Since moving to Indiana I was just waiting to get my scope out and take a few pictures. My backyard is flat and open here which is a vast improvement to the backyard I had in North Carolina. However, it has been raining here a lot this spring and so when I finally saw some clear skies the other night I decided to get out under the stars. The other thing I have learned since moving to Indiana though is that the sun does not set until late!! It is about 10 pm before I have dark enough skies to start setting up.
I did not have a long session, but the point of my night under the starts was to test some new equipment and software. If any of you are debating on whtehr to upgrade to any of this equipment, I hope this can answer a few questions you may have.
A new main camera
All of my astrophotography in the past was done with a DSLR. I started with a D90 and then moved on to a D5300. Neither camera was modded and yet they both served me well. I was using Backyard Nikon as the software to take all of pictures with my Nikon cameras. Then I started reading and researching CMOS cameras and decided to take the plunge. I moved to a ASI294 MC Pro camera with cooling which is made by ZWO.
ZWO website: https://astronomy-imaging-camera.com/
I finally had a dedicated camera for my Stellarvue 90 refractor. In addition this camera has a built in cooler which is not present in a DSLR. The more heat that is present when you take pictures the more noise you get in your pictures. So having cooling can really help decrease the noise you will see in a picture.
Connecting the camera to the scope was a breeze. Everything just screws together. Just make sure you have the needed distance to achieve focus. The ASI294 ships with an extension tube which is all I need to achieve focus.
The ASI294 is the red camera on the very right of the picture:
Focus and Polar Alignment
Polar alignment is always the one step that does not seem to always go well for me. My go to method was to have my mount facing North, focus my scope and then use the Celestron polar alignment setting in the mounts hand controller. The mount I am using is the Celestrron AVX. This worked OK, but then I read about the software Sharpcap. I am now a big fan of this software for just polar alignment alone although it has many other features like focusing. The software is free for most uses although their is a small fee for features like polar alignment.
When I was using a DSLR I hooked up the camera to BackYard Nikon to see on my computer screen what the scope was seeing. Then I could use what I saw to focus the scope and then polar align with the Celestron polar align utility on the mount's hand controller. Now that I switched to the ASI294 I needed a new software that was compatible with the camera for focusing and polar alignment. Backyard Nokon only worked with DSLRs and not this new camera. SharpCap fills in the void left by not having BYN since it recognizes the ASI cameras made by the company ZWO.
Sharpcap: https://www.sharpcap.co.uk/
So before we polar align we need to be sure the guide camera and the main camera are in focus. In my setup I am using a second smaller ZWO cameera called the ASI120 mini that is attached to a smaller finder scope. This samll cope will be my guide scope and camera. You can just plug the USB cord running from each camera into your computer. Sharpcap lets you chose the camera you want to see and brings up the image on the screen based on the exposure you chose. You basically see a live view and are able to use that view to use the focusing knobs to achieve focus on both your guide camera and your main imaging camera.
Now that both the cameras are in focus, it is time to polar align. The smaller guide camera called the ASI120 mini is the camera I also used for polar alignment. Technically you could use either camera to acheive polar alignment. I just make sure the ASI120 mini is still plugged into my computer and it is the camera that is chosen in Sharpcap. Once Sharpcap is open and your camera is selected you are able to view what the camera sees and go into the polar align function. Here the program tells you exactly what to do and I was able to align my scope in about 10 minutes on the very first try with this software.
This is a screenshot taken right from the sharpcap website. I forgot to take any screenshots when I was going through the procedure. The basic principle is you are moving your mounts adjustment knobs to follow the yellow arrow and align on Polaris. As you move the appropriate adjustment knowbs the arrow gets closer and closer to polar alignment. Polar alignment is important to make sure you can take long expsoures with start trailing.
Imaging and Guiding
Normally with a DSLR I would use BackYard Nikon to capture my exposures and PH2 to guide my scope. Since I switched to the ASI294 I needed to change programs. I could have continued to use Sharpcap to take my photos, but instead I was testing out some new hardware and software from ZWO. ZWO is the company who makes the ASI294 and the ASI120. Since both my guide camera and my main imaging camera are made by ZWO, I wanted to try their hardward and software to easily control the camera and take images throughout the night.
The ZWO hardware to specifically use with ZWO cameras is called the ASIair. The beauty of the hardware is thatASIair allows you to take all of your photos wirelessly. In theory you could sit on your couch in your living room and tell your scope what pictures to take while also viewing the pictures as they load. It seems a little lazy, but on those really cold winter nights this sounds like a great idea to me! It also means you do not need to keep you computer hooked up outside all night.
