IRSAM: The infrared extension of the Statistical Asteroid Model

Introduction:
Due to the relative stength of their apparent brightness at infrared wavelength compared e.g. to Galactic stars, asteroids are among the dominant sources at infrared wavelengths and can seriously affect the infrared observations. To check/describe their impact on IR and submm measurement a model is needed that can give the ephemerids describing most asteroid families, brightness values (at least at one wavelength), and albedos as well. These conditions are fulfilled by the Statistical Asteroid Model (Tedesco et al., 2005, AJ, 129, 2869).


The model:
Our model provides the IR and submm fluxes of all minor planets in the Statistical Asteroid Model (SAM), using the Standard Thermal Model (Lebofsky et al., 1986, Icarus, 68, 239), and therefore can be considered as the IR and submm extension of the SAM. The celestial positions of the minor planets are calculated for the time span 2000-01-01...2012-12-31, and some quantities, describing their impact on the IR and submm measurements (fluctuations powers, expected counts, surface brightness contribution) are derived for a specific sky position, date and wavelength. The model is accessible for the community through a web-interface. If you use the results of our model in your publication, please, refer to the papers below. You can read more about infrared confusion noise here.
Mission average maps:
The general impact of asteroids on the infrared and submillimetre measurements can be well described by 'mission-average' maps for a specific wavelength, i.e. average maps of full fluctuation power maps of different dates. Mission-average maps are presented in the heliecliptic coordinate system [|λ-λo|- β where λ is the ecliptic longitude, λo is the ecliptic longitude of the Sun, and β is the ecliptic latitude]. For a detailed description of mission average maps, see the related papers below.

M-band: df0_mamap_M.fits N-band: df0_mamap_N.fits Q-band: df0_mamap_Q.fits 9μm: df0_mamap_9.fits
18μm: df0_mamap_18.fits 24μm: df0_mamap_24.fits 65μm: df0_mamap_65.fits 70μm: df0_mamap_70.fits
75μm: df0_mamap_75.fits 90μm: df0_mamap_90.fits 110μm: df0_mamap_110.fits 140μm: df0_mamap_140.fits
160μm: df0_mamap_160.fits 175μm: df0_mamap_175.fits 250μm: df0_mamap_250.fits 350μm: df0_mamap_350.fits
360μm: df0_mamap_360.fits 520μm: df0_mamap_520.fits 550μm: df0_mamap_550.fits 850μm: df0_mamap_850.fits

FITS cube of mission-average maps for multiple wavelengths: df0_mamap_cube.fits
Mission-average number counts: ntot_mamap.fits


Effective solid angles to calculate confusion noise from fluctuation powers:

Instrument PACS PACS PACS SPIRE SPIRE SPIRE
Wavelength (μm) 70 100 160 250 350 500
Ωpixel (sr) 2.56×10-10 2.56×10-10 1.02×10-9 5.33×10-9 1.15×10-8 2.13×10-8
Ωeff (sr) 3.87×10-10 5.67×10-10 1.80×10-9 5.89×10-9 1.21×10-8 2.35×10-8

PACS and SPIRE are instruments of the Herschel Space Observatory. More information on the currently used solid angles for the photometric bands above can be found in The Herschel Confusion Noise Estimator, V015, release note .


Related papers:
Kiss, Cs., Pál, A., Müller, Th., Ábrahám, P., 2006, "An asteroid model of the mid- and far-infrared sky", In: Proceedings of the 4th Workshop of Young Researchers in Astronomy & Astrophysics; Budapest, Hungary, 11-13 January, 2006; Publications of the Astronomy Department of the Eötvös University (PADEU), Edited by E. Forgács-Dajka, Vol. 17., p. 135
Kiss, Cs., Pál, A., Müller, Th., Ábrahám, P., 2006, "Confusion noise due to asteroids: from mid-IR to submm wavelengths", poster, Visions of infrared astronomy, March 20-22, 2006, Paris
Kiss, Cs., Pál, A., Müller, Th., Ábrahám, P., 2008, "The impact of main belt asteroids on infrared-submillimetre photomerty and source counts", Astronomy & Astrophysics, 478, 605-613 A&A PAPER A&A paper at astro-ph

KISAG, Solar System research pages
Konkoly Infrared & Space Astronomy Group