Gamma-ray Burst 990704

On July 4, 1999 a GRB was detected by the BeppoSAX GRBM and WFC instruments. A NFI observation discovered the fading X-ray afterglow.

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• IAUC 7214 Optical observation
• IAUC 7217 WFC discovery, NFI observation, optical observation

• BeppoSAX GRB alert n. 99/12 = GCN notice #360
  On July 4, 17:30:20 UT a GRB (GRB990704) was detected simultaneously by the GRBM and WFC of BeppoSAX.
  Preliminary coordinates from WFC are:

  R.A.(2000)= 184.87
  DEC(2000)= -03.796
  

  Due to the less-than-optimal attitude configuration the error radius is of about 8'.
  A follow-on with NFI is being planned.
• BeppoSAX GRB alert n. 99/13 = GCN notice #361
  Refined coordinates of GRB990704 are :

  R.A.(2000)=184.79
  DEC(2000)= -03.80
  

  Due to the less-than-optimal attitude configuration the error radius is of about 7'
  A follow-up with NFI is in progress.
• GCN notice #362:
  Alberto. Castro-Tirado, LAEFF-INTA (Madrid) and IAA-CSIC (Granada) Maria Eva Alcoholado-Feltstrom, SMA (Malaga) Maria Marcha and Alessandro Caccianiga, University Observatory (Lissabon) Karl Heinz Mack, Radioastronomisches Institut (Bonn) Jochen Greiner, AIP (Potsdam) Javier Gorosabel, LAEFF-INTA (Madrid) Marco Feroci and Enrico Costa, IAS (Frascati) report:
  We have obtained four 4-minute R-band exposures through a cloudy sky of the GRB 990407 error box (Piro et al. GCN 360) starting at 20:50 UT on 4 July 1999 (3.33 hours after the trigger) with the 2.2 m telescope at the German-Spanish Calar Alto Observatory (CAHA). After a visual comparison with the the Digital Sky Survey, no new sources were seen to a limiting magnitude of R = 18 within the 8 arcmin radius error box. Deeper optical/IR observations are encouraged.
• BeppoSAX GRB alert n. 99/14 = GCN notice #364
  A BeppoSAX follow-up of GRB990704 started about 8 hr after the burst. Preliminary analysis of the first three orbits of the MECS data at SOC shows a previously unknown source inside the WFC error circle.
  Preliminary coordinates are:

  RA(2000)= 184.872
  DEC(2000)= -3.840
  

  The error radius is 1.7'
  BeppoSAX is continuing its observation.
• BeppoSAX GRB alert n. 99/15 = GCN notice #366
  Due to a trivial typo in coordinates conversion the reported WFC refined position in BeppoSAX Mail 99/13 is wrong.
  The real position should be read:

