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#1
March 2nd 15, 07:10 AM
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Sh2-91
SH2-91 is part of a huge super nova remnant in Cygnus. The remnant is sometimes called Cygnus' other Veil Nebula. Like the Veil it is a shock wave bubble traveling through space. You see the interstellar medium as it is shocked into visibility by the shock wave. The entire shock wave is some 3° by 4° in size and at its distance of 2,500 light-years is over 225 light-years across. Fainter parts of the shock wave are cataloged as SH2-94 and SH2-96. The remnant is known as SNR 065.2+05.7 and is thought to have blown about 20,000 to 30,000 years ago. I didn't find much agreement on its age. The bubble, while larger than the Veil is much dimmer. SH2-91 is rather easy to find thanks to HD 185735, an 8th magnitude M2III star directly under it. 5th magnitude Psi (12) Cygni is about 15 minutes north and just out of my frame.
Due to the vast number of stars around this one I gave up using the luminance frames. They were picking up far too many stars. Instead I used 2 hours of H alpha data for the luminance frame. This cut the stars down many fold making it easier to see the nebula. Like the Veil this one has lots of OIII emission but not having an OIII filter I didn't pick up much of it except at the northeastern end where it only had OIII emission for the most part. There the blue data was stronger than the H alpha data so shows through slightly. In pure RGB the nebula was all blue but so lost in the stars I gave up trying to bring it out. Most OIII/H alpha images show the left side cyan from OIII and the right side pink from H alpha. Someday I'll get an OIII filter but for now it will have to be pseudo colored by the H alpha alone. The stars are colored solely by RGB data applied to the luminance of the H alpha data. 14" LX200R @ f/10, shockwave: Pseudo L=HA4x10' R=2x10'+80% Ha G=2x10' B=2x10'+20%Ha, Stars: Pseudo L=Ha4x10', RGB=2x10', STL=11000XM, Paramount ME Rick 
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#2
March 7th 15, 07:51 PM
posted to alt.binaries.pictures.astro
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Sh2-91
Great picture Rick. This is a tough object, I imaged it for two nights two
years ago but didn't bother to process the images... Stefan "WA0CKY" schrieb im Newsbeitrag ... SH2-91 is part of a huge super nova remnant in Cygnus. The remnant is sometimes called Cygnus' other Veil Nebula. Like the Veil it is a shock wave bubble traveling through space. You see the interstellar medium as it is shocked into visibility by the shock wave. The entire shock wave is some 3° by 4° in size and at its distance of 2,500 light-years is over 225 light-years across. Fainter parts of the shock wave are cataloged as SH2-94 and SH2-96. The remnant is known as SNR 065.2+05.7 and is thought to have blown about 20,000 to 30,000 years ago. I didn't find much agreement on its age. The bubble, while larger than the Veil is much dimmer. SH2-91 is rather easy to find thanks to HD 185735, an 8th magnitude M2III star directly under it. 5th magnitude Psi (12) Cygni is about 15 minutes north and just out of my frame. Due to the vast number of stars around this one I gave up using the luminance frames. They were picking up far too many stars. Instead I used 2 hours of H alpha data for the luminance frame. This cut the stars down many fold making it easier to see the nebula. Like the Veil this one has lots of OIII emission but not having an OIII filter I didn't pick up much of it except at the northeastern end where it only had OIII emission for the most part. There the blue data was stronger than the H alpha data so shows through slightly. In pure RGB the nebula was all blue but so lost in the stars I gave up trying to bring it out. Most OIII/H alpha images show the left side cyan from OIII and the right side pink from H alpha. Someday I'll get an OIII filter but for now it will have to be pseudo colored by the H alpha alone. The stars are colored solely by RGB data applied to the luminance of the H alpha data. 14" LX200R @ f/10, shockwave: Pseudo L=HA4x10' R=2x10'+80% Ha G=2x10' B=2x10'+20%Ha, Stars: Pseudo L=Ha4x10', RGB=2x10', STL=11000XM, Paramount ME Rick -- WA0CKY
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#3
March 8th 15, 07:43 AM
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I'd have expected NB to have picked up some of this one. Not having OIII I couldn't do it justice as most images show it strong in OIII. All I have is Ha unfortunately. And I need a new Ha. The one I have came out of the wheel (unmounted and the screws worked loose. The shutter hit the half out of the wheel filter and chipped it. Still works if I use Ha for only part of the field as in this image. I just put the object between the chips. Of course once it was hit it came out of the wheel and was hit each time the shutter revolved getting chipped on all sides until it jammed the shutter letting me know there was a problem. 2" NB filters aren't cheap. Since I use it mostly for Ha in galaxies I can get by with the chipped version. For now anyway.
Rick Quote:
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