OPHIUCHUS 
(June, July, August schedule)

     Ophiuchus constellation is summer constellation and it is in best position for evening observing in July when it is on the southern sky. We will observe it in June when it is on the southeastern sky, in July when it is in best position for observing and it is on the southern sky and in August when it is on the southwestern sky.

Double and multiple stars

     36 Ophiuchi - This star in reality is triple star system. It is very close to the Earth, about 20 light years away. The first two components are twin main sequence stars both with apparent visual magnitude on the sky 5.1. They are smaller and cooler than our Sun, with each 0.85 of the mass of our Sun and 0.85 of the Sun diameter and surface temperature about 4,900 K. They are separated on the sky about 5 arc seconds. Their orbital period is about 600 years.
     The third component is similar main sequence star with the first two components, only a bit smaller and cooler. Its apparent visual magnitude on the sky is 6.5. Its mass and diameter are about 70% of our Sun and its surface temperature is about 4,500 K. It is separated from the first pair about 730 arc seconds or 12 arc minutes on the sky. All three components should have yellow-orange color when viewed in a telescope.
     Omicron Ophiuchi
- The apparent visual magnitudes of the components are 5.2 and 6.2. The separation between these two stars on the sky is 10 arc seconds. The first component is about 350 light years away from the Earth, and the second component is about 500 light years away from the Earth.
     70 Ophiuchi
- It is a binary star system. The first component is a main sequence star with apparent visual magnitude on the sky 4.2 and smaller and cooler than our Sun. Its mass and diameter are only 90% of those of our Sun and its surface temperature is 5,300 K. 
     The second component is also main sequence star with apparent visual magnitude on the sky 6.2. it is smaller and cooler than the first component. Its mass and diameter are 70% of those of our Sun and its surface temperature is about 4,400 K.
     This binary star system is very close to our solar system - it is just 17 light years away.  The separation between the two components on the sky is 5 arc seconds. The orbital period of the system is about 80 years. In a telescope the stars should appear with yellow-orange and orange color.

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

     M46