  RA(2000)= 184.873
  DEC(2000)= -3.803
  

  The error box radius is still about 7'.
• GCN notice #363
  Alain Maury (OCA), Boris Gaillard (OCA) and Michel Boer (CESR) report on behalf of the OCA/CESR GRB collaboration, the tentative identification of a possible optical counterpart for GRB990704 announced in GCN#360 and GCN#361 on CCD images obtained on the 90cm Schmidt telescope of the Observatoire de la Cote d'Azur. An object which is not detected on the POSS has been detected at RA2000.0 12h19m29.29s -03=B047'25.8" at m19.4 (unfiltered images) on July 4th 21h01 UT. Contact information : boer@cesr.fr or maury@obs-azur.fr
  Web page with images at : http://wwwrc.obs-azur.fr/schmidt/observations/GRB990704.html
• GCN notice #365
  The U.S. Naval Observatory GRB team (F.J. Vrba, A.A. Henden, C. B. Luginbuhl, B. Canzian, S.E. Levine), D.H. Hartmann (Clemson Univ.) and, M.C. Jennings (IGPP, UCR visitor) reports:
  We have obtained calibrated photometric observations, under clear sky conditions, of the 7-arcmin radius error circle for GRB 990704, reported by Gandolfi et al. in GCN 361. R-band (Cousins) observations were obtained at the U.S. Naval Observatory, Flagstaff Station 1.0-m reflector using a CCD with an 11x11 arcmin field. Four 12 minute observations were mosaiced to cover a 15x15 arcmin field centered on the GCN 361 coordinates. The observations were obtained between UT 1999 July 05 04:02 and 04:57. The frames reached a 3-sigma limiting detection of Rc = 21.2. No obvious new objects were detected in a comparison with the Digital Sky Survey.
• GCN notice #367
  The U.S. Naval Observatory GRB team (F.J. Vrba, A.A. Henden, C.B. Luginbuhl, B. Canzian, S.E. Levine), D.H. Hartmann (Clemson Univ.) and, M.C. Jennings (IGPP, UCR visitor) reports:
  The object reported as a possible optical counterpart to GRB 990704 by Maury et al. (GCN 363) was covered by the R-band frames we reported in GCN 365 and also in a single 10-min V-band frame we obtained beginning at UT 1999 July 05:00; immediately after the R-band frame covering the area. The R- and V-band frames go to similar depths. While the object is easily detected in our R-band frame, it is barely seen in the V-band image. Thus, the object is either fairly red or was fading quickly. If red, it is one of a number of objects in this region with similar red colors from visual inspection. Since the GCN 365 observations were unfiltered this could explain why the object was not seen on the DSS. We also note that the object is outside the error circle of the new X-ray source reported by Gandolfi et al. (GCN 364). While these facts do not rule out the GCN 363 source as a possible counterpart, it should probably be given lower priority than observations concentrating on the GCN 364 X-ray position.
• GCN notice #369
  Alain Maury (OCA), Boris Gaillard (OCA) and Michel Boer (CESR) report on behalf of the OCA/CESR GRB collaboration :
  We have observed the field of GRB990704 again tonight, and the 19th magnitude object announced yesterday in GCN 363 as a possible optical counterpart is still visible at the same position and roughly the same magnitude. This object is very likely NOT the optical counterpart of GRB990704. Contact information : boer@cesr.fr or maury@obs-azur.fr
• GCN notice #370
  Alan Diercks, Kevin Krisciunas, and Eric Deutsch (Univ. Washington) report on behalf of the UW and LONEOS GRB collaborations:
  The position of the possible optical counterpart to GRB 990704 reported by Maury et al. (GCN 363) (12:19:29.29 -03:47:25.8) was imaged in the course of the LONEOS project approximately one month ago, June 6, 1999. Three 60s, un-filtered CCD exposures were taken with the 60cm Schmidt telescope. Combining these images, we detect the object noted by Maury et al with an un-filtered magnitude of m = 19.6 +/- 0.3 relative to the "red" magnitude of USNO-A1.0 star U0825_07735496. We measure the following unfiltered magnitudes for three stars from the USNO-A1.0 Catalog:
  

  USNO number     RA(2000)    DEC(2000)   USNO     UW/LONEOS
                                          r_mag     mag
  U0825_07735496 12:19:33.74 -03:47:25.3  15.6     15.6 +/- 0.1 *calibrator*
  U0825_07735738 12:19:36.43 -03:47:12.6  16.5     16.8 +/- 0.1
  U0825_07735688 12:19:35.95 -03:46:32.9  16.5     16.7 +/- 0.1
  

• GCN notice #371
  B. L. Jensen, J. Hjorth, H. Pedersen (Copenhagen), T. Abbott, L. Freyhammer, M. I. Andersen, J. W. Clasen (NOT), P. Muhli (Helsinki), and A. O. Jaunsen (Oslo), report:
  On 4.92 July and 5.92 July 1999 UT we obtained R band images (FWHM = 0.9") with the 2.5-m Nordic Optical Telescope (NOT), covering the BeppoSAX 1.7' NFI error circle of GRB 990704 (GCN #364). We find no variable objects down to a limiting magnitude of R ~ 22.5 inside or near the error circle. The object noted in GCN #363 (located outside the NFI error circle) has not varied between the two epochs of observation (cf. GCN #369, 370).
• GCN notice #372
  T. Murakami, A. Yoshida, N. Kawai, T. Tamura, S. Terada and T. Tsuru on behalf of the ASCA team report :
  ASCA is observing the SAX NFI position (GCN #366) of GRB 990704 from July 5.40(UT). Preliminary analysis of the first four orbits of the SIS data at the tracking station shows an X-ray source at a position of

  RA(2000)= 184.867
  DEC(2000)= -3.833
  

  with the error radius of 1.5 arcmin. The source is fading and the average intensity of the four orbits is 2x10E-13 erg/cm2/sec in 2-10 keV band.
  ASCA is continuing its observation at least until July 6.13 (UT).
• GCN notice #374
  E. Rol, P. Vreeswijk, T. Galama (U. of Amsterdam), N. Masetti, E. Palazzi, E. Pian, F. Frontera (ITESRE, CNR, Bologna), J. van Paradijs (U. of Amsterdam and U. of Alabama in Huntsville), C. Kouveliotou (USRA/MSFC), R. Strom (NFRA and U. of Amsterdam), G. de Bruyn (NFRA and U. of Groningen) and T. Augusteijn (ESO) report:
  We have observed the BeppoSAX NFI error circle of GRB 990704 (Gandolfi 1999, GCN 364) with the Westerbork Synthesis Radio Telescope (WSRT). We observed for 9.2 hours at 4.88 GHz centered on July 5.75 UT, 1999. Within the error circle we detect two sources at 4.88 GHz. Their fluxes and positions are given below:

          flux (mJy)      RA(J2000)       Decl.(J2000)
  
