scientific abstract the purpose of this proposal is twofold. first, to provide a global picture of the zodiacal light as seen by isophot. this skeleton allows us to make consistent use of the large amount of serendipity background measurements to be expected; it allows us to adopt the results obtained with the infrared satellite cobe for use or comparison with iso; it helps to determine reliable backgrounds, which is important in particular for studies of galactic and extragalactic background, but also for the study of faint objects. second, it allows us to study aspects of the spatial distribution of interplanetary dust which have not been treated sufficiently so far: the search for arcminute structure in the zodiacal light, the out-of-ecliptic distribution, the variation of absorption cross section per unit volume with heliocentric distance, and the location of the plane of symmetry as a function of heliocentric distance, where distance is measured by the temperature of the dust. for these measurements the ability of iso to avoid stars and bright infrared cirrus and therefore to measure pure zodiacal light, is an important advantage. this proposal is part of the isophot effort to measure diffuse sky brightness. it is coordinated in some detail with the isophot proposals measurement of the extragalactic background radiation, properties of interplanetary dust and diffuse infrared emission of the galaxy. performance time overview observations priority 1 priority 2 priority 3 sum ---------------------------------------------------------------------------- global mapping - 13590 s 9060 s 22650 s (6.3 h) seasonal variation 21066 s - - 21066 s (5.9 h) arcminute structure 4614 s 4614 s 4614 s 13842 s (3.9 h) --------------------------------------------------------------------------- total 25680 s 18204 s 13674 s 57558 s (7.1 h) (5.1 h) (3.8 h) (16.0 h) 45 % 32% 24% observation summary the distribution and absolute brightness of zodiacal light is studied by means of multiband photometry. there are three parts to this proposal: \t1. to determine the global distribution of zodiacal light \t2. to measure the seasonal variations of the zodiacal light \t3. to search for arcminute structure in the zodiacal light the first two parts will be performed in sufficient extent to allow an intercomparison with cobe and use of the cobe results for inter- polation. the choice of filters has been coordinated with the proposal on extragalactic backgound light, to which the zodiacal light constitutes an important foreground. the filter at 180 micron is most sensistive to cirrus emission and is always included to improve the correction for this emission. we aim at relative photometric accuracies of a few percent or better, which is needed to separate extragalactic background light from the much brighter zodiacal light and which is highly wanted for modelling of the interplanetary dust distribution. object lists and breakdown of observations by aot.s will be given in the three separate parts. the common observing plan for photometry will be given in this summary. for all measurements the largest available aperture (180 arcsec) will be used. for a detailed observing plan, special requirements and detailed information on target positions see section scientific justification.
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, Leinert et al., 1999, 'Global mapping comma seasonal variation and search for arcminute structure of zodiacal light comma Section 3A ', 1.0, European Space Agency, https://doi.org/10.5270/esa-ode1cu5
