Rigel B.

[Geoff Barnes]

I had a good session last night under clear but slightly wobbly skies, after 6 weeks of heat and no rain our skies are polluted with dust and smoke, so not ideal. After enjoying exploring Orion it occurred to me that I've never tried to split Rigel. I had already seen Sirius B just earlier so conditions were favourable (if variable), so I aimed at Rigel and couldn't see B at all. Tried initially with the Baader zoom without success so upped the magnification with the Morpheus 6.5mm, still no luck.

I had collimated before starting observing but decided to re-check with a star test and it seemed spot on.

Okay, out with the ES 4.7mm and.....nope, not there.

Is it really that difficult. Who has had success with Rigel B and what magnification was used? 

[Klitwo]

31 minutes ago, Geoff Barnes said:

I had a good session last night under clear but slightly wobbly skies, after 6 weeks of heat and no rain our skies are polluted with dust and smoke, so not ideal. After enjoying exploring Orion it occurred to me that I've never tried to split Rigel. I had already seen Sirius B just earlier so conditions were favourable (if variable), so I aimed at Rigel and couldn't see B at all. Tried initially with the Baader zoom without success so upped the magnification with the Morpheus 6.5mm, still no luck.

I had collimated before starting observing but decided to re-check with a star test and it seemed spot on.

Okay, out with the ES 4.7mm and.....nope, not there.

Is it really that difficult. Who has had success with Rigel B and what magnification was used? 

Rigel has been known as a visual double star since at least 1822, when it was measured by Friedrich Georg Wilhelm von Struve.  The companion is not particularly faint at magnitude 6.7, and with a separation of 9.5 arc seconds both components are resolvable in most amateur astronomers' telescopes.  However, the large difference in brightness makes it a challenging target for telescope apertures smaller than 15.0 cm (5.9 in). The companion is frequently referred to as Rigel B, but more correctly as β Orionis B or by a multiple star designation such as ADS 3823 B.  >  https://en.wikipedia.org/wiki/Rigel

Klitwo

[Pete Presland]

I saw Rigel B last night with my C9.25 and 22mm Nagler, magnification x106. A comfortable split, but with such a difference in magnitude, 0.3 to 6.8 you could loose it in the glare.

[Geoff Barnes]

Yes there was certainly a lot of glare which may have been the cause, though Sirius B was still visible despite it which seemed odd.

Trapezium E and F too were clearly visible but of course no glare there.

Once we get some rain to wash the crud out of the air I'll try again. 

[Stu]

I saw it last night with the 7" Mak, relatively easy at x133 I think it was. The primary was flaring a fair bit, but with good focus the secondary is a love l y little pin point.

I actually think this one, and Polaris too are easier and more aesthetically pleasing in my 4" refractor. The primary is controlled better and the secondary is easier to see. I can't recall what magnification it splits at in this scope, but lower than x100 I should think, will try it out next time. I know Polaris will split with a 24mm Panoptic which is about x30, obviously the primary is much dimmer though, so Rigel is probably more like x60 or x70.

Bear in mind that I've not split Sirius from my location so I would expect you to be able to see Rigel b with relative ease.

[John]

I can split Rigel with my 70mm refractor at around 100x.

I tend to have a set of warm up targets before I move to Sirius. Rigel is usually the 1st, then Sigma Orionis, E & F Trapezium, Alnitak, and Eta Orionis. If those are well defined then it's on to have a crack at Sirius !

Rigel and Rigel B are separated by around the same angular distance as Sirius B is from Sirius. Their relative position angles are quite different though.

 

[Geoff Barnes]

Thanks chaps, sounds like I should've stayed with lower magnification and persevered.

[Stu]

Just a further comment on this. I tried it last night with my little 72mm, and with careful observation it was visible in a 9mm BGO which is x48. I suspect it would be possible even lower with better conditions. I suspected it with the 12.5mm at times but couldn't say for sure.

[Paul73]

Splitting bright uneven doubles is always going to be a challenge using normal Newtonian mirrors. I stick to the less challenging coloured doubles now that I’m fracless.

Paul

[Geoff Barnes]

Well we finally had some rain last night, some terrific thunderstorms actually, so I'm hoping as the clouds melt away this evening I will have better seeing than I've had for a while. Will report back if any successes occur. ?
 

[Geoff Barnes]

..….and I'm back from a very brief session in the twilight, not even remotely dark.

