{
  "bibcode": "2010GCN.10903....1P",
  "body": "D. A. Perley, S. B. Cenko, and J. S. Bloom (UC Berkeley) report:\n\nWe observed the field of GRB 090709A (Morris et al., GCN 9625) using \nNIRI on Gemini-North on the night of 2010-06-23 between 11:54 and 14:46 \nUT, under good conditions.  Our co-added stack contains a total of 146 \nimages of 60 seconds each (2.43 hours of imaging) in the K' filter.  The \n3-sigma limiting magnitude of the stack is K' ~ 23.7.  (Calibration of \nthe field was established relative to several 2MASS stars in the image.)\n\nMatching our image directly to early-time PAIRITEL imaging (Morgan et \nal., GCN 9635), we detect a faint, extended source slightly offset (0.6 \narcsec) from the position of the IR afterglow.  The orientation of the \noffset is along the apparent direction of extension of the source (E-W). \n   Aperture photometry within a 1.0 arcsec aperture centered on the \nobject gives a magnitude of K' = 22.0 +/- 0.2 mag.  The chance \nprobability for this alignment is approximately one percent (Bloom et \nal. 2002, AJ 123:1111, Djorgovski et al. 1995, ApJL 438:L13).\n\nWe therefore associate this object with the host galaxy of GRB 090709A. \n   The detection of a host galaxy confirms the extragalactic, \ncosmological nature of this event (de Luca et al. 2010, MNRAS 402:1870; \nCenko et al. 2010, AJ 140:224).  We note that deep optical imaging of \nthis field by the GTC (Castro-Tirado et al., GCN 9655) detected no \nobject at this position to a limit of i' > 25.5, suggesting that the \nhost galaxy may be internally dust-reddened.  The infrared afterglow \nalso showed evidence of strong reddening (Cenko et al. 2010), and \nforeground extinction in this direction is low; E(B-V) = 0.09 mag. \nAdditional imaging is encouraged to test this hypothesis.\n\nAn image of the field is posted to:\nhttp://lyra.berkeley.edu/~dperley/090709a/090709a_niri.png\n\nWe are happy to thank Marie Lemoine-Busserolle, Matthew Dillman, and \nAndrew Stephens for their support during our classical NIRI run.",
  "circularId": 10903,
  "createdOn": 1277786666000,
  "email": "dperley@astro.berkeley.edu",
  "subject": "GRB 090709A: Host galaxy detection",
  "submitter": "Daniel Perley at U.C. Berkeley  <dperley@astro.berkeley.edu>",
  "eventId": "GRB 090709A"
}