California Nebula in HaRGB - Reprocessed Using PixInsight

This is the same data for the Califoria Nebula (NGC 1499) collected with my modified Canon 600d that I used to produce the image in November (and December) of 2017.  I used DSS for stacking and primarily Photoshop for processing.  I have been happy with using PS and hesitant of PixInsight for the usual reason - hard to learn.  However, I recently obtained a ZWO 1600MM-Pro and think it will be easier in the long run to process the images in PI.  Also, I read a recent Sky and Telescope article by Richard Wright who discussed this very subject.  In a nutshell he recommended learning both.  He made the point PI is not any harder to learn than PS and PI can do certain functions much easier than PS.  Use the right tool for the job mentality.

I have already experienced this in my very limited time using PI.  I stacked both the Ha and RGB data using PI and it produced two images which were aligned.  I believe DSS can do this as well but I did not know it at the time so I spent few hours aligning the Ha and RGB images by hand and eye.  I then combined these images using the NBRGB script function followed by a histogram stretch.  Special thanks goes to Shannon Calvert for helping locate the NBRGB function.  The combined image looked OK.  PixInsight did in 10 minutes what me many hours to do in PS.  I then exported the image to PS and did some of my favorite PS operations on this new rendition.  Why didn't I just continue and process the whole image in PI?  The point was to start using PI not totally switch yet and I wanted to get an image done quickly.  It is going to be a long process in order to learn this program, I imagine over time I will use PS less.

The new image is sharper and show more nebulosity than the original image.  Also, the stars as well as the star colors seem much more real or balanced, at least to me.

Reprocessed - PI and PS

Original - DSS and PS

NGC 1499 - California Nebula-HaRGBLocation: Home Monroe, CT
Date: 11-28-17, 12-20-17
Camera: Canon EOS Rebel T3i(a), Backyard EOS
Telescope: Orion ED80 80mm f/7.5 Apochromatic Refractor Telescope
Barlow: None
Focal Length: 600mm
f/7.5
Focal Reducer: Orion 0.8x Focal Reducer for Refractor Telescopes
Mount: Orion Sirius EQ
Filter: Astrodon UV/IR, Astronomik Ha Clip-filter, UHC-clip
Autoguiding: QHY-5L-II-M attached to an Agena 50mm Guide Scope with Helical Focuser
Exposure: 29 x 120s, 60 x 120s
ISO: 1600
Temp: 8 C, -2 C
Post Processing: Original - Deep Sky Stacker, Photoshop, Astronomy Tools, Lightroom Reprocessed - PI and PS
https://kurtzeppetello.smugmug.com/

Altair - First Image with the ASI1600

At long last I have finally broke down and purchased a ZWO ASI1600MM Pro along with the 8 position electronic filter wheel and a complete set of 1.25 inch filters (LRGBHaOS). This will take me quite a while before I get a quality image as there is a lot more to do and learn but I was excited get these first pictures.  They are 30 second exposures at Bin 1x1.  Figure 1 is at 78% gain, Figure 2 is the same image with a slight curve adjustment, Figure 3 is 140% gain, and Figure 4 is with a slight curve adjustment.

Fig 1

Fig 2

Fig 3

Fig 4

Last night was the perfect night for getting started as it was not good enough for real imaging but clear enough to see some stars for a little while anyway.  I first connected a new 7-slot USB hub and connected the camera with the Luminosity filter to the telescope and focused on Altair.   I was ecstatic that everything worked. 

It took a while to get it focused but that is the one difficulty I have been having with APT.  In fact I have been focusing with BYEOS and then using APT to image.  I purchased a Bahtinov Mask but I must be doing something wrong as I ended up getting better focus using the normal Focusing assistant with the Bahtinov mask.

Although it is cloudy I will try to connect up the EFW tonight and see if that works.
I have a long way to go before imaging - 1) find out what Bin actually is or what affect it has, 2) what is the optimal gain setting, 3) how APT changes/advances the filter wheel.

