Charles Thomas Kowal | |
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| Born | (1940-11-08)November 8, 1940 |
| Died | November 28, 2011(2011-11-28) (aged 71) |
| Alma mater | University of Southern California |
| Known for | Discovery of outer Solar System objects |
| Scientific career | |
| Fields | Astronomy |
| Institutions | Caltech'sHale Observatory,STScI,APL |
| see§ List of discovered minor planets |
Charles Thomas Kowal (November 8, 1940 – November 28, 2011) was an Americanastronomer known for his observations and discoveries in theSolar System. As a staff astronomer atCaltech'sMount Wilson andPalomar Mountain observatories between 1961 and 1984, he found2060 Chiron, the second-largestcentaur, discovered two moons of the planetJupiter, and discovered or co-discovered a number ofasteroids,comets andsupernovae. He was awarded theJames Craig Watson Medal for his contributions to astronomy in 1979.
In the 1960s, Kowal observed with the Palomar48" Schmidt telescope, contributing observations to notedcosmologistFritz Zwicky's six-volumeCatalogue of Galaxies and of Clusters of Galaxies.[nb 1] Kowal also began to search forType Ia supernovae in other galaxies, in an effort led by Zwicky to calibrate the magnitudes of these exploding stars so that they could be used asstandard candles, reliable measures of the distance of their host galaxies (work which in the present has led to accurate measurements of theexpansion of the universe).[3] In the course of these Palomar supernovae surveys with the 48" Schmidt,[4] Kowal personally discovered 81 supernovae, includingSN 1972E.
In 1973, Caltech astronomersEleanor Helin andGene Shoemaker began an observing program to search out and track previously unknownnear-Earth asteroids, thePlanet-Crossing Asteroid Survey (PCAS), a photographic plate survey that began on the Palomar 18" Schmidt telescope. Although primarily employed by the supernova survey to observe on the 48" Schmidt, Kowal provided "crucial observations"[5] of particularly faint asteroids for the PCAS program with the larger telescope. His asteroid discoveries and co-discoveries include the notable asteroidsAten asteroid2340 Hathor; theApollo asteroids1981 Midas,2063 Bacchus,2102 Tantalus and(5660) 1974 MA; theAmor asteroids(4596) 1981 QB and(4688) 1980 WF; and theTrojan asteroids2241 Alcathous and2594 Acamas. PCAS later moved to the 48" Schmidt, and ran in total for nearly 25 years, until June 1995.[nb 2]
Kowal provided observations of new Solar System discoveries and reports of new supernovae via theIAU circular system throughout the 1970s,[6] and searched for new objects. He discovered twomoons ofJupiter:Leda in 1974 andThemisto in 1975, the 13th and 14th moons of Jupiter to be found.[7] Themisto was later lost (i.e. its orbit was not known well enough to reobserve it) and was not rediscovered until 2000.
Between December 1976 and February 1985, Kowal searched 6400 square degrees of sky in theecliptic plane for distant, slow-moving Solar System objects.[8] Only one object was found beyond Jupiter:2060 Chiron, discovered in 1977, which had the unusual characteristic of features both like an asteroid and a comet. It became recognised as the first object in thecentaur class after a second one was discovered 15 years later. Centaurs are objects with unstable orbits which orbit between Jupiter andNeptune. They are probably drawn in from theKuiper belt by alignments with larger planets. Chiron remains one of the largest such worlds known, and one of a handful that have a comet-likecoma.Kowal also discovered or co-discovered the periodic comets99P/Kowal,104P/Kowal,134P/Kowal-Vavrova,143P/Kowal-Mrkos, and158P/Kowal-LINEAR.
In 1980, Kowal's research in astronomical history found a 1613 drawing byGalileo Galilei showing Neptune near Jupiter, predating thediscovery of Neptune in 1846;[9] Kowal was awarded the inauguralR. R. Newton Award for Scientific History for this "shockingly outré" finding.[10]
Kowal moved to the newSpace Telescope Science Institute in 1985, where he monitored the instruments of theHubble Space Telescope as one of the operations astronomers. His bookAsteroids: Their Nature and Utilization was published in 1988, and a second edition in 1996.
From 1996 until his retirement in 2006, he worked at theJohns Hopkins University Applied Physics Laboratory, providing software for theNEAR Shoemaker spacecraft's mission to land on the asteroidEros and mission operations support for the NASA TIMED mission.
Kowal died on November 28, 2011, at the age of 71.[11]
| List of minor planets discovered by Charles Kowal | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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