- Comet White-Ortiz-Bolelli
Comet White-Ortiz-Bolelli (formal designations: C/1970 K1, 1970 VI, and 1970f) was a bright
comet which appeared in 1970. It was a member of theKreutz Sungrazers , a family of comets which resulted from the break-up of a large parent comet several centuries ago. It was already easily visible to thenaked eye when first discovered, and reached a maximumapparent magnitude of +1.Discovery
Comet White-Ortiz-Bolelli was first spotted on
May 18 by Graeme White, anAustralia n amateurastronomer inWollongong ,New South Wales . He sighted the comet inbinoculars shortly aftersunset , and described it as having astar -like head atapparent magnitude 1-2, and a short tail about 1 degree long. He spotted it again onMay 20 bynaked eye as well as binoculars, and by this time the tail had grown to 10° in length.The second independent discovery was made on
May 21 byAir France pilot Emilio Ortiz, from a location about 400 km east ofMadagascar . Ortiz saw the comet from his cockpit, and reported a magnitude of 0.5 to 1.0 and a tail about 5–8° long. A few hours later, Carlos Bolelli, a technician at theCerro Tololo Inter-American Observatory inChile became the third independent discoverer of the comet, although he saw only the tail, as the head was beneath the horizon.ubsequent observations
Numerous independent discoveries were made in the days immediately following the comet's discovery, but
astronomical naming conventions only allowed the comet to be given the names of the first three. All sightings of the comet were made from thesouthern hemisphere , due to the orientation of its orbit with respect to theEarth .Throughout the comet's brief appearance, it could only be seen low in the sky for a short time after sunset, but it was most easily visible on
May 24 . After that it faded rapidly, and by1 June it had already faded to below naked-eye visibility. The last definite detection of the comet was made onJune 7 , when it appeared as a faint, ill-defined nebulosity. Increasingmoon light and the comet's decreasing brightness prevented any further visual sightings of the comet.A sungrazer
The comet's sudden appearance very close to the sun and rapid subsequent decline in brightness both pointed to it being a
sungrazing comet , and calculations of itsorbit byBrian Marsden backed this suggestion. Marsden showed that the comet had reachedperihelion onMay 14 , at a distance of just 1.35 million km, or 2 solar radii.The calculated orbit pinned down White-Ortiz-Bolelli as a member of the
Kreutz Sungrazers , a group of comets which all originate from the fragmentation of one giant parent comet several hundred years ago, and which has provided some of the brightest comets ever seen. Kreutz Sungrazers all travel on similar orbits, which result in them being most easily visible from the southern hemisphere, between August and April. Kreutz sungrazers appearing between May and July may come and go unseen, as they approach from directly behind theSun as seen from Earth; the only previous Kreutz Sungrazer seen during these months was theEclipse Comet of 1882 , which was only observed once, during a totalsolar eclipse .Before White-Ortiz-Bolelli, studies had divided the Kreutz Sungrazers into two sub-groups, originating from fragmentations at different orbits, but White-Ortiz-Bolelli seemed to be a member of neither. Studies showed that it probably broke away from the comet that spawned Subgroup II, before the main fragmentation, and it was classed as the first (and so far only) member of Subgroup IIa.
References
# Roemer E. (1970), "Comet Notes", Publications of the Astronomical Society of the Pacific, v. 82, p.928
External links
* http://cometography.com/lcomets/1970k1.html
sk:C/1970 K1
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