SIMBAD references

A. Gal-Yam, D. Maoz, E. O. Ofek, D. Poznanski, K. Sharon, E. Medezinski, and Y. Lipkin, Tel Aviv University; F. Prada, Isaac Newton Group of Telescopes, Instituto de Astrofisica de Canarias; and P. Guhathakurta, University of California at Santa Cruz, report their discovery of an apparent supernova (V about 23) on unfiltered images taken by Ofek on Mar. 26 with the 2.5-m Nordic Optical Telescope (+ ALFOSC imaging spectrograph) at La Palma. The new object is located at R.A. = 16h35m47s.5, Decl. = +66o13'26".9 (equinox 2000.0), in the field of the galaxy cluster Abell 2218 (z = 0.175). SN 2003il was invisible in images obtained in Apr. and June 2002 (limiting mag V about 25.0). P. Challis, T. Matheson, and R. Kirshner report that this object is confirmed in V, R, and I frames obtained with the 6.5-m MMT telescope (+ MINICAM) on 2003 May 5. Gal-Yam and Sharon add that inspection of deep archival images of Abell 2218, obtained with the Hubble Space Telescope (broad-V F606W filter in Jan. 2000; broad-R F702W filter in Sept. 1994), reveals no sources near the location of SN 2003il (limiting magnitude equivalent to V = 27). These strong limits on the luminosity of possible host galaxies suggests that this supernova may be yet another example of the class of intergalactic supernovae in clusters (Gal-Yam et al. 2003, A.J. 125, 1087). The distance of SN 2003il from the cluster core is 76" (233000 pc, assuming a flat cosmology and a Hubble constant of 70 km/s/Mpc). Using the colors measured from the imaging data obtained by Challis et al. (I = 23.4 ± 0.12, R = 23.6 ± 0.16, V = 24.5 ± 0.16), combined with the color-classification tools of Poznanski et al. (2002, PASP 114, 833), Gal-Yam et al. find that SN 2003il is consistent with a type- Ia supernova at the redshift of the cluster, discovered some months after peak magnitude, which is also possibly somewhat underluminous for its age (by about 1 mag). They add that the supernova colors can also be explained by a higher-redshift event (i.e., behind the cluster Abell 2218) exploding in an undetected low-luminosity dwarf host.