Theta (θ) Virginis (51 Virginis) (Σ 1724) (AB is H III 50; AC is H VI 43)
HIP: 64238 SAO: 139189
RA: 13h 10m Dec: -05° 32′
Magnitudes AB: 4.4, 9.4 AC: 4.4, 10.4
Separation AB: 6.4″ AC: 71.1″
Position Angle AB: 342° (WDS 2012) AC: 300° (WDS 2002)
Distance: 125 Light Years
Spectral Classification: A0
As you can see on the chart above, it lies midway between Porrima and Spica, so it’s easy to locate. The first time I viewed it, there was so much haze in the air that the colors were a pale imitation of themselves. A couple of nights later, the haze was gone and I was thrilled to see that the colors had regained their luminous luster. The primary is a bright white, while the 9.4 magnitude secondary has a slight yellow glow to it.
I was back once more on June 5th, 2010 — and so was the harassing haze. In my 63mm Zeiss, “A” and “B” were easy to see, but “C” could only be glimpsed with averted vision at 53x. And, as is frequently the case when a lot of haze is present, increasing magnification only made it more difficult to see the fainter star because it also magnified the glare from the brighter ones. But I had the cure for that! I switched over to a 152mm f/8 refractor — and just like magic, all three were clearly visible at 76x and 98x.
If you can catch a night of good transparency, this triple star system is a very rewarding visual pleasure and offers quite a contrast with the much brighter Porrima to the west.