1830 Pogson

Lore & Background

1830 Pogson was discovered on 17 April 1968 by Swiss astronomer Paul Wild at the Zimmerwald Observatory near Bern, Switzerland. It was named after English astronomer Norman Pogson, inventor of the modern astronomical magnitude scale, who discovered eight asteroids including 42 Isis and 67 Asia. The official naming citation was published by the Minor Planet Center on 15 October 1977. The lunar crater Pogson was also named in his honor.

According to a HCM-analysis by David Nesvorný, Pogson is a member of the Flora family, a giant asteroid clan and the largest family of stony asteroids in the asteroid belt. It has also been grouped into the Augusta family by Zappalà, while for Milani and Knežević, who do not recognize the Florian clan as a family, Pogson is a non-family asteroid from the main belt's background population. It orbits the Sun in the inner asteroid belt at a distance of 2.1–2.3 AU once every 3 years and 3 months, with an eccentricity of 0.06 and an inclination of 4°.

In April 2007, photometric observations by an international collaboration revealed that Pogson is an asynchronous binary system with a minor-planet moon. The companion orbits its primary every 24.24 hours, with a diameter of 2.52 kilometers and separated by 8 kilometers from its primary. The asteroid's rotation period was measured at 2.5702 hours, later refined to 2.56990 hours. According to NEOWISE data, Pogson measures between 7.7 and 8.35 kilometers in diameter with an albedo between 0.2188 and 0.274.

Reader's Guide

1830 Pogson holds significance as an asynchronous binary asteroid system, a relatively rare configuration where the satellite's rotation is not synchronized with its orbit. Its discovery as a binary in May 2007, based on mutual eclipse and occultation events observed during photometric studies, contributed to the growing catalog of asteroids with moons. The asteroid's classification is disputed among different researchers: Nesvorný places it in the Flora family, Zappalà in the Augusta family, while Milani and Knežević consider it a non-family background asteroid. This uncertainty highlights the ongoing refinement of asteroid family boundaries. The naming after Norman Pogson honors his development of the magnitude scale and his asteroid discoveries. The asteroid's physical characteristics, including its stony S-type composition and rotation period of about 2.57 hours, were determined through collaborative international observations. NEOWISE data provided diameter and albedo estimates, though the Collaborative Asteroid Lightcurve Link adopts a specific diameter of 8.35 kilometers based on revised WISE-data. The binary nature and the multiple rotation period measurements make Pogson a well-studied object for understanding binary asteroid dynamics.

Did You Know?

• It is an asynchronous binary system with a 2.52-kilometer moon that orbits every 24.24 hours.
• Its classification is disputed: it is considered a member of the Flora family by Nesvorný, but a non-family asteroid by Milani and Knežević.