Batch Discovery of Six High-Redshift Supernovae: \\ Developing a New Tool for Cosmology

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Session 63 -- Large Scale Structure and Cosmology
Oral presentation, Thursday, 2, 1994, 10:00-11:30

[63.03] Batch Discovery of Six High-Redshift Supernovae: \\ Developing a New Tool for Cosmology

S.Perlmutter, C.Pennypacker, G.Goldhaber, S.Gabi, A.Goobar, B.Grossan, A.Kim, M.Kim, R.Pain, I.Small (LBL/CfPA/SSL, Berkeley), R.McMahon (IoA), P.Bunclark, M.Irwin (RGO), M.Postman, W.Oegerle (STScI), T.Lauer (NOAO), J.Hoessel (U.Wisconsin)

With our recent discovery of six supernovae, we have shown that batches of pre-maximum high-redshift supernovae can now be scheduled for discovery just before a chosen new moon. This makes it possible to study statistically significant samples of supernovae with scheduled photometry and spectroscopy as they brighten and then fade. We have developed this search technique in order to study populations of supernovae (mostly type Ia) at distances large enough to be useful in measuring the cosmological deceleration parameter. As we learn about their homogeneity and any evolutionary differences from nearby supernovae, we are developing a new observational tool for cosmology.

We will report on the search technique that we have developed, which we used this past winter in coordinated telescope time at the Isaac Newton 2.5m and the KPNO 4m telescopes. In approximately six nights total of useful data, we discovered six supernovae at redshifts between $z$ = 0.2 and 0.5. The rate of discovery is consistent with our initial estimates for distant Type Ia supernova rates. Every supernova discovered was followed through its lightcurve with photometry, and most with spectroscopy of the supernova and/or its host galaxy. We will show preliminary results, including spectra, and discuss the identification of supernova type and the use of these supernovae for cosmological measurements.

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