Observations - 16th December 2020

Hello, everyone.

Last Wednesday night 16th December we had a good clear night over Dublin.
Therefore I set up my William Optics 158 mm F/7 apochromatic refractor on its Berlebach Planet alt-az mount in my back garden to hunt down some goodies. Also I did observe some wonders with my WO 70 mm F/6 apochromatic refractor which I use as a finder scope. Temperatures were 4 degrees Celsius and there was a noticeable breeze occurring.
I observed from 5.15 to 6.30 pm first and then after dinner from 8.30 to 10.30 pm. That's over 3 hours in all. So it was a reasonably long time observing. And I did have 6 layers of clothing on me.

All doubles can be checked out on www.stelledoppie.it

1. Vega and its 2 optical 9.5 magnitude companions were spotted at a mere 40X. And I did notice that Vega itself was sporting its blue-white hue. Sep: 83.7" and 86.6". PA's: 184 and 39 degrees.

2. The uncertain double Zeta Lyrae was very easy to split in my 70 mm apo at 11X. Magnitudes: A = 4.3. B = 5.6. Sep = 43.7". PA = 150 degrees. The colours I am quite content to settle on are golden-white and yellow-white. But it is okay to disagree. The colours are very subtle. I did increase my magnification to 40X and 112X in the main scope to get those hues.

3. The famous double-double Epsilon 1,2 Lyrae was next of course. All 4 white stars were split at 112X with the tiniest black gap between each pair.

4. Up to Cassiopeia now. Schedar (Alpha Cassiopeiae) is easy to split at 40X. This optical double star has the designation H 5 18. Mags: A = 2.4. B = 9. Sep = 70.4". PA = 283 degrees.

5. Nearby we have Achird (Eta Cassiopeiae) of course. It still is my favourite 4th magnitude double I have observed - although there is a 3rd star. Sep: A = 3.5. B = 7.4. C = 10.2. A and B are a true double. But C is optical. Sep's = 13.4" and 75.6". PA's = 326 and 126 degrees. A is G class yellow. B is M0 or K7 almond brown. C is white. All 3 stars easily split at 40X.

6. There appears to be more K7 class stars in Cassiopeia. TYC 3657 113 is one of them. It did look distinctively almond brown at 112X. Its magnitude is 8.8.

7. Another is TYC 3661 1475. It is brighter at magnitude 8.2. I pushed up my magnifications up to 167X to admire its almond brown shading.

8. Very near Mars was the true binary Zeta Piscium which was delightful to see split at 11X in the 70 mm apo. Magnitudes: A = 5.2. B = 6.3. Sep = 23.2". PA = 63 degrees. At 40X and 112X I could see that A is A7 white and B is F7 yellow-white.

9. Then came Mars itself. Its magnitude was -0.6. Its distance was 114.7 million kilometres from us. Its angular diameter was 12.2". Seeing was not ideal at 167X. But I could make out Syrtis Major and the North Polar Hood once again.

10. After dinner I went back to Cassiopeia and found STF 7 which is an uncertain double. A = 8. B = 8.5. Sep = 1.3". PA = 210 degrees. At 112X I could see it was double. But great joy was to be had at 140X and 167X! I had a smidgen of black space between the 2 stars. To yours truly there was a blue-white hue to the secondary, but A seemed white to me.

11. And so I come to a very beautiful optical triple star: STF 3053. My special thanks to Darren for highlighting it to us here on www.irishastronomy.org . Magnitudes: A = 6. B = 7.2. C = 11. Sep's = 15" and 98.8". PA's = 70 and 291 degrees. The spectral classes of A & B are G9 or K0 and A1. At 11X in my small apo I was somewhat surprised to see A & B split quite well. But to check out the colours I used 112X, 140X and 167X. The primary appeared mostly yellow with some orange mixed in. The secondary was a distinctive and quite strong blue. Could it be it's the most blue star I have ever seen? Maybe it appears that way because STF 3053 is completely new to me personally. The 3rd star was white. I would very strongly recommend this marvellous system to anybody - especially if they are not into double stars.

12. I stayed in this area of Cassiopeia to successfully find and split HJL 1. It sure is nice to have come across Jean Louis Halbwachs first catalogued double star and it is a true binary. Magnitudes: A = 10.1. B = 11.1. Sep = 31". PA = 351 degrees. Easy split at 40X and 112X like 2 very faint eyes spaced apart.

13. HU 1006 is a true binary. Magnitudes: A = 10.5. B = 10.8. Sep = 2.8". PA = 195 degrees. I was welcomed to see a most tiny piece of black space between A and B at powers 112X, 140X and 167X. I did notice at least one of the stars was K class orange alright. A delightful double to end on.

14. Finally I do have a carbon star for you all. I had printed off a Guide 9.1 DVD for this new-to-me carbon star Case 711. Another designation is IRAS 001341 5553. That's taken from Simbad and AAVSO. But completely by accident I discovered another designation GSC 03657-00983 over on www.aavso.org . And I know some of you prefer that latter designation. Case 711's Right Ascension and Declination are: 00 hours 16 minutes 04.14 seconds and +56 degrees 09 minutes and 50.84 seconds. There is a 9.8 magnitude star very close by whose designation is TYC 3657 657 and it was easy to see at 112X. Once I found that star I set out to find my new spectral class C carbon star. For some reason I had great difficulties spotting GSC 03657-00983. I had no sight of it at powers 140X and 167X. Thankfully with my Nagler 5 mm, which gives me 225X, I was beginning to catch a glimpse of it. It was only when I increased my magnification to 320X did I see a very dim orange star. Seemingly because of the wind and not great seeing conditions I should have seen it at lesser magnifications. You see, according to Guide 9.1, Case 711 has a magnitude of +11.7. Simbad suggests its magnitude is +10.5. But they do add the ~ symbol which implies the star is variable. Maybe it goes dimmer than 11.7. I don't know. I'm not seeing a visual record on AAVSO. But never mind. It's my 18th observed carbon star in Cassiopeia and my 95th overall.

I did have a go at STT 1 during this session. It is a very challenging uncertain double with magnitudes 7.5 and 9.5. The separation is 1.6" and the PA is 212 degrees. I tried 320X but sadly I got no joy. The delta mag is too great for my scope. Larger apertures will have a better time splitting it - I am very sure.

That's it from me for now.

Comments, images and corrections are very welcome.

Clear skies, Aubrey.

Love reading all these reports. Thanks

Some interesting data on blue stars in this Cloudy Nights post Aubrey -

www.cloudynights.com/topic/568921-lists-of-most-blue-stars/

Finbarr.

Thank you, Finbarr, for that link from Cloudy Nights.
I will go through it later in more detail.
Initially these conversations sure are very interesting

Clear skies from Aubrey.

Good morning Aubrey,

You had a tremendous observational session last Wednesday - very many thanks for sharing it with us.

As Dónal said 'I love reading all these reports'. 

It was great to read that you spent time in Lyra, as you know it's my favourite constellation! The double-double is a gem, and Vega's colour, which you highlight, is striking. 

As I was reading through your observations in Cassiopeia I was wondering whether you managed to observe STF 3053, and BANG there it was listed as number 11. Your notes on it are fantastic. Who knew it was a triple? That makes it all the more interesting now. So, I must try to see that third star ASAP. Also, the colours you describe are brilliant... That's a mighty fine scope for picking out subtle hues. 

And speaking of colours, did you notice a blueish hue to the NPH? 
When I observed it last week it seemed to have a blue tinge to it!

BTW, congratulations on observing your 95th Carbon star - that's some going. 

Clear skies, well at least from 4pm  

See you later, 

Darren.