| Last Post |
Johnny
|
|
9/29/2017 1:52 PM
|
Thanks Jeff.
I'm not familiar with the Crescent Nebula, and that gives me a better perspective.
Johnny
-----Original Message-----
From: "Astrophotography" <astrophotography@centexastronomy.org>
Sent: Friday, September 29, 2017 9:45am
To: "johnnyb@reagan.com" <johnnyb@reagan.com>
Subject: re: Crescent Nebula NGC 6888 <<$181659235674$>>
Johnny,
The field of view for the C1100/Hyperstar/SX814 combination is 1.28˚ x 1.02˚. Of course, there is a very small reduction in the actual image because of cropping due to non-perfect realignment following the Meridian flip.
Jeff
On Thu, Sep 28, 2017 at 12:44 PM, Astrophotography <astrophotography@centexastronomy.org> wrote:
Very nice work Jeff. I'd be interested in knowing what the field of view was for this shot.
And, thanks for sharing your methodology that apparently works very well.
Johnny
-----Original Message-----
From: "Astrophotography" <astrophotography@centexastronomy.org>
Sent: Thursday, September 28, 2017 9:21am
To: "johnnyb@reagan.com" <johnnyb@reagan.com>
Subject: Crescent Nebula NGC 6888 <<$18157918732$>>
Here is the first fruit of Okie-Tex this year. Most of you are familiar with the Crescent, but as I searched I found little to no pure narrowband (Ha, SII, OIII) of the nebula, so I went for it. For those interested in such things, it is a bubble of ejected gas, primarily hydrogen and oxygen, from a Wolf Rayet star, most o which was ejected as the star transitioned to a red giant. The ripple effect is a result of interstellar wind interacting with the heliosphere generated by the Wolf-Rayet star (V1770 Cyg/HD 192163/WR136) between 2,500 and 5,000 ly from earth.
Imaging consists of 24 subframes of 600 sec ea in Ha, SII, and OIII (Astronomik 12nm 1.25" filters) shot with a Hyperstar mounted SX814 camera cooled to -20˚C, on a C 1100 (11" aperture) Edge HD, providing a focal length of 560mm for an f-2 lens speed. Scope/camera were mounted on a Meade LX850 w/starlock automatic guiding. Notably, polar alignment was apparently spot-on from a single Polemaster alignment that took all of about 5 minutes. Capture & processing was with Nebulosity 3.2 & Adobe Lightroom. No darks as the Sony chip has little noise and Adaptive Median Noise Reduction in Nebulosity eliminates all the hot and warm pixels. Neither did I shoot flats as with the Hyperstar setup vignetting was not noticeable and test shots indicated no visual aberrations.
I can't say enough good about Hyperstar and the SX814 as otherwise the subframes would have needed to be at least 20 minutes each, and possibly 30. I attempted this image in the past using refractors with about the same effective focal length and found the images to be less detailed and requiring 30 minute subs to get this level of exposure in narrowband. The Meade Starlock is astonishingly good. If it loses a star it immediately selects another and continues tracking flawlessly. The only possible negative is that the filters are each in magnetic, metallic drawers and must be change manually up on top of the scope, requiring a small step-ladder or stool to reach the prime focus camera. They, though, are engineered well enough that it does not at all disturb the alignment.
