An occultation of a star by Iduna was observed from Mexico on January 17, 1998.
Photometric observations of this asteroid at the Romer Observatory in Aarhus, Denmark during 1996 gave a light curve with a period of 11.289 ± 0.006 hours and a brightness variation of 0.35 in magnitude.[2] A 2008 study at the Palmer Divide Observatory in Colorado Springs, Colorado gave a period of 11.309 ± 0.005 hours, confirming the 1996 result.[5]
^Warner, Brian D. (June 2008), "Asteroid Lightcurve Analysis at the Palmer Divide Observatory - June - October 2007", The Minor Planet Bulletin, 35 (2): 56–60, Bibcode:2008MPBu...35...56W.