C/2021 T4 (Lemmon) is a long period comet discovered by the Mount Lemmon Observatory on 7 October 2021.[1] This passage through the planetary region of the Solar System will reduce the orbital period from millions of years to thousands of years.[2]
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).[4] The next day it reached its southernmost declination, at -56 degrees. On 25 July it passed next to the globular cluster NGC 6397.[5] It reached perihelion on 31 July 2023 at a solar distance of 1.48 AU. The comet brightened to around apparent magnitude 8.[6]
References
- ^ a b "MPEC 2021-U187: COMET C/2021 T4 (Lemmon)". minorplanetcenter.net. Retrieved 2021-10-30.
- ^ a b c 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
- ^ "C/2021 T4 (Lemmon) – JPL Small-Body Database Browser". ssd.jpl.nasa.gov. Jet Propulsion Laboratory. Retrieved 29 October 2024.
- ^ Earth Approach 2023 (delta. Close approach occurs when deldot flips from negative to positive.)
- ^ Dickinson, David (25 July 2023). "A Fine Southern Apparition for Comet T4 Lemmon". Universe Today. Retrieved 29 July 2023.
- ^ C/2021 T4 ( Lemmon ) mag chart by Seiichi Yoshida
External links
- C/2021 T4 at the JPL Small-Body Database
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