The Wolf Nebula

[gregbradley]

Following from Paul Haese's recent fabulous image of this object that he aptly named the Wolf Nebula. I thought I would have a go at this on the weekend.

Its only available for about 2.5 hours a night at the moment as its past its prime time to image it but it still turned out not too bad.

Using the fabulous little TEC110 fluorite and a Vixen VMC 95 guide scope and SBIG STi guider on a PMX mount. At my dark site observatory.

HaLRGB 20 20 20 20 20.
http://upload.pbase.com/image/152654633 cropped version

http://upload.pbase.com/gregbradley/image/152654630 wide field version

Here it is in Ha as well:

http://upload.pbase.com/gregbradley/image/152654669

Greg.

[LewisM]

Gorgeous Greg!

Fluorite supremacy again :thumbsup:

The satellite trail is a bugger though (but looks fine in there anyway!)

[gregbradley]

Thanks Lewis. yes Fluorite rocks!

I just noticed that satellite trail after I posted it. I suppose I could Photoshop it out. But it tends to damage something along the way.

Greg.

[Astroman]

Very cool! is that the table of Scorpius to the Left?

[RickS]

Nice image, Greg, especially for a quickie!

[Larryp]

Lovely image, Greg!

[RobF]

Really enjoyed that thanks Greg

[gregbradley]

Thanks for that. I am not sure.



Cheers Larry.



Thanks Rob. Its an interesting area and especially nice in Ha.



Yes its quite short exposure for my normal images these days but its lowish in the sky now and a few semi cloudy nights made it hard to get a lot. F5.6 helps.

Greg.

[Stevec35]

For those incredibly short exposures Greg that tuned out great!

Cheers

Steve

[rogerg]

Nice nebula :) ... I'm slowly starting to regain my appreciation for deep space photo's ....

[Paul Haese]

Looks good Greg. Colour is pleasing.

[gregbradley]

Thanks Steve. Yes its quite short but sometimes that's all you get. I was happy it came out as well as it did given the exposure time.



Thanks Roger. Its a great object.



Thanks Paul and thanks for finding it.

Greg.

[multiweb]

I can hear it howling. :lol: An old favourite. Great colours. :thumbsup:

[madbadgalaxyman]

Greg,

Looks like it is the H-alpha shell associated with the NGC6231 + Scorpius OB1 complex, that remarkable concentration of superluminous OB stars that we were discussing as being the hypothetical source of energy for the giant dust chimney in your MW image that stretched far above the galactic plane.

If I remember right, it is called Gum 55 and also RCW 113, but I don't really know if Gum and Rodgers+ Campbell+Whiteoak had the same outline for the object.

The combination of depth and high resolution in good amateur nebular imaging is surely competitive with the images in the H-alpha surveys done by professional astronomers. I discussed this fact once with the Sidonio, when it seemed that he had picked up vast areas of diffuse H-alpha that was not even associated with any particular object. (about 50 percent of the H-alpha emission from some galaxies is simply extremely-faint diffuse emission)

Sorry to say that I don't see any celestial canids here....but then again I have absolutely no imagination, and I never see animals or people in the sky!! (the best I can manage is to see squares and triangles.....)

I have a really nice scientific overview of this entire region (cluster+ OB association + nebula), but as is usual with scientific papers, the file size limit stops me from attaching it.

cheers,
Robert

[gregbradley]

:lol: Its a first for me imaging this area. There is a lot going on in it.




Cheers Robert. As usual etremely informative. Its good to have someone with such extensive knowledge of astronomy posting on this site.

Greg.

[IanP]

Greg,
I don’t mind the satellite, it’s a beautiful image.
Your “dark site observatory” must be really worth using ..
Fluorite –!
Great colours!
:thumbsup:

[gregbradley]

Thanks Ian. Yes its nice to get a slice of unlight polluted night sky.

Greg.

