Gamma-ray Burst 981226

A Gamma-Ray Burst was detected by the BeppoSAX GRB monitor on 1998 December 26, 09:47 UT and localized to 6' accuracy. A BeppoSAX NFI observation found a new X-ray source, thus reducing the error circle to 1.5 arcmin.

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• IAUC 7074 BeppoSAX detection and localization
• IAUC 7078 BeppoSAX NFI detection of fading X-ray afterglow

• BeppoSAX MAIL n. 98/24
  A GRB (GB981226) was detected by the GRBM and WFC of BeppoSAX on Dec. 26, around 9:47 U.T.

  Preliminary coordinates from WFC are:
  R.A.(2000)=352.433
  DEC(2000)=-23.942
  

  The error radius is about 8', including a systematic error due a less-than-optimal attitude configuration.
  A follow-on with NFI is being planned
• BeppoSAX MAIL n. 98/25
  Revised WFC position of GB981226 are:

  R.A.(2000)=352.4176
  DEC(2000)=-23.9257
  

  i.e. 1.3' from the preliminary coordinates distributed in BeppoSAX mail 98/24
  The error radius is 6', including a systematic error due to the less-than-optimal attitude configuration The follow-on with NFI should start around 20:30 UT this night. Preliminary results from this observation should be available tomorrow morning (Italian time).
• GCN notice #169
  Bradley E. Schaefer (Yale) reports:
  "I have obtained five 15-minute images in the R band of the BeppoSAX 6' radius region for GRB981226 (Di Ciolo et al. IAUCirc 7074). These images were obtained from UT 01:03 to 02:25 on 27 December 1998 (15.2 hours after the burst) with the Yale 1m telescope on Cerro Tololo. The GRB is close to the Sun, so the observing time on any night is short even from the southern hemisphere. The seeing varied with altitude from 1.3" to 1.7" FWHM. No variable source was identified in or near the GRB981226 region. Comparisons were made with the Digital Sky Survey, for which no 'new' stars appear. Also, comparisons were made between the first and last images, separated by roughly 1.2 hours of time. For the latter comparison, the limiting magnitude for detecting change is close to R=21 mag. Further analysis will provide both deeper and more accurate limits.
• BeppoSAX MAIL n. 98/26
  A follow-up with the NFI of GB981226 started yesterday Dec. 26 around 20:34 UT. Preliminary analysis of the LECS and MECS detectors for the first 6 orbits shows a previously unknown source (a few x 10**-13 erg/cm2/s) within the WFC error box. Preliminary position is

  R.A.(2000)= 352.400
  DEC(2000)= -23.930
  

  i.e. 1.2' from the center of the WFC error box. The error radius is 1.5'. At this stage of the observation we cannot yet establish whether the source is fading. The observation will finish tomorrow evening.
• GCN notice #172
  T.J. Galama, P. Vreeswijk (U. of Amsterdam), E. Palazzi, F. Frontera, N. Masetti (ITESRE, CNR, Bologna) J. van Paradijs (U. of Amsterdam and U. of Alabama in Huntsville), C. Kouveliotou (USRA/MSFC), and A.C. Cameron (U. of St Andrews, UK) report:
  "We have compared Anglo-Australian Telescope (AAT) R-band images (Dec 27.48 1998 UT) with the Digitized Sky Survey (DSS; 'Second Epoch Southern' survey, UK Schmidt red filter), at the position of the BeppoSAX NFI source (BeppoSAX mail 98/26) in the error box of GRB 981226 (Di Ciolo et al. IAU Circ 7074). The AAT image shows a point source at RA = 23h29m35.0s, Dec = -23d56'31'' which is not visible in the DSS. The position is accurate to 2 arcsec (1-sigma). We calibrated the field using the standard field PG0231+051 (Landolt 1992, AJ 104, 340) and obtain R = 21.04 +- 0.10 for the point source. We cannot establish whether the source is related to GRB 981226 as this is a comparison between different filters, but it is a possible candidate."
• GCN notice #173
  A. J. Castro-Tirado and J. Gorosabel, Laboratorio de Astrofisica Espacial y Fisica Fundamental, Madrid N. Drory and B. Konig, Universitaetssternwarte, Munich V. Motta, Univ. de la Republica, Montevideo N. Gonzalez, Instituto de Astrofisica de Canarias, Tenerife J. Aceituno, Calar Alto Observatory, Almeria J. Greiner, Astrophysikalisches Institut, Potsdam F. Frontera and E. Palazzi, Istituto di Astrofisica Spaziale, Frascati (on behalf of the BeppoSAX team)
  We have obtained J-band images at the 3.5-m telescope (equipped with Omega) at the German-Spanish Calar Alto Observatory, on Dec 26.76 (300-s) and Dec 27.76 (1700-s). Within the BeppoSAX position for the X-ray source in the GRB 981226 error box (di Ciola et al. IAU Circ. 7074), we find a variable object with J = 19.4 (Dec 26.76) and J = 20.5 (Dec 27.76). These values are still preliminary. The position is RA(2000) = 23 29 35.0, Dec(2000) = -23 55 42 (+/- 3"). The object reported by Galama et al. (GCN Circ. 172) does not exhibit any variability larger than 0.1 mag. Further observations are encouraged in order to confirm whether the above-mentioned object is the counterpart to GRB 981226. A finding chart can be retrieved via anonymous ftp to laeff.esa.es (under /pub/users/ajct/grb981226) and is reproduced below.
  
