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Access to the spectra in MAST HLSP Solar System Objects

The Solar System Objects' Spectra offered here are for the Sun, Jupiter, Saturn, Uranus, and Neptune. These have wavelength ranges from the visible to mid-infrared, typically 0.53 to 28.75 \(\mu m\), while for the solar spectrum the wavelength range is 0.2 to 30 \(\mu m\).

Because the NIR spectra of the planets are from observations, and the MIR spectra are largely models, the two wavelength regions do not match up neatly in the ~5 \(\mu m\) range. Additionally, there are no available spectra that adequately represent the region from ~4 to 8 \(\mu m\).

To piece the NIR and MIR spectra together, a Gaussian was extended from the shortest wavelengths of the MIR spectrum until it met up with the NIR spectrum. Random Gaussian noise was added to mimic the behavior at the shortest MIR wavelengths. The NIR wavelengths longward of the meet-up point were discarded in favor of the extended MIR data.

The wavelengths of the planetary spectra are in \(\dot{A}\), while the fluxes are tabulated in units of \(erg\ s^{-1}\ cm^{-2}\ \dot{A}^{-1}\ arcsec^{-2}\). The spectra are in surface brightness units, which are \(F_{\lambda}\)units divided by \(arsec^2\). This is a more appropriate choice than disk-integrated flux because it enables a source of any size to be specified in the ETC with the appropriate flux, as long as the normalization is in units of surface brightness.

The empirical solar spectrum uses observations from Thuillier et al., (2003) from 0.2-2.4 \(\mu m\).  Longer wavelengths are represented by a local thermal equilibrium (LTE) model from Holweger & Muller (1974). The region from 4-6.5 \(\mu m\) was modified to more accurately represent the CO absorption features, bringing the spectrum into agreement with the observations of Wallace & Livingston (2003). This spectrum was interpolated onto a regular wavelength grid with approximately the same mean spacing as the original. Normalized to 1 au heliocentric distance. The wavelengths are in \(\dot{A}\), and the fluxes were tabulated in units of \(erg\ s^{-1}\ cm^{-2}\ \dot{A}^{-1}\).

Filename          Wavelength Range (microns)
jupiter_solsys_surfbright_001.fits 0.53 - 28.75
saturn_solsys_surfbright_001.fits 0.53 - 28.75
uranus_solsys_surfbright_001.fits 0.54 - 28.75
neptune_solsys_surfbright_001.fits 0.54 - 28.75
solar_spec.fits 0.2  - 30



Jupiter and Saturn:
  • Clark, R.N., and McCord, T.B. 1979. Icarus, 40, 180-188
  • Karkoschka, E. 1994. Icarus, 111, 174-192
  • Encrenaz, T., et al. 1997. ESA SP-419, 125
  • Fletcher, L.N., Orton, G.S., Teanby, N.A., and Irwin, P.G.J. 2009. Icarus, 202, 543-564
  • Vis-NIR: Clark & McCord (1979)
  • Vis-1 micron geometric albedo: Karkoschka (1994)
  • 2.5-5 micron from ISO, cross-check: Encrenaz et al. (1997)
  • MIR, Cassini/CIRS: Fletcher et al. (2009)
  • MIR models for wavelengths <6.5 microns and >17 microns were provided by L. Fletcher (private communication).
Uranus and Neptune
  • Vis-NIR: Fink, U. and Larson, H.P. 1979. ApJ, 233, 1021-1040
  • Vis-1 micron geometric albedo: Karkoschka, E. 1994. Icarus, 111, 174-192
  • 2.5-5 micron Akari albedo: Burgdorf, M.J., Drossart, P., Encrenaz, T., Fletcher, L.N., and Orton, G. 2008. AAS/DPS 40, #50.09
  • 2.6-4 micron ISO, cross-check: Encrenaz, T., et al. 1997. ESA SP-419, 125
  • MIR, Spitzer/IRS (R~600): Orton, G.S., et al. 2014. Icarus, 243, 471-493
  • Rieke et al., 2008, AJ 135, 2245

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