September 22, 2002
On Friday, September 20th, amateur astronomer Katsumi Haseda (Aichi, Japan) found a 5th-magnitude starlike object on a routine patrol photograph of the rich Milky Way field in northeastern Sagittarius. Even though the apparent nova was included in just one of Haseda's Tri-X frames exposed that night, it was so bright that Taichi Kato of the Variable Star Network issued an urgent appeal to observers around the world for confirmation.
Within 16 hours of the discovery, Doug West in Mulvane, Kansas, obtained a CCD image of the field and measured the object's position to be right ascension 19h 01m 09.4s, declination –22° 00' 06" (equinox 2000.0). Among those confirming the new star visually was Sky & Telescope contributing editor Stephen James O'Meara. He called it magnitude 5.5, bordering on naked-eye visibility in bright moonlight from his observing site in Volcano, Hawaii.
On Sunday evening outside Boston, Massachusetts, S&T senior editor Alan MacRobert judged the star to be magnitude 6.5 in 10 x 50 binoculars. "Seems like a fast nova — fading fast," he says.
IAU Circular 7975 reports that a spectrum obtained at Fujii Bisei Observatory in Okayama, Japan, confirms that the object is a galactic nova — that is, a thermonuclear explosion on the surface of a white dwarf accreting material from a companion star — that is shortly past peak brightness. It will no doubt continue to fade, with some fluctuations, during the next few weeks.
For estimating the nova's brightness, observers can use the official comparison-star chart from the American Association for Variable Star Observers (AAVSO).
下图:The nova just discovered by Japanese amateur Katsumi Haseda lies very close to the Teaspoon asterism and northeast of the Teapot of Sagittarius. An 揦?marks its location on this chart, which includes stars to magnitude 8.5. S&T Diagram |
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