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Observation Report 28/06/06

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The sky was clear for the 1st time in several days and I managed to get a couple of hours observing in.

Transparency 4/5

Seeing 3/5

20/06/06 21.00-22.45 UT

Light pollution was noticable as the ZLM was around 4.

I only had one target in mind and that was the pair of stars TYC 2578-332-1/ TYc 2578-769-1. These are not listed a a pair in the WDS but from my observations and investigation using ALADIN/SIMBAD I suspected that this pair are actually HJ258. The current star noted as HJ258 is TYC 2578-126-1 and it is a single star!(for a full report you'll have to buy the next Webb Soc double star circular)

These star share a common proper motion through space and given there spectral classes of F6/G0 and their apparent visual magnitudes of 10.24 & 10.89 they could well be physically associated if not an orbiting pair.

I first calibrated PA dial on the scope using known bright pairs, Cor Caroli, Sigma CrB,zeta CrB.

I measured the PA and it agreed with the WDS at 254 degrees.

I took 11 measurements of the pair crossing the wire set at 0/180 degrees. The mean separation in time was 1.4 seconds.

Using the formula 15.0411x t x cosDec / sinPA. (15.0411x1.4xcos36.076/sin254) gives a separation of 17.8 seconds.

The pair is currently listed at 16.9 seconds so I was fairly happy with these initial results.

To celebrate this I thought I would have a go at Zeta Herc. This a a close (1") pair of about 3 magnitudes difference.

I did not split it but I got a clear elongation at x250. If you have a 6 inch scope and the seeing is good it is worth a go. If you do split it you will have cracked a tough one.

Cheers

Ian

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Nice report Ian.

In fact, it's got my juices going for trying some doubles observing myself :)

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Phil your 8" scope when properly cooled should get zeta.

Good Luck

Ian

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Ian,

It just so happens that Zeta Her was a suggested star in Sky and Telescope's June issue, I think. I tried it to see if it would be a good star to show at GCSP, but it was too close. My C8 split it pretty easily and I found it interesting because of the magnitude difference, but not enough so to show it to the general public. Nice star!

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So where was this Ian? I ask because I stayed out until past 11 last night as I wanted to see Polaris down the polar scope to align my pier. It wasn't dark enough by that time and I got summoned for "a chat before bedtime" at quarter past 11. No dark here yet (Yorkshire).

Captain Chaos

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Thanks Ian,

What with the short nights i'm getting a bit disheartened...However after reading your report i'm a bit more enthusiatic again.

Hopefully Satuday night wil be clear.. Going for a mega session then.

Greg

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CC

I live in SW London it get dark about 11.00 here. Zeta Herc is the bottom right hand corner of the keysrone is it is easy to find even in twilight skies.

Greg, glad you've got the bug again.

Going back to the original post it appears the pair I measured last night were caught on the UCAC2 proper motion survey and were part of a BAA paper in Dec 2004. They do not appear to have been associated with HJ258 yet.

Cheers

Ian

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Thanks Ian, it reinforces what I said to Naz, the slight differences we have in latitude makes a big difference in the amount of dark available.

Captain Chaos

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