"What a thousand acres of Silphiums looked like when they tickled the bellies of the buffalo is a question never again to be answered, and perhaps not even asked." -Aldo Leopold
At the time I am writing this, a cool new app I have, EclipseOne, tells me the next Great American Eclipse will occur in 12 days, 13 hours, 22 minutes, and 2 seconds at my primary viewing location. There is not much time left to do your planning and practicing!
This past weekend, I put in a practice session – testing out the lens and camera combination, the solar finder and solar filter that will be going over my lens, and most importantly, using my tracker to track the sun as it moves across the sky. If you have an astro-tracking device that you might use for applications like deep-sky imaging or astro landscapes, I highly recommend you consider using this for the upcoming eclipse.
I know the question you might have before you even ask it. But how do we polar align in the daytime? True, you won’t be able to get precise polar alignment without the nighttime stars to guide your efforts, or at least without a lot of extra work. However, precise P.A. is not necessary to enjoy the benefits. I simply did my best to align the tracker facing north using a compass. I then tested the amount of time it took for the sun to move one of its diameter with and without using the tracker. This was easy because in my particular lens/camera combination, the circle that represents the spot-metering option was almost precisely the same size as the sun. Without the tracker it took only one minute and 22 seconds to move one of its diameter across my frame. With the tracker engaged (don’t forget to put your tracker in solar-tracking mode!), it took 22 minutes and seven seconds to move the same distance. Yes, there is a bit of drift due to imperfect PA, but this means I need only reposition the sun to the center of my frame once or twice an hour while using the tracker as opposed to doing this step 10 times or more an hour. Saving this kind of time during the big event will be a great benefit!
My imaging rig as it will look like on April 8th. I had to use both counterweights to balance this!
If you are planning to photograph the eclipse on April 8th, hopefully you have gotten your planning done, dusted off your solar filter and gotten some practice. If not, there’s still time, assuming we have some clear skies between now and then.
Wishing you all the best of luck on the big day and that the only rain we’ll see are Sol’s golden rays coming down from the clearest of skies!
The WGNSS Nature Photography Group, led by the man with the great ideas, Casey Galvin, headed to Elephant Rocks State Park in Iron County, MO, for the group’s February field trip. Our primary target for the evening was to utilize the full moon to light our scene after sundown – images often referred to as “moonscapes.” This was my first real attempt at taking moonscapes; usually I am focused on low to no-moon nights in order to focus on stars and deep sky objects.
Reflections on Quarry Lake ISO-50, f/11, 3.2 sec. exposure, 140 mm focal length
We arrived in time to have a walk around prior to sunset and the park’s official closing time. In order to be in the park after 5:00 pm, special permission must be made ahead of time. During our stroll, we made our way to the backside of the quarry lake – somewhere I had not been in many years. This turned out to be a serendipitous experience. There we encountered some very nice golden light and excellent reflections coming from the lake’s surface. Unfortunately, the winds were just strong enough to create some obnoxious ripples on the water, ruining the mirror effect I was going for. No worries, however; I added a CPL and a pretty strong neutral density filter (in order to increase shutter speed) to my mid-telephoto lens and the ripples magically disappeared.
Several abstract-like faces appeared in tight-compositions with the rock wall mirrored off the lake’s surface ISO-100, f/9, 2.5 sec. exposure, 84 mm focal length
I find capturing enough saturation in lighter colors a challenge with digital cameras. I am finally learning how to recover this in post-processing. The pretty light helped showcase the pink granites that the St. Francois Mountains are known for. ISO-50, f/11, 5 sec. exposure, 118 mm focal length
This one was too good to pass up the opportunity to make the face more obvious by orienting it vertically. ISO-100, f/9, 4 sec. exposure, 73 mm focal length
Shortly before sunset, we headed to the other side of the park to hang out with the rocks that give the park its famous identity. The remaining images were all taken after the sun had set and were exposed using only the light of the February full “snow moon.”
