Christmas Eve observations 2020

Good evening, everyone.

Thursday 24th December 2019 was a clear night over my back garden in Dublin. Surprise! Surprise! There was another clear night to be had on 24th December 2020. How strange that is! Can someone phone Mulder and Scully? (Valerie and I have been watching the X-Files recently). Therefore I set up up my William Optics 158 mm f/7 apochromatic refractor with its WO 70 mm f/6 on their Berlebach Planet altazimuth mount. I do have mirror diagonals fitted to both scopes.Sunset had occurred at 16.10 UT. It seems our sunset times are already getting a bit later. I started observing at 18.15 UT. At the end of my session at 22.45 UT. Dinner was had at 20 UT. At the end of my observing time the temperature was 5 degrees Celsius. There was very little wind and no dew at all. Therefore I wasn't shivering.

Each double star can be checked out on www.stelledoppie.it

1. I started with Polaris once again. It is a true binary over 132 light years away. Mags: A = 2. B = 9.1. Sep = 18.4". PA = 236 degrees. However I must point out that at 18.30 UT the secondary has not made it to the 12 o'clock position. I find this charming in its own way. Split easily at 40X and 112X. The primary is F7 yellow-white. I see the secondary as white.

2. Delta Cygni or Rukh came next. It is a true binary 165 light years from us. Mags: A = 2.9. B = 6.3. Sep = <2.8" and widening. PA = 214 degrees. At the time the sky was extremely clear and calm. I haven't split this double at 112X for some time. I was getting the slenderest of black gaps between the blue-white B9.5 primary and the secondary through my Pentax 10 mm eyepiece. It also looked very good at 140X of course.

3. Before din dins I spent some time observing the 10 day old 75% lit Moon at 112X. Its magnitude was -11.1 with a distance a little over 40,000 kms from Earth. I have already discussed with Paul the occultation of Xi 1 Ceti. Therefore I will now state what else I observed. South of Clavius there were 3 oval shaped craters whose centres were in darkness - oval because they are very near to the south pole of the Moon. These were: Scheiner (110 km), Klaproth (119 km) and Casatus(111 km). Christoph Scheiner (1575-1650) was probably the first astronomer to observe sunspots with a telescope.
Up in the northern part of the Moon I noticed Vallis Alpes which is 180 kms long. To its west was the delightful smooth surfaced crater 101 kms Plato of course. The 20 km Bliss sat directly west to Plato. Then there were these satellite craters of Plato further west again: B (13 km), Y (10 km), M (8 km), O (9 km), P (8 km), D (10 km) and E (7 km). Further to the north and beyond Mare Frigoris (Sea of Cold) the crater Birmingham (92 km) had a strange shape to it. It is narrower from north to south, but wider from east to west. John Birmingham (1816-1884) lived and died as a bachelor in Milltown, Galway. He owned a 4.5 inch refractor. Stretching south of the Birmingham crater I could easily see 2 wriggly dark lines descending into mare Frigoris. which are about 90 kilometres long and widening as they did so. These were striking to my eye.
One crater which I have never observed before was the 6 km Landsteiner. It was sitting south of Carlini D (9 km). And further north were the 2 small satellite craters Le Verrier B (5.1 km) and D (9.1 km). Each of these 4 craters are placed in Mare Imbrium (Sea of Rains).

4. After dinner, I went back to Cassiopeia. So I revisited that delightful optical triple star STF 3053 which some of us greatly admire. Then I went up to a first time observed an optical double star called KR 3. Mags: A = 9.8. B = 9.9. Sep = 3.5". PA = 222 degrees. It sure looked extremely exquisite at 140X. And I did see an even tighter separation at 112X of course. The 2 stars were not quite side by side which is okay. At the time, my north is to the right and my east is downwards. KR is named after Adalbert Kruger (1832-1896). KR3 is my 3rd double star which his designation and I do consider it beautiful.

5. I close with STF ( F G W Struve) 16 which is an uncertain double. Mags: A = 7.7. B = 8.8. Sep = 5.8". PA = 40 degrees. Super tight split at 40X. I am now reckoning its colours are A3 white and blue-white when observed at 112X. In 2019 I thought the secondary had an orange tinge to it. But I was wrong then. So I am sorry about that. It's solved now.

The 24th December was my 73rd observing session of 2020 which is the most I have had during my entire life! Could I even dare to imagine to achieve such a feat in 2021?

Thank you for reading.

Comments are very welcome.

I wish you safety for the rest of the Christmas period.

And clear skies from Aubrey.

Goodness me - 73 observing sessions in one year....that is something else Aubrey. Very well done!

I really enjoyed reading your report on the Moon. I had hoped to get out Christmas Eve to some observing of the Moon myself, but the night ran away from me. So, it was great having your take on it. Valais Alpes is a very interesting part of the Lunar surface.I remember observing it early last year.

I wonder what gave STF 3053 its orange hue last year? Is the designation of STF 3053 different from Struve 3053? I observed Struve 3053 recently, and that had an orange star...must be a different designation!

Great report Aubrey,

And a very Happy New to you and Valerie.

Clear skies, 

Darren.

Hello, Darren.

And I very much would like to wish you and your family a very happy new year.

Of course, some of my 73 observing sessions were very short lived because of cloudy and appalling dew conditions. I did buy those hand warmers as Paul suggested. But as we all know I can have 9 eyepieces out sometimes splitting very tight double stars. So keeping the dew off each of them and the 2 telescopes is a big problem.

Thank you for your comments regarding my lunar report. I should have plenty more of these in 2021. That's because Luna is much higher for the first 6 months of any year.

STF or Stf does indeed stand for Mr. Struve - which is Friedrich George Wilhelm Struve who lived from 1793 to 1864. His son Otto Struve lived from 1897 to 1963 has a different designation: STT or Stt.

Anyway, I wonder if there is some confusion in regards to STF 3053 and STF 16.
STF 3053 I had never observed before 16th December 2020. I found its colours amber yellow, blue and white.

STF 16 I first observed in 2019. I don't understand why I got the colour of the secondary wrong. I had observed it 3 times. I have to say I asked the folks on Cloudy Nights to have a look at it. But no one seemed willing to take it on. That sometimes happens. Perhaps you could give it a go, Darren. STF 16 is still in a good position for you to check it out - or anyone else for that matter.

Clear skies, everyone.

Aubrey.

I have had a look at Simbad and show 2 individual images of both stars of STF 16. Both stars seem to have a spectral class of A - which implies both stars ought to be white. Maybe my eyes were playing tricks with me during those earlier times, Darren. Sissy Haas says the colours are gloss-white and whitish blue. And I do agree with her now.

Best regards,

Aubrey.

Hi Aubrey, 

My bad! I did confuse STF 3053 with STF 16 when I wrote my post last night... I'm blaming it on the trifle  

Very many thanks for highlighting that for me.

Clear skies, 

Darren.