Attachment(s):
File: Crescent_HST_North_up.jpg (7.5 MB) -- Address: http://s3.amazonaws.com/ClubExpressClubFiles/901132/attach/1815791_0_Crescent_HST_North_up.jpg
|
|
|
|
Willie
|
|
9/29/2017 12:16 PM
|
Thanks, Jeff. Willie > On Sep 29, 2017, at 9:45 AM, Astrophotography <astrophotography@centexastronomy.org> wrote: > > > > > Willie, > Sorry for not noting that this was done in HST palette (SII=Red, Ha=Green, OIII=Blue). I generally announce if a narrowband image is NOT done in HST as my experience suggests that HST is the accepted standard for such things. > I actually did create a HSO version, but the general consensus of viewers was that the HST version was much more pleasing to the eye. Folks apparently don't like deep red and purple images! The Hubble imaging team has pretty much-convinced folks that Hydrogen Alpha is green. > Jeff > On Thu, Sep 28, 2017 at 5:48 PM, Astrophotography <astrophotography@centexastronomy.org> wrote: > Very nice, Jeff. I assume the SII is green and the OIII is blue? Is that correct? Very little Ha, assuming it is red. > > Willie > > >> On Sep 28, 2017, at 9:21 AM, Astrophotography <astrophotography@centexastronomy.org> wrote: >> >> >> >> >> Here is the first fruit of Okie-Tex this year. Most of you are familiar with the Crescent, but as I searched I found little to no pure narrowband (Ha, SII, OIII) of the nebula, so I went for it. For those interested in such things, it is a bubble of ejected gas, primarily hydrogen and oxygen, from a Wolf Rayet star, most o which was ejected as the star transitioned to a red giant. The ripple effect is a result of interstellar wind interacting with the heliosphere generated by the Wolf-Rayet star (V1770 Cyg/HD 192163/WR136) between 2,500 and 5,000 ly from earth. >> >> Imaging consists of 24 subframes of 600 sec ea in Ha, SII, and OIII (Astronomik 12nm 1.25" filters) shot with a Hyperstar mounted SX814 camera cooled to -20˚C, on a C 1100 (11" aperture) Edge HD, providing a focal length of 560mm for an f-2 lens speed. Scope/camera were mounted on a Meade LX850 w/starlock automatic guiding. Notably, polar alignment was apparently spot-on from a single Polemaster alignment that took all of about 5 minutes. Capture & processing was with Nebulosity 3.2 & Adobe Lightroom. No darks as the Sony chip has little noise and Adaptive Median Noise Reduction in Nebulosity eliminates all the hot and warm pixels. Neither did I shoot flats as with the Hyperstar setup vignetting was not noticeable and test shots indicated no visual aberrations. >> >> I can't say enough good about Hyperstar and the SX814 as otherwise the subframes would have needed to be at least 20 minutes each, and possibly 30. I attempted this image in the past using refractors with about the same effective focal length and found the images to be less detailed and requiring 30 minute subs to get this level of exposure in narrowband. The Meade Starlock is astonishingly good. If it loses a star it immediately selects another and continues tracking flawlessly. The only possible negative is that the filters are each in magnetic, metallic drawers and must be change manually up on top of the scope, requiring a small step-ladder or stool to reach the prime focus camera. They, though, are engineered well enough that it does not at all disturb the alignment. >> >> Attachment(s): >> File: Crescent_HST_North_up.jpg (7.5 MB) -- Address: http://s3.amazonaws.com/ClubExpressClubFiles/901132/attach/1815791_0_Crescent_HST_North_up.jpg >> >> >> >>>> --------------------------------------------------------------------------------------<< >> You have received this message as a member of: Central Texas Astronomical Society >> Change preferences (including opt-out): https://CTAS.clubexpress.com/content.aspx?page_id=13&club_id=901132 >> >> > > > > >>> --------------------------------------------------------------------------------------<< > You have received this message as a member of: Central Texas Astronomical Society > Change preferences (including opt-out): https://CTAS.clubexpress.com/content.aspx?page_id=13&club_id=901132 > >
|
|
|
|
Jeffrey McClure
|
|
9/29/2017 9:40 AM
|
Willie,
Sorry for not noting that this was done in HST palette (SII=Red, Ha=Green, OIII=Blue). I generally announce if a narrowband image is NOT done in HST as my experience suggests that HST is the accepted standard for such things.
I actually did create a HSO version, but the general consensus of viewers was that the HST version was much more pleasing to the eye. Folks apparently don't like deep red and purple images! The Hubble imaging team has pretty much-convinced folks that Hydrogen Alpha is green.
Jeff
|
|
|
|
Jeffrey McClure
|
|
9/29/2017 9:29 AM
|
Johnny,
The field of view for the C1100/Hyperstar/SX814 combination is 1.28˚ x 1.02˚. Of course, there is a very small reduction in the actual image because of cropping due to non-perfect realignment following the Meridian flip.
