I don't recall ever seeing an amateur UV deep sky image.
This image was to determine if it there are sufficient differences between a UV and white light luminance image. In this case the answer is a clear no.
Anyway here is an uninspiring boring image of M42.
At least I suppose it is unique amongst the thousands of images taken of this object.
Very interesting!
You seem to be picking up some Ha/Hb???
Could it be that the UV filter has some resonance band pass at lower frequencies? ie up in the red???
The Balmer series of Hydrogen are much more difficult below 400nm
May be worth while trialing a combo of a blue pass filter to kill any red response???
Which camera were you using?
Normally there's a significant drop-off in CCD QE below 400nm....
Last edited by Merlin66; 04-01-2013 at 05:17 PM.
Reason: Added info
Or it's H-epsilon, -zeta & -eta? http://en.wikipedia.org/wiki/Balmer_series. But yes, best to check the filter characteristics. You might need to combine it with an IR blocker.
The Astrondon data I have shows about 60% transmission for the U filter..
Yes the bandwidth sits across the Balmer jump....compared with the Ha intensities the H10 series is much reduced.
Interesting that you achieved such success - well done!
The UV band might be useful for enhancing the contrast of O-B populations in galaxies, and implicitly therefore, shockwaves and areas of compression. etc
The Astrondon data I have shows about 60% transmission for the U filter..
Yes the bandwidth sits across the Balmer jump....compared with the Ha intensities the H10 series is much reduced.
Interesting that you achieved such success - well done!
Astrodon did at one stage sell a Schuler UV filter which gave a 65% transmission in UV.
Interesting shot Steve. I wonder if we should be using sunblock at night with that much UV coming out of the nebulas!
Greg.
Thanks Greg.
Quote:
Originally Posted by clive milne
The UV band might be useful for enhancing the contrast of O-B populations in galaxies, and implicitly therefore, shockwaves and areas of compression. etc
Hello Clive.
I've only tried the UV filter on one galaxy at this stage NGC253.
To say the result was disappointing is a bit of an understatement. It was like trying to image the galaxy through a neutral density filter.
Perhaps UV imaging might work on more active galaxies, NGC 5128 springs to mind as being a potential target.
An interesting experiment, Steven! The neb may look the same as at longer wavelengths, but the dust lanes are enhanced!
As you know, a Johnson-Cousins (or similar) U -band filter is potentially useful for emphasizing OB stars..... but the extinction is high in this regime, so the reduction of starlight by interstellar dust can greatly negate the impact of the better isolation of hot young stars when using this filter.
Short wavelength filters greatly emphasize the dust distribution within an object or in a galaxy image, and this seems to be the case in your M42 image, which shows the dust distribution in the nebula extremely obviously. Perhaps deep Ultraviolet imaging of this region can show the cold & dark and dusty Orion Molecular Cloud from which stars are forming, as seen against a stellar or nebular background?
Here is a "fun" collection of images of M51, using several individual filters of progressively longer wavelengths, in order to illustrate the effect of isolating progressively longer wavelengths with specific filters. In order, the images are taken with the following filters:
B -band ("blue")
V -band (approximately "visual")
I band (very near infrared, around 800nm)
Near-Infrared (image is a composite of J+H+K bands)(all filters in this composite are >= 1.0 microns)
Given that each colour filter gives a unique image, I will repeat a comment I made in a previous post.... that we actually lose information by adding the images together that are taken with various filters. Your experiments with imaging in various filters are a good illustration of the usefulness of not "adding everything together"!
Note added in later Edit
NGC 253 is noted for being particularly red in its optical colours, compared to the color that would be expected for its optical-wavelengths derived Hubble type; because the the dust screen is so heavy within NGC 253, it does not surprise me that very little ultraviolet light got through to your CCD!!
Last edited by madbadgalaxyman; 05-01-2013 at 12:53 PM.
Steven,
I was hoping to find a Hubble UV image of M42 for comparison, but all I can seem to find are "combined" with other wavelengths to give a "OooohhHaaa" image.
The more I think about, the more impressed I am with your results!!!!!
