420356 Praamzius

420356 Praamzius

Discovery
Discovered by	K. Černis R. P. Boyle
Discovery site	Vatican Advanced Technology Telescope (Mount Graham Obs.)
Discovery date	23 January 2012
Designations
MPC designation	(420356) Praamzius
Named after	Praamžius (Lithuanian mythology)
Alternative designations	2012 BX85
Minor planet category	TNO  · distant  (near-3:5 resonance)
Orbital characteristics
Epoch 31 July 2016 (JD 2457600.5)
Uncertainty parameter 2
Observation arc	13.08 yr (4,778 days)
Aphelion	43.027 AU
Perihelion	42.749 AU
Semi-major axis	42.888 AU
Eccentricity	0.00324
Orbital period (sidereal)	280.877 yr (102,590 days)
Mean anomaly	180.91269°
Mean motion	0° 0m 12.633s / day
Inclination	1.09128°
Longitude of ascending node	314.25447°
Argument of perihelion	359.00399°
Physical characteristics
Mean radius	101 km
Apparent magnitude	20.8–25.2; mainly 21.0-22.0
Absolute magnitude (H)	5.7

• • nb data and text in process of being updated (22:40 UTC 27/9/2017)**

420356 Praamzius, provisional designation 2012 BX₈₅, is a trans-Neptunian object and possible dwarf planet in the Kuiper belt, approximately 200 kilometers in diameter. It was discovered on 23 January 2012, by astronomers Kazimieras Černis and Richard Boyle with the Vatican's VATT at Mount Graham Observatory in Arizona, United States. The object was named after the chief god Praamžius from Lithuanian mythology.

Orbit

At 0.00324, Praamzius has the lowest eccentricity of any trans-Neptunian object (TNO) except 2003 YN₁₇₉, and a more circular orbit than any main planet (including Venus, the least eccentric at e = 0.007).

Praamzius orbits near the 3:5 resonance with Neptune, but not exactly on it, with both its period and orbital radius being slightly too large to fit an exact 3:5 ratio. This could be due to their apparent relationship being merely coincidental, and Praamzius actually being a typical non-resonant cubewano, an artefact of an orbit actually at the extreme end of a librating cycle centred on 3:5 (oscillating between otherwise non-resonant values either side), or due to it exhibiting some more exotic resonance such as 7:12, 10:17 or 17:28 which are better fits for its observed track (although the closest fit below 100 Praamzian orbits, 44:75, still exhibits an error of more than 1.5 Earth years).

However, it is difficult to yet determine which of these is true, as although Praamzius has a comparitively good observational record (with more than 200 confirmed professional sightings over nearly 14 years), with an otherwise decent Uncertainty Parameter of U = 2, or a mere 4.4 to 19.6 arc-seconds of drift expected per decade, its great orbital distance and long period mean each of its approximately 28-decade orbits accumulate 0.034 to 0.153 degrees of potential error. Whilst still a very small amount, and unlikely to cause any difficulty with predicting target areas for future imaging or the object's position for probe rendezvous, it is enough to make nearly all of the above scenarios possible (the exception being a non-librating 7:12 resonance; however, it would only require minor, long term libration for 7:12 to become realistic).

Discovery

Initial discovery was through radiometric images acquired on 23 January 2012 at VATT, on Mount Graham, Arizona; precovery observations from VATT (radiometry) and the Sloan Digital Sky Survey (visible spectrum) dating back to 31 December 2002 have been accepted by the Minor Planet Center. The object has been repeatedly tracked since then, through to at least early 2016, mostly radiometrically by VATT with some supporting observations by Las Camapanas Observatory. 420356 Praamzius is one of the most recently discovered minor planets to receive a numeric designation, confirming it as a distinct body with reasonably certain orbital characteristics. This is due to the large number of clear observations since and indeed before its discovery: about one every 23 to 24 days on average from 2002 to 2016, and in fact as many as one per 10 days made in the period between discovery and assignment, helping to quickly confirm its existence and orbit even though only a few precovery images had yet been found and accepted.

Physical characteristics

All known observations of Praamzius since 2011 have been via radio telescopes, and there is little useful data available from which to make more than the most basic estimates of its size, shape, mass, rotational period, etc. However, analysis of precovery observations in the visible spectrum between 2002 and 2007 show that it may be amongst the reddest objects in the Solar System, being more than 1.5 magnitudes fainter in the G (green) filtered versus the R (red) filtered images, which may offer some clues as to its composition and origin.

Naming

This minor planet was named after Praamžius (an epithet of Dievas), the Lithuanian mythological god of the sky, peace, and friendship. The official naming citation was published by the Minor Planet Center on 22 February 2016 (M.P.C. 98717).

External links

• 420356 Praamzius at the JPL Small-Body Database