HD 209458

HD 209458 is an 8th magnitude star in the constellation Pegasus. It is very similar to our Sun, and it is classified as a yellow dwarf (spectral class G0 V). The star is easily visible With good binoculars or small telescope.

Essential Details

Star Designation(s)

TYC 3198-1634-1 (TYC is also known as the Guide Star Catalog GSC)


J2000 RA:22h 03m 10.7723s DEC:+18° 53′ 03.548″

Magnitude (Vmag)


Expected variation



3.524748595 days


The observations below were obtained on 2009 Aug 31 by carrying out time series photometry using a C9.25 SCT @ f10 with a MX916 camera, ‘V’ filter and 10 sec exposures. The ‘V’ filter in this instance was only used because the target star is so bright for CCD work. The conditions (typically) were less than ideal with intermittent cloud and a long stretch of cloud cover interfering with the observations. The top plot shows all of the data obtained. The next set is the same data but with all of the scatter removed. The bottom plot is this data average every five data points. The dip due to the transit can be seen in this plot.