[MLParkinson]

Your Wolf Nebula shot is fabulous. However, I consider it to be one section of the much larger Broken Heart Nebula ...

http://www.flickr.com/photos/mlparkinson/6222015887/in/set-72157626809474709

[madbadgalaxyman]

Hi Greg,

I guess it is a matter of what one spends ones time with and what one focuses on in life; If the focus is on astro-imaging, then people can get very good at it, like you. For my own part, I wondered why some of the planetary Amateur Astronomers were virtually professional astronomers and why amateur astronomers seemed traditionally to know so little about galaxies....so I developed the curiosity and interest to become at least a mini Galaxies Expert.
I have probably spent less of my time and energy than average on distracting non-astronomical activities...... such as aspiring after the girl next door!!(this sort of thing tends to detract from ones scientific work.....).
On the other hand, I would have achieved a lot more in astronomy if my focus had been single-mindedly on astronomy, as I am often distracted with other sciences, in particular biology and palaeontology.

Incidentally, RCW 113 has had very little individual study by professional astronomers; its cause and origin and future evolution are currently unknown. I did a search for all papers that mention this object, since 1980, and there were only three or four that at least gave a little bit of detail about it.

cheers, Robert

"The astronomer should live in monkish tranquillity, undisturbed by worldly concerns."
- R.L.

[gregbradley]

Thanks for that. Yes very interesting. I saw that area of nebulosity when doing my larger Milky Way image. There's a nice piece of bright nebulosity to the right of the star cluster.





We are lucky to have you posting your expertise here.

Greg.

[lazjen]

Nothing much I can add other than I like it. :)

[jase]

Nice one Greg! Its be interesting to see the different renditions of this target over the last couple of months. Paul's and Marcus' are the main ones I picked out. There are likely others. You've produced another splendid rendition. You've certainly been productive of late. Well done.

[madbadgalaxyman]

The shell structure photographed by Greg appears to be just one section of an even much larger shell which extends a long way to the North.

However, the northern parts of the shell are not nearly as well behaved.....Very chaotic and complex in appearance.

A literature search for scientific papers since 1975 reveals that next to nothing is known about the origin and evolution and future of this vast H-alpha emitting shell, despite its extreme prominence in the southern Milky Way and despite the fact that the candidate energizing objects (NGC 6231, Scorpius OB1 association, plus the consequent core-collapse supernovae) seem to be obviously visible.

Here is the entire shell (in centre of image) from the SuperCOSMOS H-alpha survey.

148860

[gregbradley]

Thanks for that.



I found AAIC gave me a 2nd wind. I have a lot of images I haven't released yet. Some with the CDK17. These generally take a lot more processsing than the ones from the TEC110 which are easy.




Fantastic Robert. I noticed this area doing my Ha of the Milky Way that there was a lot of Ha near NGC6188, which is here:

Greg.

[madbadgalaxyman]

The Panther Observatory image of this region shows a plausible (arguable) outermost boundary for the overall giant shell of which Greg has photographed the most well-defined section.

http://panther-observatory.com

The overall shell might be oval in shape, but don't quote me on it.

Here I have taken Schedler's image, converted the H-alpha into some weird colour, and then made a negative, in order to show the hypothetical oval outline of the shell:

148890

P.S.
(Added in edit) Regarding NGC 6188

The NGC 6188 identifier probably refers only to the brightest section of the Norma-Ara nebula. The entire 2-degree-scale HII region is known as RCW 108
(in the Rodgers and Campbell and Whiteoak catalog)(reference: 1960, MNRAS, Vol. 121, page 103)

The RCW is the primary nebular catalog between Ara and Crux, yet many star atlases still don't display RCW objects!!!!$%^&&*&*!!!

When I had the optimal visual sensitivity, in my 20s, I could trace this nebula for 1 and a half degrees, even just using the retinal detectors. (This nebula resembles a ghostly version of the Eta Carinae Neb.)

I will attach the RCW catalog in the science forum.

[gregbradley]

Thanks for that Robert. Imaging that shell is something I have it on my list of things to do. I started to image it with a Pentax 300mm 67 lens. But couldn't locate it! The lens needed to be aligned a bit better with the go-to. Perhaps it would be a good target for the TEC110.

Greg.

[marco]

Great image Greg! A lovely and rich of objects part of sky :thumbsup:

Clear skies
Marco

[Shiraz]

that certainly is a lovely image Greg - very pleasing to look at

[gregbradley]

Cheers Marco.



Thanks very much Ray.

Greg.

