Hello, everyone.
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.
Thank you for reading my latest report.
Comments are most welcome.
We might have clear skies again over Dublin on Friday night.
I am hoping to find more new doubles in Leo the next time.
Very best regards from Aubrey.
