Observations 22nd March 2020

What a marvellous year some of us are having!
I have had 5 observing sessions in January,
5 more in February.
And now 5 more in March.
That was never the case in the last number of years.
If God protects us from the Corona Virus, it might be a bumper year for us Irish observers.
I started setting up my William Optics 158 mm F/7 apochromatic refractor with its 70 mm F/6 small apo, which is also made by William Optics, in my back garden once again from about 16.30 UT. Sunset occurred at 18.42 UT from Dublin, Ireland. The Sun was shining very strongly in the lovely blue sky before then.

My Guide 9.1 DVD provides the figures regarding Venus.

www.stelledoppie.it provides the figures for the doubles.

1. Venus is now at magnitude -4.5; 108,573,000 kms from Earth; 52.4% illuminated; angular diameter of 23". I found it in my small 70 mm apo at 11X. Then at 40X in my main scope. At 17.14 UT I could see herself with my own eyes. There was the problem of shimmering at 112X, 140X and 167X. But as the late afternoon continued that became less and less. So eventually I did use 225X as sunset approached. I could just make out that it was showing a little bit more than 50%.

2. Epsilon Arietis is a wonderful true binary which was about 1.5 degrees from Venus. And it was a real joy to see its 2 components cleanly split at 167X and 225X. It has been a number of years since I did observe this stunning double. And never have I studied it while it was positioned in the north western sky. Its magnitudes are: A = 5.2. B = 5.6. Sep = 1.3". PA = 210 degrees. Because of its position the 2 stars point downwards to the north western horizon. Very nice effect!

3. I always seem to be starting with Zeta Cancri (Tegmine) again. But it gives me the opportunity to check sky conditions before moving on. As usual I get the clean split of A and B at 167X.

4. Having observed V Cancri 2 days ago, it has become a relatively easy carbon star to find for me. And that's despite its lowly magnitude of +10.8. That's my estimate. V Cnc is definitely brighter than the 11.0 magnitude star TYC 1382 755 which is directly to its east. There is an 11.8 magnitude star in between both stars. I have discovered its spectral class is Se on Guide 9.1. Can anyone explain Se? Does it still mean it is a carbon star? Thank you very much. Observed at 40X (just visible), 112X, 140X and 167X. It is a strong orange carbon despite its faintness and I love it!

5. As I have now observed the only 6 carbon stars in Cancer, I thought I should see some of them once more. X Cancri is bright at magnitude +6.6 (my estimate) and is a reasonably strong orange star at 40X. Spectral Class: C6 or N2. The former is a more up to date classification.

6. T Cancri is an even richer orange carbon star. I am of the opinion its magnitude is +8.5 as on Sunday night, but observers on www.aavso.org seem to be disagreeing with that. I shall let John O'Neill look into this. John regularly checks out the IFAS website. This carbon was definitely my favourite of the night.

7. Not all triple stars are particularly stunning. But 80 Cancri is good to find as it leads to other doubles nearby. Magnitudes: A = 6.9. B = 9.5. C = 10.9. Sep's = 128.4" and 147.9". PA's = 253 and 317 degrees. Easily split at 40X. All 3 are white. It probably is not a true triple star system.

8. Stf 1322 is an absolute stunner! It is an uncertain double however. Magnitudes: A = 8.3. B = 8.7. Sep = 1.7". PA = 53 degrees. I thought this would have been quite difficult to split. But at 112X and 140X I had a tiny gap between the 2 white stars.

9. HDS 1328 proved quite a serious challenge. Why is it HDS designations are so difficult to separate? Anyway this is an optical double. Magnitudes: A = 9.5. B = 11.8. Sep = 4.7". PA = 145 degrees. A is yellow. I required 167X to catch an elusive glimpse of B.

10. Stf 1317 is an uncertain double. Magnitudes: A = 8.5. B = 9.9. Sep = 7.8". PA = 63 degrees. No problem here - split at 40X and 112X. A is yellow-white. B is white.

11. HJ 118 is an optical double. Magnitudes: A = 10.8. B = 11.3. Sep = 12.5". PA = 320 degrees. Easily split at 112X. Both stars are white.

