TITLE: GCN CIRCULAR NUMBER: 9639 SUBJECT: GRB090709A: High Energy BAT/XRT Analysis Suggests Low to Moderate Redshift DATE: 09/07/09 22:39:12 GMT FROM: S. Bradley Cenko at Caltech Nat Butler (UC Berkeley) Reports: We reduce the Swift XRT and BAT data using our automated pipeline (see, http://astro.berkeley.edu/~nat/swift for more details of the fits and summary plots for this and other Swift GRBs). The intermediate time PC mode XRT data (t=4-10 ksec post trigger) are well-fit (chi^2/nu=80.48/59) by an absorbed powerlaw with photon index Gamma=1.9+/-0.1 and column density 1.7+/-0.5 x 10^21 cm^-2 in excess of the anticipated Galactic contribution (6.6 x 10^20 cm^-2) at the 6.7-sigma level. This detection of an excess column is suggestive of a low to moderate redshift (i.e., z<~2) for the GRB (e.g,. Grupe et al. 2007, ApJ, 133, 2216). The time-integrated BAT spectrum is well-modeled by a powerlaw times exponential function (chi^2/nu=29.67/55). We derive Epeak,obs = 200 (176,298) keV and a rest-frame isotropic equivalent energy release Eiso ~ 1.4 x 10^53 erg (z=1). If the GRB were at very high z~8, Eiso ~ 4.5 x 10^54 erg, comparable to the intrinsically brightest few GRBs ever detected, further suggestive of a low to moderate redshift for this event.