Jeff
|
|
|
|
Dave
|
|
9/28/2017 10:53 PM
|
Very nice image Dave ---------- Original Message ---------- From: "Astrophotography" <astrophotography@centexastronomy.org> To: "jde209@netzero.net" <jde209@netzero.net> Subject: Crescent Nebula NGC 6888 <<$18157918732$>> Date: Thu, 28 Sep 2017 09:21:13 -0500 Here is the first fruit of Okie-Tex this year. Most of you are familiar with the Crescent, but as I searched I found little to no pure narrowband (Ha, SII, OIII) of the nebula, so I went for it. For those interested in such things, it is a bubble of ejected gas, primarily hydrogen and oxygen, from a Wolf Rayet star, most o which was ejected as the star transitioned to a red giant. The ripple effect is a result of interstellar wind interacting with the heliosphere generated by the Wolf-Rayet star (V1770 Cyg/HD 192163/WR136) between 2,500 and 5,000 ly from earth. Imaging consists of 24 subframes of 600 sec ea in Ha, SII, and OIII (Astronomik 12nm 1.25" filters) shot with a Hyperstar mounted SX814 camera cooled to -20˚C, on a C 1100 (11" aperture) Edge HD, providing a focal length of 560mm for an f-2 lens speed. Scope/camera were mounted on a Meade LX850 w/starlock automatic guiding. Notably, polar alignment was apparently spot-on from a single Polemaster alignment that took all of about 5 minutes. Capture & processing was with Nebulosity 3.2 & Adobe Lightroom. No darks as the Sony chip has little noise and Adaptive Median Noise Reduction in Nebulosity eliminates all the hot and warm pixels. Neither did I shoot flats as with the Hyperstar setup vignetting was not noticeable and test shots indicated no visual aberrations. I can't say enough good about Hyperstar and the SX814 as otherwise the subframes would have needed to be at least 20 minutes each, and possibly 30. I attempted this image in the past using refractors with about the same effective focal length and found the images to be less detailed and requiring 30 minute subs to get this level of exposure in narrowband. The Meade Starlock is astonishingly good. If it loses a star it immediately selects another and continues tracking flawlessly. The only possible negative is that the filters are each in magnetic, metallic drawers and must be change manually up on top of the scope, requiring a small step-ladder or stool to reach the prime focus camera. They, though, are engineered well enough that it does not at all disturb the alignment. Attachment(s): File: Crescent_HST_North_up.jpg (7.5 MB) -- Address: http://s3.amazonaws.com/ClubExpressClubFiles/901132/attach/1815791_0_Crescent_HST_North_up.jpg
|
|
|
|
Steve Brown
|
|
9/28/2017 8:08 PM
|
Good to know
-Steve
Sent: Thursday, September 28, 2017 5:48 PM
Subject: re: Crescent Nebula NGC 6888
<<$181623342152$>>
FYI,
to everyone on the list.
I’m not picking on you, Steve, just using this as an example. The
list server software (as configured by our provider) seems to attempt to
compress messages. One example is if you do not put at least 2 returns
before and after your signature or between paragraphs in general, they get run
together.
Sometimes it gets hard to tell who a message is from after several
replies.
Willie
WOW,
really nice Jeff. Thanks for sharing
-Steve From: Astrophotography Sent:
Thursday, September 28, 2017 9:21 AM To:
---------------------------------------------------------
|
|
|
|
Willie
|
|
9/28/2017 6:07 PM
|
Another excellent example. I had empty lines after list, together & replies. Did those blank lines show up on other subscribers emails? Perhaps it has another explanation. Willie > On Sep 28, 2017, at 17:48, Astrophotography <astrophotography@centexastronomy.org> wrote: > > FYI, to everyone on the list. > I’m not picking on you, Steve, just using this as an example. The list server software (as configured by our provider) seems to attempt to compress messages. One example is if you do not put at least 2 returns before and after your signature or between paragraphs in general, they get run together. > Sometimes it gets hard to tell who a message is from after several replies. > Willie
|
|
|
|
Willie
|
|
9/28/2017 5:47 PM
|
FYI, to everyone on the list.
