Gamma-ray Burst 980329

The Gamma-Ray Burst (BATSE trigger No. 6665, 22425 cts/s peak intensity) was detected by BATSE and BeppoSAX GRBM on 1998 March 29, 3:44:27 UT. With the BeppoSAX WFC the location could be deduced to a 3 arcmin error circle centered at R.A. = 07h02m41s, Decl. = +38o50'.7 degrees (2000.0). This is the brightest burst detected so far by the BeppoSAX GRBM simultaneously with the Wide Field Cameras. The peak intensity measured in WFC is about 6 Crab (2 to 26 keV).
A follow-up observation with the BeppoSAX NFI instruments was initiated within 7 hrs. Preliminary analysis of the first 3 orbits of MECS and LECS shows a source within the WFC error box at

   RA (2000) = 105.65
 Decl.(2000) = 38.85

Previous IAU Circulars

• IAUC 6853 BeppoSAX WFC detection and localisation
• IAUC 6854 BeppoSAX NFI detection of fading X-ray source 1SAX J0702.6+3850 at R.A. = 7h02m36s, Decl. = +38o50'.4
• IAUC 6855 no optical variable brighter than R=22 mag on Mar. 29-31
• IAUC 6856 possible new optical object at 7h02m38s.8, +38o50'27"
• IAUC 6860 no variation of the above optical object between Apr. 1.167-1.177 and Apr. 1.267-1.277
• IAUC 6864 object I=20 mag at radio position on Mar. 29.8-30.0 UT; I>21 on Mar. 31.8-31.9.
• IAUC 6865 R > 24.2 and > 23.9 on Apr. 1.17 and 3.10 UT at radio position.
• IAUC 6866 J>20.9 at radio position on Apr. 1.167 and 1.277 UT thus dimming by 1.7 +/- 0.9 over about 2.4 days
• IAUC 6868 JCMT + SCUBA detection at 850 microns at 5 +/- 1.5 mJy and 4 +/- 1.2 on Apr. 5.2 UT and Apr. 6.2 UT, respectively. Possible fading to 2 +/- 0.8 mJy on Apr. 7.2 UT.

• Likelihood contour map of the combined COMPTEL and BATSE RBR position (from comptel.sr.unh.edu/pub/GRB/grb980329_comptel_batsehunts_sys.ps)

  
  

• GCN# notice on 31 Mar 1998 17:17:13 UT
  Ulysses IPN trianulation arc (see URL's below for actual numbers):

  ANNULUS_RA:     154.3013d {+10h 17m 12s}   (J2000)
  ANNULUS_DEC:    13.1677d {+13d 10' 04"}
  ANNULUS_RADIUS: 49.879 [deg]
  ANNULUS_WIDTH:  0.089 [deg]  (Total width)
  COMMENTS:       Strong burst. Two overlapping pulses.
  COMMENTS:       Total duration ~40 sec.
  COMMENTS:       Seen above 300 keV.
  

  More information about this burst can be found at the GCN URLs:

        http://gcn.gsfc.nasa.gov/gcn/gcn_main.html
        http://gcn.gsfc.nasa.gov/gcn/batse_grbs.html
        http://gcn.gsfc.nasa.gov/gcn/selected.html
  

• R band image taken at OHP (see IAUC 6856):
  

  
  

• GCN3 notice #40
  G.B. Taylor, D.A. Frail (NRAO), S.R. Kulkarni (Caltech), and the BeppoSAX GRB team report: We have observed the field containing the proposed x-ray counterpart 1SAX J0702.6+3850 of GRB 980329 (IAUC 6854) with the VLA at 8.4 GHz on UT 1998 Mar 30.2, April 1.1, and April 2.1. Observations on April 1.1 detected a radio source VLA J0702+3850 within the 1 arcminute error circle of 1SAX J0702.6+3850. The coordinates of VLA J0702+3850 are: ra = 07h02m38.02170s dec = 38d50'44.0170" (equinox J2000) with an uncertainty of 0.05 arcsec in each coordinate. The size of this radio source is less than 0.25 arcsec. The density of sources on the sky stronger than 250 microJy at this frequency is 0.0145 arcmin**-2. The flux density measurements of VLA J0702+3850 are as follows:

