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Appendix A: A new eclipsing variable

A star in the WASP-3 field (UCAC3 , , epoch 2000.0; Zacharias et al. 2010), initially chosen as reference star, was found to be variable and was excluded from the reference list. A complete light curve of this variable was assembled by registering the magnitudes on the N1-2 and N4-N6 frames on a common zero point (Fig. A.1, upper panel). When folded on the P ≃ 0.3524 day peak detected in the Lomb-Scargle periodogram, the binned curve shows a periodical pattern with equal maxima and slightly different minima, typical of contact eclipsing binaries (W UMa-type; Fig. A.1, lower panel). We derived the following ephemeris, setting Φ = 0 at the phase of primary minimum and estimating uncertainties through a bootstrapping algorithm: (A.1)This variable star appears to be unpublished, and we submitted it to the International Variable Star Index (identifier: VSX J183407.3+353859). Colors from catalog magnitudes: V = 15.63, R = 14.99 (NOMAD; Zacharias et al. 2004), J = 14.64, H = 14.34, K_s = 14.21 (2MASS; Skrutskie et al. 2006), and proper motions μ_αcosδ =  −32 mas/yr, μ_δ = 19 mas/yr (UCAC3) suggest that this object could be a binary with both components of late-G spectral type.

	Fig. A.1 Light curve of a previously unreported R ~ 15 variable star in the WASP-3 field, classified as a contact eclipsing binary (see text for details). Top panel: unbinned data points folded on the best-fit period P = 0.353626 days. Different nights are coded in different colors. Bottom panel: same as above, binned on 0.02 intervals in phase.
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