We observed the field of GRB 100305A (Troja et al. GCN 10470) with the optical three color (g', Rc and Ic) CCD camera attached to the Murikabushi 1m telescope of Ishigakijima Astronomical Observatory. The observation started on 2010-03-05 13:03:55 UT (~4h after the burst). We did not find any new point source in the XRT error circle (Osborne et al., GCN 10474) in all the three bands. Three sigma...Full Text

We observed the field of GRB 100305A (Troja et al., GCN 10470) with the 0.6m Super-LOTIS telescope located at Kitt Peak National Observatory beginning 106 seconds after the trigger. Observations were carried out in the R band for approximately 45 minutes under good conditions. We do not detect any sources within the XRT enhanced error circle (Osborne et al., GCN 10474) or the source detected...Full Text

Using the data set from T-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 100305A (trigger #414905) (Troja, et al., GCN 10470). The BAT ground-calculated position is RA, Dec = 168.373, 42.381 deg which is RA(J2000) = 11h 13m 29.5s Dec(J2000) = +42d 22' 50.7" with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment). The partial coding...Full Text

"We continued our observations of GRB 100305A with the Gemini-N telescope mounted with the GMOS camera. A sequence of z'-band images has been taken for a total exposure time of 15 min. No clear object is visible in the position of the optical afterglow previously reported (GCN 10473) at the following 3-sigma upper limit: z' > 23.42 mag We also report a corrected error measure in our photometry...Full Text

The Swift/UVOT began settled observations of the field of GRB 100305A 144s after the BAT trigger (Troja et al., GCN 10470). Data summed from the first and second orbits do not reveal a source at the enhanced position of the X-ray afterglow (Osborne et al., GCN 10474) or the candidate afterglow reported by Cucchiara et al. (GCN 10473). The 3-sigma upper limits for the finding chart (fc) and summed...Full Text

We have analysed 2.5 ks of the Swift-XRT data for GRB 100305A (Troja et al. GCN 10470), from 145 s to 6.0 ks after the BAT trigger. The data comprise 84 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The best position of the X-ray afterglow is the UVOT enhanced XRT position given in Osborne et al. (GCN 10474). Analysis of the light curve shows an initial steep...Full Text

We obtained imagery of the GRB 100305A burst reported by Troja et al. (GCN 10470) using the Sonoita Research Observatory (SRO) 35cm telescope in southern Arizona, utilizing an automatic VOevent trigger. The exposures began about 3 minutes after the burst and continued for approximately two hours. 20 Rc-band, 10 V-band, and a set of BVRI exposures for field calibration were acquired. Inspection...Full Text

Using 2448 s of XRT Photon Counting mode data and 6 UVOT images for GRB 100305A, 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 = 168.36691, +42.40393 which is equivalent to: RA (J2000): 11h 13m 28.06s Dec (J2000): +42d 24' 14.1" with an uncertainty of 1.7 arcsec (radius, 90% confidence). This...Full Text

"On March 5.42 UT we observed the field of GRB 100305A (Troja et al., GCN 10470) with the Gemini-N telescope and the GMOS instrument. In our 300s r'-band and 900s i'-band images we clearly detect a source inside the XRT error circle at the following position: RA (J2000) = 11:13:28.30 Dec (J2000) = 42:24:10.50 with an uncertainty of 0.5" in each coordinate. Using 2 USNO-B1 stars we calibrated...Full Text

We observed the field of GRB 100305A (Troja et al., GCN 10470) with the 1.3m PAIRITEL located at Mt. Hopkins, Arizona. Observations began at 2010-03-05 09h29m30s UT, ~0.4 hours after the Swift trigger.  In initial mosaics (effective exposure time of ~795.6 seconds) taken simultaneously in the J, H, and Ks filters, we do not detect any sources within the XRT error circle. The preliminary photometry...Full Text

We have imaged the field of GRB 100305A (Troja et al., GCN 10470) with the automated Palomar 60-inch telescope. Images were obtained in the Sloan g', r', i', and z' filters beginning at 09:09 UT on 5 MarcHETE 2010 (~ 3.5 minutes after the burst). In coadded images, we find no sources inside the XRT error circle to the following limits (calculated with respect several point sources in the SDSS...Full Text

At 09:05:38 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 100305A (trigger=414905). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 168.365, +42.376 which is RA(J2000) = 11h 13m 28s Dec(J2000) = +42d 22' 34" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed...Full Text