  Date(UT)   8.4 GHz Flux Density
  --------   ----------------------
  Mar 30.2   166 +/- 50 microJy
  Apr  1.1   248 +/- 16    "
  Apr  2.1    65 +/- 25    "
  

  where the uncertainty in the measurement reflects the 1 sigma rms noise in the image. These measurements clearly demonstrate that the radio source is variable on timescales of less than 1 day. This rapid variability is similar to that observed in the radio afterglow from GRB 970508. We propose VLA J0702+3850 is the radio afterglow from GRB 980329. Additional radio observations are in progress.
• GCN notice #41
  S. G. Djorgovski, S. R. Kulkarni, J. Sievers (Caltech), D. Frail and G. Taylor (NRAO), on behalf of the Caltech-NRAO GRB collaboration, report: We have detected a galaxy coincident to within the astrometric errors (about 0.5 arcsec) with the variable radio source detected at the VLA by Taylor et al. (see GCNC#40) on deep R-band images taken with the Keck-II 10-m telescope on 02 April 1998 UT. The galaxy has a magnitude R = 25.7 +- 0.3 (preliminary reductions). We propose that this is the host galaxy of the radio transient detected at the VLA, which may be the afterglow of GRB 980329. The image of the field is shown at http://astro.caltech.edu/~george/grb/grb980329.html (and below).
  One of the CCD images in the R band obtained at the Keck-II telescope on UT 1998 April 02. The field shown is approximately 168 arcsec square. This is a preliminary reduction.
  A zoom-in from a CCD image in the R band obtained at the Keck-II telescope on UT 1998 April 02, with the possible GRB host galaxy marked. The field shown is about 42 arcsec square. This is a preliminary reduction of the data.
• GCN notice #43
  Sylvio Klose, Thueringer Landessternwarte Tautenburg, Germany, reports: I-Band images obtained on March on March 29.8-30.0 UT, using the Tautenburg Schmidt telescope equipped with the Schmidt focus CCD camera show an object at the position of the radio source reported by Taylor et al. [GCN Circ #40]. This object was not visible on the I-band images taken on March 31.8-31.9 UT with the Tautenburg telescope (GCN #36). It was also not found on an I-band image taken on April 1.85 UT by H. Lehmann and H. Meusinger, Thueringer Landessternwarte, with the Calar Alto 2.2-m telescope equipped with CAFOS. Since no R-band counterpart was seen on the Tautenburg images taken on March 29.8-30.0 UT, I hesitate to claim the detection of this source. This object is visible on various I-band frames, and also appears if flat-fielding is not performed. Its magnitude is about I=20, but I do not have a photometric standard. These Tautenburg I-band Images are availabe via anonymous ftp from ftp.tls-tautenburg.de in the directory /pub/klose.
• GCN notice #44
  J. Larkin, A. Ghez (UCLA) in collaboration with S. Kulkarni, S. Djorgovski (Caltech), D. Frail, and G. Taylor (NRAO) report: We have detected a near infrared counterpart to the variable radio source detected at the VLA by Taylor et al. (see GCNC#40), the R-band source reported by Djorgovski et al. (see GCNC#41), and the possible I-band transient reported by Klose (GCNC#43). Preliminary analysis of observations obtained on UT 1998 April 02 and April 03 at the Keck-I 10-m telescope reveal a K = 21.0 mag source that does not show strong variations (delta K < 0.5 mag). The infrared, optical and radio positions all agree to within the astrometric uncertainties of about 0.5 arcsecond. We suggest that a possible explanation for the relatively red color of the host galaxy (R-K = 4.7 mag) and the lack of optical transient detections may be dust obscuration.
