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Astron. Astrophys. 344, L67-L70 (1999)

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Letter to the Editor

Star-forming regions near GRB 990123 *

Stephen Holland 1 and Jens Hjorth 2

1 Institut for Fysik og Astronomi (IFA), Aarhus Universitet, Ny Munkegade, Bygning 520, DK-8000 Århus C, Denmark (holland@obs.aau.dk)
2 Astronomical Observatory, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen O, Denmark (jens@astro.ku.dk)

Received 23 February 1999 / Accepted 11 March 1999


We reduced the Hubble Space Telescope Space Telescope Imaging Spectrograph images of the gamma-ray burst GRB 990123 that were obtained on 8-9 February 1999 and find [FORMULA], which corresponds to a flux of [FORMULA] µJy for the optical transient 16.644 days after the burst's peak. The probable host galaxy has [FORMULA] ([FORMULA] µJy) and the optical transient is located [FORMULA] ([FORMULA] kpc) south of the galaxy's nucleus. We fit and subtracted a scaled point-spread function to the optical transient and found evidence for three bright knots situated within [FORMULA] ([FORMULA] kpc) of the optical transient. Each knot has [FORMULA], a rest-frame V-band luminosity of [FORMULA]-[FORMULA], and a star-formation rate of at least [FORMULA]-[FORMULA] yr-1. The knots are centrally concentrated with full-width at half-maximum of [FORMULA] ([FORMULA] kpc). Their sizes and luminosities are consistent with their being star-forming regions. The optical transient is located [FORMULA] ([FORMULA] kpc) southeast of the centre of one of these knots.

Key words: gamma rays: bursts – galaxies: starburst

* Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.

Send offprint requests to: Stephen Holland

© European Southern Observatory (ESO) 1999

Online publication: March 29, 1999