The ASIair is a small little box that is using a Raspberry Pi as the brains. My guide scope (ASI120 mini) and my imaging scope (ASI294 MC Pro) both connect to the ASIair by USB cables. This little box is basically plug and play. One USB cable runs from each camera to the ASIair. The ASIair does need a power source to run. The hand controller from my Celestron mount also attaches to the ASIair so that it can wirelessly move your scope to the object you want to capture using the software instead of manually entering in your viewing object in the mount's hand controller. Even better there is also a guiding option built into the ASIair software. It looks like a mini version of PHD which would normally be done on a computer that is hooked up to your mount. The ASIair software is only in app form and can be downloaded either with Android or Apple. I first loaded it onto my Android phone, but it was a little too much info on a small phone screen for me, so I moved on to an old Apple Ipad mini which was a much better solution in my opinion.
Here is what the ASIair looks like and footprint it takes up. It comes with some Velcro stickers so you can attach it wherever you want on your mount or scope.
So how did it all work? Much better than I thought for my first night with it. I decided my object to test was M81 and M82. These are both galaxies that are very close to Polaris in the night sky. After I had a polar align with Sharpcap I was ready to test the ASIair out. I did need to hook up a laptop to the guide camera to use Sharpcap to aceive focus and then polar align, but after the polar align I was done with all computers for my imaging session. The rest was done on the Ipad mini in my house on on the couch (well almost, as I did run into one intial problem of plate solving.)
Using the ASIair program was mostly intuitive.
1 First you connect your Android or Apple device hosting the software to the wifi channel that the ASIair is broadcasting. I just opened up wifi networks on my Ipad mini and connected to the 5G signal coming from the ASIair
2. Once connected there are a few setting you need to put in, like your mount name, the ZWO camera you are using and and the focal length of your guide scope and your image scope. The Software does support many ZWO cameras and many different mounts.
3. Next you can tell your scope where to "GOTO". Supposedly your can go into SkySafari (another planetarium app) and pick any object you want and your mount would go there. I could not get this function to work as the Skysafari app would not recognize my mount. This is something I will need to troubleshoot. However there is a "Choose Object" database located in the ASIair app that had many objects including M81 and M82 (The screenshot below shows the choose object button). When I first slewed to this object the scope did not go to the right place. This was the only other big problem I ran into during the session. I did not do any star calibration since the ASIair has a plate solving feature. Since I was polar aligned, I clicked on plate solving and the software quickly said "plate solved." I assumeted this was all I need to do to calibrate the scope and mountt to the night sky (the scope knew where it was looking and going when told to goto an object). but my first slew to M81 proved this to be untrue. I tried plate solving a few more times but could not get this function to work. I had to go back outside and use the mounts hand controller to calibrate on 3 stars. Once calibrated, I went back the Choose Object in the ASIair and everything worked perfectly.
4. Once at the proper location to see M81 and M82 I clicked on the "Guide" option to chose a star to lock onto. I set the exposure of the ASI120 mini (attached to my guide scope) to 3 seconds and 48 gain and hit the "loop" button.
The stars appeared on the screen and then I just clicked on a star with my finger and hit the "guide button". The mini PHD graph showed some nice guiding. My scope was polar aligned, focused, pointed at M81/M82 and guiding and locked on a star. Now we were ready to actually start imaging.
5. Now that you are guiding you are ready to tell your main scope to start imaging. I used a gain of 120 and an exposure of 60 seconds. I also set the camera temperature to -20 C . This camera can theoretically go down to -40 but it depends on the outside temperature as to how low it can go. Also it looks like you do not want this ASI294 camera to work to hard to cool or it actually creates more heat trying to cool to get the temperature down. I know that does not make too much sense, but there are lots of internet posts on the subject. Therefore I used -20 C as my target temp on this night.
6. Next you can just set how many lights, how many darks, etc you want and hit the Go button. The camera will do what you tell it to do. I started by telling the camera to take 30 pictures at 60 second exposure and it did just that. After each exposure the picture is sent to the device for you to view. The ASIair box has a microSD card where all the images are being stored.
Here was a single 60 second exposure picture of M81 and M82 beaming back to my iPad Mini.
All in all the ASIair worked wonderfully. I was able to image wirelessly for the most part. I still needed my laptop for just a bit to polar align and focus and I hit a few snags with the sky alignment where I still needed to manually use the hand controller. Technically I could have used the ASIair software to focus as well and ZWO have mentioned a polar align feature coming. Note the ASIair was made for cameras made by ZWO. So if you have ZWO cameras like the ASI120 mini or the ASI294 I highly recommend the ASIair device. Seeing how my imaging session was going from afar with a live feed of the incoming pictures was great instead of sitting outside all night or constantly running outside to check on the computer.
Stacking the Pictures
At the end of the session, I had 70 lights, 20 darks, and 30 flats to stack. I stacked in Deep Sky Stacker (DSS) and also tried stacking in a new software called Astro Pixel Processor (APP). Both are free and fairly straightforward although both have many little setting that you can play with to optimize the final stack. Ultimately I feel like I had a little better stacking experience with APP even though this was the first time I have ever used it.
APP: https://www.astropixelprocessor.com/
If you try out APP, you will see the steps 0-6 on the opening screen. Just follow each step chronologically. If using a one shot color camera like the ASI294 then in step 0 (RAW/FITS) be sure to check "force Bayer CFA" and chose the Bayer pattern. The ASI294 Bayer pattern is RGGB.
