Observations - 5/08/22

Hello everyone.

As promised I set up my William Optics 158mm f/7 apochromatic refractor in my back garden on Friday night 6th August 2022. Mirror diagonals were used at all times. It turned out to be a very special observing session in Boӧtes. Sunset occurred at 21.13 local time. The slight breeze was decreasing as the 2.5 hours went by. Initially there was a lot of high cloud – especially in Boӧtes, but it was thinning as the minutes went by. I finished 15 minutes after midnight. 

1. It was not until 21.42 when I found Vega high up in the south.  Epsilon 1, 2 Lyrae were next. Both doubles split at 112x. Good start!

2. Polaris’ companion was seen at 40x and 112x. The companion was in the 9 o’clock position at 10pm. 

3. Mizar and Alcor were easily found as the sky was clearing. Mizar was cleanly split at 40x. 

4. Kappa and Iota Boӧtis came next. Both doubles split at 40x. 

5. One of those great amateur astronomers on www.cloudynights.com challenged me to have a second try at STF1863 which is near Kappa and Iota in Boӧtes. The last time I tried to split STF1863 my scope was in the Sugarloaf car park. No go that time and there was a breeze. But here I was on a completely calm night. It was the right time to have a second observation of this tight double. These are the figures from www.stelldoppie.it : Magnitudes: A = 7.7. B = 7.8. Sep = 0.648”. PA = 58.4˚. So this is the tightest true binary I have ever observed in my life. At 280x I could only see one single star. But at 320x I had the “rod” effect. The secondary is straight up from the primary; and of course the 2 stars are almost identical in magnitude. My final eyepiece is a Radian 3mm and it gives 374x. I can definitely say I could see 2 stars perfectly well, but there was no black gap between. However I was overjoyed at the whole experience. I called Valerie and she could see both stars okay. But again there was no black gap. So methinks I should consider an even more powerful eyepiece for these rare occasions. Can anyone give me advice as to what to buy? Please note I’m not a fan of the Barlow. Therefore I’m thinking of some 2.?mm eyepiece. This would give me over 400x. Perhaps 450x. Any ideas? Thank you.  

6. There was an uncertain double star nearby. It’s called A 1623. Magnitudes: A = 8.7. B = 11.2. Sep = 1.9”. PA = 241˚. What a nice double it is. The secondary was pointing straight down to the northwest horizon and seen at 167x and 225x.   

7. Finally I ended with the very well known triple star Mu Boӧtis. Its name is Alkalurops. It always gives great pleasure to see the 3 stars separated at 112x with my Pentax 10mm eyepiece. 

Clear skies from Aubrey.  

Hello Aubrey,

It was great to read that you managed to get a session in last Friday. Very well done on spitting STF1863 - what a tight double! 

What is the 'Rod Effect' - that's a new term for me.

Clear skies,

Darren.

Hello, Darren. 

I have to confess I didn't split STF1863. 
I almost did, but I had no black gap between the 2 stars. 
That's because amateur astronomers on Cloudy Nights use the rod-effect term.
You see the 2 stars appear as a vertical rod pointing to the northwestern horizon. 
If the 2 stars of STF1863 had been half a magnitude fainter I reckon I would have seen that elusive black piece of space in between. 
As it stands I could see the 2 stars okay. 
But to see them split I would require a higher magnification. 

Also I would say that your 10" Dobsonian would be more successful at separating STF1863.
In these cases aperture rules the night! 

Great to hear from you, Darren. 
Please fill us in with your observations from Friday night at the Sugarloaf. 

Clear skies from Aubrey. 

By the way, lads, I did estimate S Coronae Borealis' magnitude as +5.6 on Friday night with my William Optics 70mm f/6 small apo at 11x. It still is sporting a good strong orange colour. 

Best regards from Aubrey. 

Hi Aubrey,

My mistake...I thought once one sees the second star one splits it, but it makes sense that a gap needs to be seen to truly split a star...thanks for the clarification!

I didn't make it to the Sugarloaf last Friday because the tooth was acting up, and it got worse over the weekend. So much so, that I had it pulled about an hour ago!

And there's me thinking I'd be doing a spot of observing tonight. Instead I'll be taking an early night

I believe more clear spells are coming our way though - so all's not lost I suppose.

Clear skies,

Darren.

Hello Darren. 

I'm so glad you got that nasty tooth removed by your dentist. 
You are probably bleeding a bit today. 
But you will be okay by Thursday morning.

Best regards from Aubrey.