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C/1999 H1 (Lee)

In this article, the topic of C/1999 H1 (Lee) will be addressed from a broad and detailed perspective. The impact that C/1999 H1 (Lee) has on current society will be analyzed, as well as its historical relevance and influence in various areas. Furthermore, different points of view will be discussed and arguments for and against C/1999 H1 (Lee) will be presented, in order to offer a balanced and complete view on this topic. Furthermore, the future implications of C/1999 H1 (Lee) and possible strategies to address it effectively will be explored. This article seeks to provide readers with a deep and rich understanding of C/1999 H1 (Lee), allowing them to form their own opinions and participate in an informed debate on this topic.

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C/1999 H1 (Lee)
A mosaic of C/1999 H1 (Lee) taken on 9 December 1999
Discovery[1]
Discovered bySteven Lee
Discovery siteMudgee, Australia
Discovery date16 April 1999
Orbital characteristics[2]
Epoch17 August 1999 (JD 2451407.5)
Observation arc267 days
Number of
observations		1,019
Aphelion~5,500 AU
Perihelion0.708 AU
Semi-major axis~2,800 AU
Eccentricity0.99974
Orbital period~146,000 years
Inclination149.25°
162.65°
Argument of
periapsis		40.702°
Mean anomaly0.0002°
Last perihelion11 July 1999
TJupiter–0.896
Earth MOID0.151 AU
Jupiter MOID0.257 AU
Physical characteristics[2]
Comet total
magnitude (M1)		9.4
Comet nuclear
magnitude (M2)		13.1
6.0
(1999 apparition)[3]

C/1999 H1 (Lee) is a non-periodic comet observed between April 1999 and January 2000. It is the only comet discovered by Australian astronomer, Steven Lee. Lee found the comet visually during a star party near Mudgee, New South Wales on 16 April 1999.[4] He estimated the comet had an apparent magnitude of 9.[1]

Physical characteristics

In February 1999, Comet Lee became the first moderately active comet where its properties were observed and measured by the Hubble Space Telescope in ultraviolet light.[5] Data obtained through the Telescope's STIS revealed the presence of S2 within its coma, making it the third comet known where such chemical compound was detected after C/1983 H1 (IRAS–Araki–Alcock) and C/1996 B2 (Hyakutake).[5] Observations of the coma from the La Palma Observatory in June 1999 indicated that the comet was dust-poor, with a relatively high gas-to-dust mass ratio of around 6.5–11.7 and a dust production rate of around Afρ = 500 cm.[6]

Spectrophotometric observations conducted at the European Southern Observatory between May and October 1999 detected the presence of OH, CH3OH, HCN, H2CO, and CS within its coma.[7] Water production rate while it was at least 1.3–1.7 AU (190–250 million km) from the Sun was estimated to be about 3.2×1028 sec−1 based on observations conducted by the Submillimeter Wave Astronomy Satellite (SWAS) during its outbound trajectory between September and December 1999.[8]

Additional data obtained from the Keck Observatory in August 1999 revealed that the comet is strongly depleted in carbon monoxide gas compared to other comets like C/1995 O1 (Hale–Bopp) and C/1996 B2 (Hyakutake), which may demonstrate the chemical diversity that occurred during the formation of the outer Solar System.[9]

References

  1. ^ a b S. Lee; G. J. Garradd (16 April 1999). D. W. Green (ed.). "Comet 1999 H1". IAU Circular. 7144 (1). Bibcode:1999IAUC.7144....1L.
  2. ^ a b "C/1999 H1 (Lee) – JPL Small-Body Database Lookup". ssd.jpl.nasa.gov. Jet Propulsion Laboratory. Retrieved 8 November 2025.
  3. ^ "Observation list for C/1999 H1". COBS – Comet OBServation database. Retrieved 28 November 2025.
  4. ^ S. Lee (1999). "The Discovery of Comet Lee" (PDF). www.cometchaser.de. Retrieved 8 November 2025.
  5. ^ a b P. D. Feldman; H. A. Weaver; M. F. A'Hearn; et al. (1999). "Ultraviolet imaging spectroscopy of comet Lee (C/1999 H1) with HST/STIS". Bulletin of the Astronomical Society. 31 (4): 1127. Bibcode:1999BAAS...31.1127F.
  6. ^ L. M. Lara; R. Rodrigo; G. P. Tozzi; H. Boehnhardt; P. Leisy (2004). "The gas and dust coma of Comet C/1999 H1 (Lee)" (PDF). Astronomy & Astrophysics. 420 (1): 371–382. Bibcode:2004A&A...420..371L. doi:10.1051/0004-6361:20034214.
  7. ^ N. Biver; D. Bockelée-Morvan; J. Crovisier; et al. (2000). "Spectroscopic Observations of Comet C/1999 H1 (Lee) with the SEST, JCMT, CSO, IRAM, and NanÇay Radio Telescopes". The Astronomical Journal. 120 (3): 1554–1570. Bibcode:2000AJ....120.1554B. doi:10.1086/301529.
  8. ^ K. Chiu; D. A. Neufeld; E. A. Bergwin; et al. (2001). "Post-perihelion SWAS Observations of Water Vapor in the Coma of Comet C/1999 H1 (Lee)". Icarus. 154 (2): 345–349. Bibcode:2001Icar..154..345C. doi:10.1006/icar.2001.6706.
  9. ^ M. J. Mumma; I. S. McLean; M. A. DiSanti; et al. (2001). "A Survey of Organic Volatile Species in Comet C/1999 H1 (Lee) Using NIRSPEC at the Keck Observatory". The Astrophysical Journal. 546 (2): 1183–1193. Bibcode:2001ApJ...546.1183M. doi:10.1086/318314.
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