3 16 26 6.48 -44 43 20.8 10 2.9 10 2.7 4 16 26 8.44 -44 41 25.2 33 5.0 33 5.2 5 16 26 1.71 -44 43 27.9 -- --- 16 3.7 *0.5-8.0 keV band All coordinates are given in J2000. We do not detect source #1 above SNR=2.0; a search in the corresponding error region in the second epoch CXO image reveals 5 net counts at this location. We conclude that there is no significant variation in that source within statistics. Source #2 decayed with an index of approximately 0.6 between the two CXO observations; this source, thus, seems to be most likely the candidate of the GRB 040812 afterglow, as also pointed out by Campana et al. 2004 (GCN 2649). Finally, a new source (#5) appeared within the IBIS error box; inspection of the first image reveals 3 net counts at this location, indicating a variable source. We detect two of the radio sources (#2 and #4) reported by Ishwara Chandra et al. 2004 (GCN # 2653) at the same flux level in both CXO observations. We are grateful to the Chandra Science Data Center for processing the data rapidly and in particular to Harvey Tananbaum and Andrea Prestwich for approving this DDT observation. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2656 SUBJECT: XRF040812: possible afterglow second Chandra observation DATE: 04/08/25 08:53:50 GMT FROM: Sergio Campana at INAF-OAB S. Campana and A. Moretti (INAF-Osservatorio astronomico di Brera) report on behalf of a larger team: "We analyzed the second Chandra ACIS-S observation of the XRF040812 (Gotz et al. 2004, GCN 2640). We carried out spectral analysis of our previous afterglow candidate (CXOJ162602.3-444349, Campana & Moretti GCN 2649, see also Patel et al. GCN 2648, 2655). The source is still very hard with a power law photon index of 0.9+/-0.6 (fixing the column density to the Galactic value of 5.3x10^21 cm-2 and using Cash statistics in the XSPEC fit). The spectrum is slightly softer than in the first observation (Campana & Moretti GCN 2649). The unabsorbed 0.5-10 keV source flux is 9.30x10^-14 erg cm-2 s-1 a factor of ~3 lower than in the previous Chandra observation. A constant temporal evolution is not consistent with the data at a ~4.5 sigma level. A power law decay describes better the temporal evolution with a time decay as t^-1.4(+/-0.6) (90% confidence level, note that this is different from the Patel et al. GCN 2655, since we fitted the flux evolution and not the counts evolution)." This message can be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2824 SUBJECT: HST Observations: XRF 040701 and 040812 DATE: 04/10/19 16:07:38 GMT FROM: Shri Kulkarni at Caltech S. Kulkarni, A. Soderberg and D. Fox report on behalf of the Caltech/Carnegie/NRAO collaboration: "As part of our large HST program on GRBs and XRFs, we have used ACS to observe the fields of XRF 040701 and XRF 040812. Observations were taken in the F625W (r) and F775W (i) filters 39 and 60 days after the burst (XRF040701) and 32 and 54 days after the burst (XRF040812). Comparison of the two epochs for each XRF does not reveal a variable source within the 1-arcsec position of the putative Chandra X-ray afterglow candidates (GCNs 2630 and 2655 for XRFs 040701 and 040812, respectively). Our 3-sigma limits are the following: XRF Filter Limit: ============================================== 040701 F625W 27.5 F775W 27.0 040812 F625W 27.5 F775W 27.0