Observations -1st May 2020

Hello, one and all.

I set up my William Optics 158 mm F/7 apochromatic refractor and its WO 70 mm F/6 small apo on the Berlebach Planet alt-az mount in my back garden on Friday 1st May 2020 for a marathon 4 hour session. Mirror diagonals are fitted to both scopes. Sunset occurred at 20.55 Irish Summer Time (IST). Temperatures dropped from 4˚Celsius to 2˚C between 20.30 IST to 00.30 IST. There was always a slight breeze at all times. Seeing conditions were improving as the night wore on.
I had a Guide 9.1 DVD map with me which I had printed out a few days in advance. There were 19 listed objects to observe on it, each of them in Canes Venatici. All in all, I observed 21 wonderful celestial objects including the Moon and Venus. However I didn’t find the time to observe the open star cluster Upgren 1. But I will return to this enigmatic set of stars the next time. Interestingly there does not appear to be an Upgren 2 star cluster.
I observed 14 doubles. 2 triples and 3 carbon stars.
But before I start, there could have been a major problem regarding Chinese lanterns. One flew over my area which definitely was far too low. The orange ball greatly startled me. The Gardaí helicopter was in the area and that might have prevented any more being launched. I did have my Smartphone on me. I was going to give the Gardaí a call if there were any further sightings. But thankfully there were no more. Phew!

1. A 60.2% lit 8.6 day old Moon with a magnitude of -10.6 and a distance of 368,146 kms was observed at 40X and 112X. Its angular diameter was 32.5 arc minutes. Straight away I could see my favourite lunar feature Rupes Recta easily visible at 40X. But at 112X I saw Rima Birt close to RR. It’s only my 2nd time to observe it. Somewhat shorter and narrower than Rupes Recta it’s all the same a very nice rille to see and its length is some 50 kms. After many years of seeking to get the opportunity of seeing the large 79 kms wide crater Newton, I finally got it. The centre of Newton was in darkness. (The Sun had not yet shone fully into it). But the whole rim was illuminated right on the terminator. I was very pleased.
2. Venus was a real blur as I observed her at 112X. She is still -4.7 in magnitude and was 63,467,000 kms from Earth. She was a very fine crescent 24% illuminated and definitely getting larger each time I observe the brightest planet. On Friday night she had an angular diameter of 39.3”. Maybe the next time seeing conditions will be far better. They certainly could not be much worse.

So then for the rest of the night I observed the rest of these over my 4 hour session in the great constellation of Canes Venatici. Figures for all these doubles and triples are from www.stelledoppie.it . Carbon stars’ figures are from various sources.

3. Cor Caroli was my first target of course. I managed to find it before it actually appeared with my own eyes using the WO 70 mm small apo at 11X. Magnitudes: A = 2.9. B = 5.5. Sep = 19.5”. PA = 230˚. I got a wonderful tight split at 11X. In the main scope I could once again see that A is white and B is yellow-white at 40X. The 2 stars sit side by side. Very satisfying!

4. I then starhopped my way up to Y Canum which is one of the brightest carbon stars available to us. The magnitude range is from 4.9 to 5.9. Maybe next time I will try to give an estimate. There are very few stars near it which give an easy comparison as to what magnitude it is. You are right, Paul. There is no red colour at all, but it does exhibit a good strong orange hue.

5. 2 Canum I had observed before, but not for a long time. It is an optical double star and an easy split at 40X. Magnitudes: A = 5.9. B = 8.7. Sep = 12.1”. PA = 260˚. The spectral classes of the 2 stars are A = M1. B = F8. A is more of an orange star, whilst B is to my eyes was slight blue. That’s strange. I thought B ought to be more yellow-white. I tried high powers – up to 167X in fact. But I got no change.

6. Very close by is Stf 1624 which is a triple star. A & B are an uncertain double. B & C are an optical double. Magnitudes: A = 7.3. B = 10.2. C = 9.2. Sep’s = 5.9” & 161.9”. PA’s = 153˚ and 143˚. At 40X A and C were easily split of course. But to split A and B I required 112X. It was a very nice view. A was white. B was yellow-white. C was simply white. A & B seemed to point to C – a nice effect.