I’m not picking on you, Steve, just using this as an example. The list server software (as configured by our provider) seems to attempt to compress messages. One example is if you do not put at least 2 returns before and after your signature or between paragraphs in general, they get run together.
Sometimes it gets hard to tell who a message is from after several replies.
Willie
WOW, really nice Jeff. Thanks for sharing -Steve From: Astrophotography Sent: Thursday, September 28, 2017 9:21 AM To:
--------------------------------------------------------- |
|
|
|
Willie
|
|
9/28/2017 5:32 PM
|
Very nice, Jeff. I assume the SII is green and the OIII is blue? Is that correct? Very little Ha, assuming it is red. Willie > On Sep 28, 2017, at 9:21 AM, Astrophotography <astrophotography@centexastronomy.org> wrote: > > > > > Here is the first fruit of Okie-Tex this year. Most of you are familiar with the Crescent, but as I searched I found little to no pure narrowband (Ha, SII, OIII) of the nebula, so I went for it. For those interested in such things, it is a bubble of ejected gas, primarily hydrogen and oxygen, from a Wolf Rayet star, most o which was ejected as the star transitioned to a red giant. The ripple effect is a result of interstellar wind interacting with the heliosphere generated by the Wolf-Rayet star (V1770 Cyg/HD 192163/WR136) between 2,500 and 5,000 ly from earth. > > Imaging consists of 24 subframes of 600 sec ea in Ha, SII, and OIII (Astronomik 12nm 1.25" filters) shot with a Hyperstar mounted SX814 camera cooled to -20˚C, on a C 1100 (11" aperture) Edge HD, providing a focal length of 560mm for an f-2 lens speed. Scope/camera were mounted on a Meade LX850 w/starlock automatic guiding. Notably, polar alignment was apparently spot-on from a single Polemaster alignment that took all of about 5 minutes. Capture & processing was with Nebulosity 3.2 & Adobe Lightroom. No darks as the Sony chip has little noise and Adaptive Median Noise Reduction in Nebulosity eliminates all the hot and warm pixels. Neither did I shoot flats as with the Hyperstar setup vignetting was not noticeable and test shots indicated no visual aberrations. > > I can't say enough good about Hyperstar and the SX814 as otherwise the subframes would have needed to be at least 20 minutes each, and possibly 30. I attempted this image in the past using refractors with about the same effective focal length and found the images to be less detailed and requiring 30 minute subs to get this level of exposure in narrowband. The Meade Starlock is astonishingly good. If it loses a star it immediately selects another and continues tracking flawlessly. The only possible negative is that the filters are each in magnetic, metallic drawers and must be change manually up on top of the scope, requiring a small step-ladder or stool to reach the prime focus camera. They, though, are engineered well enough that it does not at all disturb the alignment. > > Attachment(s): > File: Crescent_HST_North_up.jpg (7.5 MB) -- Address: http://s3.amazonaws.com/ClubExpressClubFiles/901132/attach/1815791_0_Crescent_HST_North_up.jpg > > > >>> --------------------------------------------------------------------------------------<< > You have received this message as a member of: Central Texas Astronomical Society > Change preferences (including opt-out): https://CTAS.clubexpress.com/content.aspx?page_id=13&club_id=901132 > >
|
|
|
|
Steve Brown
|
|
9/28/2017 5:22 PM
|
WOW, really nice Jeff.
Thanks for sharing
-Steve
Sent: Thursday, September 28, 2017 9:21 AM
Subject: Crescent Nebula NGC 6888
<<$18157918732$>>
Here
is the first fruit of Okie-Tex this year. Most of you are familiar with the
Crescent, but as I searched I found little to no pure narrowband (Ha, SII, OIII)
of the nebula, so I went for it. For those interested in such things, it is a
bubble of ejected gas, primarily hydrogen and oxygen, from a Wolf Rayet star,
most o which was ejected as the star transitioned to a red giant. The ripple
effect is a result of interstellar wind interacting with the heliosphere
generated by the Wolf-Rayet star (V1770 Cyg/HD 192163/WR136) between 2,500 and
5,000 ly from earth. Imaging consists of 24 subframes of 600 sec ea in
Ha, SII, and OIII (Astronomik 12nm 1.25" filters) shot with a Hyperstar mounted
SX814 camera cooled to -20˚C, on a C 1100 (11" aperture) Edge HD, providing a
focal length of 560mm for an f-2 lens speed. Scope/camera were mounted on a
Meade LX850 w/starlock automatic guiding. Notably, polar alignment was
apparently spot-on from a single Polemaster alignment that took all of about 5
minutes. Capture & processing was with Nebulosity 3.2 & Adobe Lightroom.
