What a late afternoon and night I had last Wednesday 25th March in my back garden!
We seem to have plenty of clear skies over Ireland right now.
I had set up my William Optics 158 mm F/7 apochromatic refractor and the usual WO 70 mm small apo at about 5 pm. Temperatures ranged from 9 to 4 degrees Celsius as the night wore on. There was no wind at all.
www.stelledoppie.it provides the figures for the doubles and triples.
1. I soon found orange Pollux and white Castor through my William Optics 70 mm small apo at 11X. Both stars were still invisible at 7 pm with my unaided eyes. In the main scope, I had that wonderful little black gap between A and B of Castor at 40X. Magnificent! Magnitudes: A = 1.9. B = 3. Sep = 5.4" and widening. PA = 52 degrees and lessening.
2. Where else was I going to go next? Only to Cancer. I soon found M44 in the 70 mm. I could barely see the open star cluster there and then. But it looked good at 40X in the main scope.
3. But what a momentous occasion was to occur next. I found Zeta Cancri (Tegmine) as a double star at 40X in the main scope. There are A and C components of course. But at 112X the scope was trying hard to split A and B. Then real personal history was made when I could see A and B split at 140X. Normally I require 167X or even 225X. The reason was the sky had not darkened enough; and that's why I was seeing all 3 stars cleanly separated at 140X. Still I was so full of joy swapping eyepieces to fully check I was not seeing things. For the record the magnitudes are: A = 5.3. B = 6.3. C = 5.9. Sep's = 1.14" and narrowing and 5.9". PA's = 5.2 degrees and lessening and 64 degrees. When will I do this feat again?
4. After dinner I headed north to Iota Cancri. I distinctly remember the late Sir Patrick Moore discussing this true binary on The Sky at Night TV show many years ago. He was very much charmed by it and rightly so. Magnitudes: A = 4.1. B = 6. Sep = 30.7". That's slightly more than Albireo. PA = 308 degrees. The spectral classes are G8 and A5. In my 158 mm apo A is strong yellow with a slight orange tint. B is a decent blue. At 40X the 2 stars have a very good gap in between. At 112X the gap is considerably wider of course. But the colours are much more vivid and are something to behold. It's a good double star for beginners.
5. Very near Iota Cnc we have a charming true binary called Stf 1266. It is a true binary. Magnitudes: A = 8.8. B = 10. Sep = 23.4". PA = 65 degrees. Barely visible and split at 40X. I noticed both stars are yellow-white particularly the brighter one at 112X and 140X.
6. I have an unusual designation for you next: CBL 32 which is a true binary. A = 7.4. B = 10.7. Sep = 41". PA = 174 degrees. I could see B at 40X. But 112X was much better. CBL refers to Roberto Caballero. I don't appear to have any information regarding him other then he is Spanish. Perhaps he is alive and well today. Could someone verify? He definitely was in 2015.
7. 57 Cancri is a glorious true binary. Magnitudes: A = 6.1. B = 6.4. Sep = 1.6". PA = 309 degrees. 10 years ago in 2010 I was in the Sugarloaf Car Park. My William Optics 158 mm apochromatic refractor was very new at the time. I sought out 57 Cnc using a very large Sky and Telescope Atlas and, after a very long time searching, I found this brilliant double star. I believe I cheered on that first night ( I had no Guide 9.1 DVD). 6 months later my wife and I were in French Polynesia to observe my 6th Total Solar Eclipse. The great TV astronomer Heather Couper was with us. I talked to her about 57 Cnc and how I greatly admired the colour of both stars: Yellow-orange. Heather Couper died 1 month ago at the age of 70. So I had a very great desire to revisit this stunning binary. This time I successfully split it at 140X. It truly is a wondrous sight. Please do check it out. You will be spoiling yourself! It also looks very good at 167X and higher. I'm sorry Heather is no longer with us.
8. 66 Cancri is a very nice double too. But it is optical. You won't think that when you view it. Magnitudes: A = 6. B = 8.6. Sep = 4.4". PA = 137 degrees. A is white. B is slight blue. I had no desire to go higher than 112X. The double star is simply stunning at that power.
9. Sigma 3 or 64 Cancri is not a particularly stunning triple star. It is an uncertain triple after all. Magnitudes: A = 5.3. B = 9. C = 10.1. Sep's = 90.3" & 160". PA's = 294 and 184 degrees. Very sprawled out at 40X and 112X. A is a reasonable yellow. B and C are slight yellow.
10. AG 159 is an optical double. Magnitudes: A = 10.8. B = 10.8 also. Sep = 6.8". PA = 101 degrees. So both stars very dim and very slightly yellow . I required 112X to see the 2 stars split. But I must say I did find it attractive in its own way.
11. Stf 1288 is another optical double. Magnitudes: A = 10.2. B = 10.2 also. Sep = 7.7". PA = 259 degrees. It is slightly brighter alright than AG 159. And it looked very good at 112X. No need to go higher.
There are some more doubles in Cancer the Crab which I was not successful in splitting on this night. Therefore I will return to this extraordinary constellation soon.
Thank you for reading.
Comments are always welcome.