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Processing the Stack
Now that we have stacked our lights, flats, and darks into one file we can process that image. This is where we need to remove background noise like light pollution, etc. I used a software called Startools. I actually struggled a little with trying to get the color processed correctly for the final image. I want to give the StarTools creator Ivo Jager I huge shout out for helping me get the most out of this data.
I shared the raw data and final stacked image before porocessing and this is the workflow that Ivo shared to get a nice result. I was able to replicate the workflow and get a similar final image.
If you would like to play with some raw data for both stacking and processing here is the link:
Stacks and individual frames hosted on Google drive
Super simple workflow below;
--- AutoDev
To see what we got, we can see noise, green/yellow bias, gradients, oversampling, stacking artifacts.
--- Crop
Removal of stacking artifacts.
Parameter [X1] set to [61 pixels]
Parameter [Y1] set to [38 pixels]
Parameter [X2] set to [4094 pixels (-50)]
Parameter [Y2] set to [2788 pixels (-34)]
Image size is 4033 x 2750
--- Bin
Parameter [Scale] set to [(scale/noise reduction 50.00%)/(400.00%)/(+2.00 bits)]
Image size is 2016 x 1375
Parameter [X1] set to [61 pixels]
Parameter [Y1] set to [38 pixels]
Parameter [X2] set to [4094 pixels (-50)]
Parameter [Y2] set to [2788 pixels (-34)]
Image size is 4033 x 2750
--- Bin
Parameter [Scale] set to [(scale/noise reduction 50.00%)/(400.00%)/(+2.00 bits)]
Image size is 2016 x 1375
--- Wipe
Vignetting preset.
Parameter [Temporary AutoDev] set to [Yes]
Parameter [Dark Anomaly Filter] set to [8 pixels]
Parameter [Drop Off Point] set to [0 %]
Parameter [Corner Aggressiveness] set to [100 %]
Parameter [Aggressiveness] set to [93 %]
Parameter [Temporary AutoDev] set to [Yes]
Parameter [Dark Anomaly Filter] set to [8 pixels]
Parameter [Drop Off Point] set to [0 %]
Parameter [Corner Aggressiveness] set to [100 %]
Parameter [Aggressiveness] set to [93 %]
--- Auto Develop
Final stretch.
Parameter [Ignore Fine Detail <] set to [2.0 pixels]
Parameter [RoI X1] set to [1126 pixels]
Parameter [RoI Y1] set to [686 pixels]
Parameter [RoI X2] set to [1389 pixels (-627)]
Parameter [RoI Y2] set to [819 pixels (-556)]
Parameter [Ignore Fine Detail <] set to [2.0 pixels]
Parameter [RoI X1] set to [1126 pixels]
Parameter [RoI Y1] set to [686 pixels]
Parameter [RoI X2] set to [1389 pixels (-627)]
Parameter [RoI Y2] set to [819 pixels (-556)]
--- Deconvolution
Worth a try.
(automatically generated mask)
Parameter [Radius] set to [1.3 pixels]
--- Color
Parameter [Radius] set to [1.3 pixels]
--- Color
Spiral galaxies like M81 tend to show a yellow core (less star formation) and a bluer outer rim (more star formation)
Something about the stars is off, as they showing fringing (it looks like DSS had trouble aligning them correctly?)
Parameter [Dark Saturation] set to [2.70]
Parameter [Blue Bias Reduce] set to [1.00]
Parameter [Green Bias Reduce] set to [1.72]
Parameter [Red Bias Reduce] set to [1.76]
Parameter [Blue Bias Reduce] set to [1.00]
Parameter [Green Bias Reduce] set to [1.72]
Parameter [Red Bias Reduce] set to [1.76]
--- Wavelet De-Noise
Switching Tracking off
Parameter [Scale 5] set to [50 %]
Parameter [Grain Size] set to [23.3 pixels]
Parameter [Smoothness] set to [85 %]
Parameter [Grain Size] set to [23.3 pixels]
Parameter [Smoothness] set to [85 %]
Final Image
When I tried to replicate a similar workflow this is the final image that finally comes at the end of the entire process:
Hello there M81 and M82!
Here is just a little more info on each galaxy from Wikipedia.
M81 and M82 taught me a lot. I really like the ZWO products, both the new ASI294 camera that has replaced my DSLR and ASIair wirelesss controller. I have only had one quick session with both of these pieces of hardware and I hit a few challenges. I need to play around to get things a little more streamlined, but I still managed to set up and get enough data for an image. Taking flats with the ASI294 is definitely something I think I need to optimize. Also I could not get SkySafari linked with the ASIair to use the Skysafari app for GOTO. The plate solving feature in the ASIair app also did not do anything for me. I still had to manually calibrate my scope with a few stars so the mount knew the layout of the sky.
I also really like APP and suggest you give it try for a stacking option. When it comes to polar alignment, I wish I had found Sharpcap a long time ago.
Clear Skies!
