Imaging in h beta

[bomberbaz]

I know that h beta is difficult to capture and note there are no imaging filters (on flo at least) that are dedicated to imaging in just this wavelength.

Hb/Sll,  Hb/Olll yes but not hb alone.

Has anyone given it a go with an hb visual filter and if so, what joy have you had please?

Steve

[DaveS]

H-Beta filter

Not usually used since the H-Beta signal can be inferred from the H-Alpha.

[bomberbaz]

22 minutes ago, DaveS said:

H-Beta filter

Not usually used since the H-Beta signal can be inferred from the H-Alpha.

I understand that but if you are using a osc camera would it not add a different blueish colour than the red from ha?

[symmetal]

I bought a set of Baader narrowband filters when i got my first CCD mono camera and that include a H-beta filter though I never used it. H-Beta is just a weaker version of H-alpha so as DaveS said it can in effect be obtained by attenuating the H-alpha signal.

H-beta is in the blue-green colour range similar to Oiii. It would be easier to colour mix some of the Red H-alpha channel into the blue and/or green channel in processing, to create H-beta, rather than using imaging time to obtain a weak H-beta signal in blue and green directly.

Alan

[Elp]

The fact is there just isn't that much signal out there to image in hb, the Hubble pallette already utilises the three strongest signals which are mostly abundant and you can map them however you wish, even with sho you have to research what elements are rich per target as some don't have much of one, sometimes the second is also faint, usually ha is the strongest but not always. If you really really really want to image hb the Optolong Lenhance allows passing of it plus ha and o3, but compare it to an lextreme which is ha and o3 only and you'll see why hb is mostly pointless in a universe rich in ha.

[ollypenrice]

The use of Ha in green and blue will replicate Hb for the reasons given by Dave and Alan. I did experiment with this years ago but the problem is that all it does is alter the hue of the red channel. It doesn't bring any new structure into play. Being cynical, you can adjust the hue of the red channel without going to the bother of adding a new layer!  Actually, I think most imagers will tune the hue of the red channel in any HaRGB image...

Olly

[bomberbaz]

Thanks for the replies all of you but one thing to note, I use Siril and Gimp for processing and although there are scripts and methods of creating SHO type results, most I have seen are not as good as those in PI. 

Also I am using a OSC and just exploring options for adding depth to images over and above those obtained by using the usual DB filters such as the L-ultimate. 

I noted the one member using the SII/OIII  filter getting some fantastic result but again he is splitting the channels to reconstitute in PI. Again, I don't have PI and don't really want to go there.

Anyway, I'll have a play around  as half the fun to me is trying something different and/or learning new techniques. My pet hate is the lack of available information regarding some matters, so god know how people got on before youtube tutorials came along.

Steve

[vlaiv]

I would say that using arbitrary ratio of Ha signal to reproduce Hb signal is "cheating"

There is no reason to suppose that:

a) this ratio is constant (and indeed it is not) in hydrogen gas

b) this ratio is constant even on selected target

Look at this example:

This is part of M42 taken as OSC image - Red versus Green channel. Red will contain Ha obviously, and Green will contain Hb. There are parts of nebula that are visible in both images - almost the same brightness - which means that Ha to Hb ratio is very close to 1:1 while some other features are present only in Ha - which means that Hb is much much weaker if present at all - and all of this in the same object.

Given that Hb series is higher energy transition than Ha - something needs to excite Hydrogen gas more in order to produce this emission - and I'm guessing that there is some interesting physics behind finding the ratio of the two.

For reference, here is list of visible Balmer series transitions and their color:

[bomberbaz]

14 hours ago, vlaiv said:

I would say that using arbitrary ratio of Ha signal to reproduce Hb signal is "cheating"

There is no reason to suppose that:

a) this ratio is constant (and indeed it is not) in hydrogen gas

b) this ratio is constant even on selected target

Look at this example:

This is part of M42 taken as OSC image - Red versus Green channel. Red will contain Ha obviously, and Green will contain Hb. There are parts of nebula that are visible in both images - almost the same brightness - which means that Ha to Hb ratio is very close to 1:1 while some other features are present only in Ha - which means that Hb is much much weaker if present at all - and all of this in the same object.

Given that Hb series is higher energy transition than Ha - something needs to excite Hydrogen gas more in order to produce this emission - and I'm guessing that there is some interesting physics behind finding the ratio of the two.

