The Hungarian-made Automated Telescope Network (HATNet), consisting of 7 11.0cm telescopes located at Fred Lawrence Whipple Observatory (Arizona), Mauna Kea Observatory (Hawaii), and Wise Observatory (Israel).
Prior to 2007 September each telescope employed a 2K x 2K CCD and a Cousins I_C filter. The 2K x 2K CCDs covered an 8.2° x 8.2° field of view at a pixel scale of 14". After this date the telescopes were refitted with 4K x 4K CCDs and Cousins R_C filters. The new CCDs cover a 10.6° x 10.6° field of view at a pixel scale of 9".
The data for this survey comes from 72 HATNet fields with declinations between +15 degrees and +52 degrees. These fields are defined by dividing the sky into 838 7.5° x 7.5° tiles. The survey covers approximately 4000 square degrees, or roughly 10% of the sky.
Both aperture photometry (AP) and image subtraction photometry (ISM) have been used for reductions. Photometry is performed at the positions of 2MASS sources transformed to the image coordinate system. For each resulting light curve the median magnitude is fixed to the I_C or R_C magnitude of the source based on a transformation from the 2MASS J,H and K_S magnitudes. For the ISM reduction this magnitude is also used as the reference magnitude for each source in converting differential flux measurements into magnitudes. For each source, light curves are obtained using three separate apertures. The aperture radii used are 1.45, 1.95, and 2.35 pixels.
The calibrated light curves for each aperture are passed through two routines that remove systematic variations from the light curves that are not corrected in calibrating the ensemble. The first routine (EPD) decorrelates each light curve against a set of external parameters. After applying EPD, the light curves 4 Hartman et al. are then processed with the Trend-Filtering Algorithm (TFA) which decorrelates each light curve against a representative sample of other light curves from the field.
The data parameters fall into the following approximate ranges:
|HJD of the
|J 2MASS magnitude||2.735||13.577|
|H 2MASS magnitude||2.735||12.967|
|K 2MASS magnitude||2.636||12.812|
|B Johnson magnitude||2.780||99.990|
|V Johnson magnitude||2.870||17.870|
|I Cousins magnitude||2.880||99.990|
|Total number of stars||-||2656|
|Number of epochs||1087||11601|
|HATNet summary file||IPAC ASCII format table|
|HATNet light curves||Download scripts|