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IAS observing at Sandymount -Friday 26 June 2015

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9 years 3 weeks ago #104318 by flt158
Thank you, Mike.
I should be down at about 9 pm.

I will be driving a blue Skoda estate.

The Great Red Spot is visible from 10 pm local time.

Aubrey.

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9 years 3 weeks ago #104326 by flt158
Hello, all. I was most privileged to meet up with the great Mike Casey and Liam Smyth last Friday night at the Martello Tower. It was also good to have Patricia for a while too.
We started observing at about 9.45 pm, and we did not finish until 12.30 am !!
Mike brought his 4" refractor, and I had my 158 mm apochromatic refractor. Refractors rule OK !
1. As ever we started off with the Moon. The eastern edge of Sinus Iridium was right on the terminator. Copernicus, Tycho and Rupes Recta were noted as observed.
2. We quickly went over to the western sky to behold the 2 brightest planets: Venus and Jupiter only 2.5 degrees apart.
Venus is now 37% illuminated and nearly as big as Jupiter (30" wide). I observed both at 40X and greatly admired the crescent of Venus. Callisto, Ganymede and Europa were on Jupiter's western side and Io was on Jupiter's eastern side. Some others saw both also.
Both the SEB and NEB were visible at this low power.
3. As Arcturus was now visible unaided, it was easy for me to find Izar. Quite a few passers saw the double star split at 112X and 140X. Some figured out the colours as yellow and blue.
4. Xi Bootis was admired next -split at only 40X
5. Some of our little group enjoyed Stf 1835 separated at 40X.
6. Stt 279 was split at 112X.
7. Finally we come to our challenging double star: 15 Bootis. It was still easy to find heading south of 20, 14 and 18 Bootis.
This time I could split it at 225X and 280X. It was a joy to split cleanly at these magnifications. i find myself still questioning the position angle that the experts tell us. I definitely agree with the 1" separation. But I do not agree with the 108 degree PA. This PA means I should see the secondary at the 4 o'clock position. However yet again last night, I see it at the 10 o'clock position. But this time I am delighted to say that I appear to have a new convert. Liam Smyth sees 15 Bootis B in the 10 o'clock position as well as me. Therefore, Liam's eyesight is really very good at present. The magnitudes of the 2 stars are 5.4 and 8.4.
Since I got rid of the dreaded spider's web simply by using my blower bellows with cleaning brush, my main triple lens is truly clean.
And so the debate continues to go on. Liam says he will do research on 15 Bootis; and he will be communicating with me. If B is really in the 10 o'clock position, then its PA ought to be about 285 degrees in true PA.
Also, Mike did perform a chromatic aberration test to see if my refractor is properly collimated by simply focusing in and out. We were delighted to state that my apo is very good in this regard.
Lastly, as many of you know, I have been discussing 15 Bootis on www.cloudynights.com .One recent individual has suggested fitting an 140 mm aperture mask on his refractor. I am considering doing the same. The advantage being that I might cut away the first diffraction ring of 15 Bootis. Thus making it easier to see the secondary star. Any opinions?

Thank you for reading.

Aubrey.
The following user(s) said Thank You: michael_murphy, lunartic_old, scfahy

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