seeing proms

[Joe_L]

Do I need anything special to see proms? Do you need Ha etc? What's the best magnification?

I've got a NExstar 6Se and Baader solar film. A couple of times when people have reported good proms I've put the scope out to have a look and seen nothing. I get a great view of the entire disk with a well defined edge, and good sunspots. On Saturday I even saw some mottling around one of the sunspot groups, but nothing around the edge looking like flares or proms. Was I just too late - do they disspappear quickly?

Joe

[DirkSteele]

Unfortunately to see such features requires a dedicated hydrogen-alpha solar scope such as those from Lunt, Coronado or Daystar.

[ronin]

You need a Ha scope, it is the narrow part of the spectrum that enable proms to be seen.

As to magnification, not a clue.

[Joe_L]

aHa! (sorry!) That explains it. Thank you.

[FunkyKoval35]

Yes, You need Ha filter.

No offense, but the first thing you need is a minimum of knowledge about the Sun, prominences, etc.

[michael.h.f.wilkinson]

Magnification does not need to be high, I regularly look at the sun at a mere 16.7 or 20x and can spot them with my Lunt Solar scope (35mm). They are not cheap, but you may find decent deals second-hand (mine was). There may be a spate of second-hand LS35 scopes as people upgrade to the new (and very promising) LS50. The Coronado PST is another good starter scope should you want to dive in to the H-alpha side of solar observation (or imaging).

[Joe_L]

How are these scopes different? Can you just add an Ha filter to an ordinary scope?

Joe

[michael.h.f.wilkinson]

How are these scopes different? Can you just add an Ha filter to an ordinary scope?

Joe

You can in principle, as long as it is a VERY narrow-band H-alpha filter (<0.07 nm, rather than 7nm which is already considered narrowband in DSO filters). You also need an energy rejection filter at the front of the scope (or halfway down if your scope is a refractor). Lunt, Coronado, Baader, and Daystar among others make them. Prices range from very expensive through eye-watering to downright insane

If you want to go down that path you need to know exactly what you are doing, or if you are lucky you will only destroy your scope. If you are unlucky you will lose an eye as well. Again, it is doable, but you need to take proper precautions.

[Uplooker]

No, you can't just add a ha filter to any scope. In really basic terms there are a couple of components that enable you to view the Sun in the H-alpha wavelength.  First - a suitable energy rejection filter (ERF) and secondly an etalon. The etalon isolates the H-alpha wavelength (which is near infra-red) 653.2nm.

If you are not familiar with the mechanics, probably best to buy an off the shelf solution from Lunt, Coronado etc.

Ian

[Joe_L]

Ok that makes sense. The implication here I presume is that standard solar film doesn't let Ha through so you need other ways of reducing the energy - is that correct? And don't worry I am listening to the warnings and not about to try DIY, I'm just wanting to understand why people use different types of scopes. Oh well, a second hand Ls35 will have to join all the other thingss at the bottom of the shopping list....

Joe

[michael.h.f.wilkinson]

Baader film rejects all wavelengths equally, whereas an ERF rejects everything except one or more narrow bands around wavelengths of interest. Good ones are interference filters which reflect the excess energy. Older or cheaper ones absorb much of the excess energy, which is fine if they are mounted in front of the scope, but less so when they sit further down the optical path. Some way behind the ERF lies the etalon, which uses interference to let through a series of wavelengths (its transmission spectrum looks like a comb with very narrow teeth where it passes light. Finally a blocking filter selects  the one transmission peak you want (H-alpha or Ca-K). In either case, you end up with an optical system that lets through a tiny fraction (in the order of 0.001%) of the light, but in the Baader film case (or indeed Herschel wedge plus filter case), all wavelengths are attenuated in the same way, whereas in the H-alpha case you reject everything except that one desired wavelength.