The Absolute Flux Calibration of the UVBY Photometric System

1996 ◽  
Vol 108 ◽  
pp. 90 ◽  
Author(s):  
Juan Fabregat ◽  
Pablo Reig

Author(s):  
J. B. Foster ◽  
J. M. Rathborne ◽  
P. Sanhueza ◽  
C. Claysmith ◽  
J. S. Whitaker ◽  
...  

AbstractWe characterise the Millimetre Astronomy Legacy Team 90 GHz Survey (MALT90) and the Mopra telescope at 90 GHz. We combine repeated position-switched observations of the source G300.968+01.145 with a map of the same source in order to estimate the pointing reliability of the position-switched observations and, by extension, the MALT90 survey; we estimate our pointing uncertainty to be 8 arcsec. We model the two strongest sources of systematic gain variability as functions of elevation and time-of-day and quantify the remaining absolute flux uncertainty. Corrections based on these two variables reduce the scatter in repeated observations from 12%–25% down to 10%–17%. We find no evidence for intrinsic source variability in G300.968+01.145. For certain applications, the corrections described herein will be integral for improving the absolute flux calibration of MALT90 maps and other observations using the Mopra telescope at 90 GHz.





1990 ◽  
Vol 122 ◽  
pp. 159-160 ◽  
Author(s):  
J. Mikołajewska ◽  
M. Mikołajewski

PW Vul (Nowa Vul 1984 #1) was a slow classical nova which began its outburst in July 1984 and reached optical maximum in the first week of August 1984. Eight low dispersion spectra (160 A/mm) in the blue spectral range (λλ3400-5100 A) were secured between October 1984 and July 1985, with the CCS spectrograph equipped with 3.5 arcsec aperture image slicer and mounted on 90 cm Schmidt-Cassegrain telescope at Toruń Observatory. Kodak IIa-O plates were used. In addition two moderate dispersion (40 A/mm) spectra in the Hγ-Hβ range were obtained on 28 October and 3 November 1984, using the same instrumentation. Standard stars were observed on each night to remove the influence of spectral sensitivity of the photographic emulssion and atmospheric extinction. The calibration of the absolute flux scale was performed by comparing synthetic B magnitudes calculated from our spectra with published B photometry of PW Vul (Voloshina 1985, Noskova et al. 1985, Kolotilov and Noskova 1986). The accuracy of the flux calibration is ±0.1 mag.



Author(s):  
G Altavilla ◽  
S Marinoni ◽  
E Pancino ◽  
S Galleti ◽  
M Bellazzini ◽  
...  

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 ten-year 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 zeropoint 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.



1976 ◽  
Vol 72 ◽  
pp. 75-78
Author(s):  
M. Grenon

The Geneva photometric system has been calibrated in terms of [M/H], θeff, Mv in the spectral range F5 to K4. As the spectral type is a datum generally available, we derive empirical relations showing the coupling of θeff and [M/H] at given spectral type and luminosity class. Similar relations are offered for the absolute magnitudes and provide a more accurate means for deriving spectroscopic parallaxes. Systematic effects on the estimation of the luminosity class are also shown.



JETP Letters ◽  
2008 ◽  
Vol 88 (7) ◽  
pp. 411-413 ◽  
Author(s):  
G. F. Krymsky ◽  
V. G. Grigor’ev ◽  
S. A. Starodubtsev


1985 ◽  
Vol 111 ◽  
pp. 479-483
Author(s):  
R. S. Polidan ◽  
J. B. Holberg

Recent results have shed new light on the status of the calibration of absolute stellar fluxes between 912 and 1200 Å. Observations of hot white dwarfs, subdwarfs and planetary nebula nuclei with the Voyager ultraviolet spectrometers provide evidence that the current calibration agrees very well with extrapolations of IUE energy distributions shortwards of 1200 Å. Voyager observations of main sequence B-stars used as flux calibration sources have revealed that many are variable in brightness in the 912–1200 Å region. We conclude there is no current observational motivation for any revision of the 912 to 1200 Å calibration described by Holberg et al. (1982).



1980 ◽  
Vol 88 ◽  
pp. 549-553
Author(s):  
R. Faraggiana

IUE spectra of VV Cep have been obtained in 1978 and 1979 during the chromospheric phase of the eclipse. The profiles of the Mg II resonance lines differ from one another and this peculiarity, common to other M type supergiants, is examined. The value of Mv derived from the extension of the Wilson and Bappu relation to Mg II lines is compared with other determinations. The variation of the absolute flux in the 1200-2000 Å range is presented.



2011 ◽  
Vol 141 (5) ◽  
pp. 173 ◽  
Author(s):  
R. C. Bohlin ◽  
K. D. Gordon ◽  
G. H. Rieke ◽  
D. Ardila ◽  
S. Carey ◽  
...  


1975 ◽  
Vol 80 ◽  
pp. 83 ◽  
Author(s):  
M. R. Viner


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