Astronomy Cast

Astronomy Cast takes a fact based journey through the cosmos as it offers listeners weekly discussions on astronomical topics ranging from planets to cosmology.

2007 WZ4

was discovered at 0510 UT on 20 Nov. by the Catalina Sky Survey (CSS). The discovery was confirmed by Mount Lemmon Survey MLS and four other observatories. The discovery was announced in MPEC K07W49 on November 21. The size is estimated with approx. 50 meters. It is an Apollo asteroid. Also known as Earth-crossing asteroids, one of three groups of near-Earth asteroids. Apollo group asteroids have semimajor axes greater than 1.0 AU and perihelia less than 1.017 AU (Earth's aphelion distance).

At discovery it was an mag 18.0 bright object and faded to mag 19.3 on November 28 as it now moves further away from earth.

30 short exposures of 20 seconds were taken and stacked to compensate for the motion of the NEO that moved with 2.8"/minute across the sky.

2007 WZ4

2007 WZ4, NEO, 19.3 mag , P.A. 35.5°, 2.82"/min

3 stacks of 600 sec. each, 14 inch Schmidt-Cassegrain, ST8-XME 2x2 binned,
image scale 1.75"/pixel, image center 04h03m35s, +23°16'32"