Observations - 21/01/2021

1 month 1 week ago #109925 by flt158
Observations - 21/01/2021 was created by flt158
Hello everyone.

I had a fairly good night observing on Thursday 21st January 2021 with my William Optics 158 mm F/7 apochromatic refractor and its WO 70 mm F/6 small apo in my back garden from 17.30 to 19.30 UT. I then had my dinner and I returned to the scope from 21.30 to 22.30 UT. Sunset had occurred at 16.47 UT. The temperatures once again went down from 0˚ to -4˚ Celsius. There was a 15 km/h breeze but I was wrapped up under 7 layers of clothing including my North Face coat. That all kept yours truly warm. As I have mirror diagonals fitted to both scopes my north is up and my east is to the right.

1. Straight away I could see Mars with my own eyes. Therefore I proceeded to check out the planetary conjunction with Uranus. Could I see both planets using my 2” 28 mm eyepiece which gives me 2˚ fov at 40X? Indeed I could! Mars at the top and Uranus right at the very bottom. Through my small apo, which was set at 11X and 6˚ fov, Valerie and I could see both planets very easily. There was a bit more orange to Mars this time – although it was still mostly yellow. For the record, Mars had a magnitude of +0.2. Its distance was a little less than 163,500,000 kms from us. As its angular diameter was 8.6” I was not surprised that I couldn’t see many dark features. But one thing I did note was its very good gibbous 88.5% illuminated phase at 225X. In John O’Neill’s edition of Sky High 2021, he states that on this precise night Mars’ gibbous phase is at its smallest. As I do not remember recording that fact ever before in my observing past, I do very much consider it a reasonable accomplishment. If you are reading this, John, I say thank you very much to you personally

2. Onto Uranus now. At 225X the planet appeared more grey than blue or green. But I did not mind that at all. It was still rather pleasant to see. It sported a nice round globe of some 3.6” in angular diameter with no cloud features at all. Its magnitude was +5.8. Its distance was 2,941,463,000 kms away. Now how do the Greeks pronounce Uranus? Well - I have since discovered they say: OO-ran-us with the emphasis on the first syllable. All together now… 1, 2, 3! Laugh!

