Observations - 31/3/22

Hello, one and all. 

I set up my William Optics 158mm f/7 apochromatic refractor with my small William Optics 70mm f/6 apo attached to it in my back garden on Thursday 31st March 2022 and did quite a bit observing -  for nearly 3 hours in fact – from 8.40 to 11.30pm Local Time.
Each of these doubles are in Leo, and as ever, I used www.stelledoppie.it for the information including magnitudes, separations, position angles (PA), spectral classes and whether a particular double is true, optical or uncertain. In addition, my Robert Burnham Celestial Handbook Volume 2 points out if a double is a common proper motion pair (cpm).     
As I have mirror diagonals on both scopes, my north is up and my east is to the right. 
The air temperature was +1˚C and getting colder. The wind was non-existent. 

Having once again observed Regulus and Algieba, I had some success, but not with them all, with these doubles. 

1. 49 Leonis (STF 1450) is a most satisfying cpm double about 7 or 8˚ east of Regulus. Magnitudes: A = 5.8. B = 7.9. Sep = 2”. PA = 157˚. I have had success splitting this double in the past. And at 112x I had a clean split once again. I also slotted in my 140x eyepiece. Either magnification worked very well. The primary has a spectral class of A2 - so it was white alright. But I did notice a slight blueness to the secondary. Good start!

2. About 2˚ below 49 Leo is a very faint double called J 79 which I came across on Stelle Doppie. I have experienced unreliable magnitudes on Stelle Doppie with these Robert Jonckhèere (1888- 1974) doubles recently. But this one proved perfectly fine. Magnitudes: A = 9. B = 10.1. Sep = 1.4”. PA = 135˚. I could see there were 2 stars at 167x. But they were not separated. 225x and 280x did the job very nicely – both stars clearly visible and split. A has a spectral class of F8 and I could see a yellow-white tint. B was white. I had never even tried to seek out J 79 before and I’m very glad I have now. 49 Leonis is a John Flamsteed designation. He lived from 1646 to 1719. 

The rest of these doubles I have split before. 

3. STT 216 is a true binary. Magnitudes: A = 7.4. B = 10.3. Sep = 2.3”. PA = 228˚. I needed 140x to split this double. A definitely is G5 yellow. B is white and nearly 3 magnitudes fainter. It also looked good at 167x. STT stands for Otto Struve (1897-1963).  

4. STF 1413 is a true binary. Magnitudes: A = 9.8. B = 9.8. Sep = 1.8”. PA = 270˚. I had a super tight split at 112x. At 140x I could see that A is yellow (G0). These 2 splendidly dim stars are very beautiful as they sit side by side like 2 eyes. STF stands for Friedrich Georg Wilhelm Struve (1793-1864). 

5. STF 1417 is a cpm double. Magnitudes: A = 9.2. B = 9.3. Sep = 2.4”. PA = 78˚. Beautiful split at 112x. I didn’t bother going any higher. By the way, if you do wish to seek out STF 1417 you will see an unusually hued star called SAO 99022 immediately to its west. It has a K5 spectral class and I must say it has a reasonably intense orange colour. Its Johnson B-V colour is 1.033. It’s not a carbon star though.

6. STF 1399 is definitely one for binocular users. It’s a true binary with magnitudes: A = 7.7. B = 8.4. Sep = 30.2”. PA = 176˚. I could see the 2 stars at 11x with my small apo for sure. What lovely colours I got with my main scope. A is G0 yellow and B was blue.  

7. Omicron Leonis (Subra) is an optical double. Magnitudes: A = 5.8. B = 10.8. Sep = 96.2”. PA = 48˚. 40x was sufficient to see the secondary. The primary is a yellow-white star. The spectral classes are F6 and A1. So B is white.

8. I finish with a triple star that has 2 designations. The A and B are called STT 204; but A and C are called WAL 56. STT 204 is an uncertain double; but WAL 56 is a true double. However the whole system is a very nice triple star. All 3 stars cleanly separated at 112x and all 3 stars are white. WAL stands for the Swedish astronomer Ake Wallenquist who lived from 1904 to 1994.   

Sadly there was another triple star which just would not split for me this time – even though I had split at 280x and 320x about a year ago. The B and C of A 2367 proved very stubborn on this very clear Thursday night. For the record, the magnitudes are: A = 9.9. B = 10.8. C = 11.5. Sep’s = 60.8” and 1.6”. PA’s = 85˚ and 85˚. The only explanation I reckon I can give is that a lot of trees have been cut down in and around my garden, and as a result, my light pollution is now a lot worse. However I will always reminisce that I did split B and C in the past. A stands for Robert Aitken who lived from 1864 to 1951. Many of his doubles are notoriously difficult to split. 

And on that note, I wish you all clear skies from Aubrey.         

Hello Aubrey, 

Very many thanks for sharing your observations with us. It seems that you had a lovely night under the stars...three hours is some going! 

Out of interest, what's the longest amount of time you've spent out with your scope? 

Also, many thanks for bringing us the term ' common proper motion'. I must look it up. 

STF1399 and the triple with two designations sound like lovely objects.

Clear skies, 
Darren. 

Hello Darren. 

I did have a 4 hour observing session on 31st May 2020. 
The first hour was all about the Moon. 
And the 3 hours after dinner were all about doubles in Boötes and Corona Borealis - until midnight. 

During the two recent nights I have had in Leo my two favourite doubles are Algieba and 49 Leonis. 
But I do assure you I have more doubles to seek out in the same area west of Regulus. 
Whenever we get a clear night (perhaps at the weekend) I will report on some more. 

Clear skies from Aubrey.  

Fours hours : 0

WOW!!!!

Fair play Aubrey! 

Wishing you more clear skies so you can observe more of those double stars in Leo. 

Darren.