Observations - 20/02/21

1 week 2 days ago #109982 by flt158
Observations - 20/02/21 was created by flt158
Good evening, everyone.

I was out observing with my William Optics 158 mm F/7 apochromatic refractor for 1 hour 15 minutes last Saturday evening 20th February 2021 - between 18.15 and 19.30 UT. Sunset had occurred at 17.46 UT. The wind was considerably stronger than previous nights whizzing around at 30 km/h. But the sky was very clear.

1.There was a 9 day old gibbous Moon in Taurus whose magnitude was -10.5. It was 59.4% lit and its distance was 395,730 kms from Earth. I didn't see anything new at 112X. My favourite lunar surface Rupes was very easy to see. Some jagged shadows were prominent inside the eastern side of the 100km crater Plato. Lovely! Vallis Alpes looked good too.

2. Staying in Taurus, I observed a double star called STF (Struve) 478. I could see it on my Guide 9.1 DVD and it is included on the website www.stelledoppie.it . But for some strange reason STF 478 is not contained in either Sissy Haas' book "double stars for small telescopes" or even Robert Burnham's Celestial Handbook - the latter of which has a huge number of such objects. Could it be because it's too faint? But never mind. I found it to be an attractive and true binary. Magnitudes: A = 8.8. B = 10.2. Sep = 9.7". PA = 139 degrees. A is F5 yellow-white. B is white. Delightful split at a mere 40X.

3. STT 70 which stands for Otto Struve came next. It is an uncertain double with magnitudes: A = 5.8. B = 11.2. Sep = 11.6". PA = 229 degrees. I needed 167X to see the dim secondary which wasn't easy to see because of the windy conditions which were not going to abate.

4. WAL 27 has the same primary star as STT 70. It also is an uncertain double. Therefore the magnitudes are: A = 5.8 as before, but this time C's magnitude is 11.7. I found it much easier to see at 112X. That's because it is much further away from the A star at 84.4". The PA is 241 degrees. The fainter two stars of STT 70 and WAL 27 point to the primary very nicely. All 3 stars are white. Oh! And it is my first ever observed WAL. But I do need to ask the question: What does WAL stand for? Could the person have the Walker surname?

5. And so lastly I observe a carbon star which has a spectral class of C4. HD 286436 is also in Taurus. It has quite a lot of alternative designations: GSC 00662-01425, HIP 18564, NSV 1426 or TYC 662-1425-1 to name but 4. Its magnitude is 1+10.2. The Right Ascension is 3 hours 25 minutes 27.21 seconds. The Declination is: +11 degrees 54 minutes 20.83 seconds. It was quite easy to find at 40X even though the bright Moon was in Taurus also on the same night. At higher magnifications 112X, 140X and 167X I could see it had a decent orange hue. It sits east of an A7 class white star called HD 286437 whose magnitude is precisely 10.0. And I could see that particular star was slightly brighter than the carbon star HD 286436. It all means I have now observed a 5th carbon star in Taurus and 97 overall.

There are some more clear skies coming in a few nights.

Therefore I do hope to have more doubles and carbon stars soon.

Very best regards from Aubrey.
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1 week 2 days ago - 1 week 2 days ago #109984 by Until_then-Goodnight!
Replied by Until_then-Goodnight! on topic Observations - 20/02/21
Hi Aubrey,

Very many thanks for your wonderful report. First up, I think I may have found out where that 'WAL' star comes from.: Walborn. For example, if you click on this link: 

articles.adsabs.harvard.edu/cgi-bin/nph-...REEN_GIF&classic=YES

it will bring you to a page where you'll see the code 'WAL' listed next to Walborn. There is also a WAL 147 that perplexed another star splitter:

bestdoubles.wordpress.com/2016/12/12/the...7-es-2725-and-ary-3/

I'm doing a bit more digging to find out additional details on it the WAL identifier for you. Although you  may already have received the answer at this stage.

I also did a search for STF 478 to check out its magnitude, but I couldn't find it anywhere - what magnitude is that star? You have me all curious!

And congratulations on bagging another Carbon star - is that two in a week? Good going : )

Clear skies,

Darren.

Wait a minute....I now think that the 'WAL' identifier you were looking at belongs to Wallenquist, A.

www.stelledoppie.it/index2.php?menu=22&iddoppia=13907

Here's a picture of the great man: 

www.astro.uu.se/history/Wallenquist.html
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1 week 1 day ago #109985 by flt158
Replied by flt158 on topic Observations - 20/02/21
Hello, Darren.

Thank you very much for your very kind comments!
It appears the designation WAL stands for Wallenquist alright.
Ake Wallenquist lived from 1904 to 1994.
He was a Swede and spent some time in Indonesia.

I did give the magnitudes of STF 478 above. But here are all the figures again.

A = 8.8. B = 10.2. Sep = 9.7". PA = 139 degrees.

Clear skies from Aubrey.
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1 week 1 day ago #109986 by Until_then-Goodnight!
Replied by Until_then-Goodnight! on topic Observations - 20/02/21
Hi Aubrey, 

How did I miss those magnitude values??? Maybe I was expecting some crazy low magnitude value... I don't know... Too much chocolate late last night probably the cause :) 

Glad to read that Ake Wallenquist belongs to the 'WAL' identifier. 

Chat soon and clear skies, 

Darren. 
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1 week 1 day ago #109987 by flt158
Replied by flt158 on topic Observations - 20/02/21
That's okay, Darren.

I am now of the opinion that STF 478 must be considered as a faint double - simply because it is not included in Robert Burnham's Celestial Handbook Volume 3.

But I am very pleased you are getting more and more acquainted with www.stelledoppie.it

I'm staying off chocolate until Easter Sunday! Ha Ha!

Clear skies and best regards from Aubrey.
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1 week 14 hours ago #109988 by Until_then-Goodnight!
Replied by Until_then-Goodnight! on topic Observations - 20/02/21
Hi Aubrey,

Many thanks for that . And yes,  I have started to familiarise myself with  www.stelledoppie.it   - it sure is an excellent resource. Thanks for drawing out attention to it.

Chat soon,

Darren.
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