1101 Clematis /ˈklɛmətɪs/ is an Alauda asteroid from the outermost regions of the asteroid belt, approximately 37 kilometers in diameter. It was discovered on 22 September 1928, by German astronomer Karl Reinmuth at the Heidelberg-Königstuhl State Observatory in southwest Germany, and assigned the provisional designation 1928 SJ.^[13] It was named for the flowering plant Clematis. The presumably carbonaceous asteroid has a relatively long rotation period of 34.3 hours.

Clematis is a member of the Alauda family (902),^[5] a large family of typically "bright" carbonaceous asteroids and named after its parent body, 702 Alauda.^[14]: 23 According to a different study, this object is also the namesake of the Clematis family, a small family of 5–16 asteroids hence they may have arisen from the same collisional event. All members have a relatively high orbital inclination.^[15]

It orbits the Sun in the outermost asteroid belt at a distance of 3.0–3.5 AU once every 5 years and 10 months (2,120 days; semi-major axis of 3.23 AU). Its orbit has an eccentricity of 0.08 and an inclination of 21° with respect to the ecliptic.^[1]

The body's observation arc begins with its observation as 1963 TG₁ at Goethe Link Observatory in October 1963, more than 35 years after its official discovery observation at Heidelberg.^[13]

Clematis is an assumed carbonaceous C-type asteroids,^[4] while the overall spectral type for members of the Alauda family is that of a somewhat brighter B-type.^[14]: 23

In September 2009, a rotational lightcurve^[a] of Clematis was obtained from photometric observations by American astronomers Brian Warner at the Palmer Divide Observatory, Colorado, and by Robert Stephens at GMARS (G79, California. Lightcurve analysis gave a synodic rotation period of 34.3 hours with a brightness amplitude of 0.16 magnitude (U=2),^[11] which significantly differs from previously reported periods of 6 to 12.68 hours (U=1/2/2/2).^[9][10] While not being a slow rotator, Clematis has a much longer period than that known for most other asteroids, and its small amplitude is indicative for a rather spheroidal shape.

According to the surveys carried out by the Infrared Astronomical Satellite IRAS, the Japanese Akari satellite and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Clematis measures between 29.13 and 37.86 kilometers in diameter and its surface has an albedo between 0.1124 and 0.190.^[6][7][8]

The Collaborative Asteroid Lightcurve Link derives an albedo of 0.0788 and a diameter of 37.60 kilometers based on an absolute magnitude of 10.5.^[4]

This minor planet was named after the flowering plant Clematis, a genus within the Ranunculaceae (buttercup or crowfoot family). The official naming citation was mentioned in The Names of the Minor Planets by Paul Herget in 1955 (H n.a.).^[3]

Due to his many discoveries, Karl Reinmuth submitted a large list of 66 newly named asteroids in the early 1930s. The list covered his discoveries with numbers between (1009) and (1200). This list also contained a sequence of 28 asteroids, starting with 1054 Forsytia, that were all named after plants, in particular flowering plants (also see list of minor planets named after animals and plants).^[16]

• Asteroid Lightcurve Database (LCDB), query form (info Archived 16 December 2017 at the Wayback Machine)
• Dictionary of Minor Planet Names, Google books
• Asteroids and comets rotation curves, CdR – Observatoire de Genève, Raoul Behrend
• Discovery Circumstances: Numbered Minor Planets (1)-(5000) – Minor Planet Center
• 1101 Clematis at AstDyS-2, Asteroids—Dynamic Site
  • Ephemeris · Observation prediction · Orbital info · Proper elements · Observational info
• 1101 Clematis at the JPL Small-Body Database
  • Close approach · Discovery · Ephemeris · Orbit viewer · Orbit parameters · Physical parameters