The Sloan Digital Sky Survey View of the Palomar-Green Bright Quasar Survey

Abstract

We investigate the extent to which the Palomar-Green (PG) Bright Quasar Survey (BQS) is complete and representative of the general quasar population by comparing with imaging and spectroscopy from the Sloan Digital Sky Survey. A comparison of SDSS and PG photometry of both stars and quasars reveals the need to apply a color and magnitude recalibration to the PG data. Using the SDSS photometric catalog, we define the PG's parent sample of objects that are not main-sequence stars and simulate the selection of objects from this parent sample using the PG photometric criteria and errors. This simulation shows that the effective U −B cut in the PG survey is U −B < −0.71, implying a color-related incompleteness. As the color distribution of bright quasars peaks near U −B = −0.7 and the 2-σ error in U −B is comparable to the full width of the color distribution of quasars, the color incompleteness of the BQS is approximately 50% and essentially random with respect to U −B color for z < 0.5. There is, however, a bias against bright quasars at 0.5 < z < 1, which is induced by the color-redshift relation of quasars (although quasars at z > 0.5 are inherently rare in bright surveys in any case). We find no evidence for any other systematic incompleteness when comparing the distributions in color, redshift, and FIRST radio properties of the BQS and a BQS-like subsample of the SDSS quasar sample. However, the application of a bright magnitude limit biases the BQS toward the inclusion of objects which are blue in g − i, in particular compared to the full range of g − i colors found among the i-band limited SDSS quasars, and even at i-band magnitudes comparable to those of the BQS objects.

The MUCHFUSS project – searching for hot subdwarf binaries with massive unseen companions

“…All spectra of point sources with colours u − g < 0.4 and g − r < 0.1 were selected. This colour criterion corresponds to a limit in the Johnson photometric system of U − B < −0.57 (Jester et al 2005), similar to the cut-off chosen by UV excess surveys, such as the Palomar Green survey (Green et al 1986). The corresponding effective temperature of a BHB star is 15 000 K (Castelli & Kurucz 2003), well below the observed range for sdB stars (>20 000 K).…”

“…The corresponding effective temperature of a BHB star is 15 000 K (Castelli & Kurucz 2003), well below the observed range for sdB stars (>20 000 K). The limit of g − r = +0.1 corresponds to B−V = +0.3 (Jester et al 2005). This ensures that sdBs in spectroscopic binaries are included if the dwarf companion is of spectral type F or later, e.g.…”

Classical T Tauri stars with VPHAS+ – I. H α andu-band accretion rates in the Lagoon Nebula M8

“…7. We converted Sung et al (2000) RI magnitudes to VPHAS+ r-band using the colour equations of Jester et al (2005). A significant fraction of VPHAS+ identified CTTS candidates are located at r > 17 mag, beyond the limiting magnitude of Sung et al (2000).…”

“…The systematic differences that would arise on adopting different stellar models are discussed in Section 4.6.1. The tracks and isochrones were converted from the luminosity-temperature plane to the colour-magnitude plane using the colour equations of Jester et al (2005). Fig.…”

Differential Rotation in Sun-like Stars from Surface Variability and Asteroseismology

“…The KIC provides g − r values that we converted to B − V using the relation B − V = 0.98 (g − r) + 0.22 given by Jester et al (2005) for stars with R-I color indices < 1.15. The B − V values are dereddened using the E (B − V) values from the KIC (see Brown et al 2011, for details on their derivation).…”