• GCN notice #45
  Bradley E. Schaefer at Yale Univ. reports: R-band observations of the GRB980329 error box were obtained with the 3.5 m WIYN telescope on Kitt Peak on UT 1998 April 1.17 and April 3.10. The position of the radio transient (see GCNC #40) was empty to limits of 24.2 and 23.9 mag respectively.
• GCN notice #46
  F. Mannucci, M. Salvati, P. Tozzi, Osservatorio Astrofisico di Arcetri, Firenze, Italy, M. Di Martino, Osservatorio Astronomico di Torino, Italy, E. Palazzi and E. Pian, Istituto di Tecnologie e Studio delle Radiazioni Extraterrestri, CNR, Bologna, Italy, on behalf of a large collaboration report: On March 29.84-29.86 UT, the SAX-WFC error box of GRB980329 (IAUC 6853) was imaged at the Gornergrat Infrared Telescope (TIRGO) with ARNICA + J band filter. A preliminary analysis of the data shows that the galaxy reported by Djorgovski et al. (GCNC #41) is detected at 2-sigma significance with a magnitude J = 19.2 (+0.8,-0.5 at 1 sigma).
• GCN notice #47
  D. M. Cole, A. R. Cooray, J. M. Quashnock, D. E. Vanden Berk, D. Q. Lamb, D. E. Reichart, G. T. Richards, K. Gloria, D. Long, and T. Hoyes, University of Chicago, on behalf of the Astrophysical Research Consortium (ARC), report: "We made near-infrared observations (GCN #39, IAUC 6860) of the SAX NFI error box for GRB 980329 (IAUC 6853, 6854) between Apr. 1.167 UT and Apr. 1.277 UT, using the GRIM II instrument mounted on the ARC 3.5-m telescope at Apache Point Observatory. We find no detectable object, down to a limiting J magnitude of 20.9 +/- 0.5 (1 sigma) at the position R.A. = 7h02m38s.02, Decl. = +38o50'44" (J2000.0) of the variable radio source VLA J0702+3850 proposed by Taylor et al. (GCN #40) to be the radio afterglow from GRB 980329. The measurement by Mannuci et al. (GCN #46) of a magnitude J = 19.2 (+0.8,-0.5) object at the position of the radio source at epoch Mar. 29.84-29.86 UT implies that this object dimmed by J magnitude 1.7 +/- 0.9 during a period of approximately 2.4 days."
• GCN notice #48
  E. Palazzi, N. Masetti, E. Pian, F. Frontera (ITeSRE-CNR, Bologna), L. Nicastro (IFCAI-CNR, Palermo), P. Vreeswijk, T. Galama, P. Groot, J. van Paradijs (U. Amsterdam), M. Della Valle (Oss. Astr. Padova), E. Costa, M. Feroci, L. Piro (IAS-CNR, Rome), C. Kouveliotou (MSFC-NASA), and C. Lidman (ESO) report:
  The error box of GRB980329 (IAUC 6853) was observed with the NTT at ESO (La Silla, Chile) on March 29.99, 30.99 and April 1.01 UT with EMMI in R and V band filters. Observations lasted 10+10 minutes per filter per night. Limiting magnitudes were ~24.0 in R and 23 in V. On March 29.99, at the position RA = 07h02m38s, Dec = +38deg50'44".1 (J2000), coincident (to within the astrometric errors) with VLA J0702+3850 (GCN #40) and with the galaxy reported by Djorgovski et al. (GCN #41), we detect an R = 23.5 (+/- 0.2) object. The source is not detected in V, and in the subsequent nights is undetected in both bands. Using R = 25.7 (April 2, Djorgovski et al., GCN #41) we obtain a luminosity power-law decay index <~ -1.3. The extrapolation of this power-law to the time of the observations reported by Guarnieri et al. (GCN #37, Mar 29.79), Brocato et al. and Cappellaro (see below) is consistent with their non-detections. The NTT R band images can be found at the Web site http://www.tesre.bo.cnr.it/~nicastro/grb980329 (and is reproduced below), as well as the TIRGO J band images reported in GCN #46.

