Editing 2001 Einstein (section)

== Physical characteristics ==

The [[Tholen classification]], ''Einstein'' is an [[X-type asteroid]], while in the [[SMASS classification]], it is an Xe-subtype which transitions from the X-type to the very bright [[E-type asteroid]].

=== Rotation period ===

Several rotational [[lightcurve]]s for this asteroid were obtained from [[Photometry (astronomy)|photometric]] observations. In December 2004, the first lightcurve by American astronomer [[Brian D. Warner|Brian Warner]] at his Palmer Divide Observatory (PDS) in Colorado, gave a [[rotation period]] of {{val|5.487}} hours with a brightness variation of {{val|0.66}} in [[Magnitude (astronomy)|magnitude]] ({{small|[[LCDB quality code|U=3]]}}).<ref name="Warner-2005f" /> Between 2008 and 2012, three additional lightcurves at the PDS gave an almost identical period of 5.485 hours with an amplitude of 0.67, 0.74 and 1.02, respectively ({{small|[[LCDB quality code|U=3/3/3]]}}).<ref name="Warner-2010e" /><ref name="Warner-2008m" /><ref name="Warner-2013d" /> Other lightcurves were obtained by Hanuš at the French [[Centre national d'études spatiales|CNES]] and other institutions, which gave a period of {{val|5.48503}} hours ({{small|[[LCDB quality code|U=n.a.]]}}),<ref name="Hanus-2016" /> and by Italian astronomer Federico Manzini at SAS observatory in Novara, Jean Strajnic and Raoul Behrend from December 2012, which rendered a period of {{val|5.4846}} hours with an amplitude of 0.66 in magnitude ({{small|[[LCDB quality code|U=2+]]}}).<ref name="geneva-obs" />

=== Diameter and albedo ===

According to the survey carried out by the [[NEOWISE]] mission of NASA's space-based [[Wide-field Infrared Survey Explorer]] (WISE), the asteroid measures 4.0&nbsp;km in diameter and its surface has an exceptionally high [[astronomical albedo|albedo]] of 0.81, for which WISE assigns an [[E-type asteroid|E-type]].<ref name="WISE" /> The ''Collaborative Asteroid Lightcurve Link'' assumes a lower, yet still high albedo of 0.40 and hence calculates a larger diameter of 5.7 kilometers, as the lower the albedo, the larger the body's diameter for a constant absolute magnitude.<ref name="lcdb" />