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Mick H

Splitting Doubles Stars

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I would like to have a go at splitting doubles stars with my NexStar 8se, I have heard about it but never really tried it.

Have viewed at Albireo which i love. 

So my question is will the NexStar 8se be good for this, and if so any advise with splitting doubles stars.

 

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SCTs don't have tight stars like refractors, but they work just fine. My C9.25 makes 0.7" look easy and well separated.

Use a power suitable for the target. Stars look better at lower powers, but, sometimes for tight doubles you have to push it a bit more than normal. I sometimes use a 6mm eyepiece which gives x392. As long as the seeing is reasonable, otherwise you'll just see fuzzy blobs.

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It should be absolutely be fine if the collimation is ok. You will need to wait for the scope to cool down before trying any close doubles (closer than 2-3 arcsec) and need steady seeing.

Wide doubles, any scope will do

The weapon of choice for close doubles is generally considered to be a long focus refractor, for reason of their contrasty diffraction patterns, but I've used all sorts successfully over the years, including short focus Nertonians. The main thing is that the optical quality needs to be good, and the seeing good enough to allow full use of the scope's resolution. Refractors really come into their own on doubles that are very unequal but your scope should not be too far behind.

 

 

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Keep in mind that seeing conditions are the difference between splitting on one night and not the next night, i have tried seeing the trapezium on several consecutive nights, then, one night it just popped out.

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Thanks for your input, I'll have a try at trapezium.

Any suggestions for other doubles?

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👍

Wow that is a list to get through, thanks cotterless.

That will keep me amused.

 

Edited by Mick H
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Orion is well placed currently and has plenty of doubles of varying degrees of difficulty. My favourites are:

- Rigel

- E & F Trapezium

- Alnitak

- Sigma Orionis

- Eta Orionis

- 32 Orionis

- 52 Orionis

The last two can be tough, especially 52 Orionis.

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2 hours ago, Sunshine said:

Keep in mind that seeing conditions are the difference between splitting on one night and not the next night, i have tried seeing the trapezium on several consecutive nights, then, one night it just popped out.

Hi Sunshine, is the trapezium the 4 stars in the center of orion? Or is there more to it than that, I have seen these many times but if they are not the trapezium what am I to look for?

Thank you

 

Baz

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Thanks John, I will have a look at those targets.

If 32 and 52 Orionis can be tough for you, then I will be struggling.

I will try hopefully Saturday night if weather is kind here.

Edited by Mick H
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I have been looking at castor when it comes around at about 3am. As I understand this is 6 sun's in binary pairs, I can see two "stars" when viewing castor does this count as a split as such?  Feel free to correct me if I am wrong about the above.

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10 minutes ago, Mick H said:

Thanks John, I will have a look at those targets.

If 32 and 52 Orionis can be tough for you, then I will be struggling.

I will try hopefully Saturday night if weather is kind here.

Hi Mick, when I am a struggling to split stars, I just drink more. That seems to help.  😁

 

Baz

Edited by Barry-W-Fenner
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1 minute ago, Barry-W-Fenner said:

Hi Sunshine, is the trapezium the 4 stars in the center of orion? Or is there more to it than that, I have seen these many times but if they are not the trapezium what am I to look for?

Thank you

 

Baz

There are the E and F components to the Trapezium which are more of a challenge. The main four can be seen in just about anything; my little 63mm showed them easily at x35 last night. E & F need good seeing as much as anything.

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10 minutes ago, Barry-W-Fenner said:

Hi Sunshine, is the trapezium the 4 stars in the center of orion? Or is there more to it than that, I have seen these many times but if they are not the trapezium what am I to look for?

Thank you

 

Baz

Yes, it is E and F stars in the trapezium which are the real challenge, for my eyes at least.