Moon rising over Elephant Rocks ISO-640, f/5.6, 10 sec. exposure, 20 mm focal length
Somewhat surprisingly, care had to be taken when shooting with the full moon at our backs as the shadows were very noticeable! ISO-3200, f/4, 6 sec. exposure, 20 mm focal length
Newer cameras shooting at longer exposures can pick up more stars than can be seen by the naked eye. I was happy to see the Pleiades and the Andromeda Galaxy in several of my moonscape images. ISO-320, f/4, 6 sec. exposure, 19 mm focal length
Can you spot the Pleiades star cluster in this moonscape? ISO-640, f/4.5, 8 sec. exposure, 15 mm focal length
This was certainly a special trip spent with friends. Temperatures and sky conditions were near perfect for photographing moonscapes. I was a bit surprised we did not have more WGNSS members take advantage of this special access. I won’t complain about that too much as I think having too many photographers would have made things more challenging with fighting shadows and finding access to good compositions.
The Heart and Soul Nebulae Located near the constellation Cassiopeia in the Perseus arm of the Milky Way lies a pair of well known nebulae, birthing stars and wonders. The well-named Heart Nebula (Sh2-190, IC 1805) and the less well-named Soul Nebula (Sh2-199, IC 1848) lie approximately 7,500 and 6,500 light years away respectively. Both are made up primarily of hydrogen gas and this condensing gas is the birth process of stars. Near the center of the Heart Nebula is an open star cluster of such newly formed stars known as Melotte 15. These stars have taken up much of the hydrogen and other gases from the nebula center and these young and bright stars light up the surrounding hydrogen gas, causing it to emit light in the red visible colors. Also of note in this image is the “fish head nebula” near the bottom of the heart, catalogued as IC 1795.
I find that the Soul Nebula, although a poetic match for its bigger neighbor, is poorly named. It may be difficult to see in my rendition, but in images with more defining details, I think this one should have been named the “chubby baby nebulae.”
Collecting the data October was another cloudy one around the new-moon period. Luckily we had what looked to be a great night on the new moon. As usual, the forecast let us down a bit. Due to issues Miguel had in one of his previous outings with a Conservation Agent at Whetstone C.A., we decided to go back to our spot at Danville C.A.
Conditions For a November outing the temperatures could have been much worse. We bottomed out at 42° F and winds never rose more than 5 mph. The forecasting apps all suggested a mostly clear night. Unfortunately, we were plagued with narrow bands of cirrus clouds that seemed to park themselves in between us and our target. These were barely perceptible to the naked eye, but they affected at least 25% of my subs over the course of the night.
Equipment Astro-modified Canon 7D mkii camera, Askar ACL200 200mm f/4 lens (260mm focal length equivalent), Fornax LighTrack II tracking mount without guiding on a William Optics Vixen Wedge Mount. QHYCCD Polemaster. Gitzo CF tripod, Canon shutter release cable, laser pointer to help find Polaris and sky targets, lens warmer to prevent dew and frost on lens, dummy battery to power camera, lithium battery generator to provide power to camera, dew heater and laptop computer.
Imaging Details Lights taken (ISO 2000, f/4, 120 second exposure): 153 Lights after cull due to tracker error, wind, bumps, clouds, etc.: 131 Used best 90% of remaining frames for stack for a total of 118 subs used for integration (3h 56m) Calibration frames: none
Processing RAW files converted to TIF in Canon DPP, stacked in Astro Pixel Processor, GraXpert for gradient removal, Starnet++ for separating nebulas from stars, Photoshop CS6 for stretching and other cosmetic adjustments.
Problems and learnings I know this section has just turned into a bitch session and this night was a bit on the rough side as well. First, I was disappointed in myself for the time it took to properly compose the target. Finding the object wasn’t too difficult, but because of the faintness of the targets, I just couldn’t get my mind together to make this tight framing (this image is only slightly cropped). After wasting nearly two hours of dark skies on getting the final composition and then having to do a second polar alignment (I think I must have nudged the tripod while making composition adjustments), I was finally taking images.