And then after that, processing...

NGC 7000 - North American Nebula

This is technically my second attempt at imaging the North American Nebula or NGC 7000, the first was a 14-minute exposure from three years ago. Needless to say I am much happier with this image although there is plenty of room for improvement. The North America Nebula is a large emission nebula in Cygnus but its surface brightness is low, therefore, is not visible with the unaided eye. It is so big I could not get the whole object in my field of view with my setup.  My image looks more like the United States Nebula.  I like how the Cygnus Wall (Mexico) came out but wish I was able to show more of it.  This also happens to be where most of the star formation occurs.

I used an Astronomik UHC filter and hoped to get some Ha data to combine but the weather as far out as predictions are made is for clouds and thunder storms so I decided to go with this.  However, since most of the photons are from the red channel, I copied it (the red channel) into a separate layer and then added it back to the original image as a luminosity layer (25%) to enhance the image.

NGC 7000 - North American Nebula
Location: Happy Frog Observatory, Monroe, CT
Date: 7-12-18
Camera: Canon EOS Rebel T3i(a), AstroPhotography Tool APT, Backyard EOS
Telescope: Orion ED80 80mm f/7.5 Apochromatic Refractor Telescope
Barlow: None
Focal Length: 600mm
f/7.5
Focal Reducer: Orion 0.8x Focal Reducer for Refractor Telescopes
Mount: Orion Sirius EQ (HEQ5)
Filter: Astrodon UV/IR, Astronomik UHC
Autoguiding: QHY-5L-II-M attached to an Agena 50mm Guide Scope with Helical Focuser
Exposure: 35 x 180s
ISO: 1600
Temp: 20 C

Post Processing: Deep Sky Stacker, Photoshop, Gradient Exterminator, Astronomy Tools, StarTools, Lightroom
https://kurtzeppetello.smugmug.com/

SH2-101 Tulip Nebula Finished

I finished this image of the Tulip Nebula (SH2-101) by adding the RGB (color) over the past few nights. The nebula is a HII region about 6,000 light years away in Cygnus.  It looks really cool that it is done but the individual frames looked like nothing.  The Ha data really made the tulip and the rest of the nebulosity stand out.  Although I took the color frames without any filter, I would recommend using a UHF if an Ha filter was not available.   For anyone who doubts the usefulness of adding Ha-images to color images I did a comparison of what I did to combine the images.  Basically I followed the Trevor Jones (Astrobackyard.com) directions for adding Ha-data to color data.

1) The Ha image (Ha) was created first over three nights when the moon was full or near full. I followed my normal procedures but stacked the frames using super pixel mode.

2) The color image (RGB) was done normally as well however at the recommendation of Shannon Calvert who was also imaging at the site, I switched to 800 ISO in order to lesson the noise which my old workhorse T3i seems to produce.

3) The Ha-image (HaR) was added to the the red channel of the color image to provide an initial boost.

4) The Final Image (HaRRGB) was produced when the Ha-image was added to the Enhanced image using the luminosity combining method. 

Addendum:
So I decided to redu my last object before changing over to PI.  I never was truly happy  background so though I would give PI a try.  I was unable to do my new normal HaRRGB method because there was a problem with the Ha stacked file, it had this horizontal -vertical pattern to it so I had to get rid of most of it with curve stretching.  It was not in the one I did four months ago with DSS so I think the problem is one set of flats is corrupt.  This also prevented the additional nebulosity from being visible.  If I get some more free time I will play with this again.  I think the star field looks really cool so I only did a 33% star reduction with morphological trans.  I am in the middle of trying to finish Andromeda but I have been very sick the last week and the weather has not been ideal either.  Also, I switched the orientation and did not us PS at all. 

