This week we have a look at a long term variable star in the P Cyg target field of HOYS. The star in question is V434Cyg, which is classified as a variable star of Mira type. Hence, this is a pulsating giant star, with a period of about 294 days. The amplitude of variation is about three magnitudes in the I-band (shown in the image) and slightly larger at the shorter wavelengths.

In the light curve there are a few outlying data points. These (especially the fainter ones) are caused by the very crowded field – the star is only 1.5 degrees away from the Galactic Plane. Hence, in high resolution images a large number of fainter stars are picked up in the vicinity of the star, which are then wrongly matched by the automatic routine as belonging to the brighter star. Some of the ‘brighter’ outliers are caused by observations with slightly different I-Band filters than our reference image. These off-sets will be corrected by our colour correction procedure, should we analyse this data for a publication.