Next the periods of clouds. I continued to let the camera go even though I knew I would be tossing some frames. I culled about 20 frames due primarily to clouds but I left another 20 or so in the stack that I thought wouldn’t hamper the final result.
Typically, I can arrange the rig and counterbalance bar so that I do not require a meridian flip. I guess in my frustrations in finding and composing, I neglected to think about this. Yep, somewhere around midnight, I realized the camera was going to be running into the tracking unit if I didn’t perform this flip. Of course, doing this manually, meant I had to go through the process of finding and composing the target again! This time didn’t take me nearly as long and I was back to shooting in about 40 minutes or so.
All of the above explains why I was only able to collect about half of the data that I should have been able to on a night like this. The clouds got bad enough towards the end of the night that I shut down with more than an hour of usable night left.
Conclusion With the challenges on this night, I guess I have to be satisfied that I have something to share. This is another popular target that most astrophotographers get to pretty early. November is by far the best month for this target as it is viewable from the beginning to the end of night. There are a few other compositions to consider here, like shooting each nebula separately, or even focusing in on the heart of the heart – Melotte 15. So, I definitely have reason to revisit this section of the night sky someday.
The Cygnus Veil Complex The Cygnus Veil, also known as the Cygnus Loop, is a large (~ 3° in diameter) emission nebula created by a supernova explosion that occurred ~ 20,000 years ago. It lies an estimated 2400 light years from our solar system within the Cygnus (Swan) constellation.
Due to the large size of this gaseous complex, most astrophotographers choose to separately photograph distinct portions of the loop, or those portions of the loop that can be seen in visible light. The nebula on the left-hand side of this image is known as the Eastern Veil (Sh2-103, NGC6992, NGC6995), and on the far right lies the Western Veil, or the Witch’s Broom (NGC6960). In between these two lies Pickering’s Triangle (NGC6979), which was first discovered by the Scottish-born photographer, Williamina Fleming in 1904.
Somewhere inside this loop is the compact stellar remnant – the remains of the star that went supernova. Depending on the size of the star, this will either be a neutron star or a black hole. Both of these options are very difficult to identify as they do not emit much in the way of detectable radiation. Despite attempts by astronomers, the identity and position of the compact stellar remnant have not yet been discovered.
Collecting the data Due to the interference of clouds and life requirements, I missed the previous two new moon phases and it had been close to three months without an AP session. I was eager to get out there under clear skies in lovely September temperatures. Miguel found us a new imaging location – Whetstone Creek Conservation Area. This location has slightly darker skies (Bortle 3 vs. Bortle 4) and is only about a ten minute longer drive from my front door. To top it off, it is also seems less popular (at least during my first visit). I definitely have a new home for my astrophotography pursuits!
Date and location Imaged on the night of 14/15 September 2023 at Whetstone Creek Conservation Area in Callaway County, Missouri (Bortle 3). Dark period: 20:46 – 05:15 Target period: 15:30 – 05:10
Conditions The forecast was great for the night we chose for this session, but it turned out not to be perfect. We lost two hours of potential imaging time due to clouds that would not clear out until about 22:00 and clouds remained in the lower west that screwed up another hour or so on the late end. Temperatures were great, but seemed quite cold, with lows in the upper 40s F. Winds speeds were perfect with nothing above 4 mph across the night.
Equipment Astro-modified Canon 7D mkii camera, Askar ACL200 200mm f/4 lens (260mm focal length equivalent), Fornax LighTrack II tracking mount without guiding on a William Optics Vixen Wedge Mount. QHYCCD Polemaster. Gitzo CF tripod, Canon shutter release cable, laser pointer to help find Polaris and sky targets, lens warmer to prevent dew and frost on lens, dummy battery to power camera, lithium battery generator to provide power to camera, dew heater and laptop computer.
This was “first-light” for my new Askar 200mm lens – a lens specifically designed for astrophotography purposes. It is excellently built and provides a distortion-free field of view which was a hindrance of my Canon 200mm f/2.8 lens. When perfectly focused (read more of this below), it will definitely shine in comparison to my old 200mm focal length option.
