Upper limits for brightness and dust concentration of the hypothetical libration cloud at L4 in the system earth-moon based on photographic surface photometry.
Abstract
Three wide-angle photographs with a field diameter of 140 deg are used to derive upper limits for the surface brightness and dust density of the hypothetical libration cloud at the L4 Lagrangian point in the earth-moon system. A region of 40 by 9.2 deg along the moon's orbit and centered on L4 was scanned with a digitized microdensitometer, and the gegenschein was scanned perpendicular to the ecliptic in an area of 4.6 by 20 deg. The results show no clear increase or decrease in brightness around L4 and a second-order variation of only 10 S10 in the brightness of the zodiacal band. Analysis of the scatter in surface brightness per sq deg about the mean indicates that the upper limit for the surface brightness of the hypothetical cloud should be less than 3 S10 and that this excess brightness corresponds to a dust density that is four times greater than the interplanetary average.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- December 1975
- Bibcode:
- 1975A&A....45..197S
- Keywords:
-
- Astronomical Photometry;
- Earth-Moon System;
- Interplanetary Dust;
- Lagrangian Equilibrium Points;
- Zodiacal Light;
- Astronomical Photography;
- Calibrating;
- Gegenschein;
- Luminous Intensity;
- Surface Properties;
- Astronomy