532037 Chiminigagua

Discovery

Chiminigagua was discovered by Scott Sheppard and Chad Trujillo on 17 March 2013,^[1] during a search for distant trans-Neptunian objects (TNOs).^[8][4] Their search was performed using the 4.0-meter Víctor M. Blanco Telescope's Dark Energy Camera (DECam) at Cerro Tololo Observatory in Chile,^[1] which repeatedly imaged large portions of the sky to reveal TNOs as slow-moving objects.^{[9]: 3 } Sheppard and Trujillo had been searching for TNOs using other telescopes since 2007, but they switched to primarily using DECam when it became operational in 2012.^{[9]: 3 }

From May 2013 to March 2014, Sheppard and Trujillo reobserved Chiminigagua using DECam and the 6.5-meter Magellan–Baade Telescope in Las Campanas Observatory, Chile.^[2] The Minor Planet Center announced the discovery of Chiminigagua on 31 March 2014 and gave it the minor planet provisional designation 2013 FY₂₇.^[2]

Before Chiminigagua, Sheppard and Trujillo had discovered several large TNOs with DECam—namely, the sednoid 2012 VP113 and the scattered disc object 2013 FZ27, which were announced along with Chiminigagua within a week of one another in late March to early April 2014.^[8][10] When Chiminigagua was discovered, it was nearly at its farthest point from the Sun (aphelion) in its orbit.^[8][4] This made Chiminigagua appear dim with an apparent magnitude of 22 from Earth.^[8] Because of its faintness, Chiminigagua likely evaded discovery by earlier, less sensitive TNO searches.^[8] Chiminigagua has been identified in precovery observations by the Pan-STARRS survey from March 2011 to February 2013.^[1]

The 4.0-meter Víctor M. Blanco Telescope at Cerro Tololo Observatory, which houses the Dark Energy Camera (DECam)

Discovery images of Chiminigagua by DECam on 17 March 2013

Naming and numbering

The object is named after Chiminigagua,^[b] a universally good god that represented the only light that existed when it was night time.^[12] She is the creator god of the Muisca (Chibcha) people that inhabit the Andes mountains in the central part of Colombia.^{[13]: 11 } The naming of this object was announced by the International Astronomical Union's Working Group for Small Body Nomenclature (WGSBN) on 11 August 2025.^{[13]: 11 } The name follows the WGSBN's recommended naming theme of mythological creation figures for trans-Neptunian objects, which includes scattered disc objects like Chiminigagua.^{[14]: 8 }

Before Chiminigagua was officially named, it was known by its provisional designation 2013 FY₂₇,^[1][4] which indicates the year and half-month of the object's discovery date.^[15] The Minor Planet Center gave it the minor planet catalog number 532037 on 18 May 2019.^[16]

Size

Chiminigagua has a diameter of about 742 km (461 mi) (full range 660 to 820 km or 410 to 510 mi when including uncertainties), according to Atacama Large Millimeter Array measurements of its thermal emission.^{[4]: 7 } Chiminigagua has an absolute magnitude of 3.15±0.03 in visible light,^{[4]: 4 } which makes it the ninth intrinsically brightest TNO known as of 2025^[update].^[23] Chiminigagua is large and bright enough that some astronomers and planetary scientists, including Scott Sheppard, Emily Lakdawalla, and Michael E. Brown, have called it a likely dwarf planet.^[8][24][25]

Among TNO researchers, Chiminigagua is better known as belonging to the proposed class of "mid-sized" TNOs^[26] between 400 and 1,000 km (250 and 620 mi) in diameter, which are believed to represent the transition between small, low-density TNOs and large, high-density dwarf planets.^{[27][4]: 1 } Planetary scientists have hypothesized that mid-sized TNOs should have highly porous and unheated interiors, because TNOs in this size range (namely 55637 Uni and 229762 Gǃkúnǁʼhòmdímà) have been found to have low densities around 1 g/cm³.^[27][26][28] The mass and density of Chiminigagua is unknown, however, because the orbit of its moon has not been determined yet.^[26][28] Hubble Space Telescope observations in December 2025 and January 2026 will be able to determine Chiminigagua's mass and density, which will verify the aforementioned hypothesis on the interiors of mid-sized TNOs.^[28]

Surface

Observations of Chiminigagua in different light filters show that it has a moderately red color, which is common among mid-sized TNOs.^{[4]: 3 } The moderately red color of Chiminigagua suggests it has an old, ice-poor surface that has been dulled by cosmic rays and micrometeoroid bombardment, in contrast to the fresh, icy surfaces of larger dwarf planets like Pluto.^{[4]: 1, 3 } Chiminigagua's brightness and diameter indicates it has a moderate geometric albedo of 0.170+0.045
−0.030,^[4] which is on the high end for mid-sized TNOs with moderately red colors.^{[4]: 8, 10 }

Rotation

The rotation period of Chiminigagua is unknown.^[4] Observations of Chiminigagua's brightness over time in March and May 2016 showed no obvious variability beyond 0.06±0.02 magnitudes over hours and days.^{[4]: 3 } The lack of brightness variation suggests that Chiminigagua has either a very long rotation period, an approximately spheroidal shape with no significant albedo variation, or a rotation axis pointing towards Earth.^{[4]: 3, 11 }

Discovery

The moon was discovered by Scott Sheppard using the Hubble Space Telescope's Wide Field Camera 3 on 15 January 2018, whose high-resolution images revealed it as a faint dot next to Chiminigagua.^{[4]: 9 }

Sheppard reported the moon to the International Astronomical Union,^{[4]: 9 } which announced the discovery on 10 August 2018 through the Central Bureau for Astronomical Telegrams.^[29]

Observations and orbit

Although Chiminigagua's moon has been observed multiple times by the Hubble Space Telescope from January to July 2018, the details of its orbit are unknown.^[7][28]

These Hubble observations from 2018 showed that the moon orbits relatively close to Chiminigagua, at least 9,800 km (6,100 mi) away (0.17 arcseconds in angular separation)^{[4]: 9 } but no farther than 0.25 arcseconds.^[26]

The orbit of Chiminigagua's moon is oriented edge-on from Earth's perspective, which means that the moon can pass in front of or behind Chiminigagua and thus evade detection.^[26][28]

The Hubble Space Telescope observed Chiminigagua and its moon in December 2025 and January 2026, which should be able to determine the moon's orbit.^[28]

Physical characteristics