C/1925 F1 (Shajn–Comas Solá)

For the other comet discovered by Josep Comas Solá, see 32P/Comas Solá.
For the comet discovered by Grigory Shajn's wife, Pelageya Shajn, see 61P/Shajn–Schaldach.
C/1925 F1 (Shajn–Comas Sola)
Comet Shajn–Comas Sola photographed by George van Biesbroeck from the Yerkes Observatory on 26 March 1925[1]
Discovery[2][3]
Discovered byGrigory Shajn
Josep Comas Solá
Discovery siteSimeis Observatory, USSR
Fabra Observatory, Spain
Discovery date22–23 March 1925
Designations
1925a[4]
1925 VI
Orbital characteristics[5]
Epoch7 September 1925 (JD 2424400.5)
Observation arc711 days (1.95 years)
Number of
observations		59
Perihelion4.181 AU
Eccentricity1.002432
Orbital period4.8 million years (inbound)
691,000 years (outbound)
Inclination146.71°
358.54°
Argument of
periapsis		205.76°
Last perihelion6 September 1925
Physical characteristics[6]
Comet total
magnitude (M1)		2.5
10.8
(1925 apparition)

Comet Shajn–Comas Solá, formal designation C/1925 F1, is a hyperbolic comet co-discovered by Grigory Shajn and Josep Comas Solá in 1925. At the time, it was the comet with the most distant known perihelion distance (until the discovery of 29P/Schwassmann–Wachmann two years later), which enabled astronomers to continue observing it until March 1927.[6]

Observational history

Discovery

The comet was first spotted by accident from the Simeis Observatory in Crimea by Soviet astronomer, Grigory Shajn, on 22 March 1925.[2] Having just recently transferred from the Pulkovo Observatory, Shajn wasn't used to operating the telescope at Simeis at the time, hence pointing the instrument to the wrong direction in his first trial run. He noticed a diffuse 11th-magnitude object in an erroneous photographic plate where he recognized it as a comet. In a letter he wrote to George van Biesbroeck, he later recalled:[7]

"Had I not made the mistake in guiding, the trail of the comet would have had nearly the same length as the star trails, and I doubt that I would have distinguished it from a star."[7]

Shortly afterwards, the comet was independently discovered by Spanish astronomer, Josep Comas Solá, from the Fabra Observatory in Barcelona, Spain on 23 March 1925, but was unable to confirm his discovery until March 25th.[3]

Orbit

At the time of discovery, the comet was located within the constellation of Virgo.[a] It was also three days before its closest approach with Earth and almost five months before perihelion. Due to its very slow motion across the sky, the comet's orbit was initially difficult to determine.[6]

Howard B. Kaster and Katherine Prescott determined a perihelion date of 17 September 1925 and a perihelion distance of 4.14 AU (619 million km).[8] Additional parabolic orbits were later calculated by Gerald Merton,[9] Hermann Kobold and others.

In 1973, Brian G. Marsden and Zdenek Sekanina revised it to a hyperbolic trajectory that is weakly bound to the barycenter of the Solar System, where they concluded that the comet reached perihelion on 6 September 1925 and had an inbound orbital period of 4.8 million years, later shortened to 683,000 years on its outbound flight.[10] This was revised yet again in 1978, with an orbital period of 4.6 million years (inbound) and 691,000 years (outbound).[11]

See also

References

Notes

  1. ^ Reported initial position upon discovery was: α = 11h 51.3m , δ = 1° 34′[6]

Citations

  1. ^ G. van Biesbroeck (1926). "On the Appearance of the Comets in 1925 from Observations at the Yerkes Observatory". Popular Astronomy. 34: 224–228. Bibcode:1926PA.....34..224V.
  2. ^ a b E. Strömgren (27 March 1925). "Two New Comets". International Astronomical Union Circular. 60.
  3. ^ a b E. Strömgren (1 April 1925). "Comet Schain (1925a)". International Astronomical Union Circular. 62.
  4. ^ "Comet Names and Designations". International Comet Quarterly. Retrieved 17 January 2025.
  5. ^ "C/1925 F1 (Shajn–Comas Solá) – JPL Small-Body Database Lookup". ssd.jpl.nasa.gov. Jet Propulsion Laboratory. Retrieved 20 November 2023.
  6. ^ a b c d G. W. Kronk (2007). Cometography: A Catalog of Comets. Vol. 3: 1900–1932. Cambridge University Press. pp. 418–422. ISBN 978-0-521-58506-4.
  7. ^ a b G. van Biesbroeck (1925). "Discovery of Comet a 1925 (Shajn)". Popular Astronomy. 33: 337. Bibcode:1925PA.....33..337.
  8. ^ H. B. Kaster; K. Prescott (1925). "The Orbit Of Comet a 1925 (Shajn–Comas Solá)". Publications of the Astronomical Society of the Pacific. 37 (217): 145–147. doi:10.1088/1925PASP...37..145K. JSTOR 40693397.
  9. ^ G. Merton (1925). "Comet 1925 a (Schain–Comas Solá)". Astronomische Nachrichten. 224 (18): 307–308. Bibcode:1925AN....224Q.307M. doi:10.1002/asna.19252241805.
  10. ^ B. G. Marsden; Z. Sekanina (1973). "On the Distribution of "Original" Orbits of Comets of Large Perihelion Distance". Astronomical Journal. 78 (10): 1118–1124. Bibcode:1973AJ.....78.1118M. doi:10.1086/111516.
  11. ^ B. G. Marsden; Z. Sekanina; E. Everhart (1978). "New Osculating Orbits for 110 Comets and Analysis of Original Orbits for 200 comets". Astronomical Journal. 83 (1): 64–71. Bibcode:1978AJ.....83...64M. doi:10.1086/112177.