  
  March 29.99: NTT + EMMI + R-band filter, 20 min exposure.

  
  March 30.99: NTT + EMMI + R-band filter, 20 min exposure.

  
  E. Brocato, A. Piersimoni, and G. Raimondo (Oss. Astr. Teramo) report: We imaged the GRB980329 error circle with the 0.72-m telescope at Campo Imperatore (Teramo) equipped with a Tek-CCD and R band filter on March 29.83 UT for 1800 s. No object brighter than R = 20 is detected at the VLA source position. E. Cappellaro (Oss. Astr. Padova) reports: On March 29.81 and 29.99 UT, the GRB980329 error circle was imaged for 1500 s using the 1.8-m telescope at the Asiago observatory with AFOSC and R band filter. Down to a limiting magnitude of R = 21, no object is found at the VLA source position.
• GCN notice #49
  K. Hurley (UCB) on behalf of the Ulysses GRB team, M. Feroci (IAS/CNR, Rome) and F. Frontera (ITESRE/CNR, Bologna) on behalf of the BeppoSAX/GRBM Team report: We have derived a preliminary IPN annulus for this burst using Ulysses and the BeppoSAX Gamma-Ray Burst Monitor. The annulus is described by a circle of radius of 49.898 degrees centered at RA(2000) = 154.298 degrees, Declination (2000) = 13.169 degrees. The half-width of the annulus is 0.022 degrees. The annulus intersects the WFC error circle (IAUC 6853) and reduces its area. The intersection points are: RA(2000) Decl (2000) 105.628 o = 7 H 2 M 30 S 38.808 o = 38 o 48 ' 29 " 105.662 o = 7 H 2 M 38 S 38.895 o = 38 o 53 ' 40 " 105.683 o = 7 H 2 M 43 S 38.796 o = 38 o 47 ' 45 " 105.716 o = 7 H 2 M 51 S 38.880 o = 38 o 52 ' 49 " This error box includes the SAX NFI X-ray source (IAUC 6854), radio source (GCN #40) and the optical transient (GCN #48). Further processing will reduce the annulus width. An image may be found at http://ssl.berkeley.edu/ipn3/980329/ .
• GCN notice #50
  I. A. Smith (Rice University) and R. P. J. Tilanus (Joint Astronomy Centre) report on behalf of the James Clerk Maxwell Telescope (JCMT) GRB collaboration: We used the SCUBA sub-millimeter continuum bolometer array on the JCMT to observe the variable radio source VLA J0702+3850 proposed by Taylor et al. (GCN #40) as the radio afterglow to GRB 980329. On UT 1998 April 5.2 we detected a source at 850 microns with a preliminary flux density of 5 +/- 1.5 mJy. This source was confirmed on April 6.2 with a flux density of 4 +/- 1.2 mJy, resulting in an average of 4.5 +/- 1 mJy over the two days. The 850 micron source is present in all our separate integrations making us confident it is real. A hint of a fading trend appears to be confirmed by observations on April 7.2 when the (preliminary) 850 micron flux density was 2 +/- 0.8 mJy. The source was not detected at 450 microns with a preliminary rms of 10.0 mJy averaged over the first two days. Assuming these fluxes are due to the burst counterpart, they should represent "clean" measures of its intensity, unaffected by scintillation and extinction. Monitoring with SCUBA is continuing. We wish to thank Dr. L. Avery and Dr. J. MacLeod for their cooperation and valuable help in obtaining these observations, and Dr. G. Watt and Dr. I. Robson for rapidly scheduling the observations.
• GCN notice #51
  J. Larkin and A. Ghez (UCLA) in collaboration with S. Kulkarni, S. Djorgovsk (Caltech), D. Frail and G. Taylor (NRAO) report: We have fully reduced our K-band images of the field surrounding the gamma ray burst GRB980329. We confirm our earlier strong detection of a compact (<0.6'' FWHM) object at the radio coordinates reported by Taylor et al. (see GCN#40) and coincident with the optical counterpart announced by Djorgovski et al. (see GCN#41). The observations include two separate 90 minute exposures at the Keck 10 meter telescope obtained on UT 1998 April 02 and April 03, respectively. The total K-band magnitudes of the object are 20.7+-0.2 mag on April 02, and 20.9+-0.2 mag on April 03. The source is unresolved in our images, even if we include only those frames taken under the best seeing conditions of 0.5 to 0.6 arcseconds. The final K band image can be found at http://www.astro.ucla.edu/~larkin/grb.html
