C/2018 Y1 (Iwamoto)

C/2018 Y1 (Iwamoto)
Comet C/2018 Y1 (February 25, 2019) from the infrared telescope NEOWISE
Discovery[1]
Discovered byMasayuki Iwamoto
Discovery dateDecember 18, 2018
Orbital characteristics[2]
Epoch19 July 2022
Observation arc348 days
Aphelion287 AU
Perihelion1.287 AU
Semi-major axis144 AU
Eccentricity0.9911
Orbital period1733 years
Inclination160.4°
147.5°
Last perihelion7 February 2019
Earth MOID0.299 AU (44.7 million km)
Jupiter MOID1.507 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]

  1. ^ a b James, Nick. "C/2018 Y1 (Iwamoto) - A new comet for the new year". Britastro.org. Retrieved 2 February 2019.
  2. ^ "JPL Small-Body Database Browser: C/2018 Y1". JPL. Retrieved 15 October 2022.
  3. ^ a b "Speedy comet approaching Earth's vicinity". Earth & Sky. Retrieved 2 February 2019.
  4. ^ Hanneke Weitering (12 February 2019). "How to See Comet Iwamoto Fly Past Earth This Week". Space.com. Retrieved 15 October 2022.
  5. ^ "Weekly Information about Bright Comets (2019 Mar. 2: North)". www.aerith.net. Retrieved 15 October 2022.
  6. ^ 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.