Thursday, March 4, 2021
Nebulae of Auriga and how my mosaic images are done.
I'll like to show the actual resolution of this and other of my large mosaic images by posting a close up from this panorama. Since there are data from so many years (2009 -2021) and it has been shot with various optical configurations, I had to develop a new method to combine frames for a mosaic image.
A closeup from the panorama
Click for a large image
Click for a large image
This closeup is reduced about 80% from the original resolution
In my last blog post I published a panoramic mosaic image showing the sky between taurus and Perseus. https://astroanarchy.blogspot.com/2021/02/a-new-mosaic-image-from-taurus-to.html
The Mosaic Work
Up to 2014 I was using an old Meade LX200 GPS 12" scope, QHY9 astrocam, Canon EF 200mm f1.8 camera optics and baader narrowband filter set. After 2014 I have had 10-micron 1000 equatorial mount, Apogee Alta U16 astro camera, Tokina AT-x 200mm f2.8 camera lens and the Astrodon 50mm square narrowband filter set. I have shot many details with a longer focal length, before 2014 by using Meade 12" scope with reducer and after 2014 Celestron EDGE 11" and reducer. Quider camera has been Lodestar and Lodestar II.
I took my current toolset as a base tool since it has a relatively high resolution combined to a very large field of view. Also it collects photons very quickly since it's undersampled and I can have very dim background nebulosity visible in very short time (many times 30 min frame is enough)
I do all my mosaic work under the PhotoShop, Matching the separate panels by using stars as an indicator is kind of straight forward work. My processing has become so constant, that very little tweaking is needed between separate frames, just some minor levels, curves and color balance.
I have used lots of longer focal length frames in my mosaic to boost details. To match them with shorter focal length shots I developed a new method.
Firstly I upscale the short focal length frames about 25% to have more room for high resolution images.Then I match the high res photo to a mosaic by using the stars as an indicator. After that I remove all the tiny stars from the high res image. Next I separate stars from low res photo and merge the starless high res data to a starless low res frame. And finally I place the removed low res stars back at top of everything with zero data lost. Usually there are some optical distortions and it's seen especially in a star field. Now all my stars are coming from a same optical setup and I don't have any problems with distortions. (I'm using the same star removal technique as in my Tone Mapping Work Flow)
Sunday, February 28, 2021
A new mosaic image from Taurus to Perseus 2009-2021
I have published several large mosaic images in past six months. This time my mosaic project took about 12 years to get finalized.
49 individual panels are covering 36 x 11 degrees of sky, total exposure time is around 250 hours. Native resolution for the mosaic is 31.000 x 8.800 pixels.
There are several rarely seen objects in my mosaic, they are very dim and majority of the 250 hours of exposures was used for them. There are three supernova remnants in the panorama, Simeis 147 at left, Sharpless 224 and Sharpless 221 are located at center of the image. They all are very dim but the Sharpless 221 is the most difficult one, it has an extremely low surface brightness and I think that my photo of Sh2-221 was the first three band color image out of it. Two large emission nebulae at right end of the mosaic must be the dimmest nebulae I have ever shot.
From Taurus to Perseus 2009-2021
Click for a large image, it's worth it!
Image in mapped colors from the light emitted by an ionized elements, hydrogen = green, sulfur = red and oxygen = blue. NOTE, the apparent size of the Moon in a lower left corner.
Frames used for the large mosaic
Click for a large image
Details and Orientation
Click for large images
Links to some of the individual images used in large panorama
Simeis 147
Sh2-221 & 216
https://astroanarchy.blogspot.com/2020/04/two-ways-to-go-in-same-field-of-view.html
older version
https://astroanarchy.blogspot.com/2014/01/sh2-221-supernova-remnant-in-auriga.html
older version
https://astroanarchy.blogspot.com/2014/01/sh2-221-supernova-remnant-in-auriga.html
Sharpless 205, NGC 1491 and Lynds Bright Nebula 696
Jus H-alpha
Sunday, February 21, 2021
Zooming in to an emission nebula Sharpless 132
Since I have shot many targets with various of focal lengths I'm able to make zoom in series out of my material. This is a nice way to show the fractal nature of our universe, there is always something new to see when the detail level gets higher.
This is also a good method to show the orientation and the scale in a large context.
