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J/A+A/523/A48       Gaia photometry                               (Jordi+, 2010)

Gaia broad band photometry. Jordi C., Gebran M., Carrasco J.M., de Bruijne J., Voss H., Fabricius C., Knude J., Vallenari A., Kohley R., Mora A. <Astron. Astrophys. 523, A48 (2010)> =2010A&A...523A..48J
ADC_Keywords: Stars, fundamental ; Photometry, UBVRI ; Photometry, ugriz; Photometry, sequences ; Photometry, special systems Keywords: instrumentation: photometers - techniques: photometric - Galaxy: general - dust, extinction - stars: evolutions Abstract: The scientific community needs to be prepared to analyse the data from Gaia, one of the most ambitious ESA space missions, which is to be launched in 2012. The purpose of this paper is to provide data and tools to predict how Gaia photometry is expected to be. To do so, we provide relationships among colours involving Gaia magnitudes (white light G, blue GBP, red GRP and GRVS bands) and colours from other commonly used photometric systems (Johnson-Cousins, SDSS, Hipparcos and Tycho). The most up-to-date information from industrial partners has been used to define the nominal passbands, and based on the BaSeL3.1 stellar spectral energy distribution library, relationships were obtained for stars with different reddening values, ranges of temperatures, surface gravities and metallicities. The transformations involving Gaia and Johnson-Cousins V-IC and SDSS g-z colours have the lowest residuals. A polynomial expression for the relation between the effective temperature and the colour GBP-GRP was derived for stars with Teff higher than 4500K. For stars with Teff smaller than 4500K, dispersions exist in gravity and metallicity for each absorption value in g-r and r-i. Transformations involving two Johnson or two SDSS colours yield lower residuals than using only one colour. We also computed several ratios of total-to-selective absorption including absorption AG in the G band and colour excess E(GBP-GRP) for our sample stars. A relationship involving AG/AV and the intrinsic (V-IC) colour is provided. The derived Gaia passbands have been used to compute tracks and isochrones using the Padova and BASTI models, and the passbands have been included in both web sites. Finally, the performances of the predicted Gaia magnitudes have been estimated according to the magnitude and the celestial coordinates of the star. The provided dependencies among colours can be used for planning scientific exploitation of Gaia data, performing simulations of the Gaia-like sky, planning ground-based complementary observations and for building catalogues with auxiliary data for the Gaia data processing and validation. Description: In table 11, we present the magnitudes values for Gaia, Johnson-Cousins, Hipparcos, Tycho and Sloan bands. These magnitude are derived for the BaSeL3.1 sample stars with four absorption values (0,1,3,5). Table 12 displays the bolometric correction un G, BP and RP for the BaSeL3.1 stars. Table 13 represents the computed ratios for interstellar absorption in different bands. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table11.dat 187 10328 Magnitudes values for Gaia, Johnson-Cousins, Hipparcos and Sloan bands for 2582 combinations of Teff, logg, [M/H] and 4 absorptions (0,1,3,5) table12.dat 39 2582 Computed bolometric corrections in Gaia bands table13.dat 107 7746 Computed ratios for interstellar absorption in different bands for 2582 combinations of Teff, logg, [M/H] and 3 absorptions (1,3,5)
Byte-by-byte Description of file: table11.dat
Bytes Format Units Label Explanations
