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Short double star session - 25th March 2022


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I had the LZOS 130mm out on the AZ100 Goto. The conditions weren’t great in terms of transparency so I decided on a short session with some doubles. I mainly used a 24mm Panoptic for finding, and either the 2 to 4 Nag zoom or the 2.5mm TOE to split the tighter doubles.

@chiltonstar had posted up two challenge doubles in Leo, Beta 603, near Beta Leonis at 1.0” and Sigma 1517 near Delta Leonis at 0.7”.

I found both very easily (using the Goto but they were quite obvious anyway) but only managed to split 603. This one was tough but clearly there, I made sure not to check the p.a. before observing and the location I identified was correct. Seeing was ok, not amazing but when it settled the secondary was a clear separated star, not just a brightening on the diffraction ring.

I tried a few more from a SkySafari list I put together for Leo.

HR4028 was a nice one. 1.6” with 7.46 and 6.83 magnitudes, it was cleanly split, slight colour difference to my eye but I don’t this I’m particularly sensitive to colours in fainter doubles.

Omega Leonis I’m pretty sure was a fail. 0.9” with 7.28 and 5.42 magnitudes, I think the mag difference defeated me but I must go back and check this one.

49 Leonis was a good one, a lot easier at 2.2” with 5.67 and 7.90 magnitudes, very clear.

p4 Leonis was a fail, I think due to the poor transparency, I just couldn’t pick up the fainter secondary at mag 9.72, even though the separation was 2.7”.

I had a look at Algieba whilst I was around, looking fab as usual, two unequal yellowish airy disks with lovely diffraction rings.

Nice little session, kit worked well and the Goto was very accurate.

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Just seen your report Stu👍.

I must try these out soon..thanks for the selection.

If your Lzos couldn't split some of them though, I wouldn't expect my FS128 to fare any better..unless the slightly longer F8 focal length makes any difference?🤔

Dave

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26 minutes ago, F15Rules said:

Just seen your report Stu👍.

I must try these out soon..thanks for the selection.

If your Lzos couldn't split some of them though, I wouldn't expect my FS128 to fare any better..unless the slightly longer F8 focal length makes any difference?🤔

Dave

Definitely worth a try Dave. Focal length, doublet vs triplet, local seeing conditions, eyesight, plenty of variables which might mean you succeed. I need to get my eyes tested again as I am wondering if I’ve now got some astigmatism affecting things. My local seeing conditions also seem a bit dodgy so I need to get somewhere away from town a bit I think.

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Had another nice session last night on a variety of objects, including some carbon stars and doubles.

UU Aurigae which has a colour index of +2.98. I wish I had seen it was a pulsating variable when I observed it, then I could have checked the brightness; it varies between +4.9 and +7.0 over 441 days. In fact most of these carbon stars seem to be long period variables which should probably have been obvious to me but wasn’t something I had considered before.

X Cancri has a colour index of +3.21

T Cancri was the best of them in terms of colour. It is quite dim at +8.68 but has a colour index of +4.88 which is very red.

Finally one from @wookie1965‘s list the other night, La Superba. This one is less red (+3.24), but brighter at mag 5.26 so is a lovely sight.

From the doubles list, I verified that I didn’t quite manage Omega Leonis, just a bit of elongation, it’s very close with a bit of magnitude difference.

Had another look at Thera Aurigae which a good one; 4.2” with +2.65 and +7.2, so the secondary is a tiny pinpoint of light very close in.

Xi Bootis was another nice one, 5.0” sep with +4.67 and +6.95, east enough and enjoyed the mag difference.

Plenty of other non double/carbon star targets seen, plus a few regulars such as Izar.

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5 minutes ago, Stu said:

Had another nice session last night on a variety of objects, including some carbon stars and doubles.

UU Aurigae which has a colour index of +2.98. I wish I had seen it was a pulsating variable when I observed it, then I could have checked the brightness; it varies between +4.9 and +7.0 over 441 days. In fact most of these carbon stars seem to be long period variables which should probably have been obvious to me but wasn’t something I had considered before.

X Cancri has a colour index of +3.21

T Cancri was the best of them in terms of colour. It is quite dim at +8.68 but has a colour index of +4.88 which is very red.

Finally one from @wookie1965‘s list the other night, La Superba. This one is less red (+3.24), but brighter at mag 5.26 so is a lovely sight.

From the doubles list, I verified that I didn’t quite manage Omega Leonis, just a bit of elongation, it’s very close with a bit of magnitude difference.

Had another look at Thera Aurigae which a good one; 4.2” with +2.65 and +7.2, so the secondary is a tiny pinpoint of light very close in.

Xi Bootis was another nice one, 5.0” sep with +4.67 and +6.95, east enough and enjoyed the mag difference.

Plenty of other non double/carbon star targets seen, plus a few regulars such as Izar.

Great to hear this Stu. We’ll make a variable star observer of you yet 👍🏻

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