A zoom in series to the Sharpless 132, Sh2-132
Click for a large image (Note a large image, 1600 x 8500 pixels)
Click for a large image (Note a large image, 1600 x 8500 pixels)
Optical configurations used for this image series, Before year 2015, Canon EF 200 mm f1.8, Baader narrowband set and QHY9 astro camera. For long focal length work Meade GPS 12". After 2015 Celestron EDGE 11", Tokina AT-x 300 mm f2.8, Apogee Ata U16 astro camera and Astrodon narrowband filters.
photos used for the zoom in series
- https://astroanarchy.blogspot.com/2021/02/this-gigapixel-mosaic-has-over-900.html
- https://astroanarchy.blogspot.com/2021/01/mosaic-image-gets-large-400-hours-and.html
- https://astroanarchy.blogspot.com/2020/11/a-new-photo-of-sharpless-132-sh2-132.html
- https://astroanarchy.blogspot.com/2021/02/sharpless-132-sh2-132-with-new-data.html
Thursday, February 18, 2021
Sharpless 132, sh2-132, with new data
I have shot a large four panel mosaic out of the Sharpless 132 emission Nebula at february 2019. At the time I was using the Celestron EDGE 11" telescope with reducer. Sh2-132 locates in the border of Cepheus and Lacerta at distance of about 10 000 ly.
I shot same object with a shorter focal length instrument, the Tokina AT-x 300mm f2.8 camera optics. Since the system is kind of undersampled, I got a very deep image of Sh2-132 just with four hours of exposures.
I have now combined those two images and the result has the best out of both worlds . All the high resolution details and the high signal to noise elements are from the long focal length photo and the dim background stuff is from short focal length photo. I have a new processing method to do this and it turned to be a very powerful for a work like this. I call it to VARES-method. Variable Resolution imaging. will be good tool when I want to go very deep very fast and have a high resolution details at the same time.
This is a way to combine best out of the correctly sampled and under sampled optical configurations!
I think this image is a good sample what VARES-technique can do.
Sharpless 132
Click for a large image
Sharpless 132 in mapped colors, from the emission of ionized elements,
R=Sulfur, G=Hydrogen and B=Oxygen. (Hubble Palette)
A version with out VARES method can be seen here, https://astroanarchy.blogspot.com/2019/02/sharpless-132-sh2-132.html
A version with out VARES method can be seen here, https://astroanarchy.blogspot.com/2019/02/sharpless-132-sh2-132.html
A closeup
Click for a large image
A wide field image of the Sharpless 132
Click for a large image
Sharpless 132 in mapped colors, from the emission of ionized elements,
R=Sulfur, G=Hydrogen and B=Oxygen. Image details can be seen here, https://astroanarchy.blogspot.com/2020/11/a-new-photo-of-sharpless-132-sh2-132.html
Technical details
Processing workflow
Image acquisition, MaxiDL v5.07.
Stacked and calibrated in CCDStack2.
Deconvolution with a CCDStack2 Positive Constraint, 33 iterations, added at 50% weight
Color combine in PS CS3
Levels and curves in PS CS3.
Imaging optics
Tokina AT-x 300mm f2.8 camera lens
Celestron EDGE 11" telescope with reducer
Celestron EDGE 11" telescope with reducer
Mount
10-micron 1000
Cameras and filters
Imaging camera Apogee Alta U16 and Apogee seven slot filter wheel
Guider camera, Lodestar x 2 and an old spotting scope of Meade LX200
Astrodon filters,
5nm H-alpha 3nm S-II and 3nm O-III
5nm H-alpha 3nm S-II and 3nm O-III
Total exposure time used for VARES-processing
Tokina camera optics
Tokina camera optics
H-alpha, 6 x 1200 s, binned 1x1 = 2 h
O-III, 3 x 1200 s, binned 1x1 = 1 h
S-II, 3 x 1200 s, binned 2x2 = 1 h
Celestron telescope
O-III, 3 x 1200 s, binned 1x1 = 1 h
S-II, 3 x 1200 s, binned 2x2 = 1 h
Celestron telescope
Total exposure time for all of the four panels together
H-alpha, 48 x 1200 s, binned 2x2 = 16 h
O-III, 24 x 1200 s, binned 4x4 = 8 h.
S-II, 18 x 1200 s. binned 4x4 = 6 h
O-III, 24 x 1200 s, binned 4x4 = 8 h.
S-II, 18 x 1200 s. binned 4x4 = 6 h
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