The short GRB 091109B (Swift/BAT trigger #375409 ; Oates et al., GCN 10148) triggered the Suzaku Wide-band All-sky Monitor (WAM) which covers an energy range of 50 keV - 5 MeV at 2009-11-09 21:49:02.83 UT (=T0). The observed light curve shows a single peak starting at T0+0.3s, ending at T0+0.6s with a duration (T90) of about 0.19 seconds. The fluence in 100 - 1000 keV was 9.98(-3.69,+0.72)...Full Text

The Swift/UVOT began settled observations of the field of GRB 091109B 84s after the BAT trigger (Oates et al., GCN 10148). We do not detect any source at the enhanced Swift XRT position (Evans et al. GCN 10151) and at the location of source A detected by the VLT (Levan et al. GCN 10154, Malesani et al. GCN 10156) The 3-sigma upper limits for the finding chart exposures (FC) and summed images...Full Text

Following the observations of GRB 091109B (Oates et al., GCN 10148) with the VLT reported by Levan et al. (GCN 10154), we obtained a further epoch of R-band imaging with mean time Nov 10.33 UT (10.22 hr after the burst), using the same instrument and configuration. Source "A" by Levan et al. (GCN 10154) is still detected, and decayed by 1.0+-0.3 mag during this time interval, implying a decay...Full Text

We have analysed 9.7 ks of XRT data for GRB 091109B (Oates et al. GCN 10148), from 86 s to 22.9 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Evans et al. (GCN. Circ 10151). The light curve can be modelled with a power-law decay with a decay index of alpha=0.62 (+0.11, -0.10). Although there is some evidence...Full Text

We observed the location of the short GRB 091109B (Oates et al. GCN 10148), with the VLT/FORS2. Observations began at 03:34 UT, approximately 5.7 hours after the burst. Within the X-ray localisation (Evans et al. GCN 10151) we identify a faint source (Source A) at: RA: 07:30:56.61 Dec: -54:05:22.85 We also identify a second, fainter source (Source B) just outside the X-ray localisation, at...Full Text

"We observed the XRT error circle (GCN 10151) of the short GRB 091109b (GCN 10152) with IMACS on the Magellan/Baade 6.5-m telescope starting on 2009 Nov. 10.167 UT (6.2 hours after the burst). In a 1200-sec stacked R-band image we find no optical sources within the XRT error circle to a 3-sigma limit of R~23 mag in comparison to several nearby stars in the USNO-B catalog. We further note...Full Text

Using the data set from T-60 to T+243 sec from the recent telemetry downlink, we report further analysis of BAT GRB 091109B (trigger #375409) (Oates, et al., GCN 10148). The BAT ground-calculated position is RA, Dec = 112.750, -54.092 deg which is RA(J2000) = 07h 30m 59.9s Dec(J2000) = -54d 05' 30.6" with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment). The partial coding...Full Text

Using 1173 s of XRT Photon Counting mode data and 1 UVOT images for GRB 091109B, we find an astrometrically corrected X-ray position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 112.73603, -54.08983 which is equivalent to: RA (J2000): 07h 30m 56.65s Dec (J2000): -54d 05' 23.4" with an uncertainty of 2.8 arcsec (radius, 90% confidence). This...Full Text

Watcher telescope, located at Boyden Observatory, South Africa, observed autonomously GRB 091109B (S. R. Oates et al., GCN 10148). We obtained a set of 5s exposures in clear filter, starting 78s after the GRB (65s after the notice). We see no new sources in the XRT error box down to the single-image limiting magnitude of 16.5. Coaddition of first 120s (mean exposure time 153s after the GRB) of imaging...Full Text

ROTSE-IIIc, located at the H.E.S.S. site at Mt. Gamsberg, Namibia, responded to GRB 091109B (Swift trigger 375409; S. R. Oates et al., GCN 10148), producing images beginning 9.4 s after the GCN notice time. An automated response took the first image at 21:49:24.5 UT, 21.6 s after the burst, under excellent conditions. We took 10 5-sec, 10 20-sec and 10 60-sec exposures. These unfiltered images...Full Text

At 21:49:03 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 091109B (trigger=375409). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 112.717, -54.080 which is RA(J2000) = 07h 30m 52s Dec(J2000) = -54d 04' 48" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows...Full Text