[madbadgalaxyman]

Hello Greg and other H-alpha imagers,

the latest professional H-alpha survey of the southern Milky Way is called VPHAS+

It utilizes the 2.6 meter VLT Survey Telescope (the VST) together with the OmegaCAM array of CCDs ( http://www.eso.org/sci/facilities/paranal/instruments/omegacam/inst/ ) , and it will survey much of the southern Milky Way:

http://www.vphasplus.org/

[[
VPHAS+ is the successor to the H-alpha survey that was done (on film!) with the UK Schmidt:
http://www-wfau.roe.ac.uk/sss/halpha/
]]

Some of the first H-alpha images from the new survey are probably available through the ESO data archive. They were made through the NB 659 filter, which is similar to an H-alpha filter :

http://archive.eso.org/wdb/wdb/adp/phase3_main/form

galaxyman's opinionated commentary :

Despite the use of a gigantic telescope, and perhaps because of the prohibitively large time and money expenditure that would be necessary to undertake the best ever survey of the Milky Way with a 2.6 meter telescope, VPHAS+ is far from being the ultimate H-alpha survey of the band of the Milky Way.....

(1)
Firstly, these Large Telescope H-alpha images are not going to be very deep images, though the angular resolution of the images is very good; 1 arcsecond or even better.
Apparently only 120 second exposures !!!....
In my view, this means that the survey won't be able to detect very faint nebular structures; It seems to me that even with a 100 inch telescope, such short exposures might not detect faint expanding supershells and faint Supernova Remnants.
Why on Earth use a giant telescope and then make shallow exposures??? (actually, the same criticism could be made about many Hubble Telescope exposures)

So I predict that the deepest H-alpha survey of the Milky Way is going to be done by an amateur astronomer.

(2)
Another deficiency of the VPHAS+ is that the survey fields do not stretch very far above the galactic equator (the apparent plane of our galaxy), so highly unusual and interesting structures high above the plane, such as those detected in Greg Bradley's very deep Milky Way exposures, will not be imaged in this survey.
Many of the least known and most interesting gaseous structures in spiral galaxies are well above the principal plane of a galaxy, e.g. gas being ejected from a galaxy and gas falling into a galaxy from its halo. Yet it is precisely these least understood H-alpha structures that won't be surveyed!

_________________________

[Paul Haese]

Urgh, Robert. It took enough time to image my image (http://paulhaese.net/DarkNebulaSL17.html)of this area. At 21 hours I have probably the deepest image of the object with 11 or 12 hours of Ha. Perhaps it might be prudent for a group of us to image the region in Ha and produce a combined survey. I am more than happy to contribute and participate in such a survey.

It goes to show that sometimes when you stubble on something and decide to image it for whatever reason; it may just be of interest to more than yourself. :)

[gregbradley]

Definitely your image sparked off all this interest in what has been a relatively unimaged part of the Milky Way.

Looking at the widefield Ha images of this area there are some other objects of interest nearby. Like directly above on the 180mm lens shot you can see a brighter area of Ha with a bit of black dust and also diagonally off to the right there is another similar patch that may be worth imaging.

I think a mosaic would be great for this area. But its too late for this year probably or perhaps over 4 nights and 1 panel per night of 2.5 hours is all that is left for this year if you got 4 nights of clear weather.

galaxyman's opinionated commentary :

Despite the use of a gigantic telescope, and perhaps because of the prohibitively large time and money expenditure that would be necessary to undertake the best ever survey of the Milky Way with a 2.6 meter telescope, VPHAS+ is far from being the ultimate H-alpha survey of the band of the Milky Way.....

(1)
Firstly, these Large Telescope H-alpha images are not going to be very deep images, though the angular resolution of the images is very good; 1 arcsecond or even better.
Apparently only 120 second exposures !!!....
In my view, this means that the survey won't be able to detect very faint nebular structures; It seems to me that even with a 100 inch telescope, such short exposures might not detect faint expanding supershells and faint Supernova Remnants.
Why on Earth use a giant telescope and then make shallow exposures??? (actually, the same criticism could be made about many Hubble Telescope exposures)

So I predict that the deepest H-alpha survey of the Milky Way is going to be done by an amateur astronomer.

(2)
Another deficiency of the VPHAS+ is that the survey fields do not stretch very far above the galactic equator (the apparent plane of our galaxy), so highly unusual and interesting structures high above the plane, such as those detected in Greg Bradley's very deep Milky Way exposures, will not be imaged in this survey.
Many of the least known and most interesting gaseous structures in spiral galaxies are well above the principal plane of a galaxy, e.g. gas being ejected from a galaxy and gas falling into a galaxy from its halo. Yet it is precisely these least understood H-alpha structures that won't be surveyed!