Quick Pic 

Ha

RGB (Color)

Enhanced HaR

HaRRGB

HaRGB

SH2-101 - Tulip Nebula
Location: Happy Frog Observatory, Monroe, CT; Paine Open Space, Easton, CT
Date: 06-25-18, 6-28-18, 6-30-18, 7-8-18, 7-9-18
Camera: Canon EOS Rebel T3i(a), AstroPhotography Tool APT, Backyard EOS
Telescope: Orion ED80 80mm f/7.5 Apochromatic Refractor Telescope
Barlow: None
Focal Length: 600mm
f/7.5
Focal Reducer: Orion 0.8x Focal Reducer for Refractor Telescopes
Mount: Orion Sirius EQ (HEQ5)
Filter: Astrodon UV/IR, Astronomik 12nm Ha
Autoguiding: QHY-5L-II-M attached to an Agena 50mm Guide Scope with Helical Focuser
Exposure: 48 x 180s, 20 x 180s, 36 x 180s, 50 x 120s, 46 x 150s
ISO: 1600 (Ha), 800 (RGB)
Temp: 18 C, 20 C, 20 C, 18 C, 17 C
Post Processing: Deep Sky Stacker, Photoshop, Gradient Exterminator, Astronomy Tools, StarTools, Lightroom
https://kurtzeppetello.smugmug.com/

SH2-101 - Tulip Nebula in Ha

Been a while since I posted anything, I actually captured this image of the Tulip Nebula (SH2-101) over three nights last week when the moon was out. The nebula is a HII region about 6,000 light years away in Cygnus. I wanted to do something slightly less imaged and decided this was it. Since the moon was out (full) Ha was the best option if not the only option. I will add RGB when I can. This was a bit hit hard to find as it was not in the PlateSolve2 database so I had to do it the old fashioned way of hoping I had good alignment and using Stelliarium. Fortunately I had both. The other tough thing about imaging in Ha using a DSLR and no filter wheel is I have to focus on a very bright star with the Ha filter and use extended time exposures for location as live view is useless.

I am not very experienced with Ha processing and am never sure of how it is supposed to be with respect to brightness, background, noise reduction, and etc. With all that, here is my first ever attempt of the Tulip Nebula.

SH2-101 - Tulip Nebula
Location: Happy Frog Observatory, Monroe, CT
Date: 06-25-18, 6-28-18, 6-30-18
Camera: Canon EOS Rebel T3i(a), AstroPhotography Tool APT, Backyard EOS
Telescope: Orion ED80 80mm f/7.5 Apochromatic Refractor Telescope
Barlow: None
Focal Length: 600mm
f/7.5
Focal Reducer: Orion 0.8x Focal Reducer for Refractor Telescopes
Mount: Orion Sirius EQ (HEQ5)
Filter: Astrodon UV/IR, Astronomik 12nm Ha
Autoguiding: QHY-5L-II-M attached to an Agena 50mm Guide Scope with Helical Focuser
Exposure: 48 x 180s, 20 x 180s, 36 x 180s
ISO: 1600
Temp: 18 C, 20 C, 20 C
Post Processing: Deep Sky Stacker, Photoshop, Gradient Exterminator, Astronomy Tools

https://kurtzeppetello.smugmug.com/

M92 - The Less Viewed Globular Cluster in Hercules

Messier 92 (M92) is a wonderful globular cluster of approximately 330,000 stars spanning 108 light-years in diameter.  This bright cluster can be spotted without a telescope under dark conditions but is often overshadowed by the bigger and brighter Great Hercules Cluster, M13, which is very close by.  I like the way this one looks when viewing through the eyepiece as it seems more well defined than M13.  Another interesting piece is that M92 is one of the oldest globular clusters in the galaxy at 14.2 billion years (sources: wikipiedia and Messier Objects).

Also, this object is the first color object I stacked using raw frames rather than converted tiff frames.  See the previous post (TIFF vs. RAW: Problem of Stacking RAW in DSS Solved!) for an explanation of why.

