My first night out imaging with the new telescope and filters was an eye opener for me. Focusing was a little more challenging and the added interconnections not only added weight to be factored in the overall balance, but also some flexure potential in the optical path. The biggest unexpected thing was the serious vignetting of the frame edges due to the light passing through the 1.25″ filter wheel onto a full frame 24mm x 36mm sensor. This is just something I’m going to have to deal with for a bit until I can find a better solution. Smaller targets being centered has become more important and larger targets are not as desirable due to the limitation in my FOV. I’m not certain at this point if spending the extra money on a 2″ filter rig would have prevented this or not.
My first stab at grabbing a couple of targets ended with 50/50 results. I initially tried to image M63, but the data just didn’t pan out. I had something terribly wrong and didn’t notice until I did the integration later.
I did manage a few short subs of M13. This is my first attempt at Messier 13 (NGC 6205), the Great Globular Cluster in Hercules and also my first integration with the new telescope. NGC 6207 is also visible in the lower left of the frame, so I intentionally didn’t crop this out. M13 was discovered by Edmond Halley in 1714, and cataloged by Charles Messier on June 1, 1764. M13 is about 145 light-years in diameter, and it is composed of several hundred thousand stars, the brightest of which is the variable star V11 with an apparent magnitude of 11.95. M13 is located 25,100 light-years from Earth.
The inability to image at home… or at least near home… is limiting my progress. I’m fairly patient, but getting out once a month is challenging. I am hungry to implement new knowledge I’ve learned through self-study and driving two to four hours a couple nights a month to hopefully practice is frustrating. Several weeks had gone by since my last imaging session out at Columbus and I hatched a plan at some point along that lull to “fix” my situation by accelerating my learning curve. I was going to leverage astronomy filters designed to attenuate certain wavelengths of light and allow the unhindered passage of other wavelengths of light in my imaging train. This is commonly called narrow-band imaging (NB). There was only one problem – no AP filters were made for my camera or lens. I even wrote the most prolific filter manufacturers asking for guidance and they confirmed my options were limited.
My long term plan was always to move into some sort of dedicated imaging telescope with an array of filters and a cooled CCD camera. I knew that is where I was headed… eventually. I didn’t think the telescope decision and purchase would be driven by the want for filters though… cart, horse, chicken, egg… this was happening.
I elected to purchase a refractor because it was closest to what I was familiar with in the “normal” photographic world and I wouldn’t have to deal with mirrors, collimation, and to a lesser extent, cooldowns, right away. I opted for a triplet to minimize chromatic aberration and flatten the field a little bit. I also decided to stick with Orion due to their tremendous customer service. I didn’t realize at the time the can of worms I was opening up, but this is clearly one of the ways to learn this hobby. By doing.
The list went something like this:
Orion EON 130mm ED Triplet Apochromatic Refractor
5-Position Manual Filter Wheel (1.25″)
1.25″ SkyGlow Imaging Filter
EZ Finder Deluxe II red/green (ordered this for visual)
I’m a big believer in not reinventing the wheel unless absolutely necessary. The best way to be successful at something is to find someone that is already very successful at it and follow in their footsteps. Learning from the mistakes of others is far less painful than learning from your own. So, when I deciding I was learning how to do this and do it well, I looked for local resources that I could plug into for Tribal Knowledge™ and assistance. Of the three major astronomy clubs in the area (that I knew of), I joined two:
One of the benefits of being a member of a local club is that they usually have access to some form of dark site for viewing (or imaging) away from the light dome of the city. These are no different. The HAAS dark site to the north is closer (Huntsville) at about 52 miles one way while the HAS dark site is west of me (Columbus) and over 100 miles one way! This really impacts the time you have to be productive when you take into account the time it takes to set all the gear up, polar align the mount, and do a star alignment. All the targets I’ve worked on thusfar (all three… woohoo) have been imaged at the HAAS observatory location, but after a month of inaction, I had a chance to image at the HAS site.
I had some trouble with star alignment that delayed data acquisition. The moon was bright and clouds were starting to roll in by the time I actually worked out the alignment. It wasn’t optimal by any means, but at least there were a few frames to be had… 26 lights and 30 darks totaling about 2.6 hours of total integration (give or take). My first attempt at Messier 101, the Pinwheel Galaxy, in wide field. Note NGC5485, NGC5474, NGC5473, NGC5457, NGC5443, and NGC5422 are also visible in this frame. Noise was a real issue here… as it has been in almost every integration. I’m learning tips and tricks along the way, but this gain noise due to sensor heat (CMOS) in my DSLR is going to have to be dealt with at some point.
The month of May was brutal with travel and weather challenges, so no imaging is done. I continue to learn with reading and observing others from afar… vicariously imaging through others and visualizing to improve. Two things that really jumped out at me when integrating the few subs I’d managed accumulate from the outing the month prior were:
I wasn’t getting enough data. I had too few lights and even fewer darks. I had no bias and no flats. This is a skill I need to work on.
My tools were lacking. Deep Sky Stacker wasn’t going to be my long term data integration solution and the 32-bit to 16-bit conversion in Photoshop was a point I was losing a lot of information that needed to be eliminated.
I applied for and downloaded a trial of the popular and immensely powerful astrophotography toolset PixInsight. Leveraging some really nice video tutorials over at Harry’s Astroshed, I went back to the original 55 sub-frames I took on May 3 of Messier 51 and started completely from scratch. With this same hour worth of RAW data, I was able to produce a much better result. There were significantly more steps in the integration, but it was well worth it. Capturing a glimpse of what can be done with the rudimentary information I had, it really made me want to improve the quantity of the data set and lower the signal to noise for next time around.
I did the same for the other two targets and feel I can see some improvement in those as well. Wanting to get some feedback and have a place to share my results, I started placing my revisions on Astrobin. My respect for some of these imagers has grown exponentially as I peel back the layers of the onion and see just how little I’ve progressed and how far there is to go. Exciting to be assured!