           0.68           12:19:27.2      -03:51:38.5
           0.35           12:19:31.0      -03:52:05.3
  

  The error in the flux is 0.065 mJy. The error in the RA and Decl. are 0.5" and 5", respectively.
  We have also observed the error circle in the R band with the ESO 2.2m (La Silla) and VLT-UT1 Antu (Paranal) telescopes, 6.5 and 30.5 hours after the burst, respectively. We calibrated these images with the Landolt SA104 field (stars 350 and 456; Landolt 1992, AJ, 104, 340). We detect an object at RA 12:19:27.20, Decl. -3:51:39.7 (J2000; positional accuracy of about 2"), coincident with the first radio source.
  We measure the following magnitudes for this object:

          UT Date         R       err.      telescope
          
          July 4.96       22.05   0.16      2.2m
          July 6.01       22.00   0.05      VLT-UT1
          July 6.07       21.87   0.07      VLT-UT1
  

  The error in the absolute calibration (estimated to be 0.2 mag.) is not included in the error listed above. The object is constant within the measurement errors and it is therefore not likely the counterpart of GRB990704.
  At the position of the second radio source, no object is detected. The 5 sigma limiting magnitudes of the 2.2m and the co-added VLT-UT1 images are R=22.2 and R=23.5, respectively.
• GCN notice #375
  M. Feroci, G. Gandolfi, Istituto Astrofisica Spaziale, CNR, Roma, L.A. Antonelli, Osservatorio Astronomico di Roma, M.R. Daniele, BeppoSAX Science Data Center, Telespazio, Roma C. De Libero, BeppoSAX Operation Control Center, Telespazio, Roma, L. Di Ciolo and V. Torroni, BeppoSAX Science Operation Center, Telespazio, Roma, F. Frontera, Istituto Tecnologie e Studio Radiazioni Extraterrestri, CNR, Bologna, and J. Heise, Space Research Organization in the Netherlands, Utrecht, on behalf of the BeppoSAX Team report:
  The BeppoSAX Narrow Field Instruments observed the region of GRB990704 (GCN #366) from July 5.064 to July 5.989 UT. The observation was then stopped to allow the follow-up observation of GRB990705. One previously unknown X-ray source (1SAX J1219.5-0350) was found inside the 7' BeppoSAX WFC error-circle (GCN #366) at a position (J2000) R.A. = 12h19m27s.3 Decl.= -03o50'22", error radius 1' (90% confidence level). The average source flux in 2-10 keV was (8.0+-0.6)x10E-3 counts/s, corresponding to about 4.4x10E-13 erg cmE-2 sE-1, assuming a power law spectrum. The source shows a fading behaviour, strongly suggesting it is the X-ray afterglow of GRB990704.
• GCN notice #379
  K. Hurley, on behalf of the Ulysses GRB team, and M. Feroci, on behalf of the BeppoSAX GRB team, report:
  We have obtained a preliminary IPN annulus for GRB990704. This annulus is centered at RA=147.4103 deg., Decl.=-7.9861 deg. (J2000), and has a radius of 37.4724 +/- 0.047 deg. (3 sigma). It intersects the BeppoSAX WFC error circle (GCN 366) to form a 75 arcmin.^2 error box whose corners are:

  RA(2000)        Decl.(2000)
  12h 19m 41.9s   -3o 54' 27"
  12h 19m 34.4s   -3o 41' 17"
  12h 19m 19.3s   -3o 54' 42"
  12h 19m 12.3s   -3o 42' 39"
  

  This error box includes, but does not reduce the size of, that of the BeppoSAX NFI source (GCN 375) and the ASCA source (GCN 372), suggesting that this fading source is indeed the X-ray counterpart to the GRB. An image may be found at ssl.berkeley.edu/ipn3/990704/. The optical source in this image is the one referred to in GCN 363 and GCN 369.
  This IPN annulus can be updated when the final Ulysses data become available, but due to the weakness of the GRB, the annulus width will probably not be reduced substantially.