P/2011 NO1 (Elenin)
Discovered byLeonid Elenin[1]
0.45-m reflector (H15)[2][3]
Discovery date7 July 2011[2]
Orbital characteristics A
Epoch15 July 2011[4]
(JD 2455757.5)
Aphelion9.8 AU (Q)
Perihelion1.24 AU (q)
Semi-major axis5.5 AU (a)
Orbital period13 ± 0.16 yr
Last perihelion20 January 2011[4]
Next perihelionaround January 2024[5]

P/2011 NO1 (Elenin) is a periodic comet with a preliminary orbital period estimated at 13 ± 0.16 years.[4] It came to perihelion (closest approach to the Sun) around 20 January 2011 at 1.2 AU from the Sun.[4] The orbit is preliminary as it has only been observed over an observation-arc of 22 days.[4] The comet was discovered on 7 July 2011[2] when the comet was 2.38 AU from the Sun and 1.4 AU from the Earth. It came to opposition 178.6° from the Sun on 22 July 2011 in the constellation Sagittarius.

The preliminary orbit shows the next perihelion passage to be around January 2024.[5] An observation arc of 30 days would allow a better refinement to the orbit of this comet.

P/2011 NO1 was the second comet discovered by Leonid Elenin. The first comet discovered by Elenin was comet C/2010 X1. Both comets were discovered with the aid of the automatic detection program CoLiTec.[6]

On 29 January 2013 the Minor Planet Center awarded Leonid Elenin a 2012 Edgar Wilson Award for the discovery of comets by amateurs.[7]


  1. ^ Sostero, Giovanni; Howes, Nick; Guido, Ernesto (19 July 2011). "New Comet: P/2011 NO1". Associazione Fruilana di Astronomia e Meteorologia. Retrieved 19 July 2011.
  2. ^ a b c "MPEC 2011-O09 : 2011 NO1". IAU Minor Planet Center. 18 July 2011. Retrieved 19 July 2011.
  3. ^ "MPEC 2011-O10 : COMET P/2011 NO1". IAU Minor Planet Center. 19 July 2011. Retrieved 19 July 2011.
  4. ^ a b c d e "JPL Small-Body Database Browser: (2011 NO1)" (last observation: 29 July 2011; arc: 22 days "preliminary"). Jet Propulsion Laboratory. Retrieved 19 July 2011.
  5. ^ a b Horizons output. "Observer Table for 2011 NO1". Retrieved 19 July 2011. (Observer Location:@sun)
  6. ^ "CoLiTec". Automatic Detection of Asteroids and Comets CoLiTec (CLT). Archived from the original on 13 May 2012. Retrieved 4 October 2012.
  7. ^ "2012 Comet Awards Announced". 29 January 2013. Retrieved 31 January 2013.