{ "id": "epr4j6vtmz", "slug": "826-henrika", "title": "826 Henrika", "updated": "2026-10-25", "topic_path": [ { "id": "places", "label": "Places and geography", "api_url": "https://www.edgepedia.org/api/v1/topics/places" }, { "id": "places.extraterrestrial", "label": "Extraterrestrial places", "api_url": "https://www.edgepedia.org/api/v1/topics/places.extraterrestrial" }, { "id": "places.extraterrestrial.small-bodies", "label": "Small bodies of the Solar System", "api_url": "https://www.edgepedia.org/api/v1/topics/places.extraterrestrial.small-bodies" }, { "id": "places.extraterrestrial.small-bodies.asteroids-main-belt", "label": "Main-belt asteroids and numbered minor planets", "api_url": "https://www.edgepedia.org/api/v1/topics/places.extraterrestrial.small-bodies.asteroids-main-belt" }, { "id": "places.extraterrestrial.small-bodies.asteroids-main-belt.outer-belt-asteroids", "label": "Outer-belt asteroids", "api_url": "https://www.edgepedia.org/api/v1/topics/places.extraterrestrial.small-bodies.asteroids-main-belt.outer-belt-asteroids" } ], "geo": [ { "id": "geo.nongeo.nodate.places.extraterrestrial.small-bodies.asteroids-main-belt.outer-belt-asteroids", "label": "Non-geographic · Not dated: Outer-belt asteroids", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.nodate.places.extraterrestrial.small-bodies.asteroids-main-belt.outer-belt-asteroids", "path": [ { "id": "geo.nongeo", "label": "Non-geographic", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo" }, { "id": "geo.nongeo.nodate", "label": "Non-geographic · Not dated", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.nodate" }, { "id": "geo.nongeo.nodate.places", "label": "Places and geography", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.nodate.places" }, { "id": "geo.nongeo.nodate.places.extraterrestrial", "label": "Extraterrestrial places", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.nodate.places.extraterrestrial" }, { "id": "geo.nongeo.nodate.places.extraterrestrial.small-bodies", "label": "Small bodies of the Solar System", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.nodate.places.extraterrestrial.small-bodies" }, { "id": "geo.nongeo.nodate.places.extraterrestrial.small-bodies.asteroids-main-belt", "label": "Main-belt asteroids and numbered minor planets", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.nodate.places.extraterrestrial.small-bodies.asteroids-main-belt" }, { "id": "geo.nongeo.nodate.places.extraterrestrial.small-bodies.asteroids-main-belt.outer-belt-asteroids", "label": "Outer-belt asteroids", "api_url": "https://www.edgepedia.org/api/v1/geo/geo.nongeo.nodate.places.extraterrestrial.small-bodies.asteroids-main-belt.outer-belt-asteroids" } ] } ], "excerpt": "826 Henrika, provisionally designated 1916 ZO, is a carbonaceous C-type asteroid in the central main belt, discovered by Max Wolf at Heidelberg in 1916 and roughly 19 to 21 km across.", "snippet": "826 Henrika, provisionally designated 1916 ZO, is a carbonaceous C-type asteroid in the central main belt, discovered by Max Wolf at Heidelberg in 1916 and roughly 19 to 21 km across.", "node": "places.extraterrestrial.small-bodies.asteroids-main-belt.outer-belt-asteroids", "markdown": "# 826 Henrika\n\n**826 Henrika** (provisional designation 1916 ZO) is a background asteroid from the central regions of the main asteroid belt, discovered by the German astronomer [Max Wolf](https://www.edgepedia.org/max-wolf) at the Heidelberg-Königstuhl State Observatory on 28 April 1916.[1](https://astronomia.zcu.cz/planety/planetka-826) It is a carbonaceous [C-type asteroid](https://www.edgepedia.org/c-type-asteroid) with a rotation period of 5.98 hours and a diameter of roughly 19 to 21 km.[2](https://irsa.ipac.caltech.edu/IRASdocs/surveys/PL-TR-92-2049.pdf)\n\n| Key fact | Detail |\n|---|---|\n| Discovery | 28 April 1916 by M. F. Wolf at Heidelberg; provisional designation 1916 ZO[1](https://astronomia.zcu.cz/planety/planetka-826) |\n| Orbit | Semimajor axis 2.7128 au, eccentricity 0.2044, inclination 7.1026°, orbital period 4.468 years (1,632.0 days)[1](https://astronomia.zcu.cz/planety/planetka-826) |\n| Size | About 21 km mean diameter; IRAS measured 19.28 km with an albedo of 0.1435[2](https://irsa.ipac.caltech.edu/IRASdocs/surveys/PL-TR-92-2049.pdf) |\n| Rotation | 5.98-hour rotation period (5.9846 h in one solution), lightcurve amplitude 0.26 mag[3](https://iaaras.ru/html/emp2021/emp_2021/parcur21.pdf) |\n| Brightness | Absolute magnitude H = 11.74 mag with phase parameter G = 0.15 (one orbit solution gives H = 11.46)[1](https://astronomia.zcu.cz/planety/planetka-826) • [4](https://occultations.org.nz/planet/2010/updates/100119_826_21920_u.htm) |\n| Observational record | 7,236 observations over 42 oppositions, 1921 to 2026; observation arc 103.52 years[1](https://astronomia.zcu.cz/planety/planetka-826) |\n\n## Orbit and classification\n\nHenrika orbits the Sun in the central main asteroid belt, the ring of rocky bodies between Mars and Jupiter.