I set up my William Optics 158 mm F/7 apochromatic refractor and its accompanying finder scope which is a William Optics 70 mm F/6 small apo in their usual place in my back garden on Monday night 5th April 2021 for 2 hours exactly.
Sunset had occurred at 20.07 local time.
I started observing at 9 pm and finished at 11 pm.
It was very cold. The air temperatures went down from -1 to -3 degrees Celsius. The wind was noticeable at about 20 km/h.
I observed these 6 easy doubles which can be checked out on www.stelldoppie.it .
These first 4 doubles I have observed in the past.
1. How can anyone not start with Regulus? But you may find that Alpha Leonis is a true binary as somewhat surprising. That's because the 2 stars are widely separated no matter what magnification any of us use. Magnitudes: A = 1.4. B = 8.2. Separation (Sep) = 179.2". Position Angle (PA) = 304 degrees. As the night became darker, the B star was even visible in my William Optics 70 mm F/6 apo at a mere 11X. Regulus has a spectral class of B7. But I could see no colour whatsoever. Both stars look white to me in my main scope at 40X and 112X. B class stars are supposed to be blue.
2. This next double is by far the most famous in Leo. Algieba (Gamma Leonis) is a true binary and also known as STF 1424. Magnitudes: A = 2.4. B = 3.6. Sep = 4.7". PA = 126.6 degrees. Stunning sight at 112X as always. The 2 stars are of spectral class K. Therefore both stars should be orange - and indeed they are. I personally describe them as golden yellow.
3. Subra (Omicron Leonis) is an optical double. Magnitudes: A = 3.6. B = 10.8. Sep = 96.2". PA = 48 degrees. Plenty of dark space between the 2 stars - even at 40X. At 112X I could see that A is an F6 class yellow-white star. B is A1 class and is white.
4. 6 Leonis is a true binary which is also called SHJ 107. Magnitudes: A = 5.2. B = 9.3. Sep = 37.1". PA = 77 degrees. Very good split at 40X of course. But at 112X I could see A is of spectral class K3 and sure enough it is certainly orange. B is white. SHJ stands for 2 great astronomers from yesteryear: James South (1785-1867) and John Herschel (1792-1871) knew one another extremely well. They were both good friends and great observers of double stars.
These last 2 doubles I have never observed before. And what good and easy ones they are. Both were discovered by our most famous acquaintance Friedrich George Wilhelm Struve (1793-1864).
5. STF 1360 is a true binary. Magnitudes: A = 9. B = 8.9. Sep = 13.8". PA = 242 degrees. I had a delightful sight at 40X - even though both stars proved seriously faint. A is G class yellow and that was easy to see at 112X. B appeared white to me. I just couldn't notice any difference between their brightness. But I must say this double was well worth looking for.
6. To find my final double I thought I should simply take my time and star hop from the previous double STF 1360 and moving northwards by quite a number of degrees to reach STF 1364. I did find along the way an interesting asterism which I found to be very similar to a cross and is a reminder to me as to what Christ achieved by hanging on a real cross. This asterism had 3 stars going across its middle which reminded me of the 3 belt stars of Orion STF 1364 is a true binary. Magnitudes: A = 8.6. B = 9.7. Sep = 16.4". PA = 155 degrees. As it is a slightly wider double than STF 1360 I knew there would be no hassle in splitting it at 40X also. It was also very nice at 112X. Both stars were white to yours truly.
Then last night, I set up once again my William Optics 158 mm F/7 apochromatic refractor and its accompanying WO 70 mm F/6 small apo in my own back garden on Saturday 10th April 2021 for 1.5 hours between 9 and 10.30 pm local time.
Sunset occurred at 20.16 local time.
Thankfully the wind wasn't strong at all - about 7 km/h from the northeast.
The air temperature was very cold at -2 degrees Celsius.
Some passing clouds passed by now and again but they kept moving on.
I'm very much had planned to look for more doubles in Leo for this observing session.
And what a great time I had!
No less than 4 new doubles I successfully separated for the first time.
1. STT 216 is right next to the brighter 6.2 magnitude star 42 Leonis. The magnitudes of STT 216 are: A = 7.4. B = 10.3. Sep = 2.3". PA = 228 degrees. STT 216 is a true binary and I was thoroughly thrilled to see the very small dot of the secondary at a mere 112X right next to the primary in the correct position angle (PA). I was greatly surprised that even with a delta magnitude of 2.9 I could clearly see a tiny amount of black space between these 2 stars. The primary is G5 yellow. B is white. It also looked delightful at 140X. STT 216 was my new showpiece of the night for sure. STT stands for Otto Struve (1897-1963).
2. WAL 56 is a nice and easy true binary very near to Omicron Leonis. Magnitudes: A = 6.7. C = 10.7. Sep = 85.7". PA = 81 degrees. Very easy split at 40X of course with plenty of black space in between these 2 stars. WAL stands for Ake Wallenquist who was a well known Swedish astronomer and lived from 1904 to 1994. You may have noticed I used A and C for these. But what about the B star?
3. Well, the B star is part of the designation STT 204 which is an uncertain double. Magnitudes: A = 6.7. B = 10.7. Sep = 8.3". PA = 99 degrees. Of course the A star is the same star as the primary of WAL 56. But it took 112X to split STT 204 cleanly. However taking these WAL 56 and STT 204 together we have a rather nice triple star which my scope separated at 112X. And I highly recommend it to you.
4. STF (Struve) 1399 is a true binary a few degrees west of Gamma Leonis. Magnitudes: A = 7.7. B = 8.4. Sep = 30.2". PA = 176 degrees. Good clean split at 40X at first. At 112X I could see that A was G0 yellow. B was white. But wait a minute! I moved myself over to the WO 70 mm apo to discover there was a tiny section of black space between the 2 stars! I do keep a 28 mm 2 inch eyepiece in the small apo at all times. 11X is its magnification. This was, for sure, a super sight for yours truly. As north is up and the PA is at 176 degrees, the secondary was seen hanging straight down from the primary.
5. Lastly, I observed STTA 103 which is an optical double a very short distance from STF 1399. Magnitudes: A = 8.4. B = 9.6. Sep = 79.9". PA = 130 degrees. Not much to get excited about here. The secondary wasn't visible in the 70 mm apo. Therefore there was a good deal of separation at 40X between these 2 white stars in my main refractor. STTA stands for Otto Struve Supplement.
I do thank you for reading my latest report.
Comments, corrections and images are very welcome.
By the way, this observing session was my 20th of 2021.
That's not bad at all - is it?
Clear skies from Aubrey.