[AAVSO-HEN] GRB 090418: PAIRITEL NIR detection

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TITLE:   GCN CIRCULAR
NUMBER:  9152
SUBJECT: GRB 090418: PAIRITEL NIR detection
DATE:    09/04/18 14:13:00 GMT
FROM:    Bethany Cobb at UC Berkeley  <bcobb at astro.berkeley.edu>

B. E. Cobb and J. S. Bloom (UC Berkeley) report:

We observed the optical afterglow of GRB 090418 (Mangano et al., GCN 9149)
with the 1.3-m Peters Automated Infrared Imaging Telescope (PAIRITEL)
beginning at 2009-04-18 11:34 UT, 26 minutes after the Swift
Trigger.  We detect the afterglow (Chornock et al., GCN 9148;  Yuan et al.,
GCN 9150) in 651 sec mosaics of 7.8 sec simultaneous individual exposures
in the J, H, and Ks filters.  Preliminary photometry for the afterglow in
these
mosaics, with midtime 2009-04-18 11:43 UT (35 minutes post-burst), yields
J = 17.7 +- 0.4, H = 17.5 +- 0.4, and  Ks = 16.1 +- 0.4
(all magnitudes given in the Vega system), calibrated to the 2MASS system.