3. Directly south of the Moon I could see Alpha Ceti (Menkar). Directly to that star’s west was my old friend Gamma Ceti which has the magnificent name: Kaffaljidhma. Some folk on Cloudy Nights are not fans of this name. But I am a big admirer of it. It's not too difficult to say. On the website wwwstelledoppie.it they state that is an uncertain double with magnitudes: A = 3.5. B = 6.2. Sep = 2”. PA = 299˚. The southern sky’s seeing must have extremely good because the 2 stars were visible at 112X and 140X. But no split was apparent until 167X was used.Success! Gamma Ceti looked magnificent at 225X. At that final magnification I noticed something I had not observed ever before. The secondary had a yellow-orange tinge to it. When I came in I headed to the Simbad website. They have produced an image for Kaffaljidhma which clearly shows that very same colour. In Robert Burnham’s Celestial Handbook Volume 1, he says the spectral classes for the 2 stars are A2V and dF3. Indeed some observers from the past have thought the secondary was tawny or dusky. For some reason both Sissy Haas and www.stelledoppie.it shy away from this issue. However I must say it was a dramatic discovery for me personally and a major surprise. What colour to you see, my friends? Gamma Ceti also is called STF 399 after our friend Mr. Wilhelm Struve.
4. I shall cover the 8.5 day old Moon now. I used powers up to 167X on our nearest neighbour. Its magnitude was – 10.4. Its distance was 399.700 kms. Its phase was 58.3%. Straight away I could see my favourite lunar feature 110 kms long Rupes Recta. It looked most similar to a sword from 112X. However at 167X the very narrow 50 kms long Rima Birt was also observed directly west of Rupes Recta. Very nice! Up in the northern part of the moon I could see some of Rima Hadley which is rare for me. The Apennines were very striking as expected. But one great surprise was to see the western part of the great 58 km crater Eratosthenes “chopped” off by the Moon’s terminator. Only the eastern part’s rim was visible. The time was 19.00 UT when Valerie and I both noticed this effect. However later at 21.30 UT the whole rim was completely visible – although the central part was in complete darkness. Eratosthenes of Cyrene lived from 276 to 195 BC. He was, amongst other things, a very great mathematician and astronomer. He could work out what the measurement of the circumference of the Earth was.The central part of the large 101 km crater Plato was also in full darkness. The 130 km and quite wide Rima Bradley was also seen. James Bradley was in regular contact with the very famous Edmund Halley. and lived from 1692 to 1762. There is a telescope which was made by him at the Greenwich observatory. Valerie and I visited this observatory in 2018. By the way,
right next to Rima Hadley was the tiny 6 km crater Hadley C.
5. Further joy was to be had when I discovered that in the current issue of Orbit an occultation of 38 Arietis was due to take place. (You may read about further occultations in the Sky Notes of the current magazine Orbit which are compiled by Michael McCreary on page 8.) At the precise time of 21.55 UT 38 Arietis was “snuffed” out in split second timing. The star’s magnitude is 5.2. It was a good one alright! To my eyes the star was white.
6.One last true stunner I most share with you all. Alnitak (Zeta Orionis) is a triple star. A and B are a true binary, but C is optical. Magnitudes: A = 1.9. B = 3.7. C = 9.6. Sep’s = 2.16” and 58.5”. PA’s = 167˚ and 10˚. Of course A and C were resolved at 40X. But I was greatly amazed A and B were split at 112X. The 2 stars are getting more narrow as the years go by. I usually require 140X. But I did use 140X also. A had a bit of blue.

Thank you for reading my report.

Comments and corrections are very welcome.

Clear skies from Aubrey.
The following user(s) said Thank You: michael_murphy, Fermidox, Until_then-Goodnight!

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1 month 1 week ago #109926 by Until_then-Goodnight!
Replied by Until_then-Goodnight! on topic Observations - 21/01/2021
Congratulations on your wonderful report Aubrey!

I was delighted to read that you have bagged a couple of planets last night - you are well on your way to observing them all this year. 

Your description of Menkar was fascinating. Like you, I really like it's more obscure name. I wonder where the name Kaffaljidhma came from?

And what a report on the Moon! You really had a great night!

Very well done, and as I understand there are a few clear nights over the week...I can't wait to get back out! 

All the best,

Darren.
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1 month 1 week ago - 1 month 1 week ago #109927 by flt158
Replied by flt158 on topic Observations - 21/01/2021
Hi Darren.

It was the Arabs who gave the name Menkar to Alpha Ceti.
And it was the Arabs who again gave the name Kaffaljidhma to the other star Gamma Ceti.
The Arabs again gave Beta Ceti another name: Diphda - which turns out to be the brightest star in Cetus.
So here we have 3 stars and 3 names.
I reckon all 3 names are obscure depending on what our sources are.

By the way, there is supposed to be some snow arriving tonight to the east coast of Ireland.
Milder conditions are maybe coming on Tuesday.

And Kevin Nolan is giving a talk regarding Mars on Monday night via zoom for the IAS. He is a very passionate man.

Aubrey.
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1 month 1 week ago #109928 by Until_then-Goodnight!
Replied by Until_then-Goodnight! on topic Observations - 21/01/2021
Very many thanks for answering my question Aubrey. Those middle-eastern astronomers gave the stars some lovely names alright. 

Another night that I had my scope set-up from 6:30pm, and another I took it without a single look through the eyepiece :(

Maybe next week?

And speaking of next week, I'm hoping to join the zoom meeting. I was at one of Kevin's talks before, and he certainly knows the Red Planet. So, Monday night should be great. 

Until then, have a great weekend! 

Darren. 
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