For reference, here is list of visible Balmer series transitions and their color:

Yes thanks vlaiv, I found some interesting comparison from data gathered last night that might be similar in the veil nebula. 

Not had chance to properly have a play around yet ( grandchildren this morning).

There was very little hb in the cocoon though as I suspected, not enough to warrant camera time anyway. 

I think hb imaging is likely to be similar to hb visual in that there are only a handful of objects that will respond well enough to warrant camera time. M43 is one such object, veil may be another. 

[symmetal]

Astronomik do an H-beta filter in their visual filter range, at a reasonable price, with a pass band of around 14nm, so i thought it could be interesting to try it on the RASA to settle the argument 😁 as it should capture the fainter data reasonably quickly.  At that pass band the fast optics may not be such a problem, compared to their 6nm filters.

Wondering what the difference between visual and imaging narrowband filters was, it turns out that the visual filters don't block IR and need an additional IR blocking filter if used for imaging. This is difficult on the RASA 11 with a mono camera as there's nowhere to fit an extra filter when using the Baader UFC system. I could use it with a OSC camera with its built in UV-IR cut protect glass I suppose, as the green should catch most H-beta.

Alan

[bomberbaz]

An hours HB filter data of the western veil, ngc 6960. I don't have any in ha/olll filter as the dew hit my setup and I didn't have any tapes on. Colours not great but I didn't put too much into this at this point.

I would like to see how the two filters results align and what the strength of each looks like for comparison. I had planned to grab 2 hours on each but dew said otherwise.

I do notice the bright halo of the central star which I have never seen before with just the ha/olll filter, curious.

However and overall I am quite impressed with the structure in the nebula but again, a comparison of both is needed and possibly other research/testing on the back of it but it is at least encouraging.

[bomberbaz]

4 hours ago, symmetal said:

Astronomik do an H-beta filter in their visual filter range, at a reasonable price, with a pass band of around 14nm, so i thought it could be interesting to try it on the RASA to settle the argument 😁 as it should capture the fainter data reasonably quickly.  At that pass band the fast optics may not be such a problem, compared to their 6nm filters.

Wondering what the difference between visual and imaging narrowband filters was, it turns out that the visual filters don't block IR and need an additional IR blocking filter if used for imaging. This is difficult on the RASA 11 with a mono camera as there's nowhere to fit an extra filter when using the Baader UFC system. I could use it with a OSC camera with its built in UV-IR cut protect glass I suppose, as the green should catch most H-beta.

Alan

Never saw this reply. My image above had an L2 filter installed at the filter nose, still managed an halo!

[symmetal]

That's not bad for just an hour. 🙂

For comparison here's a similar view in H-alpha to see if yours adds anything different. Note the RASA in NB produces circular diffraction rings on bright stars if a semicircular cable routing is used, the ring spacing depending on wavelength.

What H-beta did you use Steve?

Alan

Edited October 15, 2023 by symmetal

[Elp]

If you use a full circle from the edge of your central obstruction to the outer edge of your scope (almost like a full circle) your diffraction pattern is much improved I've found.

[bomberbaz]

47 minutes ago, Elp said:

If you use a full circle from the edge of your central obstruction to the outer edge of your scope (almost like a full circle) your diffraction pattern is much improved I've found.

I really do not understand what this means. I am using a refractor though if that makes any difference!

9 hours ago, symmetal said:

That's not bad for just an hour. 🙂

For comparison here's a similar view in H-alpha to see if yours adds anything different. Note the RASA in NB produces circular diffraction rings on bright stars if a semicircular cable routing is used, the ring spacing depending on wavelength.

What H-beta did you use Steve?

Alan

The h beta used was a cheapest svbony version I picked up somewhere down the line, remember thinking yesterday I should have used the astronomik one although both are visual and I do not know how tight the bandpass is. 

EDIT Both claim to be suitable for either visual or imaging but both say use a IR/UV cut for imaging and as mentioned I use an L2 filter for this. So still slightly perplexed re the halo.

Edited October 16, 2023 by bomberbaz

[Elp]

It was in response to @symmetals comment and doesn't apply to refractors.

[bomberbaz]

Added to extra hour so shade under two hours total, very pleased with this although may have pushed it a little too far, maybe used with star exterminator but that can wait til later, it's not the main purpose of the exercise.

Hoping to get same amount of HA/OIII data tonight, compare like for like and then combine.