• GCN notice #52
  H.Pedersen (Copenhagen University Observatory), J.Fynbo (Institute of Physics and Astronomy, Aarhus), E.Valtaoja (Tuorla Observatory, Turku), M.Tornikoski (Metsahovi Radio Observatory, Helsinki), J.Clasen (Nordic Optical Telescope, La Palma), and E.Palazzi (Istituto TeSRE, Bologna), report: Using the 2.56 m Nordic Optical Telescope, La Palma, we have obtained a total of seven 600 s R band exposures of the proposed host galaxy (ref. GCN #41, #51). The exposures were taken March 30.924 - 30.942 (2 exp.), March 31.866 - 31.882 (2 exp.), and April 01.879 - 02.029 (3 exp.). One 300 s I band exposure was obtained on March 31.919. The optical transient is not clearly detected in any single exposure, nor in the sum of exposures from any night. However, the sum of all R exposures shows a very faint object at the cited position for which we derive m(R) = 24.8 +/- 0.5 (using the R=15.8 object from IAU Circ. No. 6856 as calibration). The data files can be retrieved from http://www.astro.ku.dk/~holger/g/IMAGES/GRB980329/NOT_R.fits.gz and .../NOT_I.fits.gz
  Further to this, H.Pedersen reports: Using the 45/77 cm Brorfelde Schmidt, a series of seventeen 500 s R band exposures were obtained March 29.860 - 29.973. None of these exposures shows any object at the position of the optical counterpart. During the observing interval, the detection limit deteriorated gradually, from R=18.5 to 18.0 K.Augustesen kindly performed the Schmidt observations.
• GCN notice #55
  M.R. Metzger (Caltech) reports: Near-infrared K-band images of the area surrounding the variable radio source detected by Taylor et al. (GCNC #40), possibly associated with GRB 980329 (IAUC 6853, 6854), were obtained on Apr 6.27 and Apr 8.28 with the Keck-I 10m telescope. The source reported by Larkin et al. (GCNC #51, coincident with the galaxy reported by Djorgovski et al., GCNC #41) was detected on both nights, at K=21.4 +/- 0.2 mag (6.27) and K = 21.9 +- 0.4 mag (8.28). Comparison with the magnitudes reported by Larkin et al. indicates that the source has faded by about 1 mag between Apr 2.3 and Apr 8.28. This suggests that part of the K flux may be IR afterglow of GRB 980329. It is consistent with fading, detections, and upper limits reported previously (GCNC #41, #46, #48, IAUC 6864, 6866, 6868). Further measurements are suggested to estimate the IR brightness of any underlying host.
• GCN notice #59
  J. Greiner (AI Potsdam, Germany), W. Voges (MPE Garching) and F. Frontera (Bologna, Italy), E. Costa and L. Piro (IAS Rome, Italy) report: A ROSAT target-of-opportunity observation was performed towards the position of GRB 980329 (IAUC 6853) between April 1--3, 1998. The total exposure time was 33.5 ksec. No X-ray source is detected within the WFC error box at the 3 sigma significance level or higher (upper limit of 0.0001 cts/s). Adopting a power law spectrum with photon index of 2.0 and only galactic absorption (9*10^20 cm^-2), this corresponds to a flux limit of 9.3E-15 erg/cm^2/s in the 0.1-2.4 keV band. The non-detection of the X-ray afterglow source 1SAX J0702.6+3850 as detected with the BeppoSAX NFI (IAUC 6854) implies that the X-ray flux of the GRB 980329 afterglow decayed according to t^-1.8 or steeper.