No darks as the Sony chip has little noise and Adaptive Median Noise Reduction
in Nebulosity eliminates all the hot and warm pixels. Neither did I shoot flats
as with the Hyperstar setup vignetting was not noticeable and test shots
indicated no visual aberrations. I can't say enough good about Hyperstar
and the SX814 as otherwise the subframes would have needed to be at least 20
minutes each, and possibly 30. I attempted this image in the past using
refractors with about the same effective focal length and found the images to be
less detailed and requiring 30 minute subs to get this level of exposure in
narrowband. The Meade Starlock is astonishingly good. If it loses a star it
immediately selects another and continues tracking flawlessly. The only possible
negative is that the filters are each in magnetic, metallic drawers and must be
change manually up on top of the scope, requiring a small step-ladder or stool
to reach the prime focus camera. They, though, are engineered well enough that
it does not at all disturb the alignment.
Attachment(s): Crescent_HST_North_up.jpg (7.5 MB)
|
|
|
|
abrickhouse
|
|
9/28/2017 12:45 PM
|
|
Hi Jeff, I have one other comment on your excellent picture.
If you have the ability in Adobe Light Room, you might try the minimize function on the stars. That will make the Crescent and filaments "pop" a lot more. Since the image is of the Crescent it makes it stand out a lot more without the overpowering of all the stars. Not sure if you would like it but might add to the image.
Thanks
Aubrey
-----Original Message-----
From: mailer@mail2.clubexpress.com [mailto:mailer@mail2.clubexpress.com] On Behalf Of Astrophotography
Sent: Thursday, September 28, 2017 9:21 AM
To: abrickhouse1@att.net
Subject: Crescent Nebula NGC 6888 <<$18157918732$>>
Here is the first fruit of Okie-Tex this year. Most of you are familiar with the Crescent, but as I searched I found little to no pure narrowband (Ha, SII, OIII) of the nebula, so I went for it. For those interested in such things, it is a bubble of ejected gas, primarily hydrogen and oxygen, from a Wolf Rayet star, most o which was ejected as the star transitioned to a red giant. The ripple effect is a result of interstellar wind interacting with the heliosphere generated by the Wolf-Rayet star (V1770 Cyg/HD 192163/WR136) between 2,500 and 5,000 ly from earth.
Imaging consists of 24 subframes of 600 sec ea in Ha, SII, and OIII (Astronomik 12nm 1.25" filters) shot with a Hyperstar mounted SX814 camera cooled to -20˚C, on a C 1100 (11" aperture) Edge HD, providing a focal length of 560mm for an f-2 lens speed. Scope/camera were mounted on a Meade LX850 w/starlock automatic guiding. Notably, polar alignment was apparently spot-on from a single Polemaster alignment that took all of about 5 minutes. Capture & processing was with Nebulosity 3.2 & Adobe Lightroom. No darks as the Sony chip has little noise and Adaptive Median Noise Reduction in Nebulosity eliminates all the hot and warm pixels. Neither did I shoot flats as with the Hyperstar setup vignetting was not noticeable and test shots indicated no visual aberrations.
I can't say enough good about Hyperstar and the SX814 as otherwise the subframes would have needed to be at least 20 minutes each, and possibly 30. I attempted this image in the past using refractors with about the same effective focal length and found the images to be less detailed and requiring 30 minute subs to get this level of exposure in narrowband. The Meade Starlock is astonishingly good. If it loses a star it immediately selects another and continues tracking flawlessly. The only possible negative is that the filters are each in magnetic, metallic drawers and must be change manually up on top of the scope, requiring a small step-ladder or stool to reach the prime focus camera. They, though, are engineered well enough that it does not at all disturb the alignment.
