the zodiacal light will be the dominant source of background emission over the wavelength range of isocam. most of this background varies smoothly but there are structures resulting from comet trails ( subject of another proposal) and the zodiacal bands discovered by low et al (1984). the zodiacal bands, up to seven pairs of which have now been identified, have widths which range from 0.5 to 3 degrees. these bands appear to be unstructured on scales of a few arc minutes but the small scale (arc second) structure of the bands is unknown. if the bands do have structure on a scale of a few arc seconds then they may present problems when using isocam to observe extended objects that lie close to the ecliptic plane. the origin of the bands is unknown. there are three plausible alternatives (sykes et al 1989) which are: 1) the dust is produced by a slow grinding away of asteroids by mutual collisions. 2) each band is produced by the complete destruction of a single asteroid with a diameter of the order of 10km. 3) each band arises from the destruction of a large comet nucleus or from the superposition of materail ejected from a number of comet nuclei. to date, comparison of models with iras data has only been partly sucessful, for example the models predict much sharper structure than is revealed by the iras data. iso is the only instrument capable of examining these structures in detail. in the case of isocam a full understanding of the small scale structure of the bands is essential for background subtraction required when making deep images. the object of this proposal is to examine a known band to determine if structure exists at the level of a few arc sec . if the bands do have characteristic structure, then this may help to identify other, unknown bands, which might be found serendipitously. observing strategy to determine the small scale structure of a band we need a mosaic which runs across the band at 90 degrees to it. since it will be essential to have good information on the background from the smooth component of the zodiacal light a 0.5 degree wide zody band requires a strip no less than 1 degree wide. the best way to obtain such data is to use the 6 arc sec fov lens, the lw10 filter and the cam01 aot with microscanning to scan across a band. we propose to make a mosaic of two sections of the beta band. this band is about 0.5 degree wide and lies at low ecliptic lattitude. the flux from the band is of the order of 3 * 10-5 jy/sq arc sec which implies that we can obtain s/n of about 10 using the microscanning aot. use of the cam simulator has shown that each strip requires a total spacecraft time of 1 hour. fixed time observations: the bands can be observed at almost anytime, but are regarded as non solar system fixed time observations with precise details to be agreed between the pi and the sot near to the time of the observation.
Instrument
CAM01
Temporal Coverage
1996-06-22T20:22:36Z/1996-06-22T21:19:50Z
Version
1.0
Mission Description
The Infrared Space Observatory (ISO) was the worlds first true orbiting infrared observatory. Equipped with four highly-sophisticated and versatile scientific instruments, it was launched by Ariane in November 1995 and provided astronomers world-wide with a facility of unprecedented sensitivity and capabilities for a detailed exploration of the Universe at infrared wavelengths.
European Space Agency, DAVIES et al., 1999, 'Is there sub arc minute structure in the Zodiacal BandsquestionMark', 1.0, European Space Agency, https://doi.org/10.5270/esa-ikf3h98