  An image of the ROSAT observation is shown below (inner 15 arcmin):

  
• The following figures are from Taylor et al: The Discovery of the Radio Afterglow From the Optically Dim GRB of March 29, 1998 (astro-ph/9805333).
  
• Decay lightcurve in the X-rays (astro-ph/9807314):
  
• Photometry suggests z=5 (astro-ph/9810224):
  
• GCN notice #157
  James Rhoads, Arjun Dey, Buell Jannuzi, and Megan Sosey (on behalf of the KPNO GRB followup team); Sylvio Klose; Daniel Reichart; Andrew Fruchter; and Francisco Castander report:
  We have used data obtained by Rhoads on the night of 980403 UT to calibrate Klose's I band measurement of the optical transient associated with GRB 980329 (GCNC #43). We find an optical transient magnitude I=20.8 +- 0.3 on March 29.8-30.0 (cf. Reichart et al, in preparation). The corresponding flux density is 11 +- 3 microJansky. The data consisted of 1200 seconds integration per filter on the GRB 980329 field in R band (April 3.147) and I band (April 3.167) at airmass 1.1, plus brief R and I band observations of the SA107 field at airmass 1.4. The data were taken with the 4 meter Mayall telescope and Mosaic CCD Imager at Kitt Peak National Observatory. Weather was photometric with poor image quality (from 1.25 to 1.75 arcsec). Details of the photometric calibration and a table of reference star magnitudes in the GRB 980329 field are at the end of this circular.
  We used the same data to measure the flux at the location of the transient. No obvious source is present at the location of the transient (7:02:38.0 +38:50:44 J2000.0) in either filter. R band photometry using a 0.75 and 1.25 arcsecond radius apertures, corrected for aperture losses using the curve of growth, yield flux estimates of 0.40 +- 0.25 and 0.80 +- 0.25 microJansky, where the error bar includes contributions from photon counting noise and from sky subtraction uncertainties only. Conservatively, this gives a 3 sigma upper limit of 1.50 microJansky (for a one-sided confidence interval with probability 99.73%) and R > 23.3 magnitudes.
  In addition, we report a K band upper limit using data obtained by Dey, Jannuzi, and Sosey (on behalf of the NOAO Deep Widefield Survey team) on 1998 April 3.205 using the Kitt Peak National Observatory 2.1 meter telescope and ONIS camera. No point source is apparent at the location of the transient. The RMS counts in the image imply a 3 sigma upper limit of 13.4 microJansky for a point source (in a 1 arcsec radius aperture and corrected using the curve of growth), which corresponds to K > 19.2 at the 3 sigma level.
  - Details of the photometric calibrations -
  Reliable optical fluxes were measured for the Landolt standard stars SA107-212, 213, 357, 359, 351, 457, 456, 600, 599, 612, 626, and 627. Standard star and GRB field photometry was done in a similar fashion, with growth curves derived from multiaperture photometry used to correct all magnitudes to an effective 7" radius. The photometric errors in the GRB frame were taken from the IRAF "mkapfile" task, which applies the aperture corrections. Additional errors were added in quadrature to account for uncertainties in the photometric zero point (+- 0.004 mag in both R and I), color correction terms (+- 0.07*[R-I - 0.42]), and airmass correction term (+- 0.01 mag for I band and +- 0.024 mag for R band).
  The table of measured magnitudes for objects near GRB 980329:

  # RA (J2000) Dec        R     err(R)      I    err(I)
  
  7:02:39.0 38:50:32.7  15.7     1.0      15.300  0.2 
  7:02:37.5 38:50:33.5  15.85    1.0      15.450  0.12
  7:02:35.1 38:50:23.2  16.30    0.3      15.988  0.036 
  7:02:40.1 38:50:11.8  16.9664  0.0314   16.647  0.0155
  7:02:39.4 38:50:03.1  18.4428  0.0275   18.093  0.0175
  7:02:38.7 38:50:26.9  20.655   0.0646   19.473  0.0623
  7:02:36.6 38:50:36.3  20.3862  0.0536   19.331  0.0478
  7:02:36.3 38:50:19.8  20.5135  0.0464   19.625  0.0459 
  7:02:38.4 38:50:50.7  21.2876  0.0688   20.026  0.0711 
  7:02:51.0 38:49:31.0  17.6592  0.0456   16.668  0.0399 
  7:02:50.4 38:49:57.1  17.9663  0.0258   17.539  0.0161
  

