Hello everyone.
Would you believe it?
We still have another week of April 2020 to go and I have observed no less than 10 times so far.
On Sunday evening 19th April I set up my William Optics 158 mm F/7 apochromatic refractor and the WO 70 mm F/6 small apo in my back garden. I observed the heavens from 6 to 7 pm; and then again from 8.30 to midnight. Sunset occurred at 8.33 pm. Temperatures dropped from 16˚ C to 4˚C at midnight.
1. Of course, first on the menu was Venus. I found her with my small apo at 11X at precisely 6 pm which is a whacking 2 hours 33 minutes before sunset. At 6.10 pm I could see her with my unaided eye. Her magnitude is now a steady -4.7 with a distance of less than 76,300,000 kms from us. Her phase was 34.3% illuminated and had an angular diameter of 32.7” on this particular Sunday night. I have to say she is getting bigger as each week goes by. But that is perfectly logical as her distance is becoming less. Unfortunately, she is shimmering or “boiling” every time I observe her. This time she was doing so at lowly power of 40X. How sad! I refused to go higher than 167X, but I did notice those bright cusps once again at both ends of her poles even during the appalling seeing conditions.
Figures for these doubles, triples are from
www.stelledoppie.it
as per usual.
2. After dinner at 8.45 pm, I found Castor in my small apo at 11X. Switching over to the main scope using my 2 inch 28 mm eyepiece at 40X, the 2 brightest stars were split. This occurred 12 minutes after sunset – amazing! It is only the 2nd time I have achieved this feat. But I did increase my magnification from 112X up to 225X. Seeing conditions were clearly improving all the time. The C and D companions were visible at 40X at 9 pm. For the record, Castor’s magnitudes are: A = 1.9. B = 3. C = 9.9. D = 10.1. Sep’s from A are 5.4”, 69.8” and 179.8”. PA’s are 52˚, 163˚ and 221˚. A, B and D are all white. But C is red. How extraordinary! A, B and C are a true triple. But D is optical.
3. Off to Lynx once again. I did have a most excellent time in this elusive constellation. 38 Lyncis which is a true binary is as wondrous as ever - split at 112X. Magnitudes: A = 3.9. B = 6.1. Sep = 2.5”. PA = 229˚. The B star has starting to “point” downwards to the western horizon. The “teardrop” effect is particularly stunning at any magnification. Both stars are white. Of course those of us who have reflectors will see the B star pointing upwards. Never mind! It’s still a great sight.
4. Over on
www.cloudynights.com
we have been discussing 20 Lyncis. It is a true binary. Magnitudes: A = 7.5. B = 7.7. Sep = 14.9”. PA = 256˚. As usual it is effortlessly easy to split at 40X. But to check out those subtle hues, I went up to 167X. I had no problem figuring out the colours from 112X. A's spectral class A6 and it is blue-white. B is F0 and is yellow-white. That information is from Robert Burnham's Celestial Handbook. The “6” must refer to the strength of the blue colour of the primary. F always is yellow-white, but the “0” must make it a very weak yellow-white. That is my consensus. See what you think.
5. The rest of these 7 doubles are first timers for me. The first 3 are in a very confined space of 1 degree east of 20 Lyn. 22 Lyncis is an optical double. Magnitudes: A = 5.4. B = 10.1. Sep = 179.7”. PA = 304˚. This double has the alternative designation ENG 31. George Engelmann is the discoverer. He lived from 1809 to 1884. He was born in Frankfurt, Germany and emigrated to Baltimore, USA. It is very easy to see plenty of space in between the 2 stars at 40X. A is yellow-white (F6). B is white.
6. Stf 1091 is an optical double. Magnitudes: A = 9.5. B = 10.1. Sep = 29.9”. PA = 322˚. Very easily split at 40X of course and very similar in magnitude. Both stars are yellow – like 2 eyes.
7. What a difficult true double is right next to Stf 1091. I knew full well Stf 1093 was going to be one tough cookie to split. Magnitudes: A = 8.8. B = 9. Sep = 0.9”. PA = 206.4˚. The separation and the PA are increasing. I could see 2 stars at 225X. But no split was to be had at that power. However I could see the tiniest black space between the 2 stars at 280X and 320X alright – but only when the seeing conditions were decent. Thankfully the 2 stars are nearly identical in magnitude. There is the minimal delta magnitude difference of 0.2 – which proved to be a major advantage on this occasion.
8. The rest of these were easy to separate. Stf 1096 is a true binary. Magnitudes: A = 8. B = 10.6. Sep = 29”. PA = 327˚. 2 white stars clearly split at 40X.
9. ES 2622 is an optical double. Magnitudes: A = 8.2. B = 9.5. Sep = 46.7”. PA = 127˚. Split at 40X. A is a good yellow star alright (G5).
10. Stf 1032 proved to be a little challenge. It is both an uncertain and optical triple. Magnitudes: A = 7.3. B = 10.3. C = 9.5. Sep’s = 2.7” & 131”. PA’s = 113˚ & 319˚. At first I had all 3 visible at 167X. But I decreased my magnifications back to 140X and 112X. The B star proved to be very tight to the A star. All 3 stars are white.
11. Stf 1040 is a true binary. Magnitudes: A = 8.8. B = 10.3. Sep = 7.3”. PA = 261˚. Good and tight at 40X. Very pleasing at 112X too.
12. Finally to fill the page of my diary, I could see Porrima, otherwise known as Gamma Virginis, over my neighbour’s house. Magnitudes: 3.5 & 3.5. Sep = 2.9”. PA = 357˚. Of course, we all know of this hugely famous binary. Its separation is increasing and its PA is decreasing year on year. My scope is just about splitting it at 112X now. But what a glorious sight it is at 140X! Both stars’ spectral classes are F0. There are most certainly yellow-white for me.
And on that note I would like to thank everyone for reading this my latest report.
Comments are most welcome.
Clear skies from Aubrey.
