Contact information

Ursa Astronomical Association
Kopernikuksentie 1
00130 Helsinki

Ursa Astronomical Association

Telescopic comet NEOWISE - 16.2.2021 at 22.15 - 16.2.2021 at 23.55 Helsinki, Maunula Observation number 96216

Visibility II / V

Jorma Ryske, Etelä-Suomen kosmol. seura

Comet C/2021 A2 (NEOWISE) cyanogen CN radical gas coma diameter 1,7'/50000km and wide fan-shaped cyanogen gas tail length 3,4'/100000km towards PA 10° is visible in this 3870Å narrowband filter image. Comet distance from sun is 1,46au so the sun heat and UV radiation is strong enough to sublimate comet icy surface and photodissociate gases like CN at 3883Å. 


Image 1) 30x180s=90min with CN 387nm narrowband filter at 2021-02-16 20:15-21:50UT

Image 2) Processed cropped image 1 with CometCIEF to enhance coma and tail morphology. No significant details visible.

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Additional information
  • Observation target
    • Comet
  • Name of the observation target
    • C/2021 A2 (NEOWISE)
    • Heikosti näkyvä
  • Brightness in magnitudes
    • 12
  • Tail length
  • 3,4 arc minutes
  • Coma diameter
  • 1,7 kaariminuuttia
  • Weather
    • -10C, some wind gusts shaking telescope Moon 23% SQM-L zenit 17,16 (snow on ground, strong light pollution)
  • Title for the comet
    • Telescopic comet
Technical information

TS 305/1200mm Newton, TS KomakorrF4, QSI690, Semrock CN filter 387nm/15nm, CEM60. FoV 25' x 20'. North up, east left. CometCIEF Samarasinha, N. H., Martin, M. P., Larson, S. M, 2013. Cometary Coma Image Enhancement Facility,

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