  Users of this table should be aware that the magnitude uncertainties for the different stars include some sources of systematic error (airmass and color terms) that are not independent from star to star. Also, the first two entries are substantially saturated in R and I; the third is substantially saturated in R and perhaps marginally in I; and the fourth may be marginally saturated in R. Photometric errors quoted for saturated stars are approximate guesses.
  More detail, and sections of the processed R and I band images, are available from http://www.noao.edu/noao/grb/980329.html.
• light curve from Reichart etal (astro-ph/9806081 = ApJ 517, 1999, 692)
  
• Redshift determinations:
  either 2 or 3 < z < 5 (Lamb et al 1999, AAS 338, 479)
  < 3.9 (Djorgovski et al 1999, Santa Barbara)
• GCN notice #778
  Stephen Holland, Bjarne Thomsen (University of Aarhus), Jens Hjorth, Johan Fynbo (University of Copenhagen), Michael Andersen (University of Oulu), Gunnlaugur Bjornsson (University of Iceland), Andreas Jaunsen (ESO), Priya Natarajan (University of Cambridge, & Yale), and Nial Tanvir (University of Hertfordshire)
  We have used the Space Telescope Imaging Spectrograph (STIS) on the Hubble Space Telescope to image the host galaxy of GRB 980329. We obtained 8072 seconds of STIS/CCD images with the 50CCD (clear) aperture and 5416 seconds with the F28X50LP (long pass) aperture. This data was taken as part of the Survey of the Host Galaxies of Gamma-Ray Bursts (Holland et al., GCN 698) approximately 880 days after the burst occurred. Combined images are now available at http://www.ifa.au.dk/~hst/grb_hosts/data/index.html. The drizzled F28X50LP image is based on two orbits worth of data, and will be updated when the data from the third orbit is available.
  A preliminary determination of the location of the radio transient VLA J070238.0+385044 associated with GRB 980329 (Taylor et al. 1998, ApJL, 502, L115), based on the astrometry of three USNO-A2.0 stars, is (X,Y) = (1039,1027) where the three-sigma uncertainty in the astrometric solution is 20 drizzled STIS pixels (0.5 arcsec). There is a faint, extended object at (X,Y) = (1031,999) in our drizzled 50CCD image. This object is also visible in the F28X50LP image. The object is approximately three sigma southwest of the position of the GRB, and is the best candidate for the host galaxy of GRB 980329. An image showing the location of the galaxy and the GRB is available at http://www.ifa.au.dk/~hst/grb_hosts/data/grb980329cd.gif. The probable host galaxy has AB magnitudes, in an aperture of radius 0.25 arcsec, of CL = 28.6 +/- 0.3 and LP = 28.1 +/- 0.3. If we assume that the galaxy has a power-law spectrum then the preliminary Kron-Cousins R-band magnitude is R = 27.7 +/- 0.3. We also derived a preliminary calibration based on two stars from Rhoads et al. (GCN 157) and found R = 28.2 +/- 0.3. These results are consistent with each other, and are consistent with the host magnitude being 26.8 < R < 29, as determined by Gorosabel et al. (1999, A&A, 347, L31) from the decay of the optical light curve. The faintness of the galaxy is consistent with it having a redshift of z > 2 (Fruchter 1999, ApJ 512, L1; Lamb et al. 1999, A&AS, 138, 479), although we can not rule out z < 2 from the HST/STIS data alone.
• Photometric redshift z~3.5: Jaunsen et al. 2003, A&A 402, 125