Data Reduction And Sample Analysis Based On Observations By TNT

Supernova is one of the most energetic phenomenon in the cosmos.One of its observational property,light curve of supernova is important for studies of cosmology,physics of supernova,stellar evolution and so on.Requiring large samples of light curves of supernovae are especially important for those studies.This paper will introduce photometry monitoring of supernovae using TsinghuaNAOC Telescope(TNT)and related data reduction and analysis.From the end of October 2004 to December 2016,we monitored 398 supernovae using TNT,required 36647 images with a total exposure time of 3914 hours.To reduce these data,we have developed a pipeline,named ZrutyPhot,which have implemented functions including astrometrical calibration,template subtraction,photometry and flux calibration for images of TNT.We have used ZrutyPhot to reduce the images of supernovae and acquired a sample of light curves of 201 supernovae.Type Ia,Ib/c or II,all supernovae in the sample have a redshift no more than 0.102.The sample contains light curve data points of a total number of 18108,with a band coverage of U BV RI.We have used SALT2 to fit light curves of type Ia supernovae in the sample and obtained their basic parameters of light curve,like peak magnitude and its epoch,shape parameters and color.Using these parameters,we have constructed a Hubble diagram containing 84 type Ia supernovae.Through comparison and analysis,we find that our result is consistent with the result of SDSS-II/SNLS3 Joint Light-Curve Analysis,while the scatter of our result is slightly larger than theirs.Using by-product of data reduction,we have briefly analyzed some observing conditions of Xinglong Station,including seeing,night sky brightness and atmospheric extinction coefficients.The analysis results are consistent with previous works of others and showing these conditions were changed little for the past few years.