5CF211AB-F8EA-4616-A55C-C205C34E0CD6.jpeg

Edited by Sunshine
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1 minute ago, Stu said:

There are the E and F components to the Trapezium which are more of a challenge. The main four can be seen in just about anything; my little 63mm showed them easily at x35 last night. E & F need good seeing as much as anything.

Thanks Stu, I assumed the 4 you can see are A to D  so I need to spot E & F now then! I though seeing the main 4 was to easy to count as a split 😂

What is there rough location to the main 4 stars? I should check the app really!

 

Baz

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3 minutes ago, Barry-W-Fenner said:

I have been looking at castor when it comes around at about 3am. As I understand this is 6 sun's in binary pairs, I can see two "stars" when viewing castor does this count as a split as such?  Feel free to correct me if I am wrong about the above.

Yep, splitting the two close ones is the goal there. They are unequal brightness but similar colour ie white. The others show as much wider separation but they have not be anything I was aware of before checking Skysafari just now.

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3 minutes ago, Barry-W-Fenner said:

Thanks Stu, I assumed the 4 you can see are A to D  so I need to spot E & F now then! I though seeing the main 4 was to easy to count as a split 😂

What is there rough location to the main 4 stars? I should check the app really!

 

Baz

This shows the locations. F is more difficult because C is relatively bright. When the seeing is good they are much easier. Good cooling and collimation, plus the right magnification and patience are all required.

20200130_213217.jpg

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21 minutes ago, Sunshine said:

Yes, it is E and F stars in the trapezium which are the real challenge, for my eyes at least.

5CF211AB-F8EA-4616-A55C-C205C34E0CD6.jpeg

Excellent thanks for the attached info Sunshine! I didn't know about E & F

Baz

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15 minutes ago, Stu said:

This shows the locations. F is more difficult because C is relatively bright. When the seeing is good they are much easier. Good cooling and collimation, plus the right magnification and patience are all required.

20200130_213217.jpg

Thank to you to Stu, orion is in a great position around 9pm so I will give this a go. Seeing and cloud permitting

 

Baz

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26 minutes ago, Sunshine said:

Yes, it is E and F stars in the trapezium which are the real challenge, for my eyes at least.

5CF211AB-F8EA-4616-A55C-C205C34E0CD6.jpeg

Looking at this diagram, I assume it is not possible to see I&G. They look like they could be a bit on the small side.

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1 hour ago, John said:

The last two can be tough, especially 52 Orionis.

Hi @John,

I don't recall having split this one,

Have you managed to split 52 Orionis and if so with what equipment?

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I've never managed I or G with my 12 inch dob.

I find getting E & F both seeing dependant and also finding the "goldilocks" magnification. Too high or too low and you don't seem to see them. I often find 150x - 200x just right. I can see E easily enough with my 100mm scopes and F from time to time under excellent seeing, E & F more regularly with my 120mm and above. At 200x with my 12 inch dob they are very clear indeed unless the seeing conditions are awful - in which case I should not be trying to observe uneven double stars anyway !

 

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Thanks John. This write up gives me confidence that I can find E & F under the right conditions. I guess I am being optimistic about I&G then. A bit like some of the Uranus and Neptune moons 😂

Baz

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13 minutes ago, Geoff Barnes said:

Hi @John,

I don't recall having split this one,

Have you managed to split 52 Orionis and if so with what equipment?

I've split 52 with my 12 inch dob and my 130mm triplet refractor. I've had a close split (ie: snowman or peanut shape) with my 120 and 100mm refractors. It's a tough one though. Chris (chiltonstar) observed it recently with his 180mm mak-cass:

 

 

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1 minute ago, Barry-W-Fenner said:

Thanks John. This write up gives me confidence that I can find E & F under the right conditions. I guess I am being optimistic about I&G then. A bit like some of the Uranus and Neptune moons 😂

Baz

Triton at Neptune should be possible at high power Baz but you need to keep trying for it. Its magnitude 12 and quite close to Neptunes disk but its position changes night to night as it orbits.

 

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