An interesting experiment, Steven! The neb may look the same as at longer wavelengths, but the dust lanes are enhanced!
As you know, a Johnson-Cousins (or similar) U -band filter is potentially useful for emphasizing OB stars..... but the extinction is high in this regime, so the reduction of starlight by interstellar dust can greatly negate the impact of the better isolation of hot young stars when using this filter.
Short wavelength filters greatly emphasize the dust distribution within an object or in a galaxy image, and this seems to be the case in your M42 image, which shows the dust distribution in the nebula extremely obviously. Perhaps deep Ultraviolet imaging of this region can show the cold & dark and dusty Orion Molecular Cloud from which stars are forming, as seen against a stellar or nebular background?
You are correct the dust lanes are much more pronounced, more so in M43 than M42. I think I suffered from "mind blindness" by concentrating on differences in the highlight areas and failing to note changes in the shadow or dust areas.
Quote:
Here is a "fun" collection of images of M51, using several individual filters of progressively longer wavelengths, in order to illustrate the effect of isolating progressively longer wavelengths with specific filters. In order, the images are taken with the following filters:
B -band ("blue")
V -band (approximately "visual")
I band (very near infrared, around 800nm)
Near-Infrared (image is a composite of J+H+K bands)(all filters in this composite are >= 1.0 microns)
Given that each colour filter gives a unique image, I will repeat a comment I made in a previous post.... that we actually lose information by adding the images together that are taken with various filters. Your experiments with imaging in various filters are a good illustration of the usefulness of not "adding everything together"!
NGC 253 is noted for being particularly red in its optical colours, compared to the color that would be expected for its optical-wavelengths derived Hubble type; because the the dust screen is so heavy within NGC 253, it does not surprise me that very little ultraviolet light got through to your CCD!!
The moral of the story here is that UV imaging requires far more preparatory work than simply finding the RA and Dec of the object you want to image.
The dust lane detail in NGC 5128 is making it a far more interesting proposition to image in UV.
Steven,
I was hoping to find a Hubble UV image of M42 for comparison, but all I can seem to find are "combined" with other wavelengths to give a "OooohhHaaa" image.
The more I think about, the more impressed I am with your results!!!!!
Ken,
Given that Hubble is imaging above the Earth's atmosphere I wonder if the images are taken at shorter wavelengths in the UV range.
NASA's Galex probe as an example images in the 135-280nm range.
Given that Hubble is imaging above the Earth's atmosphere I wonder if the images are taken at shorter wavelengths in the UV range.
NASA's Galex probe as an example images in the 135-280nm range.
Regards
Steven
I just tried the GalexView "virtual telescope" interface of the GALEX imaging data (//galex.stsci.edu/GalexView) and it said that it had no ultraviolet imaging available for the Orion Nebula.
This is weird, because you would think that they might have had a go at imaging this object with the satellite, just to see what it would look like in short wavelength UV.
I just tried the GalexView "virtual telescope" interface of the GALEX imaging data (//galex.stsci.edu/GalexView) and it said that it had no ultraviolet imaging available for the Orion Nebula.
This is weird, because you would think that they might have had a go at imaging this object with the satellite, just to see what it would look like in short wavelength UV.
cheers, Robert
Robert,
Other well known objects that one would expect to be good UV targets are also not available. I couldn't find images of NGC3372 or M1.
I still have had little luck finding Ultraviolet images that are easily comparable with yours.
However, here is a preview of a Hubble Space Telescope image of the Orion Nebula that I just downloaded from hla.stsci.edu(the Hubble Legacy Archive), which was taken at similar wavelengths to your image.
This Hubble image is a composite of an F439W filter image (this filter is similar to the standard Johnson B ("blue") filter) and another image taken with the F336W filter (which is very roughly similar to a U filter image)
Both images were taken with the HST and its WFPC2 instrument. The Principal Investigator of the program in which these images were taken was Beckwith, and the Proposal ID is 8894.
(I have not displayed only the UV image, as it is very ratty indeed)
I agree with Ken's comment that you are "boldly going" (!!)
There are always a few individuals who will be in the lead, while the others, like sheep, just go on doing what everybody else is doing.
