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C/2018 Y1 (Iwamoto)

C/2018 Y1 (Iwamoto)

Comet C/2018 Y1 (February 25, 2019) from the infrared telescope NEOWISE
Discovery[1]
Discovered by	Masayuki Iwamoto
Discovery date	December 18, 2018
Orbital characteristics[2]
Epoch	19 July 2022
Observation arc	348 days
Aphelion	287 AU
Perihelion	1.287 AU
Semi-major axis	144 AU
Eccentricity	0.9911
Orbital period	1733 years
Inclination	160.4°
Longitude of ascending node	147.5°
Last perihelion	7 February 2019
Earth MOID	0.299 AU (44.7 million km)
Jupiter MOID	1.507 AU (225.4 million km)
Comet total magnitude (M1)	13.6

C/2018 Y1 (Iwamoto) is a long period comet with a retrograde orbit discovered on December 18, 2018, by Japanese amateur astronomer Masayuki Iwamoto.^[1] Its period is estimated to be 1,733 years. It passed closest to Earth on February 13, 2019.^[3] It was expected to reach a magnitude of between 6.5 and 7.5, visible in binoculars or a small telescope^[3][4] and was reported to reach a magnitude of 5.5 by Juan Jose Gonzalez on February 13, before fading to 7.6 two weeks later.^[5]

The comet was observed by iSHELL spectrograph at the NASA Infrared Telescope Facility (IRTF). Overall, the measured spatial distributions for polar molecules (in particular, H₂O and CH₃OH) were broader, exhibiting more complex structure compared with nonpolar or weakly polar species (CH₄, C₂H₆, and CO). Compositionally, compared to their respective mean abundances among comets from the Oort cloud, C₂H₆ and CH₃OH were enriched, CH₄ and HCN were near normal, and all other species were depleted. The abundance ratio CH₃OH/C₂H₆ was higher by 45% ± 8% on January 13 versus February 5, whereas CH₄/C₂H₆ was unchanged within the uncertainty, suggesting nonhomogeneous composition among regions of the nucleus dominating activity on these dates.^[6]

Gallery[edit]

• 
  Animation of C/2018 Y1 orbit
     Mercury ·    Venus ·   Earth ·   Mars ·    C/2018 Y1
• 
  Animation of C/2018 Y1 orbit 1600-2500
     Sun ·    Uranus ·    C/2018 Y1
• 
  Comet C/2018 Y1 (Iwamoto) with M44, 13. February 2019, 23:04 Uhr
• 
  Comet C/2018 Y1 (Iwamoto) with the spiral galaxy NGC 2903, 13 February 2019, 23:19 Uhr
• 
  Comet C/2018 Y1 (Iwamoto) with nebulae IC 410 and IC 405

References[edit]

^ DiSanti, Michael A.; Bonev, Boncho P.; Dello Russo, Neil; McKay, Adam J.; Roth, Nathan X.; Saki, Mohammad; Gibb, Erika L.; Vervack Jr., Ronald J.; Khan, Younas; Kawakita, Hideyo (9 November 2021). "Volatile Composition and Outgassing in C/2018 Y1 (Iwamoto): Extending Limits for High-resolution Infrared Cometary Spectroscopy between 2.8 and 5.0 μm" (PDF). The Planetary Science Journal. 2 (6): 225. Bibcode:2021PSJ.....2..225D. doi:10.3847/psj/ac07ae. ISSN 2632-3338. S2CID 229008642. This article contains quotations from this source, which is available under the Creative Commons Attribution 4.0 Unported (CC BY 4.0) license.

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