Viewing a second 'double double' and 'discovering' a third!

Seems I learn something new every night – and maybe discover something new to.

I always thought the Double Double was, well THE Double Double. I'm talking about the well-known – and challenging pair of double stars known as Epsilon Lyra. I check it frequently – gives me a quick idea of what seeing is like and how my scope is performing, and besides, I like it.

But I decided to prowl around the big cat tonight – Leo – and see what doubles were over his way. My guide is "double stars for small telescopes" by Sissy Haas. (Yes, she uses all lower case in the title.) Wonderful book, organized by constellation, so I flipped to Leo and checked off about eight of the best ones. Seeing turned out to be lousy and the full moon wasn't a big help, but I had a good time in mild spring weather and found a few gems.

What she calls "a double double" was near the end of the list and it looked quite easy and was – except it needs a wide field. I used a 25mm Sirius Plossl in the LX90 8-inch and the result is something close to a 40 minute field. When I asked the LX90 to go to the coordinates given (11'26.8" +03°01'), however, I only saw one of the pairs. I had to prowl around a bit to see the second one. But she's right – this is a cool combination and I suspect just about any scope would show it.

The first pair, called 83 Leonis, are fairly closely matched at 6.6 and 7.5 and widely separated - 28.6" – so there's no question of splitting them. The second pair, Tau Leonis, is off to the east and has about three times the separation. I didn't find them until I searched a bit, but the primary is Tau and at 5.1 should be visible to the naked eye in dark skies. The position angle for both pairs is just off of a north-south line, one a bit to the east and the other almost due north/south. The companion of the first pair looked reddish to me, the companion in the second pair bluish. The primaries were white. Real nice – as Haas says, "splendid double-double."

I'll rmember it, but I got a real surprise when I went to the next star on my list for the night, 93 Leonis (11h 48.0" + 20° 13'). When it came into view I saw a second pair just below. With 83 and Tau Leo, the separation was vastly different – the Tau pair is nearly three times the separation of the 83 Leo pair. In this case what I saw, in the same roughly 40-minute field, was 93 Leo with a comfortable separation of 74" and a second pair nearly due south of it with a similar separation! A second double double? Well, I mean a third? 93 Leo consists of a 4.6 and 9th magnitude stars. I would put this other pair at roughly 7 and 10. And while the position angle on 93 Leo is given as 387 degrees, I would guess on the second pair it was more like 30 degrees.

Hmmm…. Wonder what Starry Nights doftware shows? Ahhh – seems I was looking at HIP57529 which is listed as a multiple star! And yes, both 93 Leonis and HIP557529 fit very comfortably in the 25mm Plossl field. Here's what it looks like in Starry Nights. (And a good idea of what I saw/) Oh – and Starry Nights says the magnitude of this second pair are 7.3 and 9.8, so my guestimate of 7 and 10 was certainly in the ballpark. Do't you love it when the books and software confirm your guestimates at the eyepiece? I do. I mean, I think it's important to prepare well for an observing session – or at least have a rough plan. But it's even more fun to "discover" something, take notes, make a rough sketch, then be able to track it down when you come inside.

So that makes three double doubles and I'm sure there must be more. Funny. Haas didn’t mention this, though. Not as pretty as the one she does mention, but still worth a look.