Horsehead Nebula (B33)
6 views
Skip to first unread message
Trev S
Feb 13, 2025, 11:39:29 AMFeb 13
to croydonastro
Attached is my attempt at imaging the Horsehead Nebula processed in a slightly unusual pallette OHS (O-red, H-green, S-blue). I think this colour combination shows the depth of the nebula better than the standard HSO pallette (or it might just be my eyesight). This was taken on the 1st and 2nd February 2025 from my back garden in Surrey.
The Horsehead Nebula (also known as Barnard 33 or B33) is a small dark nebula in the constellation Orion.The nebula is located just to the south of Alnitak, the easternmost star of Orion's Belt, and is part of the much larger Orion molecular cloud complex. It appears within the southern region of the dense dust cloud known as Lynds 1630, along the edge of the much larger, active star-forming Ha region called IC 434. The Horsehead Nebula is approximately 1,375 light-years from Earth. It is one of the most identifiable nebulae because of its resemblance to a horse's head.
Celestron C925 with 0.63 reducer giving f6.3
ZWO ASI1600MM camera
Antlia filters
AZ-EQ6GT mount
Ha (green) 25x300s
Sii (blue) 25x300s
Oiii (red) 15x300s
RGB 10x30s (stars only)
Thanks for looking
trevsie7
Feb 13, 2025, 12:12:22 PMFeb 13
to 'J R' via croydonastro
For comparison, this is the HSO version
--
You received this message because you are subscribed to the Google Groups "croydonastro" group.
To unsubscribe from this group and stop receiving emails from it, send an email to croydonastro...@googlegroups.com.
To view this discussion visit https://groups.google.com/d/msgid/croydonastro/833dd6da-4a55-4913-9032-3ea74498f7efn%40googlegroups.com.
William Bottaci
Mar 8, 2025, 2:56:36 PMMar 8
to croydo...@googlegroups.com
Hello Trevor, that's not just an attempt, it's a result!
Each mapping of gas to colour - known as a palette - shows something different, possibly enhancing something, as yours does.
I've mentioned this before, for anyone not knowing about palettes:
HSO palette; Hydrogen shown as red, Sulphur as green, Oxygen as blue.
Sulphur is ionised by having lost 1 electron (counted as two 'ii's), Oxygen missing 2 electrons (counted as three 'iii's) and Hydrogen is not ionised but its electron moves about the atom.
SHO stands for the 3 gasses, Sulphur II, Hydrogen Alpha & Oxygen III. These are three select parts of the colour spectrum. Imagers collect these colours using three narrowband filters (not at the same time) and then combine the three separate images to make a false colour image. SHO is known as the Hubble Palette, which it often uses, though mostly for us public - the HST has 63 filters in all.
One thing Trevor, don’t know if you know, is there a standard for the order in which gases and colours are presented? I refer to a particular order of colours as RGB, and wondering that when mentioning a palette, using the letters for the three gasses S, H, O, if there was a standard then we can tell which is mapped to what. For instance, the Hubble Palette of SHO map these 3 gases to the three colours of RGB in that order.
If anyone is confused by this, you would not have been alone, why bother mapping and not just show the colours as they are? It doesn’t help that the two gases of Ha and SII are very close together and so both shine red. Of course they can't both be the same colour, and with the HST sulphur won, relegating hydrogen to green (and turquoise oxygen to blue).
One day in the future when amateur astronomers evolve to have tetrachromatic eyes through perpetually looking at nebulae we may better distinguish between hydrogen and sulphur...
Thank you for sharing - both images. I see the difference, well worth doing, but overall I prefer the red, maybe because it's what I'm used to but also because it shows more stars (one can never have enough :).
William
Each mapping of gas to colour - known as a palette - shows something different, possibly enhancing something, as yours does.
I've mentioned this before, for anyone not knowing about palettes:
HSO palette; Hydrogen shown as red, Sulphur as green, Oxygen as blue.
Sulphur is ionised by having lost 1 electron (counted as two 'ii's), Oxygen missing 2 electrons (counted as three 'iii's) and Hydrogen is not ionised but its electron moves about the atom.
SHO stands for the 3 gasses, Sulphur II, Hydrogen Alpha & Oxygen III. These are three select parts of the colour spectrum. Imagers collect these colours using three narrowband filters (not at the same time) and then combine the three separate images to make a false colour image. SHO is known as the Hubble Palette, which it often uses, though mostly for us public - the HST has 63 filters in all.
One thing Trevor, don’t know if you know, is there a standard for the order in which gases and colours are presented? I refer to a particular order of colours as RGB, and wondering that when mentioning a palette, using the letters for the three gasses S, H, O, if there was a standard then we can tell which is mapped to what. For instance, the Hubble Palette of SHO map these 3 gases to the three colours of RGB in that order.
If anyone is confused by this, you would not have been alone, why bother mapping and not just show the colours as they are? It doesn’t help that the two gases of Ha and SII are very close together and so both shine red. Of course they can't both be the same colour, and with the HST sulphur won, relegating hydrogen to green (and turquoise oxygen to blue).
One day in the future when amateur astronomers evolve to have tetrachromatic eyes through perpetually looking at nebulae we may better distinguish between hydrogen and sulphur...
Thank you for sharing - both images. I see the difference, well worth doing, but overall I prefer the red, maybe because it's what I'm used to but also because it shows more stars (one can never have enough :).
William
On Thu, 13 Feb 2025 at 17:12, trevsie7 <trevs...@gmail.com> wrote:
For comparison, this is the HSO version
On Thu, 13 Feb 2025 at 16:39, Trev S <trevs...@gmail.com> wrote:
Attached is my attempt at imaging the Horsehead Nebula processed in a slightly unusual pallette OHS (O-red, H-green, S-blue). I think this colour combination shows the depth of the nebula better than the standard HSO pallette (or it might just be my eyesight). This was taken on the 1st and 2nd February 2025 from my back garden in Surrey.
Attached is my attempt at imaging the Horsehead Nebula processed in a slightly unusual pallette OHS (O-red, H-green, S-blue). I think this colour combination shows the depth of the nebula better than the standard HSO pallette (or it might just be my eyesight). This was taken on the 1st and 2nd February 2025 from my back garden in Surrey.
The Horsehead Nebula (also known as Barnard 33 or B33) is a small dark nebula in the constellation Orion. The nebula is located just to the south of Alnitak, the easternmost star of Orion's Belt, and is part of the much larger Orion molecular cloud complex. It appears within the southern region of the dense dust cloud known as Lynds 1630, along the edge of the much larger, active star-forming Ha region called IC 434. The Horsehead Nebula is approximately 1,375 light-years from Earth. It is one of the most identifiable nebulae because of its resemblance to a horse's head.
Reply all
Reply to author
Forward
0 new messages