The GAia Map of the Brightness Of Natural Sky

About GAMBONS

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What is GAMBONS?

GAMBONS (GAia Map of the Brightness Of the Natural Sky) is a model of the natural night brightness of the sky in cloudless and moonless nights. GAMBONS is based on the extra-atmospheric star radiance obtained from the Gaia catalogue. For the brightest stars, not included in Gaia-DR3, we have used the Hipparcos catalogue instead. After adding up to the star radiance the contributions of the diffuse galactic and extragalactic light, zodiacal light and airglow, and taking into account the effects of atmospheric attenuation and scattering, the radiance detected by ground-based observers is estimated. At the moment, GAMBONS does not include the Moon and Sun contributions.

The citation for GAMBONS is Masana et al. 2020 (MNRAS 501, 5443-5456). Download the paper here.


Running GAMBONS


Scattering model

In this web version the scattering is computed in a simpler, but less accurate, way than the full scattering model described in the paper. It consists in replacing τ0(λ) by an effective optical depth τ0(λ)eff = γ τ0(λ), (see Duriscoe D. M., 2013, PASP, 125, 1370), with a value of γ=0.5. The results obtained with this simplified scattering model could differ from the results get with the full model. At zenith, the simplified model tends to be darker (compared with the full model) in around 0.075 - 0.1 mag arcsec-2, whereas near the horizon it is brighter in 0.1 - 0.2 mag arcsec-2. The implementation of the full model is not feasible in this version due to the CPU time needed. If more accurate results are required, contact whit us.


Photometric systems

The currently available photometric bands in GAMBONS are:

Johnson-Cousins system (UBVRI)

The UBVRI magnitudes are defined in the Vega system. The fluxes in those bands correspond to filters with transmission peak equal to 1.

Gaia filter (G)

The Gaia magnitude is defined in the Vega system. Note that the filter's transmission is not normalized to 1.

RGB System

The RGB magnitudes are defined in the AB system. The fluxes in those bands correspond to filters with transmission peak equal to 1

Human vision (photopic and scotopic)

Photopic and scotopic magnitudes are defined in the Vega system.

Sloan system (ugriz)

The Sloan magnitudes are defined in the AB system. Note that the filter transmission are not normalized.


Contact

Contact addresses: emasana at fqa.ub.edu (E. Masana; astrophysical sources, website), salva.bara at usc.gal (S. Bará; atmospheric modeling).