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Keywords:

  • astronomical data bases: miscellaneous;
  • surveys;
  • stars: variables: RR Lyrae;
  • Galaxy: stellar content;
  • Galaxy: structure

ABSTRACT

We present results for the QUEST RR Lyrae Survey at low Galactic latitude, conducted entirely with observations obtained with the QUEST mosaic camera and the 1.0/1.5-m Jürgen Stock Schmidt telescope at the National Observatory of Venezuela. The survey spans an area of 476 deg2 on the sky, with multi-epoch observations in the V, R and I photometric bands for 6.5 × 106 stars in the Galactic latitude range −30° ≤ b ≤ +25°, in a direction close to the Galactic anticentre 190° ≤ l ≤ 230°. The variability survey has a typical number of 30 observations per object in V and I and ∼25 in R, with up to ∼120–150 epochs in V and I and up to ∼100 in R in the best sampled regions. The completeness magnitudes of the survey are V = R = 18.5 mag, and I = 18.0 mag. We identified 211 RR Lyrae stars, 160 bona fide stars of type ab and 51 candidates of type c, ours being the first deep RR Lyrae survey conducted at low Galactic latitude, in the Galactic disc. The completeness of the RR Lyrae survey was estimated in >rsim95 and ∼85 per cent for RRab and RRc stars, respectively. Photometric metallicities were computed based on the light curves and individual extinctions calculated from minimum light colours for each RRab star. Distances were obtained with typical errors ∼ 7 per cent. The RR Lyrae survey simultaneously spans a large range of heliocentric distances 0.5 ≤ Rhel(kpc) ≤ 40 and heights above the plane −15 ≤ z(kpc) ≤ +20, with well-known completeness across the survey area, making it an ideal set for studying the structure of the Galactic thick disc.