7. Again very close by to the 2 systems above there was another true binary. Stf 1610 has magnitudes: A = 8.6. B = 10.6. Sep = 29.5”. PA = 331˚. There was no need to go higher than 40X. Both stars easily seen. A is yellow.

8. Now that the sky was as dark as it could be I could take my time in seeking about more doubles near Cor Caroli. Stf 1688 is an optical double. Magnitudes: A = 9.2. B = 11.1. Sep = 14.4”. PA = 344˚. I split it first at 112X, but then discovered I could do the same at 40X. A is yellow.

9. Stf 1702 is a true binary on the other side of Cor Caroli. Magnitudes: A = 8.7. B = 9.4. Sep = 35.9”. PA = 83˚. Both stars are a nice orange. Wide split at 40X.

10. The next star TT Canum is easy to see with its reasonably strong orange colour. It’s just the 2nd carbon star I have observed in Canes Venatici. The next time I observe it I will give an estimate to what its magnitude is. Recently on www.cloudynights.com someone suggested one could fit Cor Caroli, Stf 1688 and Stf 1702 split and in the same fov. With my 2” 28 mm eyepiece I did precisely that. All 3 doubles split. But I could also fit TT Canum into the frame while I was at it. Excellent!

11. Es 1405 is a triple star and is north of Cor Caroli. A & B are optical. B & C are an uncertain double. Magnitudes: A = 9.9. B = 11.7. C = 11.9. Sep’s = 65.8” and 4.4”. PA‘s = 283˚ and 253˚. I had no trouble splitting A and B of course. But B and C were a different matter. The 2 stars are so faint. Up I went in magnifications 112X, 140X and 167X. Still no split. So out came my 5 mm Nagler which yields 225X. At this point I did succeed in seeing the 2 stars split. How tough that was!

12. Stf 1723 is an easy true double east of Cor Caroli by about 2˚. Magnitudes: A = 8.7. B = 10.1. Sep = 6.3”. PA = 12˚. Good tight split was to be had at 40X. But the yellow colours of both stars were very good at 112X.

13. Directly below Stf 1723 we have a challenger of a true binary. 15 Canum has magnitudes: A = 6.3. B = 9.2. Sep = 1.3”. PA = 269˚. So it is seriously tight at whatever power I planned to use. I had no split at 167X. Therefore once again my 5 mm Nagler came to the rescue. Beautifully tight split at 225X. Success!

14. The rest of these systems proved to be easy. HJ 530 is an optical double. Magnitudes: A = 8.9. B = 10.5. Sep = 39”. PA = 49˚. Easy split at 40X and 112X. Both stars have spectral classes G5. The stars portrayed very fine yellow colours.

15. HJ 529 is very close by and is a true binary. Magnitudes: A = 9.6. B = 11.9. Sep = 17.8”. PA = 132˚. A’s spectral class is M1. B is M3. A is red okay. But with the strong Moon shining brightly there was no way could I figure out B’s colour. But I got a nice view at 112X and 167X.

16. 25 Canum is a true binary. Magnitudes: A = 5. B = 7. Sep = 1.7”. PA = 94˚. There was evidence of a secondary at 112X. But what a magnificent split I had at 140X and 167X. It was my first time to observe 25 CVn. It won’t be my last. Both stars were white to me. Spoil yourself with this one. I can guarantee you will not be disappointed!

17. Seriously close by to the south of 25 CVn there is another great treat to be had. AG 191 may be an optical double; but what a remarkable sight it truly is! Magnitudes: A = 9.8. B = 10.1. Sep = 9.3”. PA = 299˚. Finely split at 40X, but of course I went up to 112X for the colours. The spectral classes are F8 and K2. A is yellow-white. B is orange. It is a rare combination indeed.

18. Stf 1755 is north of 25 CVn and is an optical double. Magnitudes: A = 7.3. B = 8.1. Sep = 4.1”. PA = 133˚. A is yellow; while fainter B is slight yellow. I was very surprised I had a very tight split at 40X. But to get a bigger black gap between them 112X and 140X proved that Stf 1755 is a true gem!

