TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3679 SUBJECT: GRB 050724: GMOS Imaging and Spectroscopy DATE: 05/07/26 00:44:54 GMT FROM: Jason Prochaska at UCO/Lick Obs J.X. Prochaska (UCO/Lick), H.-W. Chen (MIT), J.S. Bloom (UCB), and A. Stephens (Gemini) report on behalf of the GRAASP collaboration: We have obtained GMOS/R400 spectroscopy (2400s) of the Sources identified as A, B and D in GCN #3672. We confirm the identification of Source B as a Galactic star (GCN #3675). We tentatively identify Source A as a Galactic star based on its PSF and featureless spectrum. Our acquisition image of the field clearly demonstrates that Source D is extended and therefore a galaxy. Our spectrum of the galaxy is nearly featureless (lambda=5000-9000A), indicating the galaxy is an early type consistent with its red color (GCN #3673). We assign a possible redshift of z=0.257 based on absorption features at ~6510A and ~7415A which we associate with MgI and NaI. The galaxy is located 7.2" from the refined XRT position (GCN #3678) which would correspond to 27kpc at z=0.257. Further observations are encouraged. We thank the Gemini staff for their help in acquiring this dataset. Plots of the data can be found here: http://www.graasp.org/Data/050724 ---------------------------------------------- Jason X. Prochaska UCO/Lick Observatory UC Santa Cruz Santa Cruz, CA 95064 xavier@ucolick.org http://www.ucolick.org/~xavier/ 831-459-2135 (Direct) 831-459-2991 (UCO/Lick Main) 831-459-5244 (Fax)