Observations - 19th March 2020

3 months 3 weeks ago #108435 by flt158
Observations - 19th March 2020 was created by flt158
Hello everyone.

Once again I had to set up my William Optics 158 mm F/7 apochromatic refractor in my back garden complete with its 70 mm F/6 small apo attached. Both scopes are placed on a Berlebach Planet mount. Mirror diagonals are fitted to both scopes. I observed on Thursday night 19th March when the temperatures decreased from 4 degrees Celsius down to 0 degrees by 23.00 UT. Sunset occurred at 18.37 UT. Cloud amounts varied from time to time, but it was mostly clear. All 3 weather websites www.met.ie , www.clearoutside.com and www.yr.no were all convincing me I was going to have clear skies. So out I went!

1. Venus is now of magnitude -4.4. It's 53.9% illuminated. Its distance was slightly less than 112 million kilometres from Earth. Its angular diameter was 22.3". 12 minutes before sunset I could see the brightest planet very easily with my eyes. At 11X it was a bright star. At 40X my main scope was showing half phase. But at 112X, 140X, 167X and 225X I could figure that it's not quite 50% phase. It was in fact 53.9%.The famous Schroter Effect is due to occur next Thursday 26th March. I could not see any darker markings in Venus' upper clouds. There was a fair amount of shimmering 167X and 225X.

2. Having swung around the scopes back up to Cancer the Crab, I found M44 the Beehive cluster very quickly in both scopes. West of it is the wide optical double Theta Cancri. Magnitudes: A = 5.5. B = 11.8. Sep = 74.5". PA = 62 degrees. The faint secondary was barely visible at 112X. 140X and 167X was a little bit better.

3. Seeing I was in the same area, I couldn't resist observing Zeta Cancri (Tegmine) one more time. Magnitudes: A = 5.3. B = 6.3. A = 5.9. Sep's = 1.142" (narrowing) and 6.3". PA's = 5.2 degrees (lessening) and 51 degrees. Because of the calm conditions my scope was trying to split A & B at 140X. But success was to be had at 167X. 225X is utterly glorious. Zeta Cancri is still spectacular in every sense.

4. Very nearby Zeta is my 5th carbon star in Cancer. V Cancri has been invisible to me up to now. But I did discover that an observer on www.aavso.org had very recently observed it and suggested it had reached +11.0 magnitude. I was delighted to say the least. I have now given an estimated magnitude of +10.8. There are 2 stars east of V Cnc. From east to west the first star TYC 1382 755 has a magnitude of 11.0.The second star 3UC215-102578 has a magnitude of 11.8. So seeing V Cnc is that little bit brighter than this 1st star it was relatively easy to estimate its magnitude. I will be recording its magnitude later on www.aavso.org . It is my 84th observed carbon star overall. I could see the star at the very lowly power of 40X which did surprise me. However its colour got stronger as I increased from 112X, 140X, 167X and 225X. At that final power V Cnc revealed itself as a very strong orange indeed - albeit very faint. For me it was a magnificent sight!

5. KU 33 is an optical double very near Delta Cancri. Its magnitudes: A =10.5. B = 10.8. Sep = 8.6". PA = 100 degrees. It's just above an 8.6 magnitude star. At 112X it was easy to see the 2 components of KU 33. Both stars had very slight yellow colours. I then discovered I could see both stars split at 40X. They are seriously dim. KU stands for Karl Friedrich Kustner who lived from 1856 to 1936. He was a German astronomer and he has been recognised to have discovered the Polar motion of the Earth.

6. X Cancri is a carbon star which I did observe before. The planet Jupiter passed by it a few years ago. I used 40X and 112X to observe that it is bright and a pleasing orange colour right now. I now estimate its varying magnitude as +6.6.

7. AG 338 is a magnificent double star. Astronomers reckon it is an uncertain double which surprises me somewhat. But they know best. Magnitudes: A = 9.0. B = 9.2. Sep = 2". PA = 165 degrees. It truly was a stunning sight at 112X. There was a delightful black gap between the 2 yellow stars at that power. It's very nice too at 140X and 167X. AG stands for Astronomische Gesellschaft.