19. HLM 5 is the first true binary I have which has this designation. Perhaps someone can tell me what HLM stands for? It has magnitudes: A = 10.1. B = 10.9. Sep = 6.1”. PA = 161˚. It sits beside the M1 star CP Canum. At first I had no problem splitting HLM 5 at 112X. But I was pleasantly surprised I could split it at 40X with the tiniest gap in between. At either power it definitely is yet another wondrous gem!

20. A1855 is very close by. It’s a true binary with magnitudes: A = 9.7. B = 10.5. Sep = 3.7”. PA = 291˚. I had little difficulty splitting is at 112X.

21. Finally I do have one more carbon star for you all. TYC 2548 690 is the 3rd such star in Canes Venatici and it’s quite near the globular star cluster M3. There is an alternative designation – NSV 20027. But I prefer TYC’s. I believe it is not a variable star. The magnitude is +9.5. And the spectral class is R2. It’s placed right beside a K class orange star called TYC 2548 307 which is brighter at +8.9. The 2 stars are 1 arc minute apart and it is easier to figure out which star has the stronger orange hue. Of course it’s TYC 2548 690. I recommend both stars to each of you.

No stargazing tonight as there is too much high cloud.

April 2020 will go down as the only month I had 14 observing sessions.
I wonder how many I will have in May 2020.

Thank you for reading.
Comments are very welcome.

Clear skies from Aubrey.

Hi Aubrey,

Your brilliant observational report was so enjoyable to read. At times, it felt I was reading a script from one of those old Westerns starring Clint Eastwood. Between your 158mm, and your 5mm Nagler - those tight doubles didn't stand a chance : ) 

Congratulations, on observing Rima Birt. Until your description, I was unaware of it - so many thanks for bringing that Lunar feature to our attention.

Also, congratulations on managing to place those four objects (Cor Caroli, Stf 1688 and Stf 1702, and TT Canum) in the same FOV - what a sight that must have been.

You make a great case for observing 25 Canum, and 25 CVn. I must add them to the list of objects that you've recommended we take a look at. Unfortunately, I've not had the chance to get out with my scope so far this month. In saying that, I did set it up yesterday evening, but clouds rolled in. I did manage to take a quick look at the moon tonight through my 10 X 50s, but I missed the occultation, and Venus' crescent shape. Hopefully, we'll have clear skies tomorrow night.

You'll be glad to know that I believe I have identified what the letters HLM represent. In his book 'Double & Multiple Stars, and How to Observe Them', James Mullaney states that they are an IDS/WDS code. Double stars that are listed under this code are attributed to the discoverer E. Holmes. I have read that that the 'E' stands for Edwin. He was an amateur astronomer who observed double stars through his home-made 12 inch reflector. He is best known for discovering Comet 17/P Holmes.You can read more about the rather interesting Mr. Holmes here.

arxiv.org/ftp/arxiv/papers/1405/1405.7723.pdf

Chat soon,

Darren.

Hi Darren.
It's always great to hear from you.
I'm finally going to add Edwin Holmes to that long list of double star discoverers.
There. I've done that!
I forget who sent me the list. Finbarr or Keith come to mind.

Comet Holmes was one of the few comets I have successfully observed when it exploded in 2007. Did it really happen that long ago??

So now I'm being compared to Clint Eastwood. Ha ha ha.
He was one cool dude!
The Good, the bad and the ugly is probably my favourite movie of his.

Clear skies tonight!

Aubrey.

HI Aubrey,

I agree 'The Good, the bad and the ugly' is the finest of his Western films. I've seen it a few times now, and it always captivates me. Clint Eastwood is a cool dude alright,  but anyone who manages to achieve 14 observation sessions in a month would give him a run for his money in my eyes : )

I'm about to have a look at the Moon now. I managed to see Venus earlier tonight. She looked great, and her crescent phase was very nice indeed. Here's hoping those clouds cleared off,

Clear skies?

Darren,