Observations - 6/2/22

Hello everyone. 

Having arrived home from a walk on Sunday 6th February 2022 I noticed that the sky was clearing above me and the weather forecasters were saying that it was going to stay clear until way after midnight. So I set about placing my William Optics 158mm f/7 refractor in my back garden. Sunset had occurred at 17.18UT, and I started observing at 17.45 and did not stop until 20.30.

The Moon was first on the menu of course followed by some double stars nearby. As I have a mirror diagonal fitted my north is up and my east is to the right. The temperatures were very cold to say the least: 2˚ Celsius – and feeling colder during the 2 hours 45 minutes – thanks to a quite strong wind (27 – 18 km/h) which although was decreasing – never died down altogether at all. 

 I observed the 3.5 day old Moon at 112x and it was a beautiful crescent 32.1% lit. Its angular diameter was the standard 30.7’. As usual I had Antonin Rukl’s Map of the Moon with me, and I observed along the terminator almost all the time. Maps 46, 47 and 36 were used throughout. 

What a cracker of an event was immediately occurring live right on the terminator! The whole        crater Theophilus looked glorious with its entire centre in complete darkness. But the entire rim was 100% illuminated by the Sun - especially on the eastern side. I have observed this event before – but it always succeeds in taking one’s breath away - does it not?. The diameter of Theophilus is precisely 100 kms and is named after the Bishop of Alexandria, Egypt. The depth of the crater is 4400 metres. The rim is 1200 metres high. By 20.00UT 2 tiny mountain peaks appeared like a double star inside! The tallest is 1400 metres high. It was such a beautiful sight and one I will remember at the end of 2022.
              
Next to Theophilus is of course Mädler whose central floor was also in darkness. It has no central peak and its diameter is 28km with a depth of 2670m. Northeast of it were the “twins” of Isidorus (42km; 1580m deep) and Capella (49km). Isidorus lived from 560 to 636 AD. He believed that the Earth was a sphere - clever chap. Capella was a 5th century lawyer who believed that Mercury and Venus orbited the Sun – another clever chap! Vallis Capella was easily seen descending north and south through the crater. 
            
The pear-shaped crater Torricelli looked very good at 112x too. It definitely is one of the strangest lunar craters. Mr. Evangelista Torricelli was a Italian physicist who lived from 1608 to 1647 and he did know our friend Galileo.  

Further north on Map 36, I observed Maskelyne (24km) which is named after Nevil Maskelyne from England. He was the 5th Astronomer Royal. Maskelyne B (9kms) was also seen. 2 new craters to me were Wallach (6km) and flooded Aryabhata (22km). Wallach was so tiny at 112x but was easily identified next to 2 strange looking mountains. Very nice! On the same map I saw the 12.4km 2610 metre deep crater Cauchy with the 120km long fault Rupes Cauchy to its south. I did not see Rima Cauchy or the 2 domes tau and omega. But I didn’t mind. The great crater Theophilus made my night! 

And now I turn to my double star observations for this Sunday night. All figures are from www.stelledoppie.it . And these 3 doubles were rather near to the -9.2 magnitude 3.5 day old crescent Moon. But they proved to be not too faint. 

1. Alrischa (Alpha Piscium or STF 202) is a true binary. Magnitudes: A = 4.1. B = 5.2. Sep = 1.9”. PA = 261˚. I had no separation at 112x. But I had success at 140x but only when the wind died down for a few moments. My 167x and 225x eyepieces gave seriously good views as always. The white stars sit side by side at that point. What a magnificent double this is! A great one for first timers. 

2. Up into Aries I went. It had been recommended to me by a guy on www.cloudynights.com in 
recent times to observe the true binary STF 173. Magnitudes: A = 8.6. B = 10.8. Sep = 22.4”. PA = 205˚. I saw no sign of the secondary at 40x. That was probably because the Moon was about 8 or 9˚ away. But I had no hassle seeing the tiny star at 112x and 140x. The primary’s spectral class is G0, but as it is faint in its own right, I saw little evidence of its yellow colour. The even fainter secondary was an even tinier star and quite some distance from the primary as you might imagine. 

3. I had noticed on Stelle Doppie that there was a tight true binary 80’ from STF 173 which is called BU 260. BU stands for Sherburne Burnham (1838-1921). Magnitudes: A = 8.8. B = 9. Sep = < 1.1”. PA = 262˚. I found it easily enough at 40x and set out to the business of splitting it. At 167x I could see something happening. There seemed to be 2 stars alright but no split was evident. At 225x I had a much better view. The 2 stars were stronger – but still no split. My William Optics 4mm eyepiece which yields 280x brought great success. I finally had the perfect view with that miniscule black gap we all look for between the 2 stars. The wind had decreased to 17 km/h at this stage. Still a bit blustery - mind, but enough to announce it was such a thrilling observation to end the night! I never went higher than 280x because of the wind of course. But once again my William Optics 158mm apochromatic refractor did a super job for yours truly. Owners of larger aperture telescopes might consider having a go. 

Replies are very welcome as always. 

Clear skies from Aubrey.     

Hello Aubrey, 

That seemed like a fantastic session, especially your time with Luna. I have observed Theophilus other craters South of it before  but never with terminator casting such beautiful shadows... What a sight that must have been. Your description of your Lunar observation was a fantastic read - it felt as if I was observing those features myself. Very well done! 

And congratulations on splitting BU 260, and this other doubles. 

Clear skies, 
Darren.