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Observing Report 050506

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I managed to get out last night for a few hours.

Due to a family commitment I did not start observing until 10pm (21.00 UT)

I have list of doubles in Leo I had been planning to observe all in the Mag 7.5-9.5 range. I have noticed that the Moon would be in Leo and was probably going to cause difficulties.

Seeing was 2-3/5 and the transparancy was 3/5

By the time I got out Saturn was sinking fast in the West and Leo & the Moon were prominent.

My 1st target was STF1438. This had not been measured since 1926 and I was hoping to check it out.

Unfortunaely by fears about the Moon meant that any faint star in the West of Leo was a pain to observe.

So ever the pragmatist I came inside and got my A607 point & shoot and took some shots of the Moon, as were a number of the SGL team :D.

I also tried tracking down SW3 but even in my 10x50's the sky was to light to see it, as East is towards London so the sky is most light polluted there.

At about 11pm (22.00 UT) the Moon dropped below some tress and this enabled me to track down STF1504 a pair of 7.5 Mag stars separated by 1.2".

The star is very close to 58 Leo (about a degree to the East) and should be in the same FOV with a wide angle eyepiece.

The star looked 'squashed' at x48. Deeply notched at x133 and clearly split at x266.

The stars were both white with the primary having a faint hint of blue. They are a very tight pair but being of equal brightness are easier to split than you would expect.

I estomated the PA at 120 degrees. (More on this below!!)

I moved onto STF 1825 a Mag 6 star just North East of Arcturus. This is an easy split at 4.4 degrees sep anf the primanry being mag 8.4.

I then line up IZAR (epsilon Boo). This is the opposite to STF1504 as it can be a real pain to split even though the secondary is mag 4.8 the problem is the Mag 2.5 Primary swamps the view. I did get a split at x266 and it is a fantastic contrast of yellow/orange primary and pale blue secondary. Definately worth the effort.

I had another go at SW3 and although I failed I did get a nice view of M13 which through the binos looked a bit like a comet (what would Mr Messier think eh?)

At this point I came in to upload the moon pics and check my info on STF1504. Too my surprise the PA in CduC was 301 and in the 33 doubles list 296. I was a bit concerned at this but after a few moments of thought the solution became apparent. I had reversed the primary and secondary. If you add 120 too 180 you get 300.

This got me thinking if both stars are the same Mag who decides which one is the primary??

The final star I wanted to check on was Porrima (gamma Vir) The split is currently 0.8" and this is within the reach of my scope. I can split zeta Cnc at 0.9" but Porrima has 2 factors that make it harder to split.

1- it is at a lower declination (-1) vs +18) so the 'seeing' is always worse than for a relatively high pair.

2- both stars are Mag 3.5 (zeta Cnc is 5.3-6.3) this make their discs appear larger so they overlap more and take more magnification to split. Last night x266 got the star elongated but not split.

at 1.30 AM (00.30 UT) called it a night as Saturday was going to be a busy family day.

Cheers

Ian

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Ah quite a good night then Ian well done on ya doubles :D

James

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It was good to read your report Ian. I have tried to split Izar a couple of times, as when you read about this double in some guides, it suggests it is easy for a small to mid sized 'scope. I tried twice this Spring using my LX90 and a 13mm EP (x154) to no avail - now I know that it needs a much higher magnoification to split, I will try again using my 9mm EP (x222).

Thanks for the report.

Tom

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Tom

x222 should do it.

But even at that mag you may have to let the seeing settle down for the secondary to be seen clearly.

Good Luck and let me know how it goes.

Cheers

Ian

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An excellent report as always Ian :D

Glad some people are getting out. I am also hampered with family stuff, well, that and clouds !

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Daz

Family comes 1st but you can g'tee that family stuff and clear night always co-incide :D

Cheers

Ian

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Yeah, but it's a close 1st!!!! :D

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Another nice report there, thanks for a good read! :D

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Just a quck update.

I managed to observe STF1438 and it looked singular. :D

Looks like this companion is going to be a pain to observe.

The clouds have rolled in again.........

One the plus side the micrometer seems ok after initial tests on Castor & Regulus.

Cheers

Ian

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