First time double splitting

[Pixies]

13 minutes ago, MylesGibson said:

Also, if you are around the Beehive, there is another good triple system, Tegmine (Zeta Cancri) if I recall the name correctly! All reasonably well matched in visual magnitude. I've always liked that one. Splitting into 2 is fairly easy, but trying to get all 3 is a real challenge. I think I've only managed it the once with exceptionally good seeing. I must have another go soon!

Blimey - that's tight.

It's on the list

[John]

Tegmine is a fun challenge with smaller scopes:

 

[wibblefish]

1 hour ago, Bongo said:

Yeah, same here. I think there's a point when I'll have to actually start planning things out, rather than pointing the 'scope at anything that catches my eye or springs to mind while I'm out there. Not that the latter strategy hasn't been good fun, of course! Given the scarcity of decent clear night - got to make the most of those brief windows of opportunity, I guess.

I am currently trying out various types of object to see what I can get out of my telescope and to see what I enjoy doing. I have tried a bit of everything though so far the telescope is really shining when looking at wide field objects (constellation / star clusters), DSO's can be challenging and frustrating in equal measure but amazing when I can hit them  I am also hoping to get a clear night with the moon at some point!

With the rubbish UK cloud cover at present I am starting to have to try to plan sessions to feel like I get the most of them! 

I probably need to look back through my notes and have another go with new eye pieces as they are definitely a massive upgrade. 

@MylesGibson @John  @Pixies added a couple more the list now, cheers!

Edited January 20, 2021 by wibblefish

[Marvin Jenkins]

Hi wbblefish, good to see the enthusiasm is still high. I noted an earlier post you made about the questionable idea of posting your newbie observations. I can say that newbie observations are often the most revealing and informative.

We have all been there at some point and the obvious questions are not something to shy away from. I now realise that posts like yours, charting your journey are of major benefit to the newbies right behind you.

At the beginning of the journey the last thing you need is endless stuff about eye relief and calculations regarding aperture and focal length, that will all become a lot clearer when you have loads of scopes and no more money.

I will say that I put a lot more currency in planning and opportunity over equipment, especially when starting out. Hard to believe but your biggest drawback is lack of knowledge not scope size. I do not mean that in a derogatory way, but we all learn the skies as we go. There are veterans that can see stuff in your scope you think impossible.

I have been at this remarkable journey for just three years and I have so much to learn and this forum has been a God send. However, when you can get on Stellarium or whatever you use and plan what is possible, it will become easier.

Just to show you how planning should be perfect I am 109 of 110 in the Messier list. Due to the lack of planning I missed M68 in Hydra so I have my fingers crossed for the future. So close but so far due to poor planning. It is a summer target!

Good luck wibblefish, I think with better weather you are going to see what you want.

Marv

[lunator]

On 20/01/2021 at 11:07, wibblefish said:

Thanks, thats a great list

Hi Ian, Thanks, I think I was running at about 110x magnification according to the fov calculator I just ran through 90mm apeture / 660mm focal length + a BST 12mm and x2 barlow  I suspect it was more down to the CA glare masking the smaller secondary, now I have done a little more research into what I am looking for I will give it another go next time and see if I can spot it! 

I spent last night tightening up some lose bolts across the tripod to see if that will help with the shake at high magnification with and my light yellow filter arrived to see if it might reduce the CA slightly to assist focus so I am all set for another go whenever the skies next clear  

 

Hi Wibblefish

I have had a couple of clearing nights here so I thought I would have a look at Rigel.

23/01/2021

In my new ST80: 80mm/400mm on an alt/Az mount it took x133 to split Rigel. I was then able to just split them at x100 with a 4mm orthoscopic.

25/01/2021

Using my OMC250. 250mm/2250mm on an EQ6. I was able to split Rigel at x70. This is the lowest magnification I can get on this scope. It was close but obvious. It was very clear at x94. 

With your scope the pair should be split at x110 but I think the seeing will make it quite hard. If you can get your magnification up to x130-150 I think you would split it easily and then be able to split it a lower mags.

Cheers

Ian

 

[wibblefish]

5 minutes ago, lunator said:

Hi Wibblefish

I have had a couple of clearing nights here so I thought I would have a look at Rigel.

23/01/2021

In my new ST80: 80mm/400mm on an alt/Az mount it took x133 to split Rigel. I was then able to just split them at x100 with a 4mm orthoscopic.

25/01/2021

Using my OMC250. 250mm/2250mm on an EQ6. I was able to split Rigel at x70. This is the lowest magnification I can get on this scope. It was close but obvious. It was very clear at x94. 

With your scope the pair should be split at x110 but I think the seeing will make it quite hard. If you can get your magnification up to x130-150 I think you would split it easily and then be able to split it a lower mags.

Cheers

Ian

 

Thanks for the info Ian, yeah I haven't be able to get a clear night to have another go yet but I will try it when I can! 

[John]

Double stars where there is a significant brightness difference between the component stars are more difficult to split. The most extreme example is Sirius. The actual gap between Sirius A and Sirus B is currently about 11 arc seconds which is a touch more than the gap between Rigel and it's companion star  but the huge brightness difference (Sirius A is 10 magnitudes or 10,000x brighter than Sirius B ) is what makes the pair so hard to split.

Unequal brightness doubles with close separations are tough challenges for the seeing conditions, the optical instruments and the observer but satisfying when they are eventually split

[wibblefish]

Update!

So I managed to get out over the weekend and despite the nearly full moon (and a dropped 12mm EP!) I had a good night hunting doubles

- Almach, split at 12mm and well defined at 6mm (12mm + barlow), smaller secondary, I didn't observe any colours (gold / blue) this time alas

- Beta Mon, split at 12mm into two components, 12mm + barlow split into three components, it appeared as two primaries and a smaller secondary

- Zeta Cancri, had a little trouble finding this due to the excessive moonshine but I definitely found a star which split at 18mm into two components in the right sort of place. No further split at 12mm and then I lost my positioning when adding the barlow so will have to try again  

I did have a try at Sirius but its much to bright and to low so even filtered its to difficult  

Unfortunately Rigel and several of my other targets were either to low in the sky or had moved to be covered by buildings in various directions.

Will have to build a new double list for next time, good fun!