C/1930 L1 (Forbes)
{{short description|Non-periodic comet}}
{{For|other comet discoveries by Alexander Forbes|37P/Forbes|C/1932 Y1 (Dodwell–Forbes)}}
{{Infobox comet
| name = C/1930 L1 (Forbes)
| discovery_ref = {{r|IAUC_285}}
| discoverer = Alexander F. I. Forbes
| discovery_site = Cape Town, South Africa
| discovery_date = 31 May 1930
| designations = 1930e{{r|ICQ1}}
1930 V
| orbit_ref = {{r|jpl|Vitagliano_2020}}
| epoch = 6 June 1930 (JD 2426133.5)
| observation_arc = 49 days
| obs = 54
| perihelion = 1.1528 AU
| aphelion =
| semimajor =
| period = <270,000 years
(inbound)
| eccentricity = ~1.000
| inclination = 97.0912°
| asc_node = 279.265°
| arg_peri = 320.966°
| tjup =
| Earth_moid =
| Jupiter_moid =
| M1 =
| M2 =
| magnitude = 9.0
(1930 apparition)
| last_p = 10 May 1930
| next_p =
}}
Comet Forbes, formally designated as C/1930 L1, is a parabolic comet that was only observed through optical telescopes in the year 1930.
Observational history
The comet was discovered by Alexander F. I. Forbes as a 9th-magnitude object on the early morning skies of 31 May 1930. It was the fifth new comet of the year and the second of three comets he discovered overall.{{r|s2a3}} He immediately informed the Union Observatory in Johannesburg after an exact position was determined about two days later.{{r|IAUC_285|van_Biesbroeck_1930a}}
The comet was already on its outbound flight since it reached perihelion on 10 May 1930, about three weeks before discovery, but was still approaching Earth at the time, allowing it to be regularly observed from Johannesburg until the end of June.{{r|union1}} It was only visible in the southern hemisphere until June 23, when first northern observations were recorded by the National Observatory in Athens, Greece.{{r|Plakidis_1930}}
George van Biesbroeck made his first observations of the comet from the Yerkes Observatory on June 21, with Georg von Struve following suit from the Berlin Observatory shortly afterwards,{{r|van_Biesbroeck_1930b}} however by that time it rapidly faded away from magnitude 11 to 15 by the end of the month, though a short tail was reported.{{r|van_Biesbroeck_1930a}} Van Biesbroeck continued his photographic observations of the comet until July 17, and its last known position was recorded on July 21.{{r|Crommelin_1931}}
Orbit
In 1952, Austrian astronomer Erich Senftl of the Vienna Observatory was able to calculate a retrograde parabolic orbit based from 54 observations over 49 days, which is inclined to 97 degrees from the ecliptic.{{r|Merton_1953}} It reached perihelion at a distance of {{convert|1.12|AU|e6km|abbr=unit}} on 10 May 1930, and made its closest approach to Earth at a distance of {{convert|0.37|AU|e6km|abbr=unit}} on June 21. Due to limited data acquired, it is unknown whether it remains bound to the Solar System or it was ejected into interstellar space.{{r|Vitagliano_2020}}
References
{{Reflist|refs=
| author1= A. C. D. Crommelin
| title= Report on Comets in 1930
| url= https://academic.oup.com/mnras/article-pdf/91/1/210/2855778/mnras91-0210.pdf
| journal= Monthly Notices of the Royal Astronomical Society
| volume= 91
| issue= 4
| year= 1931
| pages= 376–380
| doi= 10.1093/mnras/91.4.376
| doi-access= free }}
| author1= E. Strömgren
| title= New Comet Forbes (1930e)
| url= http://www.cbat.eps.harvard.edu/IAUCs/IAUC0285.jpg
| journal= Central Bureau for Astronomical Telegrams
| volume= 285
| date= 4 June 1930 }}
| title= Comet Names and Designations
| url= http://www.icq.eps.harvard.edu/names1.html
| website= International Comet Quarterly
| access-date= 12 December 2024 }}
| title= C/1930 L1 (Forbes) – JPL Small-Body Database Lookup
| url= https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=1930L1
| website= ssd.jpl.nasa.gov
| publisher= Jet Propulsion Laboratory
| access-date= 12 December 2024 }}
| author1= G. Merton
| title= Comets (1952)
| url= https://academic.oup.com/mnras/article-pdf/113/3/386/8077733/mnras113-0386.pdf
| journal= Monthly Notices of the Royal Astronomical Society
| volume= 113
| issue= 3
| year= 1953
| pages= 386–392
| doi= 10.1093/mnras/113.3.386
| doi-access= free }}
| author1= S. Plakidis
| title= Observations of the Comet Forbes (1930e), made with the Doridis Refractor (Gautier 40 cm.) of the National Observatory of Athens
| url= https://academic.oup.com/mnras/article-pdf/91/1/210/2855778/mnras91-0210.pdf
| journal= Monthly Notices of the Royal Astronomical Society
| volume= 91
| issue= 1
| year= 1930
| page= 210
| doi= 10.1093/mnras/91.1.210
| doi-access= free }}
| author1= C. Plug
| title= Forbes, Mr. Alexander Forbes Irvine (astronomy)
| url=https://www.s2a3.org.za/bio/Biograph_final.php?serial=955
| website= Biographical Database of Southern African Science
| access-date= 2 August 2019 }}
| title= Photographic Observations of Comet 1930e (Forbes)
| url= https://ui.adsabs.harvard.edu/link_gateway/1931CiUO...84..172./ADS_PDF
| journal= Circular of the Union Observatory Johannesburg
| volume= 84
| year= 1931
| page= 172
| bibcode= 1931CiUO...84..172. }}
| author1= G. van Biesbroeck
| title= Comet Notes
| url= https://ui.adsabs.harvard.edu/link_gateway/1930PA.....38..439V/ADS_PDF
| journal= Popular Astronomy
| volume= 38
| year= 1930
| page= 439
| bibcode= 1930PA.....38..439V }}
| author1= G. van Biesbroeck
| title= Observations of comets at the Yerkes Observatory
| url= https://ui.adsabs.harvard.edu/link_gateway/1930AJ.....41....1V/ADS_PDF
| journal= The Astronomical Journal
| volume= 41
| issue= 949
| year= 1930
| pages= 1–4
| bibcode= 1930AJ.....41....1V
| doi= 10.1086/105006
| doi-access= free }}
| author1= A. Vitagliano
| title= SOLEX 12.1
| url= http://www.solexorb.it/
| website= solexorb.it
| access-date= 9 July 2020 }}
}}
External links
- {{JPL Small Body|id=1001014}}
{{Comets}}
{{Authority control}}
{{DEFAULTSORT:Forbes, 1930 L1}}