CORONA BOREALIS 
(May, June, July, August, September schedule)

     Corona Borealis is spring-summer constellation and it is in best position for evening observing in June when it is close to the zenith. We will observe it in May when it is high on the eastern sky, in June when it is in best position for observing and it is close to the zenith, in July when it is high on the southwestern sky, in August when it is on the western sky and in September when it is low on the western sky.

Double and multiple stars

     Zeta Coronae Borealis - The combined visual magnitude of this binary star system is 4.6. The brighter component has apparent visual magnitude on the sky 5.0. The dimmer component has apparent visual magnitude on the sky 5.9. Both components are about 500 light years away from the Earth. Their separation on the sky is 6 arc seconds. Both stars are similar main sequence stars and with bigger mass, diameter and temperature than our Sun. Given their true separation in the space, their orbital period is probably several thousand years. It is known that the brightest component by itself is multiple star system (maybe four stars) in close orbit.
     Sigma Coronae Borealis - This star is triple star system in reality. The combined visual magnitude on the sky of this system viewed as a single star is 5.3. It is about 70 light years away from the Earth. The brighter component has visual magnitude 5.6. The dimmer component has visual magnitude 6.5 and it is separated 7 arc seconds from the brightest component. The orbital period of these two components is about 800 years. The brighter component is in fact spectroscopic binary star system with components in a very close orbit. They are main sequence stars only several percent more massive and bigger than our Sun - almost like twins to our Sun. The dimmer component is also main sequence star yellow dwarf and again is twin of our Sun - have same mass, diameter and surface temperature. That is how our own Sun will look if we place it about 70 light years away from the Earth.

Deep sky objects
(will be observed only from dark location outside of the city)

     M46