Attachment(s):
File: Crescent_HST_North_up.jpg (7.5 MB) -- Address: http://s3.amazonaws.com/ClubExpressClubFiles/901132/attach/1815791_0_Crescent_HST_North_up.jpg
|
|
|
|
Johnny
|
|
9/28/2017 12:35 PM
|
Very nice work Jeff. I'd be interested in knowing what the field of view was for this shot.
And, thanks for sharing your methodology that apparently works very well.
Johnny
-----Original Message-----
From: "Astrophotography" <astrophotography@centexastronomy.org>
Sent: Thursday, September 28, 2017 9:21am
To: "johnnyb@reagan.com" <johnnyb@reagan.com>
Subject: Crescent Nebula NGC 6888 <<$18157918732$>>
Here is the first fruit of Okie-Tex this year. Most of you are familiar with the Crescent, but as I searched I found little to no pure narrowband (Ha, SII, OIII) of the nebula, so I went for it. For those interested in such things, it is a bubble of ejected gas, primarily hydrogen and oxygen, from a Wolf Rayet star, most o which was ejected as the star transitioned to a red giant. The ripple effect is a result of interstellar wind interacting with the heliosphere generated by the Wolf-Rayet star (V1770 Cyg/HD 192163/WR136) between 2,500 and 5,000 ly from earth.
Imaging consists of 24 subframes of 600 sec ea in Ha, SII, and OIII (Astronomik 12nm 1.25" filters) shot with a Hyperstar mounted SX814 camera cooled to -20˚C, on a C 1100 (11" aperture) Edge HD, providing a focal length of 560mm for an f-2 lens speed. Scope/camera were mounted on a Meade LX850 w/starlock automatic guiding. Notably, polar alignment was apparently spot-on from a single Polemaster alignment that took all of about 5 minutes. Capture & processing was with Nebulosity 3.2 & Adobe Lightroom. No darks as the Sony chip has little noise and Adaptive Median Noise Reduction in Nebulosity eliminates all the hot and warm pixels. Neither did I shoot flats as with the Hyperstar setup vignetting was not noticeable and test shots indicated no visual aberrations.
I can't say enough good about Hyperstar and the SX814 as otherwise the subframes would have needed to be at least 20 minutes each, and possibly 30. I attempted this image in the past using refractors with about the same effective focal length and found the images to be less detailed and requiring 30 minute subs to get this level of exposure in narrowband. The Meade Starlock is astonishingly good. If it loses a star it immediately selects another and continues tracking flawlessly. The only possible negative is that the filters are each in magnetic, metallic drawers and must be change manually up on top of the scope, requiring a small step-ladder or stool to reach the prime focus camera. They, though, are engineered well enough that it does not at all disturb the alignment.
Attachment(s):
File: Crescent_HST_North_up.jpg (7.5 MB) -- Address: http://s3.amazonaws.com/ClubExpressClubFiles/901132/attach/1815791_0_Crescent_HST_North_up.jpg
|
|
|
|
abrickhouse
|
|
9/28/2017 12:35 PM
|
|
Well Jeff. It looks like you got a winner on this one. It is amazingly detailed and has excellent S/N. You did a great job on this. It would be great to see it in natural color with this level of detail.
I enjoyed the time we had at OkiTex with you folks and Dave. Only downer was the rain this year and my camera. I found the problem and it was simple to fix. The heat of Texas had caused a flat on the rubber band that drives the shutter wheel. They are sending me a replacement rubber band but for now it seems to be working ok.
Regards.
Aubrey
-----Original Message-----
From: mailer@mail2.clubexpress.com [mailto:mailer@mail2.clubexpress.com] On Behalf Of Astrophotography
Sent: Thursday, September 28, 2017 9:21 AM
To: abrickhouse1@att.net
Subject: Crescent Nebula NGC 6888 <<$18157918732$>>
Here is the first fruit of Okie-Tex this year. Most of you are familiar with the Crescent, but as I searched I found little to no pure narrowband (Ha, SII, OIII) of the nebula, so I went for it. For those interested in such things, it is a bubble of ejected gas, primarily hydrogen and oxygen, from a Wolf Rayet star, most o which was ejected as the star transitioned to a red giant. The ripple effect is a result of interstellar wind interacting with the heliosphere generated by the Wolf-Rayet star (V1770 Cyg/HD 192163/WR136) between 2,500 and 5,000 ly from earth.
