GRB 061121: Optical follow-up

GCN Circular #5840 GRB 061121: MDM Optical Observations

J. P. Halpern, N. Mirabal, & E. Armstrong (Columbia U.) report on behalf of the MDM Observatory GRB follow-up team: "We began R-band observations of GRB 061121 (Page et al., GCN 5823) 20.57 hr after the burst using the MDM 2.4m. Preliminary results from raw images are: ----------------------------------------------------------- Date(UT) Mid-time(UT) t-t0(hr) Exp(s) R(mag) ----------------------------------------------------------- Nov. 22 11:57 20.57 300 21.06 +/- 0.03 Nov. 22 12:49 21.44 300 21.13 +/- 0.04 ----------------------------------------------------------- These are referenced to the USNO B1.0 magnitude R=18.02 for the star at (J2000) R.A.=09h48m54.77s, Decl.= -13d11'17.9". Quoted errors are statistical only. Refined magnitudes and additional results will be forthcoming. This message may be cited."

(J2000) 09h 48m 54.58s, -13° 11′ 42.8″

MDM 2.4m R-band Nov. 22.52 UT

MDM 2.4m R-band Nov. 23.52 UT

MDM 2.4m R-band Nov. 24.50 UT

MDM 2.4m R-band Nov. 25.50 UT

GCN Circular #5847 GRB 061121: MDM Optical Decay

J. P. Halpern, N. Mirabal, & E. Armstrong (Columbia U.) report on behalf of the MDM Observatory GRB follow-up team: "We observed the afterglow GRB 061121 (Page et al., GCN 5823) in the R band for a second night using the MDM 2.4m telescope. The following magnitudes from fully reduced images supersede and extend those reported by us in GCN 5840. --------------------------------------------------------- Date(UT) Mid-time(UT) t-t0(hr) Exp(s) R(mag) +/- --------------------------------------------------------- Nov. 22 11:57 20.57 300 21.10 0.03 Nov. 22 12:18 20.93 300 21.09 0.03 Nov. 22 12:26 21.06 300 21.10 0.03 Nov. 22 12:33 21.18 300 21.11 0.03 Nov. 22 12:41 21.32 300 21.15 0.03 Nov. 22 12:49 21.44 300 21.15 0.03 Nov. 23 11:46 44.39 300 22.08 0.08 Nov. 23 12:02 44.66 300 21.90 0.06 Nov. 23 12:08 44.76 300 21.92 0.06 Nov. 22 12:14 44.86 300 22.02 0.07 Nov. 23 12:20 44.96 300 21.98 0.07 Nov. 23 12:28 45.09 300 22.08 0.07 Nov. 23 12:36 45.23 300 21.99 0.07 Nov. 23 12:46 45.40 600 22.01 0.05 Nov. 23 12:57 45.58 600 22.13 0.07 --------------------------------------------------------- Magnitudes are referenced to a single USNO-B1.0 star at (J2000) R.A.=09h48m54.77s, Decl.= -13d11'17.9" with R=18.02. Quoted uncertainties are statistical only. The power-law decay index from 21 to 45 hours is -1.08+/-0.03. Images are posted at http://www.astro.columbia.edu/~jules/grb/061121/ This message may be cited."

GCN Circular #5851 GRB 061121: MDM Continuing Optical Decay

J. P. Halpern & E. Armstrong (Columbia U.) report on behalf of the MDM Observatory GRB follow-up team: "Continuing observations of GRB 061121 for a third night on the MDM 2.4m telescope yield the following results, using the same calibration as in GCN 5847: --------------------------------------------------------- Date(UT) Mid-time(UT) t-t0(hr) Exp(s) R(mag) +/- --------------------------------------------------------- Nov. 24 11:43 68.34 900 22.32 0.04 Nov. 24 12:04 68.69 1200 22.33 0.03 Nov. 24 12:35 69.21 1500 22.41 0.03 Nov. 24 12:55 69.54 600 22.36 0.08 --------------------------------------------------------- This indicates a slight flattening or deviation from the previously fitted power-law decay. Images and light curve are posted at http://www.astro.columbia.edu/~jules/grb/061121/ This message may be cited."

GCN Circular #5853 GRB 061121: MDM Continued Monitoring

J. P. Halpern & E. Armstrong (Columbia U.) report on behalf of the MDM Observatory GRB follow-up team: "Continuing observations of GRB 061121 for a fourth night on the MDM 2.4m telescope yield the following results, using the same calibration as in GCN 5847: --------------------------------------------------------- Date(UT) Mid-time(UT) t-t0(hr) Exp(s) R(mag) +/- --------------------------------------------------------- Nov. 25 11:42 92.33 900 22.69 0.06 Nov. 25 12:02 92.66 900 22.64 0.05 Nov. 25 12:20 92.96 900 22.75 0.08 --------------------------------------------------------- A power-law decay index of -0.979+/-0.015 is fitted to the four nights. Images and light curve are posted at http://www.astro.columbia.edu/~jules/grb/061121/ This message may be cited."

Last Modified: November 25, 2006	jules@astro.columbia.edu