Ha, and the Horseshead nebular

[alan potts]

First off I would like to know is the Horseshead the only target with a Ha filter?

Secondly I guess this is a target for only the 12 inch LX and the 190mm M/N. What sort of magnification would one use to look for this nebular?

I am wondering if the 1.25 size filter will be enough with the bigger one costing a good deal for a filter, I was thinking Lumicon or Astronomik. The problem is I only have the 16mm Nagler and the 24mm Panoptic with any size to them, all my other 1.25 EP's are shorter. I don't think this is going to be a problem with the M/N as it is 1000mm F/L but the LX is 3048mm so around X125 is the smallest magnification I can get with a 1.25 EP.

many thanks,

Alan.

[faulksy]

i didnt think it was visible with your eye only with ccd ?

[michael.h.f.wilkinson]

H-beta is used for visual, as H-alpha is not visible to the rods in the retina. There are some other object like the California Nebula which apparently benefit from an H-beta filter.

[Damo636]

Here's a list of targets that a H-Beta is useful on Alan...

http://jaysastronomy...gets-for-h.html

From what I gather, exit pupil is as important as magnification on the Horsehead, with between 4-7mm being desirable. Your incoming 31 Nagler should be perfect in your 190 MN (5.8mm exit pupil)

Your 55mm Televue plossl in the LX would be another option (5.5mm exit pupil)

[Mark at Beaufort]

Alan at the SGL8 star party I viewed the Horsehead Neb through Luke and Sarah's 16" Skywatcher flextube Dob. They had an Astronomic 2" H-Beta filter and we used a 19mm and 24mm Panoptic.

The HH was quite noticeable but to train the eye to view it I made reference points to the surrounding star patterns.

Whether you can see it in a smaller scope I don't know. I have a 10" Dob and a thousand oaks H-Beta filter and have never seen it at home. I live only a short distance from the SGL star party camp site and have similar skies.

I have loaned the H-Beta filter to John to see if he can detect it with his 12" Orion. I hope he does.

Mark

[alan potts]

Well, I found out I would have got the wrong filter, that is a good thing. But it is sounding like rather a lot of money on something that may not show me a thing. I think the thing to do here is keep an eye on what John finds before moving forward.

I do have skies that will be every bit as good as the SGL site even though I have never been there. It was one reason I bought the place, no light, apart from Sun and Moon.

Alan.

[John]

I'm aiming for a 4.5mm exit pupil with my 12" dob and the filter that Mark has kindly lent me

Can't see it with all these clouds around though !

[rwilkey]

Hi Alan, I haven't managed it yet, but I have the Orion H-beta 2" filter at the ready which I bought second hand off AB&S, going to try with my 200P when I get the chance, the HH is pretty small I understand, so once the general area around Alnitak is found I would probably go for my 13mm LVW (76x) to start with.

[Mark at Beaufort]

I found this image that I produced from Stellarium to make life easier to find the HH. There are some star patterns that you can see with a reasonable sized scope and go from there. Well it worked for me.

http://stargazerslou...rs/page__st__20 - Its post number 28 under this thread.

Mark

[alan potts]

I thank you all for the contributions and I will maybe leave it to try next year. By the time I get a filter which will be when I am in England, Orion will be way past it's best. I may well have a try without a filter to see if I can see anything once the Moon goes away.

Alan.

[Ohmless]

gives you a bit of time to find one used. maybe next year

[John]

It's worth doing a bit of reading on how best to tackle this challenge. It seems that, as well as very dark skies, the h-beta filter and an eyepiece that generates a suitable exit pupil, the eyepiece should not have a particularly wide field of view. This apparently helps block out the light from one or two bright stars in the vicinity of the HH nebula which can reduce the contrast further on what is already a very indistinct target. My conclusion is that you might as well use a 1.25" h-beta filter with a good ortho or plossl eyepiece.

[crazyjedi]

It's worth doing a bit of reading on how best to tackle this challenge. It seems that, as well as very dark skies, the h-beta filter and an eyepiece that generates a suitable exit pupil, the eyepiece should not have a particularly wide field of view. This apparently helps block out the light from one or two bright stars in the vicinity of the HH nebula which can reduce the contrast further on what is already a very indistinct target. My conclusion is that you might as well use a 1.25" h-beta filter with a good ortho or plossl eyepiece.

Could be a job for my 18mm BGO perhaps?

[Mark at Beaufort]

My conclusion is that you might as well use a 1.25" h-beta filter with a good ortho or plossl eyepiece.