Baader zoom on 12mm, straight onto Sirius and there was the Pup nice and clear. Okay, Rigel was just visible in the half light so over to it I swung the 12 inch Dob and bingo!

Rigel B as clear as day, much easier than the Pup, I feel embarrassed that I missed it the other night, but just goes to show how dust and smoke can affect the seeing.

I'm going back out when it's really dark to seek out some more goodies now I've got decent clear skies again. ?

[John]

Yay ! - result

I got the Pup last night as well. Not as easy from here due to the low altitude of Sirius but it was one of my easier sightings of it. Maybe practice helps too !

[markclaire50]

Hi Geoff, I was using my 'new' second-hand 127 mm Mak for the very first time last Wednesday night, when it was particularly cold here in the UK. I was using my synscan pro app to guide me to various double stars and I remember Rigel was a double, so thought I would give it a go. My scope had been cooling down for about 3 hours before I used it, so I assumed it was ready. I did this based on everyone saying it was important to make sure a Mak is cooled. Anyway, I looked at Rigel, and I could definitely see a smaller much less bright star about 150-160 degrees (or in plain English about SSE) relative to Rigel. I'm guessing it might be opposite for you in Australia (i.e. NNW or top left of Rigel, or maybe it doesn't work that way - my head hurts trying to visualise if the relative angle of Rigel B would change based on being in southern hemisphere?). I remember when I was in Ayr's rock 2 years ago, find it strange seeing Orion upside down (from how I usually see it!). Before I forget, I was using a Baader mkiV zoom at about 12-14 mm, so around the 100-120 x mag range, when I saw it, but I think I could have seen it at lower mag.

Anyway, I digress. On that same night, I also tried seeing the E and F stars. I had failed to see these with my 80mm ED a month before, and had high hopes with the Mak. Absolutely nothing! :-(. Whereas Rigel B had been easy, there was no way I could see E and F, even after staring for ages, adjusting the mag between 60-180 with the zoom. Rather annoying.

In addition to this, I looked at Sirius to see if I could see the double. Not a chance! Simply nothing. Sirius seems like a much tougher challenge. It was simply sparkling in my Mak and I could even detect the Chrom Ab for the first time. I turned it to the next double that my Synscan app suggested - CASTOR

Now, this is a beautiful double! My first time for this too. Sparkling white pair.  I was very very impressed with my little MAK for splitting this pair, as according to the Synscan app, it was 1.8" seperation. So impressive for a scope with a RAyleigh limit of 1.1". I keep thinking, WOW, I can see a clear dark space between this pair at 1.8"!

That is, until last night, when my suspicions were confirmed. I found a website saying that Castor pair are now 5.3" apart. I spent some time today and found the StelleDopie website (wonderful double star database using data from WDS) which confirmed by suspicions. THAT explains why it was so easy for my scope!

Now, going back to the E and F stars, from what I know, the separations of these stars should be doable for my MAK. And yet, nothing! However, I note that their magnitudes are over 10, and I now wonder if, despite my MAK having a theoretical limit of 13.4, whether the sky is not dark enough around me, or whether the mistiness from the nebula is somehow making it harder. 

I am planning on investing in a bigger weapon later in the year. Possibly a 180 mm MAK, having been very impressed with the refractor-like appearance of the stars I looked at. But, I am also wondering about a 9.25" SCT, 8 inch skywatcher (200pds) or Orion Optics 8 or 10 inch newtonians. Surely any of these would see both E and F stars??

Mark

[markclaire50]

On 31/01/2019 at 15:49, John said:

Yay ! - result

I got the Pup last night as well. Not as easy from here due to the low altitude of Sirius but it was one of my easier sightings of it. Maybe practice helps too !

Hello

Please can you tell me which scope you have successfully seen the pup?

Thank you

Mark

[Geoff Barnes]

Hi Mark,

Whilst I can see Sirius B with my 12 inch Dob and using my Baader Mk 4 zoom at 8mm max, it is certainly still a challenge solely because of the glare. In my upside down back to front view the Pup appears almost directly above Sirius, say 350 degrees NNW, whereas with Rigel B it appears almost directly below Rigel, say 190 degrees SSW.

E and F in the Trapezium I'm seeing quite easily at 8mm (187x) again with the 12 inch Dob.  The beauty of this scope is the huge amount of light it captures, which makes dim objects so much easier to see. I see no reason why any of those larger instruments you mention would not allow you to see E and F on a night of good seeing, and the Pup as well, but be warned Sirius glare is the biggest obstacle to overcome. Good luck!