12. HJ 115 is also an optical double. Magnitudes: A = 9.4. B = 11.0. Sep = 18.9". PA = 121 degrees. Easily split at 40X and 112X. A is yellow alright.

13. Seeing I was in the area again. GM Cancri was my last carbon star on this Sunday night. It has a magnitude of 8.6 or thereabouts. Easily visible at 40X and 112X and I describe it as an orange star.

14. And to conclude my night I went back to SLE 339. As we all now know, Guy Soulié was its discoverer. It is an uncertain double. Both stars have magnitudes 10.2. Sep = 6.7". PA = 121 degrees. Barely split at 40X. But good at 112X. What a great Frenchman the main man was!

That's my lot.

Thank you for reading.

Comments, as ever, are very welcome.

Clear skies to all,

Aubrey.

Superb stuff Aubrey, maybe we should have a new designation AUB to honour Ireland's most prolific doubles observer . Our trusty search engines seem to think that S (or Se stars) are next in line to the M giants, but contain equal amounts of carbon and oxygen. So more of a CO star than a plain carbon... I'm sure you're still entitled to add it to your list though.

Clear skies,
Finbarr.

Thank you, Finbarr.
Your totally correct regarding S class stars.
My copy of Burnham's Celestial Handbook volume 1 didn't go into that detail.
But I have no doubt there are many websites which clear it up.

12 months a guy on Cloudy Nights issued me a list of 2343 carbon stars which are brighter than magnitude 13. That list includes southern hemisphere carbon stars.
So I do realise I don't have to seek them all out.

But I do wish there was a way to rearrange the whole list.
You see, a lot of it is not in Right Ascension order.
I've asked Simbad, but so far I have had no reply.

What I need is to make a list of all carbon stars which are visible from 53 degrees north. The list I was given is a bit haphazard and it goes on for 24 pages. I have to go down through it with estimated Right Ascension and Declination in hand.
Take Cancer for example. Its RA ranges from 7 hours 55 minutes to 9 hours 21 minutes. Its declination ranges from +33 to +6. I then have to go through all these 24 pages to come across any possible carbons. I will take any advice on this issue.

By the way, I should have stated T Cancri has a spectral class of N5.
GM Cancri is C4.
And as V Cancri is contained in the list it must be a carbon star.

Kind regards to you Finbarr and everyone.

Aubrey.

Hi Aubrey,

Another fantastic report from you, and I second Finbarr with regards to the AUB designation

I very much like how you describe Epsilon Arietis as pointing down towards the NW horizon... Lovely description!

Very well done on splitting HDS 1328, that must have felt great. 

And what about all those carbons stars... Does that bring close to 100 now? 

The skies are once again clear. I believe you're right: At this rate it'll be a bumper year for Irish Astronomy. 

Long may these clear skies last. 

Darren. 

Good evening, Darren and Finbarr.
It's Tuesday night and I now realise I should have set up the scope once again. But I didn't like the sky the way it was looking at 6 pm. So I thought on this occasion I would give it a miss. What a mistake that was!

However I have now planned my next observing session which will probably Wednesday evening.
I have 12 doubles to seek out in and around Iota Cancri and 57 Cancri. These are both spectacular double stars which I have observed before.
When I do successfully split 57 Cnc I will think of Heather Couper who tragically died on 19th February 2020. I had met Heather in French Polynesia as part of the Total Solar Eclipse in 2010. It was my 5th TSE. I had told her about my new William Optics 158 mm apochromatic refractor on that holiday and my very first observation of 57 Cancri.

Of course Venus will also be observed all being well.

I have now observed 85 carbon stars.
And I'm now wondering about Lynx. 

Clear skies,

Aubrey.

Hi Aubrey, 

At 7pm this evening I was at the dinner table with the family. The kitchen is at the front of the house, and our table is next to the window. Meaning, we could see Venus in the evening sky. Once, we cleared the table, I decided to set-up the scope out front to have my first look at the planet this year. Several eyepieces were used, but Venus look best at 200X. Needless to say, your recent observational reports encouraged me to take a look at it. 

It looked so bright, and it's shape was captivating. So, many thanks for your recent reports on Venus because without them I probably would not have viewed it earlier. 

Also, what a touching tribute to Heather Couper... Sorry to read she passed away. 

Clear skies, 

Darren.