C/2021 T4 (Lemmon)

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C/2021 T4 (Lemmon)
C2021 T4 2022-12-21 image ZTF-sso-295-zg-fov-5.6arcmin.png
The comet on 21 December 2022, by ZTF
Discovery
Discovery date7 October 2021
Designations
CK21T040, C6131F2
Orbital characteristics
Observation arc 1.7 years
Aphelion ≈44,000 AU (inbound) [1]
≈2,200 AU (outbound)
Perihelion 1.4823 AU
Eccentricity 0.99970
Orbital period millions of years (inbound) [1]
≈36,000 years (outbound)
Inclination 160.76°
257.79°
Argument of
periapsis
329.78°
Next perihelion31 July 2023
Earth MOID 0.497 AU (74.4 million km)
Jupiter MOID 0.869 AU (130.0 million km)
Comet total
magnitude
(M1)
6.9

C/2021 T4 (Lemmon) is an inbound long period comet discovered by the Mount Lemmon Observatory on 7 October 2021. [2] This passage through the planetary region of the Solar System will reduce the orbital period from millions of years to thousands of years. [1]

It has been south of the celestial equator since October 2022. On 13 June it was 1.5 degrees from magnitude 2 Beta Ceti. Closest approach to Earth was on 20 July 2023 at a distance of 0.54  AU (81 million  km ). [3] The next day it reached its southernmost declination, at -56 degrees. On 25 July it passed next to the globular cluster NGC 6397. [4] It reached perihelion on 31 July 2023 at a solar distance of 1.48 AU. The comet brightened to around apparent magnitude 8. [5]

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<span class="mw-page-title-main">7P/Pons–Winnecke</span> Periodic comet with 6-year orbit

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<span class="mw-page-title-main">C/2018 C2 (Lemmon)</span>

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<span class="mw-page-title-main">Comet NEOWISE</span> Bright comet of July 2020

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C/2019 U6 (Lemmon), or Comet Lemmon is a long period comet with a near-parabolic orbit discovered by the Mount Lemmon Survey on October 31, 2019. It made its closest approach to the Sun on June 18, 2020. In June 2020 it was visible near the naked eye limit at an apparent magnitude of 6.0. It is the 3rd brightest naked eye comet of 2020 after C/2020 F3 (NEOWISE) and C/2020 F8 (SWAN). It remained visible near the naked eye limit in June.

<span class="nowrap">2016 DV<sub>1</sub></span> Apollo near-Earth asteroid

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C/2021 O3 (PanSTARRS) is perhaps an Oort cloud comet, discovered on 26 July 2021 by the Pan-STARRS sky survey. It came to perihelion on 21 April 2022 at 0.287 AU (42.9 million km). from the Sun.

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C/2022 E3 (ZTF) is a non-periodic comet from the Oort cloud that was discovered by the Zwicky Transient Facility (ZTF) on 2 March 2022. The comet has a bright green glow around its nucleus, due to the effect of sunlight on diatomic carbon and cyanogen. The comet's systematic designation starts with C to indicate that it is not a periodic comet, and "2022 E3" means that it was the third comet to be discovered in the first half of March 2022.

<span class="mw-page-title-main">C/2023 A3 (Tsuchinshan–ATLAS)</span> Comet from the Oort cloud

C/2023 A3 (Tsuchinshan–ATLAS) is a comet from the Oort cloud discovered by the Purple Mountain Observatory on 9 January 2023 and independently found by ATLAS South Africa on 22 February 2023. The comet will pass perihelion at a distance of 0.39 AU on 27 September 2024, when it could become visible to the naked eye. As of September 2023, the comet is currently 5.5 AU from the Sun, approaching at 17.9 km/s, with an uncertainty region of ±8,000 km.

References

  1. 1 2 3 Horizons output. "Barycentric Osculating Orbital Elements for Comet C/2021 T4 (Lemmon)" . Retrieved 2023-04-26. (Solution using the Solar System's barycenter (Sun+Jupiter). Select Ephemeris Type:Elements and Center:@0) Epoch 1800 has PR= 1E+9 / 365.25 days = millions of years
  2. "MPEC 2021-U187 : COMET C/2021 T4 (Lemmon)". minorplanetcenter.net. Retrieved 2021-10-30.
  3. Earth Approach 2023 (delta. Close approach occurs when deldot flips from negative to positive.)
  4. Dickinson, David (25 July 2023). "A Fine Southern Apparition for Comet T4 Lemmon". Universe Today. Retrieved 29 July 2023.
  5. C/2021 T4 ( Lemmon ) mag chart by Seiichi Yoshida