• GCN notice #174 (late distribution)
  L. Piro and the BeppoSAX team report:
  A GRB (GB981226) was detected by the GRBM and WFC of BeppoSAX on Dec.26, around 9:47 U.T. Preliminary coordinates from WFC are: R.A.(2000)=352.433 DEC(2000)=-23.942 The error radius is about 8', including a systematic error due a less-than-optimal attitude configuration. A follow-on with NFI is being planned. [GCN OP NOTE: This Circular was received 26 Dec 1998 15:00 UT. However, it was not sent to the automated system, and I was away on holiday without any computer access to catch it sitting in my inbox. I am distributing it for the record even though most of the community knows of this burst, and several have made follow-up observations: GCN Circulars 169, 172, and 173. I will attempt to correct such shortcomings plus the GCN Notice format problem for future events.]
• GCN notice #177
  Przemyslaw R. Wozniak reports for OGLE team:
  An attempt to observe optical transient of GRB981226 was made in BeppoSAX 6' radius region reported by Di Ciolo et al. (IAUCirc 7074). On three nights following the announcement, Dec 27-29, approximately between 1:15 and 2:30 UT I collected 10 and 15-minute frames in I band, with the 1.3 m Warsaw University Observatory Telescope on Las Campanas. This amounted to 70,70,80 minutes of integration each night at 1.4, 1.3 and 1.2" seeing respectively.
  On the first night a faint object at R.A. = 23h29m27s.3, Decl. = -23d56'54" with approximate magnitude I = 20.3 showed some evidence for decline of the flux. Two following nights did not confirm variability. It is most likely a faint galaxy close to detection limit on single exposures.
  I also looked at object reported by Castro-Tirado et al. (GCN#173) at R.A. = 23 29 35.0, Dec = -23 55 42 (J2000). On averages of frames from each night I can barely discern the object at estimated I = 21.4, close to detection limit, however I don't see evidence for variability in my data.
• GCN notice #178
  L. Piro on behalf of the BeppoSAX team report:
  A follow-up with the NFI of GB981226 started yesterday Dec.26 around 20:34 U.T. Preliminary analysis of the LECS and MECS detectors for the first 6 orbits shows a previously unknown source (a few x 10**-13 erg/cm2/s) within the WFC error box. Preliminary position is:

  R.A.(2000)= 352.40
  DEC(2000)= -23.93
  

  i.e. 1.2' from the center of the WFC error box The error radius is 1.5'. At this stage of the observation we cannot yet establish whether the source is fading. The observation will finish tomorrow evening.
• GCN notice #180
  D. A. Frail (NRAO), and S. R. Kulkarni (Caltech) report on behalf of a larger NRAO/Caltech collaboration:
  "We have observed the X-ray source (GCN #178) in the error box of GRB 981226 (GCN #174) with the Very Large Array (VLA) at 4.86 GHz on Dec. 27.00 UT and at 8.46 GHz on Dec 29.92 UT. No sources are visible within the region bounded by the NFI error circle above a 4-sigma level of 148 microJy (4.86 GHz) and 108 microJy (8.46 GHz) on these two days. In particular, we find no radio counterparts to the two optical objects noted by Galama et al. (GCN #172) and Castro-Tirado et al. (GCN #173)."
• GCN notice #181
  James Rhoads (KPNO), Jerome A. Orosz (Penn State University), John Lee (Yale University), and Keivan Stassun (U Wisconsin); report on behalf of the KPNO GRB followup team:
  We have observed the field of GRB 981226 on 1998 December 27.156 (J. Lee observing), 28.100 (J. Lee observing), and 29.096 (K. Stassun observing) using the 0.9m telescope and CCD Mosaic Camera at Kitt Peak National Observatory. Total integration times were 24, 24, and 40 minutes on the three nights. Intermittent cloud on the first night resulted in a comparatively shallow image, with limiting magnitude R ~ 20.5. Limiting magnitudes on the 2nd and 3rd nights were R ~ 21. (These are very approximate estimates based on the USNO-A catalog magnitude R=16.9 for the star at 23:29:29.3 -23:57:36 [J2000].) The full field of view is 1 degree, and so covers the entire BeppoSAX WFC error region and more. Sections of the reduced images are available in FITS format at http://www.noao.edu/noao/grb/981226.html together with further details. Preliminary analysis yields no new sources clearly above the detection limits for the POSS plates, and no convincingly variable sources. We do not detect any object at the position of the J band transient reported by Castro-Tirado et al. The source reported by Galama et al (GCNC 172) is apparent in all of our images and does not appear to vary more than 20%; tighter limits will require deeper images.
  In addition, J. Orosz observed the field on the same three nights using the KPNO 2.1m telescope with R band (Dec 27, 28 UT) and I band (Dec 29 UT) filters. The data cover part of the original BeppoSAX WFC error box. These data are also available from the same web site. Further analysis of both data sets is underway.
• GCN notice #182
  J. S. Bloom, R. R. Gal, and J. Meltzer (Caltech), on behalf of the Caltech/NRAO GRB collaboration, report:
  "On 27.1 and 28.1 December 1998 UT we obtained optical images of the X-ray localization (GCN #174; GCN #178) of GRB 981226 at the Palomar 60-inch. Total integration time was 1800-s and 3450-s with an approximate gunn-i object detection threshold of 23.5 and 24.3 (on 27.1 Dec, 28.1 Dec, respectively). An astrometric plate solution was obtained by comparing field stars to that from USNO-A2 Catalogue; the rms fit in either axes was found to be 0.18 arcsec. We assumed the standard zero-point for the instrument; for comparison, this zero-point gives gunn-i = 20.47 for the star at ra: 23:29:43.5, dec: -23:54:13.8 (J2000).
  The J-band source reported by Castro-Tirado et al. (GCN #173) is not detected at either epoch, implying a J - i of greater than about 3.5 mag on 27.1 Dec UT. The source reported by Galama et al. (GCN #172) did not vary significantly (delta m = 0.12 mag, consistent within the photometric error of r.m.s. = 0.1 mag) and is not likely to be the optical transient of this GRB. These statements are consistent with those by Rhoads et al. (GCN #181).