 

[John]

2 hours ago, markclaire50 said:

Hello

Please can you tell me which scope you have successfully seen the pup?

Thank you

Mark

My 12 inch dobsonian at around 260x and also my 130mm triplet refractor at around the same magnification. It's not easy at at all even with these excellent scopes. Much tougher than E & F Trapezium.

I've not (quite) yet managed it with my ED120 or smaller refractors.

 

[John]

1 hour ago, Geoff Barnes said:

E and F in the Trapezium I'm seeing quite easily at 8mm (187x) again with the 12 inch Dob. ..

 

I find around 180x - 220x the optimum power for seeing E & F Trapezium. Crowding on more power does not help really. There seems to be a "goldilocks" magnification for this target.

[markclaire50]

1 hour ago, Geoff Barnes said:

Hi Mark,

Whilst I can see Sirius B with my 12 inch Dob and using my Baader Mk 4 zoom at 8mm max, it is certainly still a challenge solely because of the glare. In my upside down back to front view the Pup appears almost directly above Sirius, say 350 degrees NNW, whereas with Rigel B it appears almost directly below Rigel, say 190 degrees SSW.

E and F in the Trapezium I'm seeing quite easily at 8mm (187x) again with the 12 inch Dob.  The beauty of this scope is the huge amount of light it captures, which makes dim objects so much easier to see. I see no reason why any of those larger instruments you mention would not allow you to see E and F on a night of good seeing, and the Pup as well, but be warned Sirius glare is the biggest obstacle to overcome. Good luck!

 

Thanks Geoff. 

Interestingly, it appears that Rigel B is at the bottom in both cases. I wondered if that might be the case, as being 800 light years away it still has same orientation. The difference of course is that the stars rise in reverse order. 

I'm still deciding if I want to have portability (sct, mak) over length. Plus, I have a feeling I have refractor bias with my liking of pin point stars. Plus I like planets and contrast. Can't decide yet. I wonder if a 9.25" sct may be best compromise of aperture and nearer to refractor than newtonian for stars. 

[Arcturus D]

Rigel B is a very easy split, at about 130x in a 8" dobs.

Trapezium E and F are reasonable at 130x, but need very steady seeing.

Sirius B needs magnification (180x-220x) and experience to overcome the massive glare caused by Sirius.

Sirius B is also very tiny, which was causing me problems, when I was trying to see it. 5 nights of trying and I found it. I was surprised how small it actually was.

 

[Geoff Barnes]

I've decided to resurrect my dear old Celestron C4R from the cobwebs in the corner of the lounge and I'm going to have a session with it spotting just doubles/triples etc. While my 12 inch Dob excels at seeing fainties like E &F in the Trapezium it struggles a bit with the brighter stars because of the glare and diffraction spikes. It will be a good exercise for the frac to see how well it handles targets like the Pup, Alnitak and Regal B etc. We've had our first rain for a month today and the skies are clearing now, so fingers crossed - if no go tonight then tomorrow.

[Geoff Barnes]

Okay, well that was very interesting. Because I've exclusively been using my 12 inch SW Dob for the past 10 months I had forgotten just how dim and poor the views were in comparison through the old Celestron C4R.

I had thought that being a refractor it might have given the Dob a run for its money on doubles, but apart from vaguely being able to see Regal B, I could not see Sirius pup, I could not split Alnitak and I could not see E & F in the Trapezium, all with the 8mm setting on my Baader zoom.

The chromatic aberration through the C4R also was shockingly bad, purple and blue all around the brighter stars, the Dob obviously shows none at all.

The aperture advantage of the Dob clearly has a lot to do with it, but I think it also highlighted just how very good the optics are in the SkyWatcher Dob.

Maybe one day I'll get a chance to look through a top class ED refractor and see what can be achieved, but it will have to work darn hard to equal the Dob! ?

[Stu]

Very interesting Geoff. I guess it's not so surprising, particularly when those objects are so high in the sky for you. When they are low down for us, a decent 4" apo  can get closer to a 12" because the cut through poor seeing better. The C4R probably didn't stand much chance!

 

[Saganite]

A bit late to this thread, but looking at my notes, the last split of Rigel was 26/1/2019 , OOVX12L with binoviewers set at 2.5 X and a pair of 35mm Eudiascopics = 113X