Photometry of Betelgeuse at daylight

In a backyard observatory in Mainz, Germany, several stars have been observed at daylight using a 250mm Newton telescope and a CCD camera. The sky background was measured on several days; values of 1.8 - 4.7 mag/arcsec2 were found at angles of 10°-100° distance to the Sun. Photometry of Betelgeuse was performed as a first attempt in 2020 with stacked images of Betelgeuse; it was improved in 2021 by using a neutral density filter (1 percent transmission) and measuring calibration and extinction coefficients on 4-8 bright reference stars. Photometry of Betelgeuse resulted in calculated errors of less than 0.05 mag from February to July 2021. It could be shown, that daylight observations of Betelgeuse can fill the observational gap with reliable magnitude data, when Betelgeuse is near to the Sun.