  We do find that the object at ra: 23:29:27.33, dec: -23:56:53.7 (+/- 0.18 arcsec), reported as possibly variable by Wozniak (GCN #177), to have faded by 0.46 (+/- 0.09 rms) mag between the two epochs. Our preliminary photometry gives i=22.9 +/- 0.2 and i=23.4 +/- 0.2 on the first and second epochs, respectively. We note that this source is well-outside (~1.5 arcmin) the formal error box of the X-ray NFI position (GCN #178), so its connection with GRB 981226 remains to be established. If indeed this source is the transient afterglow of the GRB, then the measured time decay constant is alpha = -0.5; this is shallower than those found in other afterglow but can be reconciled if the underlying galaxy host is of comparable brightness to the transient.
• GCN notice #183
  T.J. Galama, P. Vreeswijk (U. of Amsterdam), 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) report:
  "We have observed the location of the X-ray source (GCN #178) in the error box of GRB 981226 (GCN #174) with the Westerbork Radio Synthesis Telescope (WSRT). We observed for 6.4 hours at 4.88 GHz on Dec 29.70 UT, 1998. We find no sources at the location of the X-ray source down to 360 microJy (4 sigma). In particular, we find no radio counterparts to the optical objects noted by Galama et al. (GCN #172), Castro- Tirado et al. (GCN #173) and Wozniak et al. (GCN #177). These results are consistent with those by Frail et al. (GCN #180)."
• GCN notice #184
  F. Frontera, E. Montanari, Universita' Ferrara, Italy, L. A. Antonelli, Osservatorio Astronomico di Roma, Italy, P. Giommi, Agenzia Spaziale Italiana, Rome, Italy, M. R. Daniele, D. Ricci, SAX-SDC, Rome, Italy, A. Coletta, M. Smith, A. Tesseri, SAX-SOC, Rome, Italy, C. De Libero, SAX-OCC, Rome, Italy, L. Piro, IAS, CNR, Rome, Italy, on behalf of a large collaboration, report:
  "The BeppoSAX Wide Field Camera error box of GRB981226 (IAUC 7074) was observed with the BeppoSAX Narrow Field Instruments (NFI) starting about 11 hr after the burst in the period Dec. 26.878-29.148 UT. Preliminary analysis of the MECS2+3 data shows a previously unknown X-ray source, 1SAXJ2329.6-2356, located at RA = 23h29m36s, Dec = -23o55'58'' (equinox 2000.0), with an error radius of 1'. This position is very close to the centroid of the WFC error box. During the first 33.3 hours of observation, the 2-10 keV source flux decreases by a factor 3, from (4.3 +-1.0)x10E-3 cts/s, corresponding to (3.0 +- 0.7)x10E-13 erg sE-1 cmE-2, down to (1.67+-0.46)x10E-3 cts/s corresponding to (0.98 +- 0.30)x10E-13 erg sE-1 cmE-2. The measurements during the subsequent 18.36 hours show that the flux of 1SAXJ2329.6-2356 does not vary significantly from the last value.
• GCN notice #185
  Bradley E. Schaefer (Yale U.), Jonathan Kemp, Irina Feygina, Jules Halpern (Columbia U.) report:
  We have obtained B, V, and R images with the 0.9-m and 1.0-m telescopes on Cerro Tololo of the GRB981226 position on the nights of 26/27, 27/28, and 30/31 December 1998. We find no variable sources, and no significant changes from the Digitized Sky Survey. This includes the entire BeppoSAX WFC error circle (Di Ciolo et al. IAUCirc. 7074) as well as the BeppoSAX NFI error circle (Frontera et al. IAUCirc. 7078). A journal of our observations, the corresponding magnitudes, and limits are presented in the table below. Our limiting magnitudes are quoted for a signal-to-noise ratio of 4. For the three variables that have been proposed previously, we find as follows:

  (1) No source is visible at the position of the proposed IR variable 
      (Castro-Tirado et al. GCN 173) to the limits stated below.  This
      implies R-J > 1.7 for this source if it is the afterglow.
  
  (2) There is no significant evidence for variability of the proposed
      candidate of Galama et al. (GCN 172).
  
  (3) The source identified by Wozniak et al. (GCN 177) is clearly 
      visible, but we have no significant evidence of its variability.
  
      -----------------------------------------------------------------
      Telescope    UT start   Band  Limit    Mag(Galama)   Mag(Wozniak)
      -----------------------------------------------------------------
      CTIO 1.0m   Dec 27.044   R    21.6     20.74+-0.13   21.20+-0.20
      CTIO 0.9m   Dec 27.064   V    21.8    >21.8         >21.8
      CTIO 0.9m   Dec 27.071   B    21.5    >21.5         >21.5
      CTIO 1.0m   Dec 28.034   R    21.7     21.06+-0.15   21.15+-0.24
      CTIO 0.9m   Dec 28.065   V    21.7    >21.7         >21.7
      CTIO 0.9m   Dec 28.072   R    21.0     20.8 +-0.3    21.03+-0.24
      CTIO 0.9m   Dec 31.052   R    22.1     21.10+-0.10   21.61+-0.20
      -----------------------------------------------------------------
  

• GCN notice #186
  Sylvio Klose, Thueringer Landessternwarte Tautenburg, Germany, reports:
  "The error box of GRB 981220 was observed with the Tautenburg Schmidt telescope in the night from Dec. 23 to 24. For any OT at the position of the radio counterpart of GRB 981220 (Galama et al., GCN #168; Frail et al., GCN #170) the following preliminary data point can be provided: Dec. 23.717 UT, Gunn z >~ 17 +/- 1 mag (observations from 16:48 to 17:36 UT). A more accurate limit will be published, when photometric standards are available. Observations have also been performed in the I-band, but do not reach the limiting magnitude reported by Vrba et al. (GCN #171). Images are posted on the WWW at http://www.tls-tautenburg.de/research/grb.html.
  The error box of GRB 981226 was observed with the Tautenburg Schmidt telescope only 6.5 hours after the burst, but under very critical observing conditions (zenith distance ~75 deg). For the proposed NIR counterpart of GRB 981226 (Castro-Tirado et al., GCN #173), the object noted by Galama et al. (GCN #172), as well as for the variable object reported by Wozniak et al. (GCN #177) and Bloom et al. (GCN #182), the following data point can be provided: Dec. 26.682 UT, I >~ 16 (observations from 16:07 to 16:40 UT). This magnitude limit is based on the Hipparcos star 115941 which has I=7.9 (see http://astro.estec.esa.nl/hipparcos_scripts/ HIPcatalogueSearch.pl?hipId=115941) and which is very close to the GRB error circle."
• GCN notice #188
  I. A. Smith (Rice University), R. P. J. Tilanus and F. Baas (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 source suggested by Castro-Tirado as being the counterpart to GRB 981226 (GCN #173: 23:29:35.0 -23:55:42 J2000). The observation, performed in mediocre weather, started UT 1998 Dec 30.15 and lasted 44 minutes. No source was detected at this location: the 850 micron flux density was 0.6 +/- 3.8 mJy.
• GCN notice #190
  B. Lindgren, J. Hjorth, H. Pedersen, (University of Copenhagen), M. I. Andersen (NOT), A. O. Jaunsen (University of Oslo), J. Sollerman (Stockholm Observatory), J. Smoker, C. Mooney (Queens University, Belfast) and E. Palazzi (Istituto TeSRE, Bologna; on behalf of the SAX GRB team) report:
  "R band images of parts of the BeppoSAX WFC error circle of GRB 981226 (Piro, GCN Circ. 174), covering the NFI error circle (Di Ciolo et al., IAU Circ. 7074; Frontera et al. IAU Circ. 7078), were obtained on 1998 December 26.82 UT (1440 sec, seeing FWHM = 1.7"), Dec 27.85 UT (2400 sec, FWHM = 1.6") and Dec 28.83 UT (2400 sec, FWHM = 1.0") with the 2.5-m Nordic Optical Telescope (NOT) on La Palma and on Dec 27.06 UT (500 sec, FWHM = 1.5") and Dec 28.09 UT (500 sec, FWHM = 1.5") with the 1.5-m Danish telescope, La Silla. An I band image was obtained with the NOT on Dec 28.86 UT (2100 sec, FWHM = 1.2").
  Down to a limiting magnitude of R ~ 23 we have found no significant evidence for a variable source inside the NFI error circle. Finding charts of the field are posted at http://www.astro.ku.dk/~brian_j/grb981226 The results we obtained for two field reference stars (A,B) and the three candidate optical counterparts to GRB 981226, reported by Galama et al. (GCN Circ. 172), Castro-Tirado et al. (GCN Circ. 173) and Wozniak (GCN Circ. 177), respectively, are presented in the table below.
  The photometric zero point is tied to that of Galama et al. (GCN Circ. 172), assuming R = 21.04 for their reported object. All photometry is based on PSF photometry of the NOT R images, and assumes unresolved objects. The data obtained at the Danish 1.5-m telescope are consistent with these results. The quoted photometric uncertainties include formal fitting errors only. The astrometry refers to the USNO-A2.0 system (J2000) and is accurate to +- 0.23" (mean absolute deviation).
  