Imaging Details Lights taken (ISO 3200, f/4, 120 second exposure): 178 Lights after cull due to tracker error, wind, bumps, clouds, etc.: 146 Used best 95% of remaining frames for stack for a total of 138 subs used for integration (4h 36m) Calibration frames: none
Processing RAW files converted to TIF in Canon DPP, stacked in Astro Pixel Processor, GraXpert for gradient removal, Starnet++ for separating nebulas from stars, Photoshop CS6 for stretching and other cosmetic adjustments.
Problems and learnings
Canon banding After months of diving into the forums and other online sources of information, I came away with only one strategy to hopefully avoid the terrible “Canon banding” problem I faced in a couple of previous sessions during warmer temperatures. In order to get my target above the sources of noise, I elevated the ISO used. In addition, I increased the sub exposure time. Increasing the sub times was partly in necessity of using a lens with an f/4 widest available aperture. I also moved the peak of the histogram for these exposure further to the right than I typically have. Thankfully, with my new tracker and polar alignment process, two-minute subs were easily accomplished without any issues. I could definitely go longer, but keeping the ISO at or above 3200 would not allow for this in order to keep the histogram where it needed to be.
After reading from a number of trusted sources, suggesting dark frames offer little-to-no benefit using my particular camera, I eliminated taking dark frames and any other calibration frames. This was an experiment. In practice, with enough total integration time to remove noise in the stack, I do conclude that dark frames/calibration are not necessary in my AP process. Additionally, there is some thought that using dark frame calibration can increase the potential for Canon banding and other issues that can show up during the stretch. This is a welcome finding indeed! With taking longer sub-exposures now, taking the required number of dark frames could add well over an hour to my night sessions.
The downside of using such an elevated ISO setting is the reduction in dynamic range. This probably does mean I am losing some tonal gradients and perception of sharpness in the final image. However, this is better than dealing with the banding problem that almost kills the project. I will keep this strategy moving forward.
Focusing The new lens offers great focusing aid. It has two focusing rings – one for coarse and one for fine focus, and each of these has a lock so that you will not inadvertently change these over the course of the evening. But, the tool is only as good as those who yield it. I had a little trouble with the fine adjustment and realized that the majority of my frames were not optimally focused. Overall, the image doesn’t suffer too badly from this oversight. With the focus problem and the never-optimal seeing conditions in Missouri, my FWHM (Full Width at Half Maximum) were in the 6-8 range. An FWHM of two or less is considered optimum for the uber astrophotographers out there. Always learning!
Processing I would really like to improve my processing skills for this work. Although I love the amount of hydrogen-alpha (the reds and magentas) that my sensor collects, the blues and star colors seem to get lost in the stretch. From my knowledge, I am using the correct curves adjustments that are supposed to avoid this, but there should be a lot more of the blues that are emitted from oxygen emission in this target. In addition, the blues are coming out more teal-colored, which I do not find all that attractive.
Conclusion With all the challenges I discussed above, I suppose I am relatively pleased with this one. I think I left some detail on the table, but there is enough there to make it interesting. The image handled the stretch well with no real signs of the dreaded Canon banding. This is an impressive and interesting target. I may try again using the 300mm lens. At that focal length, it is a tight fit. I hesitated to use it this time because of the potential of losing some of the target during cropping to eliminate stacking artifacts around the frame edges.
What do you think? Is this worth the time and effort? After looking at these images for so long, I find myself unable to really give them the critical eye needed to make this judgement. Feel free to leave a comment with your opinion.
Rho Ophiuchi Cloud Complex Within the constellation Ophiuchus (the Serpent Bearer) lies one of the most spectacular scenes in the summer night’s skies. It is arguably one of the most interesting as well. This area holds one of the closest stelar nurseries to our Sol and is composed of six primary bright objects and some dark nebula to boot.