Imaging consists of 24 subframes of 600 sec ea in Ha, SII, and OIII (Astronomik 12nm 1.25" filters) shot with a Hyperstar mounted SX814 camera cooled to -20˚C, on a C 1100 (11" aperture) Edge HD, providing a focal length of 560mm for an f-2 lens speed. Scope/camera were mounted on a Meade LX850 w/starlock automatic guiding. Notably, polar alignment was apparently spot-on from a single Polemaster alignment that took all of about 5 minutes. Capture & processing was with Nebulosity 3.2 & Adobe Lightroom. No darks as the Sony chip has little noise and Adaptive Median Noise Reduction in Nebulosity eliminates all the hot and warm pixels. Neither did I shoot flats as with the Hyperstar setup vignetting was not noticeable and test shots indicated no visual aberrations.
I can't say enough good about Hyperstar and the SX814 as otherwise the subframes would have needed to be at least 20 minutes each, and possibly 30. I attempted this image in the past using refractors with about the same effective focal length and found the images to be less detailed and requiring 30 minute subs to get this level of exposure in narrowband. The Meade Starlock is astonishingly good. If it loses a star it immediately selects another and continues tracking flawlessly. The only possible negative is that the filters are each in magnetic, metallic drawers and must be change manually up on top of the scope, requiring a small step-ladder or stool to reach the prime focus camera. They, though, are engineered well enough that it does not at all disturb the alignment.
Attachment(s):
File: Crescent_HST_North_up.jpg (7.5 MB) -- Address: http://s3.amazonaws.com/ClubExpressClubFiles/901132/attach/1815791_0_Crescent_HST_North_up.jpg
|
|
|
|
Jeffrey McClure
|
|
9/28/2017 9:11 AM
|
|
Here is the first fruit of Okie-Tex this year. Most of you are familiar with the Crescent, but as I searched I found little to no pure narrowband (Ha, SII, OIII) of the nebula, so I went for it. For those interested in such things, it is a bubble of ejected gas, primarily hydrogen and oxygen, from a Wolf Rayet star, most o which was ejected as the star transitioned to a red giant. The ripple effect is a result of interstellar wind interacting with the heliosphere generated by the Wolf-Rayet star (V1770 Cyg/HD 192163/WR136) between 2,500 and 5,000 ly from earth.
Imaging consists of 24 subframes of 600 sec ea in Ha, SII, and OIII (Astronomik 12nm 1.25" filters) shot with a Hyperstar mounted SX814 camera cooled to -20˚C, on a C 1100 (11" aperture) Edge HD, providing a focal length of 560mm for an f-2 lens speed. Scope/camera were mounted on a Meade LX850 w/starlock automatic guiding. Notably, polar alignment was apparently spot-on from a single Polemaster alignment that took all of about 5 minutes. Capture & processing was with Nebulosity 3.2 & Adobe Lightroom. No darks as the Sony chip has little noise and Adaptive Median Noise Reduction in Nebulosity eliminates all the hot and warm pixels. Neither did I shoot flats as with the Hyperstar setup vignetting was not noticeable and test shots indicated no visual aberrations.
I can't say enough good about Hyperstar and the SX814 as otherwise the subframes would have needed to be at least 20 minutes each, and possibly 30. I attempted this image in the past using refractors with about the same effective focal length and found the images to be less detailed and requiring 30 minute subs to get this level of exposure in narrowband. The Meade Starlock is astonishingly good. If it loses a star it immediately selects another and continues tracking flawlessly. The only possible negative is that the filters are each in magnetic, metallic drawers and must be change manually up on top of the scope, requiring a small step-ladder or stool to reach the prime focus camera. They, though, are engineered well enough that it does not at all disturb the alignment.
|
|
|
|