Hello everyone.
On the evening before my 60th birthday, I set up up my William Optics 158 mm F/7 apochromatic refractor and its accompanying WO 70 mm F/6 small apo in my back garden.
1. I searched diligently for the razor sharp 3.9% illuminated crescent Moon low in the northwestern sky. At the time Luna was of -5.7 in magnitude. Its distance was about 387,000 kms from Earth. And its angular diameter was 30.8'. Initially many clouds were passing by in that area of the sky. But joy was to be had when I observed our Moon at 11X in the small apo as a very faint crescent. In the main refractor at a mere 40X, I could make out 1 large crater and some very small ones along the extremely narrow terminator. I have since checked that the large crater must have been Petavius. Of course there was no sign of its marvellous rille. But I am thoroughly amazed I could see any detail at all on our nearest neighbour!
2.I then set out to observe both Venus and Mercury. I experienced great joy when Venus "popped" into view through various gaps between the mischievous clouds as a extremely thin crescent. The 3.6% illuminated crescent was, at the time, 45,435,000 kms from Earth and her magnitude was -4.2. That's quite a bit fainter than -4.7 earlier during the month of May. Her angular diameter was very large at 54.9". I only used my 28 mm 2" eyepiece which gives me 40X on her. The seeing was very bad with much shimmering even at that power. Still it was a real pleasure to observe our nearest neighbouring planet one more before she leaves our evening skies. I promise I will try to continue to observe Venus over the coming evenings should the skies remain relatively clear.
3.I was not expecting to observe any detail with regards to Mercury. The Messenger's distance was 155,279,000 kms from us. Its magnitude was -0.4 and its angular diameter was minuscule at 6.5". But I was pleased to notice its 62% illumination using my Pentax 10 mm eyepiece which yields 112X. It definitely had a gibbous phase alright. Because of the shimmering conditions Mercury has flashing all sorts of colours. But I was happy making out its gibbous phase at some vital moments.
I only have 3 doubles which I have never observed before that I wish to share with you all. Each of them were found within the boundaries of Corona Borealis.
Before I start I should also say I had a very successful split of Izar and Castor at 112X. As a result I knew I was going to have a good night of splitting doubles.
All figures are from
www.stelledoppie.it
4. Struve (STF) 1935 may be an uncertain double but it is a very fine spectacle. Magnitudes: A = 9.9. B = 10.2. Sep = 8.6". PA = 289 degrees. I had the slightest split at 40X. But from 112X, 140X and 167X, I kept thinking B had an orange hue. Other observers might see it differently - and that's fine. I thought A was white.
5. STF 1941 stands alone as my favourite new double of the night. Magnitudes: A = 9.7. B = 9.8. Sep = 1.4". PA = 289 degrees. As soon as I had noted this uncertain binary before my evening commenced, I knew I was going to be in for a real treat! I could see the 2 suns touching at 112X. This was followed by a smidgen of a black gap between the 2 stars at 140X. At 167X I figured both stars have the slightest of a yellow-white hue.
6. Finally, as midnight drew near, I observed a true binary called GRV 903. Magnitudes: A = 9.1. B = 11.1. Sep = 69.2". PA = 243 degrees. With that wide separation I had no difficulties seeing A & B split at 40X of course. But the spectral classes are A = K2. B = K7. So I knew I had to go up in magnification. At 112X, 140X and 167X I could easily see A was orange and B was one of those enigmatic almond brown stars. Sweet! GRV stands for John Greaves. I'm sorry it has not been possible to discover when he lived.
I hope to see more doubles in Corona Borealis.
It most certainly is a very fine constellation for these great stars.
I have 2 carbon stars for you. Both are within the boundaries of Corona Borealis.
7. Much to my embarrassment I have never observed in my entire life the variable star R Coronae Borealis. High time to put that right!
Also much to my surprise I never realised that it is a carbon star - albeit not a very obvious one.
On the famous website
www.aavso.org
the good people there say its spectral class of C0. So it must be a very hot star.
For beginners I would like to share what most folk have discovered.
On having done some further research by reading Robert Burnham's Celestial Handbook Volume 2, I discovered that there is up to 67% carbon on the star's atmosphere.
That is official enough for me. It's a carbon star. So off I went to find it.
As the star is bright in magnitude at about 6.0 or a little bit fainter, I had no problems finding it at 11X through my William Optics 70 mm F/6 small apochromatic refractor.
R Coronae is directly north of Delta Crb by a short distance. I did find it has an orange hue which is not strong at all even at magnifications 112X, 140X, 167X and 225X. The higher I went the more distinctive the colour became though - which is normal.
However it still counts as a carbon star even though Burnham says that the authorities in the past classify it as type F7, G, or even M.
The star has had a very colourful history because its sudden decline of its magnitude since it was first observed by Edward Pigott who lived from 1753 to 1825. He discovered R Crb in 1795.
Burnham states that it is a very remarkable variable star. It stays at maximum magnitude throughout most of its cycle. But then it suddenly begins to fade and in a few weeks and it could drop down to magnitude 15. Indeed it has been known to fluctuate erratically during the last 150 years.
R Crb acts like a reverse nova.
A dark soot cloud appears to be the most popular theory as to what causes the major dimming of the star.
The cloud covers the star causing it to dim.
So there must be all sorts of strange goings on within R Crb.
That's why it has had over 300,000 observers throughout its history on the AAVSO website.
8. My 2nd carbon star on Corona Borealis is V Coronae Borealis. Its spectral class is C6 or N2. As midnight occurred it meant I could start my 60th birthday celebrations.I was observing V Crb at just 40X through my main 158 mm refractor at the time.
Then my smartphone had to be answered.
A good friend wanted to wish me Happy Birthday which was fair enough.
But I had enough time to see that V Crb has a fairly decent orange colour.
I did observe this carbon star back in May 2002. So it was nice to find it once again.
As far as I know, there are no more carbon stars in this compact constellation.
R Coronae Borealis is my 91st carbon star.
9 to go to 100!
By the way I am counting IY Comae Berenices as a carbon star.On Simbad its spectral class is C.
Thank you for reading this report.
Clear skies from Birthday Boy, Aubrey.
  