A new apparent supernova has been reported independently by R. Arbour, South Wonston, Hampshire, England, and by the Lick Observatory Supernova Search (LOSS; cf. IAUC 6627, 7126). On behalf of LOSS, M. Papenkova, W. D. Li, and A. V. Filippenko, University of California at Berkeley, report that SN 1999by was found and confirmed on unfiltered CCD images taken with the 0.8-m Katzman Automatic Imaging Telescope (KAIT) on Apr. 30.2 (mag about 15.7) and May 1.2 UT (mag about 15.0). Arbour's unfiltered CCD discovery image (limiting mag about 17.5), taken on Apr. 30.8749 with a 0.3-m f/6.3 Schmidt-Cassegrain reflector in the course of his supernova patrol, yields an estimate of the new star's magnitude to be 15.1 and its offset to be 96" west and 86" north of the center of NGC 2841. Arbour forwards the following position obtained by M. Armstrong from an image obtained on Apr. 30.904: R.A. = 9h21m52s.07, Decl. = +51o00'06".6 (equinox 2000.0). Papenkova et al. provide position end figures 52s.18, 07".2, which is about 100" west and 91" north of the galaxy nucleus; they add that there is a bright star (mag about 11.1) located 11".7 west and 29".5 north of the supernova. A KAIT image of the same field on Apr. 25.2 (limiting mag about 19.3) showed nothing at the position of the new star. Arbour found a prediscovery image taken on Apr. 28.8786 that shows SN 1999by at mag about 16.0-16.5, though the supernova was not visible on images taken on Apr. 10, 14, 22, 23, or 27 (limiting mag about 17.5). Papenkova et al. note that NGC 2841 is a well-known Sb galaxy and the host of three past supernovae (1912A, 1957A, 1972R), and they urge spectroscopic and photometric observations for this early and potentially bright supernova.
International Astronomical Union Circular
- Pub Date:
- May 1999