Photometry and Light Curves in the Solar System (Abstract)

Volume 37 number 2 (2009)

Jay M. Pasachoff

Abstract

(Abstract only) In a coordination between Williams College and MIT, we have been observing Pluto and Charon as they occult stars, the resulting light curves revealing changes in Pluto’s atmosphere and the sizes, shapes, densities, and other aspects of these bodies in the outer solar system. We have seven of our POETS (Portable Occultation, Eclipse, and Transit System) sets of apparatus, mostly for travel to large telescopes in the path of the occultations but two on long-term status in New Mexico at a 2.5-m telescope and in Hawaii on a 3-m telescope, respectively. Each system includes an Andor Technology DV-887 frame-transfer CCD (often used at 10 Hz readout), a GPS for accurate time, and associated computer. During my sabbatical at Caltech, I am associated with Mike Brown’s group, and we are observing mutual occultations of Haumea (the second dwarf planet past Eris, which he also discovered) and its moon Namaka, which should establish the size, gravitational fields, and many other aspects of each. We even have an excellent, absolutely calibrated, set of light curves from the ACRIMsat of the light curves showing the total solar irradiance of the sun during transits of Venus and Mercury. Reference: Souza, Steven P., et al. 2006, Publ. Astron. Soc. Pacific, 118, 1550.