Two groups have been using the CCD mosaic imager known as the Big Throughput Camera in systematic programs to determine cosmological parameters using distant supernovae. The search strategy involves finding probable supernovae by imaging fields of galaxies with massive near-real-time data reduction, and subsequent photometric and spectroscopic followup observations. This can require the meshing of observing schedules with other groundbased sites and HST, which can be a headache for the scheduler! The payoff is illustrated in the following list of supernovae discovered in two nights with BTC on the 4-m, by the Lawrence Berkeley Labs Supernova Cosmology Project headed by Saul Perlmutter:
SN 1997 UT R.A. (2000) Decl. R z Type 1997ek Dec. 28 4 56 11.63 - 3 41 26.0 23.8 0.86 Ia 1997el Dec. 28 4 56 41.21 - 3 27 54.7 23.1 0.64 Ia 1997em Dec. 28 4 56 50.44 - 3 51 37.1 23.6 0.46 Ia 1997en Dec. 28 4 56 57.21 - 4 11 46.0 24.4 0.77 Ia? 1997eo Dec. 28 4 57 32.35 - 3 30 06.2 24.5 0.70 Ia? 1997ep Dec. 28 4 57 48.59 - 3 42 44.7 22.4 0.46 Ia 1997eq Dec. 28 4 58 56.32 - 3 59 29.4 22.5 0.54 Ia 1997er Dec. 28 5 00 38.56 - 3 59 32.2 22.3 0.47 Ia 1997es Dec. 28 8 18 40.65 + 3 13 36.5 24.3 0.65 Ia? 1997et Dec. 28 8 22 53.73 + 3 52 14.7 23.2 0.63 Ia 1997eu Dec. 28 8 23 00.45 + 4 08 27.3 22.4 0.59 Ia 1997ev Dec. 28 8 24 20.28 + 3 51 36.0 23.0 0.43 II? 1997ew Dec. 28 8 24 25.09 + 3 49 08.0 23.9 0.59 II/Ic? 1997ex Dec. 28 8 24 27.87 + 3 52 05.8 21.6 0.36 Ia 1997ey Dec. 29 4 56 58.19 - 2 37 36.7 22.9 0.58 Ia 1997ez Dec. 29 8 21 38.13 + 3 25 10.5 23.4 0.78 Ia 1997fa Dec. 29 8 22 03.72 + 3 24 24.9 22.5 0.50 Ia
All were discovered near maximum light and confirmed spectroscopically within a few nights of discovery using the Keck telescope. Photometric follow-up is proceeding from the ground and, in some cases, with HST. These discoveries were reported in IAU Circular #6804.
The Big Throughput Camera was developed by Tony Tyson (Bell Labs) and Gary Bernstein (Michigan) and has been made available to the CTIO user community by a cooperative agreement. Prospective users may consult the BTC website at http://www.astro.lsa.umich.edu/btc/btc.html or by links from the CTIO webpages.
Malcolm Smith (msmith@noao.edu)