                 RA (J2000)   Dec (J2000)  Dec 26.83    Dec 27.85    Dec 28.83
  star A         23 29 29.28  -23 57 36.9  16.79+-0.00  16.79+-0.00  16.79+-0.00
  star B         23 29 29.57  -23 57 45.6  18.79+-0.01  18.77+-0.01  18.80+-0.00
  Galama         23 29 34.94  -23 56 30.5  21.01+-0.05  21.09+-0.07  21.07+-0.04
  Castro-Tirado  23 29 34.92  -23 55 41.3  22.47+-0.14  22.36+-0.16  23.05+-0.18
  Wozniak        23 29 27.31  -23 56 53.5 (21.31+-0.06)(21.58+-0.11)(21.60+-0.05)
  

  Galama's object is constant within +- 0.05 mag during our observations. This is consistent with the findings of Castro-Tirado et al. (GCN Circ. 173), Bloom et al. (GCN Circ. 182) and Schaefer et al. (GCN Circ. 185).
  Castro-Tirado's object is close to the detection limit in our images, and we conclude that there is no evidence for variability of this object. In a combined image of all our R band data the object has R = 22.9 +- 0.1. If Castro-Tirado's variable (J band) object is the optical afterglow to GRB 981226, then the object we have detected is the likely host galaxy. It would be among the brightest host galaxies detected so far.
  In our combined R image (FWHM = 1.2") Wozniak's object is clearly extended. While consistent with that found by Schaefer et al. (GCN Circ. 185), our PSF photometry is therefore biased and seeing dependent. We conclude that this object is a galaxy with a constant R = 21.16 +- 0.05 and that any contribution from a variable source must be small in R.
  For our Dec 28.86 I band NOT image we find I = 18.1 (based on an approximate photometric zeropoint accurate to an estimated +- 0.2 mag) for the reference star reported to have i = 20.47 (Bloom et al., GCN Circ. 182). In what follows we adopt our own preliminary zero point and offset the Bloom et al. values to this system for comparison.
  Galama's object has I = 20.35 +- 0.05, i.e., R - I = 0.7. Castro-Tirado's object is not detected down to I = 22. Wozniak's object is close to the detection limit; we find I = 21.9 +- 0.5 on Dec 28.86. This value should be compared to I = 20.3 on Dec 27.1 UT (Wozniak, GCN Circ. 185), and to the corrected values I = 20.55 on Dec 27.1 UT and I = 21.05 on Dec 28.1 UT (based on Bloom et al., GCN Circ. 182). Thus, Wozniak's object has continued to fade.
  In the simplest scenario, Wozniak's object is a fading red source (R - I > 2.6) superposed on an extended blue (R - I < -0.7) object. It is tempting to interpret this as a rapidly fading red optical afterglow originating in a bright, blue host galaxy. However, given its position more than one error radius (70") outside the NFI error circle, its relation to GRB 981226 remains questionable.
  The results reported in this circular are preliminary. A more detailed analysis is ongoing."
• GCN notice #195
  D. A. Frail reports on behalf of a larger NRAO/Caltech collaboration:
  There is a faint radio source within the NFI error circle (GCN #184) of GRB 981226 at RA = 23h29m37.21s, DEC = -23d55'53.8" with an error of +/-0.5". The source was first detected at the VLA on Jan 3.95 UT with an 8.46 GHz flux density of 169 +/- 28 microJy. It is present but at a weaker level on at least three other epochs (Dec. 29, Jan 7 and Jan 11), where its average flux density is 76 +/- 17 microJy. On January 19.89 UT, the flux density of the source had dropped below detectablity, with an upper limit of 28 microJy.
  This level of short term variability is characteristic of radio afterglows at early times. In contrast, two other radio sources in the field have remained constant during this same period. We urge optical observers to re-examine this location for any indication of a transient or a faint host galaxy.