Crop

Wide Field

M92
Location: Happy Frog Observatory, Monroe, CT
Date: 06-17-18
Camera: Canon EOS Rebel T3i(a), AstroPhotography Tool APT
Telescope: Orion ED80 80mm f/7.5 Apochromatic Refractor Telescope
Barlow: None
Focal Length: 600mm
f/7.5
Focal Reducer: Orion 0.8x Focal Reducer for Refractor Telescopes
Mount: Orion Sirius EQ (HEQ5)
Filter: Astrodon UV/IR
Autoguiding: QHY-5L-II-M attached to an Agena 50mm Guide Scope with Helical Focuser
Exposure: 50 x 90s
ISO: 1600
Temp: 18 C
Post Processing: Deep Sky Stacker, Photoshop, Gradient Exterminator, Astronomy Tools, StarTools, Lightroom2
https://kurtzeppetello.smugmug.com/

TIFF vs. RAW: Problem of Stacking RAW in DSS Solved!

So, along time ago when I first started out using Deep Sky Stacker (DSS) to stack frames captured with my Canon T3i/600D, DSS would not read the CR2 images generated by my camera so I had to convert them to tiff format.  I read this as a workaround somewhere.  I used Canon's Digital Professional to convert the raw frames.  The Clarkvision website actually recommended converting to tiff on one of the threads and gave some technical explanation as to why but it went over my head. 

After a couple of years and updates, DSS was finally able to stack the raw images. Eureka! It will be much quicker to process, however, when I examined the the stacked image I noticed the stars looked like dim donuts.

For this experiment I used M92 as an example.
- 50 light frames, 90s, ISO 1600
- 10 dark frames, 90s, ISO 1600
- 12 flat frames, ISO 1600
- 10 bias frames, 1/4000s, ISO 1600

Image 1 is the autosave file generated by DSS with the default settings. Notice the poor quality stars.

Image 1 - autosave image stacking raw frames

As I normally do, I converted the raw frames to tiff and the stacked image with the same default settings. Image 2 was the result. Notice the more well defined stars.  This has been my normal procedure for years.

Image 2 - autosave image using converted tiff frames 

I posted the question of why stacking my raw frames gave such poor results on Cloudy Nights and got plenty of reasons why stacking raw frames is much better.  The check out the link to Cloudy Nights to see all of the responses.

Mark summarized it as follows:
"When you stack TIFF files, you are stacking files that have been processed by the raw converter. The data are no longer linear but have been transformed into a non-linear colour space (e.g. sRGB or AdobeRGB). The stacked image is therefore also non-linear. When you subtract light pollution (which is typically high in red and low in blue because it is dominated by sodium street lights) from non linear stacked image, the result tends to have increasing blue with decreasing scene intensity and it tends to have very oversaturated colours."

The original question, however, was answered by another responder.

Wei-Hao summarized it as follows:

"The donut-shaped stars are likely caused by the cosmetic correction or hot pixels removal in DSS. If the setting is too aggressive, DSS would take all stars as hot pixels and remove them, leaving the stacked images no stars or dim stars with funky shapes.

You can first disable all options related to these and see if it solves the problem. Once you confirm the problem is indeed caused by the cosmetic correction, then you can try various settings there to find the best combination for your images."

I did what Wei had suggested and finally, after many years, my stacked raw image looks much better! I wish I posted this a long time ago, I don't know why I did not...

Image 3 - autosave image using raw frames with hot pixel removal disabled

The stars on this image are well defined as they are in the single raw image frames. Although converting to tiff was a pain I don't think my final images were of poorer quality, I believe they were potentially just as good, but I think I had to to a heck of a lot of extra processing in order to accomplish a decent image.  

To end with I have attached final versions of both methods.

Image 4 - Final stacking with tiff

Image 5 - Final stacking with raw (disabled hot pixel)

Hope this helps anyone with similar problems, 

Cheers Kurt