J/MNRAS/501/2848 Spectrophotometric standard cand. photometry (Altavilla+, 2021) ================================================================================ The Gaia spectrophotometric standard stars survey. IV. Results of the absolute photometry campaign. Altavilla G., Marinoni S., Pancino E., Galleti S., Bellazzini M., Sanna N., Rainer M., Tessicini G., Carrasco J.M., Bragaglia A., Schuster W.J., Cocozza G., Gebran M., Voss H., Federici L., Masana E., Jordi C., Monguio M., Castro A., Pena-Guerrero M.A., Perez-Villegas A. =2021MNRAS.501.2848A (SIMBAD/NED BibCode) ================================================================================ ADC_Keywords: Stars, standard ; Photometry, UBVRI ; Photometry, CCD Keywords: techniques: photometric - catalogues - surveys - stars: general Abstract: We present Johnson-Kron-Cousins BVRI photometry of 228 candidate spectrophotometric standard stars for the external (absolute) flux calibration of Gaia data. The data were gathered as part of a 10-yr observing campaign with the goal of building the external grid of flux standards for Gaia and we obtained absolute photometry, relative photometry for constancy monitoring, and spectrophotometry. Preliminary releases of the flux tables were used to calibrate the first two Gaia releases. This paper focuses on the imaging frames observed in good sky conditions (about 9100). The photometry will be used to validate the ground-based flux tables of the Gaia spectrophotometric standard stars and to correct the spectra obtained in non-perfectly photometric observing conditions for small zero-point variations. The absolute photometry presented here is tied to the Landolt standard stars system to ~1 per cent or better, depending on the photometric band. Extensive comparisons with various literature sources show an overall ~1 per cent agreement, which appears to be the current limit in the accuracy of flux calibrations across various samples and techniques in the literature. The Gaia photometric precision is presently of the order of 0.1 per cent or better, thus various ideas for the improvement of photometric calibration accuracy are discussed. Description: Johnson-Kron-Cousins BVR(I when available) magnitudes of 198 out of 228 candidate spectrophotometric standard stars (SPSS) for the external (absolute) flux calibration of Gaia data. The missing 30 stars were rejected (data available in Table 5 in the paper). File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table4.dat 159 198 BVRI program stars magnitudes -------------------------------------------------------------------------------- See also: J/MNRAS/426/1767 : Gaia spectrophotometric standard stars I. (Pancino+, 2012) J/MNRAS/462/3616 : Gaia SPSS variability monitoring (Marinoni+, 2016) Byte-by-byte Description of file: table4.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 3 I3 --- SPSSID [1/355] SPSS internal ID 6- 27 A22 --- Name SPSS name 30- 31 I2 h RAh Right ascension (J2000) 33- 34 I2 min RAm Right ascension (J2000) 36- 40 F5.2 s RAs Right ascension (J2000) 43 A1 --- DE- Declination sign (J2000) 44- 45 I2 deg DEd Declination (J2000) 47- 48 I2 arcmin DEm Declination (J2000) 50- 53 F4.1 arcsec DEs Declination (J2000) 56- 61 F6.3 mag Bmag Johnson B magnitude 64- 69 F6.3 mag Vmag Johnson V magnitude 72- 77 F6.3 mag Rmag Cousins R magnitude 80- 85 F6.3 mag Imag ?=99.999 Cousins I magnitude 88- 92 F5.3 mag e_Bmag Bmag uncertainty 95- 99 F5.3 mag e_Vmag Vmag uncertainty 102-106 F5.3 mag e_Rmag Rmag uncertainty 109-114 F6.3 mag e_Imag ?=99.999 Imag uncertainty 117 I1 --- NB Number of nights for B 120 I1 --- NV Number of nights for V 123 I1 --- NR Number of nights for R 126 I1 --- NI Number of nights for I 129-130 I2 --- o_Bmag Number of measurements for B 133-134 I2 --- o_Vmag Number of measurements for V 137-138 I2 --- o_Rmag Number of measurements for R 141 I1 --- o_Imag Number of measurements for I 144 I1 --- f_Bmag [0/1] 1 if no fully photometric nights 147 I1 --- f_Vmag [0/1] 1 if no fully photometric nights 150 I1 --- f_Rmag [0/1] 1 if no fully photometric nights 154-155 I2 --- f_Imag ?