\n\nIts orbit has a semimajor axis of 2.7128 au, an eccentricity of 0.2044, and an inclination of 7.1026° to the ecliptic, giving perihelion and aphelion distances of 2.158 au and 3.267 au and an orbital period of 4.468 years.[1](https://astronomia.zcu.cz/planety/planetka-826) The orbit is well determined: the observational record covers 1921 to 2026, with 7,236 accepted positions over 42 oppositions and an observation arc of 103.52 years.[1](https://astronomia.zcu.cz/planety/planetka-826) A 2010 occultation prediction computed from 907 used observations spanning 1921 July 2 to 2009 March 29 placed the 1-sigma uncertainty ellipse at about 0.032 by 0.017 arcseconds.[4](https://occultations.org.nz/planet/2010/updates/100119_826_21920_u.htm)\n\n## Physical properties\n\nThe IRAS Minor Planet Survey, a thermal-infrared all-sky survey, measured a diameter of 19.28 km and a visible geometric albedo of 0.1435.[2](https://irsa.ipac.caltech.edu/IRASdocs/surveys/PL-TR-92-2049.pdf)\n\nOn 19 January 2010 UT, Henrika occulted a 9.9-magnitude star, TYC 6120-00450-1, in the constellation [Virgo](https://www.edgepedia.org/virgo-constellation), for observers along a path crossing [New South Wales](https://www.edgepedia.org/new-south-wales) at low altitude near Sydney and across the south island of New Zealand.[4](https://occultations.org.nz/planet/2010/updates/100119_826_21920_u.htm) During the event the combined light of asteroid and star was predicted to drop by 6.3 mag to 16.2 mag, the asteroid's own magnitude, for at most 1.1 seconds.[4](https://occultations.org.nz/planet/2010/updates/100119_826_21920_u.htm) The asteroid was 2.28200 au from Earth, and its shadow swept across the ground at about 16.89 km/s with an approximate projected path width of 34 km.[4](https://occultations.org.nz/planet/2010/updates/100119_826_21920_u.htm) The prediction carried a 1-sigma path uncertainty of plus or minus 2.57 path widths (about 3.6 seconds), and observers were advised to watch within 3 sigma of the nominal path, or out to about 10 path widths when monitoring for possible satellite events.[4](https://occultations.org.nz/planet/2010/updates/100119_826_21920_u.htm) The update was computed by Steve Preston of Medina, Washington, using OrbFit.[4](https://occultations.org.nz/planet/2010/updates/100119_826_21920_u.htm)\n\n## Naming\n\nThe [Minor Planet Center](https://www.edgepedia.org/minor-planet-center) catalog number is 826 and the name Henrika. According to the *Dictionary of Minor Planet Names*, any reference of this name to a person or occurrence is unknown.[5](https://ndl.ethernet.edu.et/bitstream/123456789/32939/1/Lutz%20D.%20Schmadel.pdf) A distinct asteroid, (7840) Hendrika, discovered in 1994, carries a different name.[6](https://astronomia.zcu.cz/planety/planetka-7840)\n\n## References\n\n1. [Planetka Henrika (826), Planety sluneční soustavy, ZČU](https://astronomia.zcu.cz/planety/planetka-826)\n2. [IRAS Minor Planet Survey (PL-TR-92-2049), IPAC](https://irsa.ipac.caltech.edu/IRASdocs/surveys/PL-TR-92-2049.pdf)\n3. [EPM2021 ephemerides, rotation parameters, IAA RAS](https://iaaras.ru/html/emp2021/emp_2021/parcur21.pdf)\n4. [RASNZ Occultation Section: Henrika occultation update, 2010 Jan 19](https://occultations.org.nz/planet/2010/updates/100119_826_21920_u.htm)\n5. [Lutz D. Schmadel, Dictionary of Minor Planet Names, 5th ed.](https://ndl.ethernet.edu.et/bitstream/123456789/32939/1/Lutz%20D.%20Schmadel.pdf)\n6. [Planetka Hendrika (7840), Planety sluneční soustavy, ZČU](https://astronomia.zcu.cz/planety/planetka-7840)\n\n---\n*Topic: Encyclopedia › Places and geography › Extraterrestrial places › Small bodies of the Solar System › Main-belt asteroids and numbered minor planets › Outer-belt asteroids*\n\n*Initially written Oct 21, 2026 · Edited: Oct 25, 2026*\n\n*Copyright 2026 EdgeChat AI, a subsidiary of Biostate AI.*\n\nLicense: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license\n", "same_as": [], "url": "https://www.edgepedia.org/826-henrika", "markdown_url": "https://www.edgepedia.org/826-henrika.md", "license": { "name": "Edgepedia Community License 1.0", "url": "https://www.edgepedia.org/edgepedia/license", "summary": "Free with credit, commercial use included. AI training is open to everyone. For other uses, organizations over USD 100M in revenue or 100M monthly users license separately.", "spdx": "LicenseRef-Edgepedia-Community-1.0" }, "credit": "\"826 Henrika\", Edgepedia (EdgeChat), https://www.edgepedia.org/826-henrika. Edgepedia Community License 1.0.", "credit_md": "\"[826 Henrika](https://www.edgepedia.org/826-henrika)\", Edgepedia (EdgeChat), [https://www.edgepedia.org/826-henrika](https://www.edgepedia.org/826-henrika). [Edgepedia Community License 1.0](https://www.edgepedia.org/edgepedia/license).", "credit_html": "\"826 Henrika\", Edgepedia (EdgeChat), https://www.edgepedia.org/826-henrika. Edgepedia Community License 1.0.", "speakable": "826 Henrika, provisionally designated 1916 ZO, is a carbonaceous C-type asteroid in the central main belt, discovered by Max Wolf at Heidelberg in 1916 and roughly 19 to 21 km across." }