J/MNRAS/454/507 Short-period var. stars OmegaWhite survey (Macfarlane+, 2015) ================================================================================ The OmegaWhite survey for short-period variable stars. I. Overview and first results. Macfarlane S.A., Toma R., Ramsay G., Groot P.J., Woudt P.A., Drew J.E., Barentsen G., Eisloffel J. =2015MNRAS.454..507M (SIMBAD/NED BibCode) ================================================================================ ADC_Keywords: Surveys ; Milky Way ; Stars, variable ; Photometry Keywords: methods: data analysis - methods: observational - techniques: photometric - surveys - binaries: close - Galaxy: bulge Abstract: We present the goals, strategy and first results of the OmegaWhite survey: a wide-field high-cadence g-band synoptic survey which aims to unveil the Galactic population of short-period variable stars (with periods <80min), including ultracompact binary star systems and stellar pulsators. The ultimate goal of OmegaWhite is to cover 400deg^2^ along the Galactic plane reaching a depth of g=21.5mag (10{sigma}), using OmegaCam on the VLT Survey Telescope (VST). The fields are selected to overlap with surveys such as the Galactic Bulge Survey and the VST Photometric H{alpha} Survey of the Southern Galactic Plane for multiband colour information. Each field is observed using 38 exposures of 39s each, with a median cadence of ~2.7min for a total duration of two hours. Within an initial 26deg^2^, we have extracted the light curves of 1.6 million stars, and have identified 613 variable candidates which satisfy our selection criteria. Furthermore, we present the light curves and statistical properties of 20 sources which have the highest likelihood of being variable stars. One of these candidates exhibits the colours and light-curve properties typically associated with ultracompact AM CVn binaries, although its spectrum exhibits weak Balmer absorption lines and is thus not likely to be such a binary system. We also present follow-up spectroscopy of five other variable candidates, which identifies them as likely low-amplitude {delta} Sct pulsating stars. Description: OmegaWhite observations are taken in g band using the wide-field instrument OmegaCAM on the VST. The VST is a 2.65-m wide-field survey telescope situated at the ESO Paranal Observatory in Northern Chile. The sole instrument on the telescope, OmegaCAM is a 16kx16k imaging camera, covering one square degree with 32 CCDs (each 2kx4k) at a plate scale of 0.216arcsec/pix. File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file tablea2.dat 82 613 Parameters of the 613 variable candidates (selected using n=15) -------------------------------------------------------------------------------- See also: J/MNRAS/429/385 : Short-period variables near Galactic Centre (Matsunaga+ 2013) Byte-by-byte Description of file: tablea2.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 2 A2 --- --- [OW] 4- 22 A19 --- OW OW designation (JHHMMSS.ss+DDMMSS.s) 24- 25 I2 h RAh Right ascension (J2000) 27- 28 I2 min RAm Right ascension (J2000) 30- 34 F5.2 s RAs Right ascension (J2000) 36 A1 --- DE- Declination sign (J2000) 37- 38 I2 deg DEd Declination (J2000) 40- 41 I2 arcmin DEm Declination (J2000) 43- 46 F4.1 arcsec DEs Declination (J2000) 48- 53 F6.2 min PLS Lomb-Scargle period of the highest peak in the periodogram 55- 59 F5.2 [-] log10(FAP) False alarm probability (FAP) of the highest peak in the periodogram 61- 65 F5.2 mag OWgmag OW calibrated g-band magnitude 67- 71 F5.3 mag e_OWgmag rms uncertainty on OWgmag 73- 76 F4.2 mag g-r ? VPHAS+ g-r colour index 78- 82 F5.2 mag u-g ? VPHAS+ u-g colour index -------------------------------------------------------------------------------- History: From electronic version of the journal ================================================================================ (End) Patricia Vannier [CDS] 24-Jun-2016