One really cool aspect of imaging deep sky objects is that the photons of light come into the camera randomly. This makes it possible to image the same object with different equipment (cameras, telescopes, etc) multiple times across multiple years, and combine all that data for an additive effect. Since all the light data is random, you’re only going to enhance any image you’ve already taken by adding more data to it.

In the image above, I took photos of M101 for the first time in April of 2018. I captured 17.5 hours over multiple nights using my AT6RC telescope, along with the ZWO ASI1600MM-C camera. This was monochrome data captured with LRGB filters.

My original capture of M101 on the ZWO ASI1600MM-C of 17.5 hours.

About two weeks ago, I again captured this same galaxy while trying out a new color camera the ZWO ASI071MC-Pro on the same telescope. This provided a much wider view thanks to the larger APS-C sized sensor in the new camera. I managed to capture another 9.5 hours.

The wider field of view captured with the ZWO ASI071MC-Pro for 9.5 hours.

Then I decided to combine both sets of data in Astro Pixel Processor. I did this by loading the final calibrated and combined data sets (two files, one from each session) into APP as light frames. APP gives a warning that these two images are integrations. That’s ok. I next went into the analyze stars tab and analyzed the stars for both frames, then I went into the register tab scrolled to the bottom started registration, after complete, I pressed “save registered frames”. This writes out two new files that are now aligned and registered to each other.

I pulled both registered images into PixInsight and combined them with Image Integration. Very happy with the new combined result, I had a 27 hours worth of image data in a new image of M101.

Then last night, thinking of how I could enhance the image further, I thought I could take some Hydrogen Alpha data to add to the set. I only had an hour of clear skies, so I set up all the equipment, aimed the AT6RC once again at M101 and started imaging with the HA filter. Most of the nebulas in our night sky are made up primarily of Hydrogen Alpha. Well, those nebulas also exist in other galaxies, and we can see them (although very small) by imaging the galaxies with a Hydrogen Alpha filter.

I followed the tutorial for PixInsight over on Light Vortex Astronomy to merge the HA data with the 27 hour image I already had. This created the final 28 hour image you see at the top of this post.

In total, this image was the combined process involving KStars/EKOS for image capture, Astro Pixel Processor for calibration and integration of frames, stretching and enhancement in PixInsight, and final touch up in Adobe Photoshop all on the Mac. The following equipment was also used. AT6RC telescope, ZWO ASI071MC Pro, ZWO ASI1600MM-C, Astrodon 5nm narrowband and LRGB filters, a Moonlite focuser, the Celestron CGX mount, and the Celestron AVX mount, a 60MM Orion guide scope, and the ZWO ASI290MM Mini guide camera.