This page is devoted to information on Supernova 1999gn in NGC 4303 (= M61 ) Basic information on this SN, including the last reported brightness, on this Supernova can be found on the main supernova page. Information on the original web pages for many of these images can be found on the Supernova links web page. ... SEDS has a Supernova 1999gn page . ... Seiichi Yoshida has a 1999gn page . ... Kopernik 's M61 and supernova 1999gn page . ... vsnet-alert 3835 ] SN 1999gn in NGC 4303 = Messier 61 . ...

... September 5, 1998 . The Pulsar Powered Crab . Credit: J. Hester and P. Scowen ( ASU ), NASA . ... Using a stunning series of visible light images taken with the Hubble Space Telescope (HST) , astronomers have discovered spectacular pulsar powered motions within the Crab nebula. Highlights of this HST Crab "movie" show wisps of material moving away from the pulsar at half the speed of light, a scintillating halo, and an intense knot of emission dancing, sprite-like, above the pulsar's pole. ...

... We have compiled the Catalogue of extragalactic supernovae using the GCVS card catalogue. ... Doubtful (?), or rejected (-) SN 8 A1 --- RemFlag [*] The '*' indicates a remark in sn_rem.dat 10- 19 A10 --- Gal Parent galaxy designation 21- 22 I2 h RAh Right Ascension 1950 of Parent galaxy 23- 24 I2 min RAm Right Ascension 1950 (minutes) 25- 28 F4.1 s RAs Right Ascension 1950 (seconds) 29 A1 --- DE- Declination 1950 (sign) 30- 31 I2 deg DEd Declination 1950 of Parent ...

... Here is a brief outline of the current theory of the events in the early history of the solar system: . A cloud of interstellar gas and/or dust (the "solar nebula") is disturbed and collapses under its own gravity. ... The gas cools off enough for the metal, rock and (far enough from the forming star) ice to condense out into tiny particles. (i.e. some of the gas turns back into dust). ... Once the larger of these particles get big enough to have a nontrivial gravity, their growth accelerates. ...