Contact information

Skywarden,
Ursa Astronomical Association
Kopernikuksentie 1
00130 Helsinki
taivaanvahti(at)ursa.fi

Ursa Astronomical Association

11780 Thunder Bay - 28.9.2019 at 21.30 - 28.9.2019 at 21.49 Orimattila, Artjärvi, Tähtikallio Observation number 86131

Visibility III / V


11780 Thunder Bay (1942 TB, 1990 KE3,1994 LK10) An asteroid in the central zone of the main zone was photographed on the second night of the September 2019 Extraordinary Talks (storm bongar event). Finland 100 is the target of our project 190. The asteroid of the slow (very slow rotation time) family was discovered by Liisi Oterma on October 3, 1942 in Iso-Heikkilä, Turku. The asteroid is named after Thunder Bay in northwestern Ontario, Canada on the shores of Lake Superior. It is also known as the "Lakehead" because it is the westernmost port on Canada's Great Lakes, source Wikipedia https://en.wikipedia.org/wiki/Thunder_Bay . Finnish Wikipedia https://en.wikipedia.org/wiki/Thunder_Bay . The World Ski Championships were held in Thunder Bay in 1995. The best finishers were the team-hill jumpers, Jani Soininen, Janne Ahonen, Mika Laitinen, Ari-Pekka Nikkola, who received golden World Cup medals around their necks. Finland was in 5th place, source Wikipedia https://en.wikipedia.org/wiki/Hiihdon_maailmanmestaruuskilpailut_1995 . The size of the asteroid is 5.59km and the rotation speed is very slow 295h / r. The orbit of the asteroid was not confirmed until 48 years after its discovery (095 - Crimea-Nauchnij) 1990 05 20.92566, when it was given the number 11780. When discovered, its brightness was 14.9mag and when rediscovered 16.5mag. Why aren't there any observations in between? Would the reason be that this is a pile of rock that has disintegrated due to rotation and left the patterns for decades and returned to slowly rotating and being identified? This theory is speculation :). 1Picture. first image measured, 2019-09-28T 18: 29: 59UT 2458755.27082JDUT 21h22m45.02s -18d13'02.8 "15.7mag Std Dev 356.631, JPL Horizon 18: 29: 59UT 21h22m45.02s -18d13'03.1" 15.81mag.
2Picture. last image measured, 2019-09-27T 18: 48: 46UT 2458755.28386JDUT 21h22m45.19s -18d13'07.3 "15.6mag Std Dev 364.301, JPL Horizon 18: 48: 46UT 21h22m45.18s -18d13'07.1" 15.81mag.
3Picture. sum view of stack, motion not visible. No other asteroids below 18.7mag are shown. TYC 6314-1120-1 v.11.90mag stars used to calibrate the luminance measurement.
#Suomi100asteroidit


Additional information
  • Observation target
    • Asteroid
  • Name of the observation target
    • 11780 Thunder Bay
    • Keskitaso
  • Seeing
    • Average
Technical information

Alluna RC16, C415 / 3320, SBIG 1001E, filter L, 10 x 120s

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