5 Struve doubles in Canes Venatici

Hello, all.

On Tuesday night 5th May 2020 I set up my William Optics 158 mm apochromatic refractor in the back garden.
A mirror diagonal is fitted at all times. North is nearly upwards. East is a little bit below right of centre.
The temperature was a cool 6 degrees Celsius but there was no wind.
As the Sun had set at 9.02 Irish Summer Time, I observed Venus and the 4 stars of Castor first.

Then it was down to business in Canes Venatici.

The information for each of these doubles can be found on www.stelledoppie.it

They are all first time observations for me.

1. Stf 1632 is a true binary. Magnitudes: A = 6.8. B = 10. Sep = 10.1". PA = 192 degrees. A bit difficult to split at 40X. But at 112X and 140X it was easier to see A was yellow-orange (K0). B was white. It's near 6 Canum whose magnitude is 5.0

2. Stf 1607 is an optical double and is about 3 degrees west of Stf 1632. Magnitudes: A = 8.9. B = 9.8. Sep = 26.7". PA = 28 degrees. This one is even easier to split at 40X. Both stars are white.

3. Stf 1613 is an uncertain binary and is very close by. Magnitudes: A = 9.3. B = 9.4. Sep = 1.2". PA = 7 degrees. When I had written this one down in my preparations I fully knew it was going to be the toughest double of the night. At 112X and 140X my scope was trying very hard to see A and B. But even at 167X I had no black space in between them. So I grabbed my 5 mm Nagler which gives me 225X and I got success. How relieved I was! One star sits above the other. At no time did I experience any strange colours. So both are white to me.

4. Stf 1645 is a true binary. Magnitudes: A = 7.5. B = 8.1. Sep = 9.8". PA = 156 degrees. After Stf 1613 this one is seriously easy to split. 40X was sufficient. At 112X I could see A is yellow-white (F9). B is white.

5. I then discovered there was a problem with my scope. It turned out the barrel of my 2" 28 mm eyepiece would not move to the left. The reason was the barrel which is so wide was touching one of the legs of my Berlebach Planet alt-az mount. You see, Stf 1642 is right next to Stf 1645. And both are very close to my zenith. For the record: Stf 1642 is an uncertain binary. Magnitudes: A = 8.8. B = 9.4. Sep = 2.5". PA = 180 degrees. However to solve this mini crisis my 1.25" Pentax 10 mm eyepiece has a narrower barrel. So I did achieve a beautiful split at 112X for a few seconds of this final double star. In fact at 112X, Stf 1645 and Stf 1642 were split in the same field of view. Sheer joy! I must revisit this duo again.

Of course I will be adjusting my telescope mount a bit more for my next session in Canes Venatici.

Thank you for reading my latest report.

Comments are very welcome.

Clear skies from Aubrey.

HI Aubrey,

Very many thanks for sharing another detailed report with us. My heart sank when I read 'I then discovered there was a problem with my scope.' For a moment I thought you were going to be out action for while. Thankfully, nothing serious! 

Apart ffrom that, you seemed to have a great session - so many new objects for you! Well done, on splitting Stf 1613 - that 5mm Nagler did the job again.

All the best,

Darren.

Hi Darren and everyone.

I observed a non Struve double on Thursday night 7th May.

HO 536 is just north of a 7.1 mag. star called SAO 62964.
HO stands for George W. Hough who lived from 1836 to 1909 in USA. He discovered 627 double stars.
It was quite an initial test to split.
Magnitudes: A = 9.6. B = 11.3. Sep = 3.8". PA = 63 degrees.
I'm not sure what was preventing me from separating it at first. But I did see A and B with some black space in between at 167X. Then I returned to 140X and 112X and I had no problem splitting the 2 stars. It's often a good idea to use higher powers before lower ones. A is yellow - G class.
It's only my 3rd split double which starts with the designation HO.

Clear skies,

Aubrey.

Hello Aubrey,

Many thanks for your report on HO 536, and congratulations on splitting it. 

I never heard of George W. Hough before you posted about him. Amazing to think that he discovered so many double stars over the the course of his life. Did he use a reflector telescope? 

Good advice on using a lower power first when trying to split a star, I must try it next time round.

Clear skies,

Darren.