=99 [0,1] 1 if no fully photometric nights 158-159 I2 --- Note [1/36]? Individual notes, see (1) -------------------------------------------------------------------------------- Note (1): Individual notes as follows:: 1 = Literature data available in: Landolt A.U. & Uomoto A.K., 2007AJ....133..768L, CALSPEC g191b2b_mod_011 2 = Literature data available in: Landolt A.U. 2009AJ....137.4186L, Clem J.L. & Landolt A.U. 2013AJ....146...88C, CALSPEC gd71_mod_011 3 = Literature data available in: Bohlin R.C. Landolt A.U. 2015AJ....149..122B, CALSPEC gd153_mod_011 4 = Literature data available in: Landolt A.U. 1992AJ....104..372L 5 = Literature data available in: Landolt A.U. 2009AJ....137.4186L, CALSPEC gd50_004 6 = Literature data available in: Landolt A.U. & Uomoto A.K. 2007AJ....133..768L, CALSPEC hz2_005 7 = Literature data available in: Landolt A.U. 2009AJ....137.4186L, Clem J.L. & Landolt A.U. 2013AJ....146...88C, CALSPEC gd108_005 8 = Literature data available in: Landolt A.U. & Uomoto A.K. 2007AJ....133..768L, CALSPEC feige34_stis_006 9 = Literature data available in: Landolt A.U. & Uomoto A.K. 2007AJ....133..768L, CALSPEC feige66_002 10 = Literature data available in: Landolt A.U. & Uomoto A.K. 2007AJ....133..768L, CALSPEC hz44_stis_006 11 = Literature data available in: Landolt A.U. & Uomoto A.K. 2007AJ....133..768L, CALSPEC grw_70d5824_mod_001 12 = Literature data available in: Landolt A.U. 2009AJ....137.4186L, Clem J.L. & Landolt A.U. 2013AJ....146...88C, CALSPEC g93_48_004 13 = Literature data available in: Landolt A.U. & Uomoto A.K. 2007AJ....133..768L, CALSPEC ltt9491_002 14 = Literature data available in: Landolt A.U. & Uomoto A.K. 2007AJ....133..768L, CALSPEC feige110_stisnic_008 15 = Literature data available in: Landolt A.U. & Uomoto A.K. 2007AJ....133..768L, CALSPEC agk_81d266_stisnic_007 16 = Literature data available in: Landolt A.U. & Uomoto A.K. 2007AJ....133..768L, CALSPEC feige67_002 17 = Literature data available in: Landolt A.U. 1983AJ.....88..439L 18 = Literature data available in: Landolt A.U. 2009AJ....137.4186L 19 = Literature data available in: CALSPEC 1743045_mod_003 20 = Literature data available in: CALSPEC 1805292_mod_003 21 = Literature data available in: CALSPEC 1812095_mod_003 22 = Literature data available in: CALSPEC p041c_mod_003 23 = Literature data available in: Bohlin R.C. Landolt A.U. 2015AJ....149..122B, CALSPEC p177d_mod_003 24 = Literature data available in: Bohlin R.C. Landolt A.U. 2015AJ....149..122B, CALSPEC p330e_mod_004 25 = Literature data available in: CALSPEC kf08t3 mod 002.fits 26 = Literature data available in: CALSPEC kf06t2_mod_004 27 = Literature data available in: CALSPEC gj7541a_mod_001 28 = Literature data available in: Landolt A.U. 2013AJ....146..131L, Clem J.L. & Landolt A.U. 2016AJ....152...91C 29 = Literature data available in: Landolt A.U. 2009AJ....137.4186L, Clem J.L. & Landolt A.U. 2013AJ....146...88C 30 = Literature data available in: Landolt A.U. & Uomoto A.K. 2007AJ....133..768L 31 = Literature data available in: Landolt A.U. 2007AJ....133.2502L, Clem J.L. & Landolt A.U. 2013AJ....146...88C 32 = Misidentified with WD 1211-169 in literature and in Pancino et al. 2012MNRAS.426.1767P 33 = Candidate binary star (Hoard et al. 2007AJ....134...26H) 34 = Literature data available in: Landolt A.U. 2013AJ....146..131L 35 = Coordinates from The USNO-B1.0 Catalog (Monet et al. 2003AJ....125..984M, Cat. I/284), included after Pancino et al. 2012MNRAS.426.1767P publication 36 = Coordinates from SDSS DR7 (Abazajian K.N et al. 2009ApJS..182..543A), included after Pancino et al. 2012MNRAS.426.1767P publication -------------------------------------------------------------------------------- Acknowledgements: Giuseppe Altavilla, giuseppe.altavilla(at)inaf.it References: Pancino et al., Paper I 2012MNRAS.426.1767P, Cat. J/MNRAS/426/1767 Altavilla et al., Paper II 2015AN....336..515A Marinoni et al., Paper III 2016MNRAS.462.3616M, Cat. J/MNRAS/462/3616 ================================================================================ (End) G. Altavilla [INAF-OAR, SSDC-ASI, Italy], P. Vannier [CDS] 18-Jan-2021