• GCN notice #749
  Stephen Holland, Bjarne Thomsen (University of Aarhus), Michael Andersen (University of Oulu), Gunnlaugur Bjornsson (University of Iceland), Johan Fynbo, Jens Hjorth (University of Copenhagen), Andreas Jaunsen (University of Oslo), Priya Natarajan (University of Cambridge, & Yale), and Nial Tanvir (University of Hertfordshire)
  We have obtained 7865 seconds of HST/STIS images with the 50CCD (clear) aperture and 7909.63 seconds of HST/STIS images with the F28X50LP (long pass) aperture of the host galaxy of GRB 981226. These data was taken as part of the Survey of the Host Galaxies of Gamma-Ray Bursts (Holland et al. GCN 698) approximately 555 (clear) and 558 (long pass) days after the burst. Combined (drizzled) images are now available at http://www.ifa.au.dk/~hst/grb_hosts/data/index.html.
  The galaxy identified by Frail et al. (1999, ApJL, 525, L81) is the only object within the error circle of the radio transient (VLT J232937.2-235553) associated with GRB 981226. This galaxy is located at (X,Y) = (1033,1056) on the drizzled STIS clear image, has an ellipticity of approximately 0.65, and its major axis has a position angle of approximately -75 degrees east of north. We measured the following AB magnitudes for this galaxy using an aperture with a 1.1 arcsecond radius: CL = 25.04 +/- 0.07 in the STIS clear aperture and LP = 24.50 +/- 0.10 in the STIS long pass aperture. We used the photometry of Walker (1994, PASP, 106, 828) to calibrate our data (see Holland et al. 2000, in preparation, for details) and found V-R = 0.50 +/- 0.14, V = 24.80 +/- 0.08, and R = 24.30 +/- 0.11 in the Johnson and Kron-Cousins systems. We note that the northeast side of the galaxy is significantly bluer than the rest of the galaxy (see http://www.ifa.au.dk/~hst/grb_hosts/data/grb981226_colour.gif). We estimate that the blue structure on the north side of the galaxy has V-R = 0.1 and the south edge of the galaxy has V-R = 1.5. There is a compact source at each end of the blue structure. The west source corresponds to the photometric centre of the galaxy.
  Frail et al. (1999) found that the galaxy was located 0.55 +/- 0.53 arcseconds west and 0.41 +/- 0.43 arcseconds south of the radio afterglow. This error ellipse encompasses the eastern half of the galaxy and the eastern compact source in the blue structure.
  We also note the presence of a faint point source (V ~= 28.4, V-R ~= 0.3), at (X,Y) = (1015,1064) in the drizzled STIS clear image, approximately 1.0 arcseconds from the nominal position of the radio afterglow.
• GCN notice #1032
  P. Saracco, G. Chincarini, S. Covino, G. Ghisellini, M. Longhetti, F. Zerbi (Osservatorio Astronomico di Brera, Merate, Italy) D. Lazzati (Institute of Astronomy,Cambridge, UK) P. Severgnini (Osservatorio Astronomico di Arcetri, Firenze, Italy)
  We have obtained 9720-second exposure (18 dithered images, 540 s each) in the Rc (Bessell) at the position of GRB 981226. Data have been carried out from 4th to 5th October 2000 at the ESO-VLT UT1 telescope with FORS1 under seeing conditions of ~0.7 arcsec.
  These observations are part of a survey of host galaxies (Saracco et al. 2000; Prog. ID: 66.B-0539(A)).
  We reach a limiting magnitude fainter than Rc=27.5 in the final co-added image (S/N=3 within the seeing disk). We clearly detect a galaxy at the position of GRB 981226 as previously found by Holland et al. (2000; GCN #749).
  We measure a magnitude (Vega) Rc=24.8(+-0.1) (galactic extinction A(R)=0.06) within an aperture radius of 2 arcsec.