Editing 3 Juno (section)

== Observations ==

Juno was the first asteroid for which an [[occultation]] was observed. It passed in front of a dim [[star]] ([[SAO 112328]]) on 19 February 1958. Since then, several occultations by Juno have been observed, the most fruitful being the occultation of [[SAO 115946]] on 11 December 1979, which was registered by 18 observers.<ref name="millis1981">{{cite journal
 | display-authors= 8
 | last= Millis
 | first= R. L.
 | author2= Wasserman, L. H.
 | author3= Bowell, E.
 | author4= Franz, O. G.
 | author5= White, N. M.
 | author6= Lockwood, G. W.
 | author7= Nye, R.
 | author8= Bertram, R.
 | author9= Klemola, A.
 | author10= Dunham, E.
 | author11= Morrison, D.
 | title= The diameter of Juno from its occultation of AG+0°1022
 | journal= Astronomical Journal
 | volume= 86
 | pages= 306–313
 | date= February 1981
 | bibcode= 1981AJ.....86..306M
 | doi= 10.1086/112889
 | url= http://library2.smu.ca/bitstream/01/26050/1/Dupuy_David_L_article_1981.pdf
 | access-date= 4 September 2019
 | archive-date= 14 December 2023
 | archive-url= https://web.archive.org/web/20231214154823/https://library2.smu.ca:443/bitstream/handle/01/26050/Dupuy_David_L_article_1981.pdf;jsessionid=FA53E7FF3F1BCDB4CC3B578960F38AB8?sequence=1
 | url-status= live
 }}</ref>
Juno occulted the magnitude 11.3 star [[PPMX 9823370]] on 29 July 2013,<ref>[https://archive.today/20130729233004/http://www.asteroidoccultation.com/2013_07/0729_3_30531.htm Asteroid Occultation Updates – 29 Jul 2013]</ref> and [[2UCAC 30446947]] on 30 July 2013.<ref>[https://archive.today/20130729232944/http://www.asteroidoccultation.com/2013_07/0730_3_29995.htm Asteroid Occultation Updates – 30 Jul 2013].</ref>

Radio signals from spacecraft in orbit around [[Mars]] and on its surface have been used to estimate the mass of Juno from the tiny perturbations induced by it onto the motion of Mars.<ref name="Pitjeva04">
 {{cite conference
 | first=E. V. | last= Pitjeva
 | title= Estimations of masses of the largest asteroids and the main asteroid belt from ranging to planets, Mars orbiters and landers
 | book-title= 35th COSPAR Scientific Assembly. Held 18–25 July 2004, in Paris, France
 | pages= 2014 | date= 2004
 | bibcode= 2004cosp...35.2014P}}</ref> Juno's [[orbit]] appears to have changed slightly around 1839, very likely due to perturbations from a passing asteroid, whose identity has not been determined.<ref name="usno1999">{{cite journal |last=Hilton |first=James L. |title=US Naval Observatory Ephemerides of the Largest Asteroids |journal=Astronomical Journal |volume=117 |issue=2 |pages=1077–1086 |date=February 1999 |doi=10.1086/300728 |bibcode=1999AJ....117.1077H |doi-access=free }}</ref>

In 1996, Juno was imaged by the [[Hooker Telescope]] at [[Mount Wilson Observatory]] at visible and near-IR wavelengths, using [[adaptive optics]]. The images spanned a whole rotation period and revealed an irregular shape and a dark albedo feature, interpreted as a fresh impact site.<ref name="baliunas2003"/>
<gallery mode="packed" heights="200px">
File:Juno 4 wavelengths.jpg|Juno seen at four wavelengths with a large [[Impact crater|crater]] in the dark ([[Hooker telescope]], 2003
File:Juno mpl anim.gif|Juno moving across background stars
File:3Juno-LB1-apmag.jpg|Juno during opposition in 2009
File:Animation of the asteroid Juno as imaged by ALMA.webm|Video of Juno taken as part of ALMA's Long Baseline Campaign
</gallery>