2021 AO4
ephemeris	date	magn	radius	delta (AU)	delta (LD)	delta (km)	ra	dec	elong	phase
Today	4 Dec 2024	30.5	0.756 AU	0.297 AU	115.45 LD	44,388,433 km	18h22m	-49°12'	33.6°	133.9°
Approach	4 Jan 2025	20.8	0.989 AU	0.015 AU	5.83 LD	2,242,355 km	10h07m	-26°44'	113.3°	65.9°
Brightest	5 Jan 2025	20.3	0.998 AU	0.018 AU	7.07 LD	2,717,466 km	09h04m	+04°02'	146.1°	33.3°

Based on its absolute magnitude (Hₒ) of 27.6 and an albedo between 0.25 and 0.05, the estimated diameter of 2021 AO4 is 8 - 18 m.

The interactive orbit chart above shows the near-earth object's path through the solar system and its position at the given date. Green and blue lines are shown perpendicular to the ecliptic plane: Green if the path is above the ecliptic plane, blue if it is below.

(Left-click and drag to rotate the view; right-click and drag to move the view; use scroll wheel to zoom in our out.)

The light curve chart below shows the estimated development of the NEO's magnitude during its approach to earth.

The following all-sky chart shows the path of the NEO in the coming months.

The following chart shows the path of the NEO in the coming days or hours. The field of view is optimized for (~10x50) binoculars and finderscopes. A more printer-friendly version of the same chart can be found below.

    Terminology:
            
    delta:  distance between NEO and earth in AU or LD 
    radius: distance between NEO and sun in AU
    magn:   magnitude (brightness) estimate    
    ra:     right ascension in hours (24h = 360deg)
    dec:    declination in degrees
    elong:  elongation in degrees (angle sun-earth-NEO)    
    phase:  phase angle in degrees (angle sun-NEO-earth)        
    AU:     Astronomical Unit: mean distance between earth and sun (149597870.7 km)
    LD:     Lunar distance: Mean distance between earth and the moon (~0.00257 AU)
    

Orbital elements provided by the MPC (Minor Planet Center).
Calculations by a modified version of AAPlus, a C# implementation of the AA+ project by PJ Naughter from the algorithms presented in the book "Astronomical Algorithms" by Jean Meeus.
NGC2000 dso catalog and star labels from VizieR as provided by the Strasbourg astronomical Data Center.
Tycho2 catalog from the ESO archive.