1- 5 I5 K Teff [2000/50000] Effective temperature of the star 7- 10 F4.1 [cm/s2] logg [-0.7/5.5] Surface gravity of the star 12- 15 F4.1 [Sun] [M/H] [-2/0.5] Metallicity of the star 17- 20 F4.1 mag A550 [0/5] Absorption coefficient, A(λ=550nm) 22- 27 F6.3 mag G-Gbp Gaia G-GBP (blue passband) color index (G1) 30- 35 F6.3 mag G-Grp Gaia G-GRP (red passband) color index (G1) 38- 43 F6.3 mag Gbp-Grp Gaia GBP-GRP color index (dG) (G1) 46- 51 F6.3 mag G-V Gaia and Johnson G-V color index combination (G1) 54- 59 F6.3 mag V-Ic Johnson-Cousins V-Ic color index (G1) 62- 67 F6.3 mag V-Rc Johnson-Cousins V-Rc color index (G1) 70- 75 F6.3 mag B-V Johnson-Cousins B-V color index (G1) 78- 83 F6.3 mag Gbp-V Gaia and Johnson-Cousins GBP-V color index combination (G1) 86- 91 F6.3 mag Gbp-Ic Gaia and Johnson-Cousins GBP-Ic color index combination (G1) 94- 99 F6.3 mag Grp-V Gaia and Johnson-Cousins GRP-V color index combination (G1) 102-107 F6.3 mag Grp-Ic Gaia and Johnson-Cousins GRP-Ic color index combination (G1) 110-115 F6.3 mag G-Hp Gaia and Hipparcos G-Hp color index combination 117-123 F7.3 mag G-BT Gaia and Tycho G-BT color index combination (G1) 126-131 F6.3 mag G-VT Gaia and Tycho G-VT color index combination (G1) 134-139 F6.3 mag BT-VT Tycho BT-VT color index (G1) 142-147 F6.3 mag g-r SDSS g-r color index (G1) 150-155 F6.3 mag r-i SDSS r-i color index (G1) 157-163 F7.3 mag G-g Gaia and SDSS G-g color index combination (G1) 166-171 F6.3 mag G-r Gaia and SDSS G-r color index combination (G1) 174-179 F6.3 mag G-i Gaia and SDSS G-i color index combination (G1) 182-187 F6.3 mag G-z Gaia and SDSS G-z color index combination (G1)
Byte-by-byte Description of file: table12.dat
Bytes Format Units Label Explanations
1- 5 I5 K Teff Effective temperature of the star 7- 10 F4.1 [cm/s2] logg Surface gravity of the star 12- 15 F4.1 [-] [M/H] Metallicity of the star 18- 23 F6.3 mag BCG Bolometric correction in G 26- 31 F6.3 mag BCGbp Bolometric correction in GBP 34- 39 F6.3 mag BCGrp Bolometric correction in GRP
Byte-by-byte Description of file: table13.dat
Bytes Format Units Label Explanations
1- 5 I5 K Teff Effective temperature of the star 7- 10 F4.1 [cm/s2] logg Surface gravity of the star 12- 15 F4.1 [-] [M/H] Metallicity of the star 18- 23 F6.3 mag (V-Ic)0 Unredenned Johnson-Cousins V-I color index 25- 28 F4.1 mag A550 Absorption coefficient A(λ=550nm) 30- 35 F6.3 --- AG/E(B-V) Ratio of total-to-selective absorption in G to E(B-V) 38- 43 F6.3 --- AG/E(V-Ic) Ratio of total-to-selective absorption in G to E(V-Ic) 46- 51 F6.3 --- AG/AV Ratio of total absorptions in G to V 53- 59 F7.3 --- E(dG)/E(V-Ic) Ratio of color excess E(Gbp-Grp)/E(V-Ic) 62- 67 F6.3 --- E(dG)/E(B-V) Ratio of color excess E(Gbp-Grp)/E(B-V) 70- 75 F6.3 --- AG/E(dG) Ratio of total-to-selective absorption in G to E(Gbp-Grp) 77- 83 F7.3 mag (r-i)0 Unredenned SDSS r-i color index 86- 91 F6.3 --- AG/E(g-r) Ratio of total-to-selective absorption in G to E(g-r) 94- 99 F6.3 --- AG/E(r-i) Ratio of total-to-selective absorption in G to E(r-i) 102-107 F6.3 --- AG/AHp Ratio of total absorptions, G to Hp
Note (G1): Central wavelengths and their FWHM are (in nm, from table 1): ±---------------±------------------±-------------------±-----------+ | Gaia | Johnson-Cousins | SDSS | Hipparcos | | G Gbp Grp Grvs| U B V R I | u g r i z | Hp Bt Vt | |----------------±------------------±-------------------±-----------+ |673 532 797 860 |361 441 551 647 806| 357 475 620 752 899| 528 420 532| |440 253 296 28 | 64 95 85 157 154| 57 118 113 68 100| 222 71 98| ±---------------±------------------±-------------------±-----------+
Acknowledgements: Carme Jordi, carme(at)mizar.am.ub.es
(End) Carme Jordi [Univ. Barcelona, Spain], Patricia Vannier [CDS] 06-Aug-2010
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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