456 Abnoba

456 Abnoba (provisional designation 1900 FH) is a main-belt asteroid of the S spectral class, discovered on 4 June 1900 at Heidelberg by Max F. Wolf and Arnold Schwassmann.^{1 • 2} It is named for Abnoba, the Celtic-Roman deity of the Black Forest, whose name appears as "Diana Abnoba" in old inscriptions left by Roman troops in southern Germany.²

Discovery and name

The asteroid was found at the Heidelberg observatory on 4 June 1900 and received the provisional designation 1900 FH.^{1 • 2} The discovery is credited to M. F. Wolf and A. Schwassmann, a pairing that produced several other Heidelberg asteroids in 1899 and 1900, including 455 Bruchsalia, 457 Alleghenia, and 458 Hercynia.¹

The name comes from Abnoba, a deity of the Black Forest recorded in Roman-era inscriptions as Diana Abnoba, a Celtic-Roman goddess of that mountainous region.²

Orbit

Abnoba orbits in the main asteroid belt. An orbit solution based on observations spanning 15 June 1900 to 20 March 2007 gives a semimajor axis of 2.78757067 AU, an eccentricity of 0.18176738, an inclination of 14.44853317 degrees, and a perihelion distance of 2.28088124 AU.³ The corresponding orbital period is 4.659 years.² The 2007 solution used 734 observations, of which 68 were rejected, and carried a 1-sigma uncertainty ellipse with major and minor axes of 0.031 and 0.020 arcseconds.³

Physical properties

Abnoba belongs to the S spectral class, the stony type common in the inner main belt, with a geometric albedo of 0.2335 and an absolute magnitude of 9.1.⁶ A Minor Planet Bulletin target table lists an albedo range of 0.23 to 0.32 and a rotation period of 18.281 hours.⁵ Diameter estimates cluster near 40 km: the RASNZ occultation update gives an approximate diameter of 40 km,³ a 2026 occultation prediction uses 38 km,⁴ and a compiled physical-characteristics table gives 39.76 km with a mass of 6.58 × 10¹⁶ kg.⁶

Abnoba has been observed at infrared wavelengths. The 2MASS all-sky release includes J, H, and Ks photometry of the asteroid from 1999 observations,⁷ and it is among the targets of the Small Main-belt Asteroid Spectroscopic Survey (SMASS) datasets in the NASA archive, which hold visible-wavelength spectra from 0.435 to 0.925 microns.⁸

Occultations

Because its orbit is well determined, Abnoba is a usable occultation target, in which the asteroid briefly blocks the light of a background star for observers along a narrow ground track. On 4 June 2007 UT, the roughly 40 km asteroid occulted an 11.4-magnitude star in the constellation Ophiuchus along a path across south-eastern Australia at very low altitude, including Melbourne at about 9 degrees elevation.³ An occultation of a 13.3-magnitude star by (456) Abnoba was observed in March 2020 as part of asteroid orbit-improvement work.⁹ A further occultation of a 10.5-magnitude star is predicted for 13 October 2026, with a shadow path 38 km wide moving at 12.5 km/s and the asteroid 2.3 AU from Earth.⁴

References

1. Named asteroids: Main-belt Asteroid, AsteroidName
2. Abnoba, horoskoop.ee asteroid information
3. RASNZ Occultation Section, Abnoba Occultation Update (2007)
4. (456) Abnoba hides a star, Occult
5. The Minor Planet Bulletin 48-2
6. (456) Abnoba physical characteristics
7. 2MASS All-Sky Data Release PSC Asteroid Associations
8. NASA Open Data Portal, datasets tagged 456-abnoba
9. Improvement of Asteroid Orbits for and with Occultations, IOTA

Initially written Oct 21, 2026 · Edited: Oct 25, 2026

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