TITLE: GCN CIRCULAR NUMBER: 9835 SUBJECT: GRB 090823 Long burst with IPN triangulation and BAT position DATE: 09/08/25 01:36:20 GMT FROM: Jay R. Cummings at NASA/GSFC/Swift J. R. Cummings (NASA/GSFC/CRESST) on behalf of the Swift-BAT team, S. Golenetskii, R. Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, and T. Cline on behalf of the Konus-Wind team, M. Marisaldi, F. Fuschino, C. Labanti, M. Galli, G. Di Cocco on behalf of the AGILE team, K. Yamaoka, M. Ohno, Y. Fukazawa, T. Takahashi, M. Tashiro, Y. Terada, T. Murakami, K. Makishima, and Y. Hanabata on behalf of the Suzaku-WAM team, and K. Hurley for the IPN At 16:11:12 on 2009-08-23, GRB 090823 triggered the Suzaku WAM. The IPN was notified, and the burst was also observed by KONUS-Wind, Agile-MCAL, and (during a slew maneuver) Swift-BAT. A source was found in ground analysis of BAT event data, which is routinely collected during many pre-planned slews, and the source location was confirmed by IPN triangulation. The BAT position is RA, Dec 228.711, 60.660 which is equivalent to RA, Dec (J2000): 15:14:50.6, 60d 39' 36" with an uncertainty radius of 4 arcmin (estimated 90% containment, stat+sys). We have triangulated GRB 090823 to a Konus-WAM annulus centered at RA(2000)=141.472 (09h 25m 53s) Dec(2000)=+9.275 (+9d 16' 31"), whose radius is 52.640 ± 4.346 deg (3 sigma). The BAT source is 0.384 deg (0.27 sigma) from the center line of the annulus. As observed in Suzaku-WAM and Agile-MCAL, the burst had two peaks at about T+1 and T+4 seconds, and had emission above 700 keV but not above 1.4 MeV. The BAT lightcurve shows that the emission began with a slow rise beginning about T-3 seconds, and decayed back to background rates by about T+20 seconds. The BAT event data, from which mask-weighted spectra and images are constructed, began at about T+10.5 seconds, missing 99% of the burst. A Swift Target of Opportunity has been requested and approved to follow up this burst with the Swift XRT and UVOT about 32 hours after the burst.