VISUAL AND PHOTOGRAPHIC OBSERVATIONS OF SUNSPOTS

Visual observations of sunspots have been made at the Smolyan Planetarium since 1986, photographic ones too.

1. Visual observations are made using combined methodology-plotting and eyepiece observations.

The plottings are made with a refracting telescope 60/600 on a circle 10 cm in diameter. On this image of the Sun is marked the position of every sunspot and its direction of motion. Every plot is accompained by the following data: universal time, date of observation, measure of visibility, which is made on the Kiepenheuer’s scale and observer’s name.

Eyepiece observations are made with a reflecting telescope Cassegrain 150/2250, type "Meniscas".

The application of this combined methodology impruves the observational efficacy of either method alone. Our regular observer Sijka Simeonova has a coefficient of observational efficacy k=0.96 for 1995.

Initial calculations of the acquired data include: the calculation of Wolf’s number for the visible disk; estimating northern, southern hemispheres and central zone of the Sun; and determination of the sunspot’s area.

Every month results are sent to SUNSPOT INDEX DATA CENTER in Brussels with wich we have been carrying on a collaboration since 1990.

2. The photographic observations of the Sun are made with a small format camera which is put in the general focus of the Cassegrain telescope 150/2250, type "Meniscas".