_________________________[/QUOTE]

http://www.pbase.com/gregbradley/image/152449036 Closer up shot of the MW Wolf Nebula is top right corner area showing the broader shell of Ha

http://www.pbase.com/gregbradley/image/152595727/original most of the Milky Way Wolf Nebula is to the left side near the big loop RCW114
so you get oriented where this is overall.

That big loop of Ha is worth a mosaic. It doesn't show up in O111 unfortunately so that limits its beauty for a pretty picture.

Greg.

[DavidTrap]

Nice image Greg.

Couple of queries - can you tame the cluster of stars in the widefield. I think they add to the overall image, but I find them distracting. Have they blown out in the long images required for the nebulosity? Would a HDR with some shorter images help?

Paul - your image has bigger halos around the bright stars. What do you think is the reason for this?? You're both using good quality glass to image??

Ta
DT

[gregbradley]

I did a minor repro on the image. I toned down the glob without losing its relative brightness and reduced the overall red look to the image.

Same links. I am happier with this version.

Greg.

[Paul Haese]

Most likely the filters used and the f ratio. Mine is at f5.8 and I am using Astronomiks type II C. The Ha filter produces really large halos despite being replaced. I am about to change out my filters for Astrodons.

[Paul Haese]

I have also considered that it could be partly the imaging window on the QSI683. When I finish the current project I will find out the answer to that question.

[gregbradley]

Roland Christen posted something about that at one time he was using one.

Greg.

[David Fitz-Henr]

That's a great image Greg; nice colour processing! My imagination is only slightly better than madbadgalaxyman; I can see the wolf but not sure about the broken heart ...

[DavidTrap]

I think it's better Greg, but the stars are all white - I was wondering if some shorter subs might give you back some star colour??





I've never seen halos like that with my QSI583, Astrodons and my Tak. Hope it's not the imaging window - rather fond of my QSI...

DT

[madbadgalaxyman]

Greg.

I think it worth mentioning that the pioneering original H-alpha imaging surveys and the consequent catalogs of HII regions that were produced from these surveys, for example Gum, Rodgers Campbell Whiteoak (RCW), Georgelin et al , do not even go as deep as your 180mm exposure!!

To me, the latest H-alpha shots by experienced imagers like yourself and Paul are a discovery machine.

There is so much diffuse Ha on your image that it is going to be difficult to distinguish individual objects from the Ha background, in ultra-deep Ha exposures!

Actually, the main scientific interest of deep amateur Ha imaging might be the detection of highly unusual Ionized Gas structures far above the plane of the Milky Way, like ultra-faint outflows and supergiant Ha shells.

cheers, Robert

Frankly, I am disappointed with the limited sky coverage and limited depth of the VPHAS+ survey. All that effort, for a partial coverage of the Milky Way plus limited depth......
Maybe amateurs can do better than this hurried project with a 100 inch telescope.

[gregbradley]

[QUOTE=DavidTrap;1022464]I think it's better Greg, but the stars are all white - I was wondering if some shorter subs might give you back some star colour??



Not sure which stars you are referring to - the ones in the glob? I think they probably are white.

The rest of the stars do have colour, mostly yellow and some subtle blue ones. Your monitor? The 16803 has a well depth of at least 100,000 electrons and even a half hour exposure is unlikely to lose star colour except in the very brightest perhaps. I noted that R Jay Gabany and Don Goldman both now use 30 minute exposures as their standard. They use 16803 cameras too.

Greg

[gregbradley]

To me, the latest H-alpha shots by experienced imagers like yourself and Paul are a discovery machine.

There is so much diffuse Ha on your image that it is going to be difficult to distinguish individual objects from the Ha background, in ultra-deep Ha exposures!

Actually, the main scientific interest of deep amateur Ha imaging might be the detection of highly unusual Ionized Gas structures far above the plane of the Milky Way, like ultra-faint outflows and supergiant Ha shells.

cheers, Robert

That's an interesting concept. Where would you point the scope to pick that area up? Above the Milky Way centre star area?

Greg

[madbadgalaxyman]

I express the opinion that the most relevant posts about the possibility of a deep H-alpha Imaging Survey by amateur astronomers, should soon be copied into the Science Forum.

