We have measured the periods and light curves of 148 RR Lyrae variables from V=13.5 to 19.7 from the first 100 deg 2 of the QUEST RR Lyrae survey. Approximately 55% of these stars belong to the clump of stars detected earlier by the Sloan Digital Sky Survey. According to our measurements, this feature has ∼10 times the background density of halo stars, spans at least 37.5 • by 3.5 • in α and δ (≥ 30 by ≥ 3kpc), lies ∼ 50 kpc from the Sun, and has a depth along the line of sight of ∼ 5 kpc (1σ). These properties are consistent with the recent models that suggest it is a tidal stream from the Sgr dSph galaxy. The mean period of the type ab variables, 0.58 d , is also consistent. In addition, we have found two smaller over-densities in the halo, one of which may be related to the globular cluster Pal 5.

With the 1 m Schmidt telescope of the Llano del Hato Observatory and the QUEST CCD camera, 380 deg 2 of the sky have been surveyed for RR Lyrae variables in a band 2 .3 wide in declination (centered at = À1) and covering right ascensions from 4C1 to 6C1 and from 8C0 to 17C0. The bright limit (due to CCD saturation) and the faint limit are V $13.5 and $19.7, respectively, which correspond to $4 and $60 kpc from the Sun. We present a catalog of the positions, amplitudes, mean magnitudes, periods, and light curves of the 498 RR Lyrae variables that have been identified in this region of the sky. The majority of these stars (86%) are new discoveries. The completeness of the survey has been estimated from simulations that model the periods and light curves of real RR Lyrae variables and take into account the pattern of epochs of observation. While the completeness of the survey varies with apparent magnitude and with position, almost everywhere in the surveyed region it is quite high (>80%) for the type ab RR Lyrae variables and between 30% and 90% for the lowamplitude type c variables.

We present variability and multiwavelength photometric information for the 933 known quasars in the QUEST Variability Survey. These quasars are grouped into variable and nonvariable populations based on measured variability confidence levels. In a time-limited synoptic survey, we detect an anticorrelation between redshift and the likelihood of variability. Our comparison of variability likelihood to radio, IR, and X-ray data is consistent with earlier quasar studies. Using already known quasars as a template, we introduce a light-curve morphology algorithm that provides an efficient method for discriminating variable quasars from periodic variable objects in the absence of spectroscopic information. The establishment of statistically robust trends and efficient nonspectroscopic selection algorithms will aid in quasar identification and categorization in upcoming massive synoptic surveys. Finally, we report on three interesting variable quasars, including variability confirmation of the BL Lac candidate PKS 1222+037.