John I thought that the recommended EP was a 25mm Plossl with a 52 degree FOV (magic EP or so they say!!). I agree that you need to move Alnitak out of the FOV so that you see the 3 mag 7 stars below it.

However, I would state that at SGL8 I was looking through a 19mm and 24mm Panoptic.

Mark

[Moonshane]

I read that there's a 'best' eyepiece focal length for every scope and it depends on focal ratio. basically, aim for an exit pupil of 5mm so in an f5 scope it would be a 25mm plossl but in my f4 scopes it would be a 20mm plossl. this equates to 60x and 90x in my two scopes (12" and 16" f4) but it's the exit pupil that's most vital. I have a SW H-beta filter but have not had a chance to use it since buying it in mid February!

[alan potts]

This is beginning to sound like a tricky little horsey. Now not having a filter to do this is one think but me not having the eyepiece to do it, well that's a difficult one to swallow. I will just have to try with my 24mm Panoptic, though I did say I was thinking of getting an 18mm Hutech Orthoscopic, so maybe that will do it.

Alan

[Moonshane]

there is a range of exit pupils from 3mm-7mm so with an f5 scope this equates to a 15mm to a 35mm eyepiece. 25mm is optimal (for f5) but if your skies are good and you have decent aperture then you may well be Ok with anything between the 3-7mm.

[John]

I believe the optimum exit pupil can vary a little. It's probably going to be sensible to have a range of eyepieces to try in the hope that one will be "just right" for the observing conditions. Everything I've read and heard about observing the Horsehead nebula suggests to me that it's going to be on the very edge of visibility even if other factors are good. My tactics will be to give it every chance by using low glass eyepieces with a constrained field of view and a max transmission h-beta filter. Fortunately the 1000 Oaks that Mark has lent me is one of the best in this respect.

Even with the above I'm not over-optimistic about seeing it - I've read of folks with larger apertures than mine trying many times to see this object without success. I wish I'd been at Lucksall one day earlier and I might have managed a glimpse of it through Luke and Sarah's 16" dob.

[Naemeth]

Alan, as your scope is F/10, I'd recommend using a 50mm eyepiece (if you have one), failing that use your 55mm TV Plössl if you still have it. Get out to the darkest skies you can, make sure you're fully dark adapted, and try to get it. I doubt the 24mm would give a large enough exit pupil, as others have said you need to aim between 3 and 7mm exit pupil. Which in your Meade equates to 30mm to 70mm.

HTH

[alan potts]

I have a good range of exotic glass in that area well from 30mm to 55mm, I will have the Nagler both Panoptics and the battlescarred 55mm Plossl ( don't look like I can sell it ) This will of course mean I would need the 2 inch filter which is expensive for what it is.

I am going to take the lead from John here, he may not have the sky I have but me has the expirence. BTW they have started turning the village lights off now later on ( about six 60w bulbs ) so it's is as black as it can ever be, I don't even think Keilder would be darker, the other thing is there is little in the way of factory polution as wel.

All in all, not bad.

alan.l

[Stargazer_00]

http://www.astrobuys....php?view=67561

dunno if any interest, seems quite cheap for a punt

another one, twice the price

http://www.astrobuysell.com/uk/propview.php?view=67548

[Moonshane]

This is beginning to sound like a tricky little horsey. Now not having a filter to do this is one think but me not having the eyepiece to do it, well that's a difficult one to swallow. I will just have to try with my 24mm Panoptic, though I did say I was thinking of getting an 18mm Hutech Orthoscopic, so maybe that will do it.

Alan

I'd like to buy a 20mm TV plossl but funds won't allow currently. I am hoping that my newly acquired Antares 1.6x barlow plus my 32mm TVP (effectively creating a 20mm TVP) will allow me to make do. it still have the fewer elements/narrow field but not sure of the effect that the barlow elements will have yet as I have not used it.

[ollypenrice]

I've seen it a few times in the 20 inch here. I can't say that the filter made that much difference, having tried O111, H Beta and UHC. You need a cracking night, a high horse ( ) and the right EP for the scope.

And when I say 'see' it I'm using the word as DS imagers use it. that is, it wasn't entirely absent...

Olly

[John]

I love this quote from Jeremy Perez on trying to see the Horsehead :

".....it's like trying to see a little bit of nothing with a little bit of less than nothing resting over it....."

[ollypenrice]

Sorry, I meant to say 'as DS observers use it...'

Olly