I am happy to copy an edited version of them into that forum, and to continue this discussion in the 'heavier' forum!



Greg,

I will find some H-alpha images of edge-on spiral galaxies that show unusual HII distributions extending outwards at right angles to the plane of a galaxy. This might give us a better idea of what to look for.

As mentioned in my thread "massive molecular outflow in NGC 253"(in Science Forum), there is often an outflow of gas "vertical" to the plane of a spiral galaxy, an outflow which has several components, e.g. neutral atomic hydrogen gas (detectable at 21cm in the radio regime), ionized gas (e.g. OIII, Ha, etc), and molecular gas (millimeter and submillimeter emission).

The extraplanar or above-plane Ha emission in our own Galaxy will be very very faint and very very extended, but well above the Galactic Equator there is at least the possibility of discovering something that was previously unknown.

Generally, gas is often pushed out of the disk component of spiral galaxy above those parts of the disk where there are very multiple OB stars and supernovae; hence my interest in the possible dust+gas chimney above NGC 6231+Scorpius OB1 .

I have downloaded nearly every paper that was ever written about NGC 6231 and Sco OB1 and RCW 113......the cluster is often studied, but the nebular shell surrounding it is hardly ever studied by professional astronomers!!

cheers,
Robert


Paul,

I have enjoyed your very deep image of a section of RCW113.
A hypothetical "vertical" dust chimney above the N6231 + Scorpius OB1 + Supershell complex is well shown in your image entitled "Galactic Centre"....this feature is Quite suggestive of gas & dust expulsion from the Galactic plane, as was first discovered on Greg's 11 hour Milky Way image.

I am fascinated with the Giant Shell Structure of which RCW113/Gum 55 is a part. It may well be a complete shell, and it should have some astrophysicalinterest.

I believe that deep Survey Images of the wide-scale spatial distribution of HII over the face of the apparent Milky Way, imaging multiple Deep fields, could potentially be useful, especially for the very very faint Ionized Gas Features such as :
- expanding supershells of ionized gas that are powered by OB stars and supernovae. For instance, what is the origin and future evolution of the shell nebula that includes RCW 113? Stellar winds? Supernovae?
- material being pushed far above the galactic plane, e.g. chimneys and plumes of H-alpha emitting gas that is outflowing from spiral galaxies, at 90 degrees to the plane of the disk component

(subtracting out the stellar continuum light from the Ha filter images would be necessary, so as to leave only the light from the Halpha line)

It seems to me that amateur nebulae imaging could overcome the deficiencies of some of the professional H-alpha surveys of the Milky Way :
(1) Big Telescope sky surveys of Large Areas of Sky are often not optimized for depth , because individual fields in these surveys usually have to be a "rush jobs" so as to avoid cost and time overruns.
(2) H-alpha surveys of the Milky Way done by professional astronomers generally stick to fields that are relatively near to the galactic equator (e.g. VPHAS+ does not go beyond +/- 5 degrees galactic latitude), which means that these surveys miss a lot of the faint and little-understood features that may exist far above the galactic plane; there is significant scientific uncertainty about what happens to gas as it is ejected to far above the plane of a spiral galaxy (at the "disk-halo interface").

It is now a long time since the publication of the pioneering large-sky-area Southern Milky Way HII region surveys and catalogs of Rodgers & Campbell & Whiteoak (RCW), Gum, Bart J Bok, Georgelin et al., and others;
and I think today's amateur astronomers could do better than these people if amateurs were to undertake large area H-alpha surveys of the Milky Way. For instance, the RCW catalog, which is probably the most important and useful general-purpose catalog of southern HII regions, was made with an 8 inch Schmidt Camera and Kodak 103a-E emulsion !

It is hard to say if Deep imaging of HII features by amateur astronomers can actually lead to useful science, but discoveries are always possible when images or sky surveys reach a greater depth and/or achieve greater sky coverage. (this has occurred in the case of deep galaxy imaging by amateurs....)

Best regards,
Robert Lang

[multiweb]

I have imaged this area repeatedly in the past at various focal lengths in Ha and more recently in infrared. The shells seem to be going on both sides of the milkyway band, up and down.