8. Omicron Cancri is a real enigma to me. Its 2 stars are a true binary according to www.stelledoppie.it . Magnitudes: A = 5.2. B = 5.7. Sep = 975.7". PA = 18 degrees. That separation is 17 arc minutes ('). Could I have come across the widest true binary in the entire sky? Please feel free to comment. Easily observed at 11X in my small apo and 40X in the main scope. The colours are very subdued. A is blue-white. B is yellow-white.

9. And now a real showpiece. Extremely close to Omicron Cancri is a true double star. My only Struve which is Stf 1300. Magnitudes: A = 9.5. B = 9.7. ENG 9001 makes it a quadruple system. Magnitudes: C = 9.9. D = 10.2. Sep's = 5", 202.5" and 198.4". PA's = 178, 13 and 61 degrees. I had a marvellous time seeing all 4 stars. A & B were split at 40X. But I did increase up to 112X, 140X, and 167X because of the colours. The spectral classes are: M0, M0, G0 and F8. So I was seeing red, red, slight yellow and rich yellow-white. Brilliant!!

10. My final observation of this great night was a carbon star: GM Cancri. Its magnitude barely varies at all: either 8.6 or 8.7. It was very easy to see at 11X through my small apo. It's that bright. Its colour is a decent orange at 40X, 112X, 140X, 167X and 225X. The higher the magnification the stronger became the colour. GM Cancri is the 6th and final carbon star in Cancer and my 85th such star overall.

Comments are very welcome.

Clear skies,

Aubrey.
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3 months 3 weeks ago #108439 by Fermidox
Replied by Fermidox on topic Observations - 19th March 2020
Another very productive night Aubrey. Omicron Cancri 1 and 2 are described as a co-moving pair, travelling through space together but, over a light year apart, not orbiting each other. There a quite a lot of stars that are widely separated in the sky but have a similar orbital motion, having originated from the same cluster.

Clear skies,
Finbarr.
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3 months 3 weeks ago #108440 by flt158
Replied by flt158 on topic Observations - 19th March 2020
Thank you, Finbarr, for this vital piece of information.
We live in a wonderful universe!

Kind regards,

Aubrey.
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3 months 3 weeks ago #108441 by Keith g
Replied by Keith g on topic Observations - 19th March 2020
Good stuff Aubrey, it won’t be long until you observe 100 carbon stars, they are just so beautiful.

did you try for VY Canis Majoris, the largest known red giant, it’s very low in the south, a red/ orange pin prick of light at magnitude 8.5 last night

Keith..

If a telescope can fit into your backyard it's too small. If you can't move it, it's too big." -- John Dobson
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3 months 3 weeks ago #108444 by flt158
Replied by flt158 on topic Observations - 19th March 2020
No, Keith.
I never have.
Is it a carbon star?
My Guide 9.1 DVD suggests its spectral class is M3 or M4.
Maybe it will become a carbon some day.
Unfortunately the star is too low from my back garden anyway.
This corona virus is preventing many of us to head up to the Sugarloaf where I would give VY Cma a go.
Still M class stars are fascinating too - as you can see from my report in Cancer.
Some are variable also.

Now when are we going to have another clear night?
I was so much looking forward to do some more observing tonight (Friday) from my backyard.

Aubrey.
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3 months 3 weeks ago #108447 by Until_then-Goodnight!
Replied by Until_then-Goodnight! on topic Observations - 19th March 2020
Wow, what a great report Aubrey!

I was reading about the the Schroter Effect in the IAS magazine 'Sky High' only this morning. It's a great resource packed with so much information, and I'm looking forward to the 26th.

Very well done on observing another two carbon stars. They add a lovely splash of colour in the eyepiece, and I did not realise that the colour can get stronger under higher magnifications, so thanks for that info.

Your description of Stf 1300 is wonderful, and I must take a look at it for myself at the next available opportunity. Also, many thanks for the historical information on the German astronomer Karl Friedrich Kustner - I always enjoy learning about these interesting people.

Clear skies,

Darren.  
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3 months 3 weeks ago #108451 by Keith g
Replied by Keith g on topic Observations - 19th March 2020
VY Cma is not a carbon star, but it's nice knowing that you are looking at the largest star known to man as yet.

I think Sunday night will be clear...

Keith..

If a telescope can fit into your backyard it's too small. If you can't move it, it's too big." -- John Dobson
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