Hydrogen Alpha: 35mm (https://public.bay.livefilestore.com/y2pZWl-w6tIGUt3dJPN7E6ym-t35tyP1TxHFnw3xDEtuyHZUs40vS1tCj24s Z2mxoIxrKHMkNiIF94oPKeDIsyctp08PNxU nFC5Z-L1w0riK1k/prawn_35mm_ha_ff.jpg?psid=1), 50mm (https://public.bay.livefilestore.com/y2pCPSko7OpwcdZJ7Mo9XCsN9wvFK6PyERF ZJxVBylZsTpzLMmFBI20szPX_wbm8ezI2K_ ArwNEWyl6hTTlAdaX-WyTHBqItR4-Qd6NPWePq1w/milkyway_ha_aratoscorpius_ff.jpg?ps id=1), 100mm (https://public.bn1.livefilestore.com/y2ptUaLvcG5mxlfug8mUWaWFV764X9OrfoL mPP-edGGbsqkhFgMvMle7CjKrWGDncUNS4Lw795 qjMHbKbvu_yr7ozvU4IICYXY3r1Hp4xTPRU Y/scorpius_ha_100mm_fff.jpg?psid=1)
Infrared: 100mm (https://public.dm1.livefilestore.com/y2p0C0x20JhbgYYDcJyUibL9wGqH9XKyTlD UsakusHGHyRL8fa4IT8LiUt8a6IUqPEdteC 34R6MCHjTljbogv-2IejoFuL_DlxToADaYOv9Bkg/mw_scp_ir_ff.jpg?psid=1)

[madbadgalaxyman]

Marc,
very good observations, and an extremely interesting interpretation.

As I suggested in my previous post, it may be necessary to subtract out the stellar red light contribution from the light that is admitted by the Ha filter, in order to go further in our understanding of the structures of extremely faint nebulae like this one.
(there are various mathematical "fudge factors" that model stellar light in the red band)
Also, there is a lot of diffuse Ha which makes it hard to see the outlines of individual HII regions.

Robert

[multiweb]

Hi Robert, I'm not sure how to do that but I'd love to learn more about it. The Ha filter I use has a bandpass of 7nm around 650nm. The IR filter was blocking everything up to 740nm and letting everything in onwards. Sii and Ha are below and out. That's why you can't see the prawn and NGC6188. A lot of obscured clusters come up though at that wave length. The QE of my camera drops dramatically from 800nm onwards and is quasi inexistant at 900nm onwards.

[naskies]

Another great image, Greg! Nice to see you've been productive with deep imaging again :)

This has also been a great thread to read - a mix of pretty pictures and science.

[madbadgalaxyman]

Indeed, amateurs could benefit from the ability to produce "images in the h-alpha line only ".(showing only nebular light, without stellar contamination)

I wonder if Richard Crisp (I think I remember the name properly) knows how to do it; he does a lot of amateur Ha of galaxies.

In the jargon of professional astronomy, these are referred to as "continuum subtracted" images. i.e. the stellar continuum has been subtracted out of the image, leaving only the nebular light from the actual Ha line itself.

Most professional galaxy images in the Halpha line are presented with the continuum already subtracted.

I believe that the procedure involves making a red light image, and subtracting it from the Ha image, taking into account various mathematical transformations that are necessary.

If I get "a round tuit", I will try to find a quick and easy way to do this; there must be some procedures for continuum subtraction in the professional literature.

[marc4darkskies]

I guess I missed this one! A belated well done - a very nice rendition Greg!

Cheers, Marcus

[naskies]

Astrodon sells a 5 nm red continuum filter, for subtracting stars from Ha images:

http://www.astrodon.com/products/filters/narrowband/

[gregbradley]

Thansk Dave. Yes it has been an interesting thread.



Cheers Marcus. Hows the Officina Stellare scope coming along?



Yeah that is the one I was thinking of.

Greg.

[multiweb]

So basically it lets only starlight through, then you subtract this from your Ha correct? Like a star mask?

[madbadgalaxyman]

Subtracting the red image should work, but I think there is still some maths involved to adjust the images.

Perhaps contact Richard Crisp :
rdcrisp@earthlink.net

His website is : www.narrowbandimaging.com (http://www.narrowbandimaging.com)

I think most of us in this thread would agree that when there is a really intense stellar background from the Milky Way, continuum subtraction is highly desirable.

Obviously, if there were nebular emission lines somewhere within the bandpass of the filter that is used as a red stellar continuum filter, this would stuff things up completely.