Starting at the bottom point that makes up the pentagon of this object, we find the red supergiant star, Antares, and it’s accompanying cloud of warmly-colored, ionized hydrogen gas. Up and to the left of Antares is the blue reflection nebula, IC 4605, and continuing along the pentagon, we next come to a smaller blue reflection nebula – IC 4603. Outside the pentagon, just to the upper left of IC 4603 is yet another reflection nebula, illuminated by the five-star system known as Rho Ophiuchi. Moving to the next point in the pentagon, the upper right as seen in this image, lies Sh2-9, a combination reflection and emission nebula. Finally, making up the last point of our pentagon is M4, a fantastic globular star cluster comprised of at least 100,000 stars.
But it doesn’t end there! Also visible in this image are several named dark nebula, streaming away from the cloud complex moving towards the core of the milky way, just to the east of my frame. The primary dark nebula is catalogued as B44 and is known by its apt common name of the Dark River.
Collecting the data Miguel and I have had a rough couple of months for our astrophotography goals. We were completed clouded out during the new moon period in April, but we did get a session in in May, where we focused on the Blue Horsehead Nebula (IC 4592). But, due to some issues with working with some new gear (more on this below) and an unexpected processing issue, this one is still in the works for me.
In June, the weather (clouds and smoke from the big Canadian forest fires) was touch and go, but we did get a night that turned out to be about as close to perfect as you can expect for a summer night.
Date and location Imaged on the night of 19/20 June 2023 at Danville Conservation Area in Montgomery County, Missouri (Bortle 4). Dark period: 22:32 – 03:41 Target period: 20:27 – 03:06
Conditions Clear skies over the course of the session. Temperature ranged from 67-62 F. Winds at or below 5 mph.
Equipment Astro-modified Canon 7D mkii camera, Canon 90mm f/2.8 macro tilt-shift lens (144mm focal length equivalent), Fornax LighTrack II tracking mount without guiding on a William Optics Vixen Wedge Mount. QHYCCD Polemaster. Gitzo CF tripod, Canon shutter release cable, laser pointer to help find Polaris and sky targets, lens warmer to prevent dew and frost on lens, dummy battery to power camera, lithium battery generator to provide power to camera, dew heater and laptop computer.
Let’s talk about the new equipment used in the making of this image. First off, the Canon 90mm f/2.8 macro tilt-shift lens got its “first light” in astrophotography use. I suspected this lens could be very good for AP use due to its relatively wide open aperture and its larger imaging circle. This lens has next to no distortion or vignetting on my crop sensor body. I was looking for a good AP lens option around 100mm and am very excited about how this lens performed. I love a multi-trick pony!
Bill with his new AP rig set up and ready to rock!
The big new toy is the tracker I picked up for my birthday. The Fornax LighTrack II is likely the best portable and “affordable” tracking mount you can buy for optimal star tracking without guiding. I will likely publish a full review of this tracker system here in the future. I had some big issues when using it with the manual polarscope I purchased with it. This was a source of frustration for a while, but was solved by getting some more technology. In order to get the most precise polar alignment possible, which this mount needs to really shine, I picked up the QHYCCD Polemaster. This is basically a small camera that you attach to the mount and uses a computer program to allow you to perfectly align the mount to the north celestial pole. With this, I was able to get as accurate of a polar alignment as possible in less than 15 minutes. To use this, I did have to buy my first ever personal laptop computer – a nice refurb that only set me back $200. The main point here is that this new mount will allow me to get up to 4 times the exposure length for my sub-frames than what I was able to get with the Star Adventurer mount with no star trailing or drifting.
Imaging Details Lights taken (ISO 800, f/2.8, 90 second exposure): 150 Lights after cull due to tracker error, wind, bumps, etc.: 150! Used best 95% of remaining frames for stack for a total of 142 subs used for integration (3.56 hours) Darks: 30 taken at same exposure time and ISO as lights
Miguel tried out his big new toy. Say hello to “Brutus the Beefcake” Schmidt–Cassegrain!
Processing RAW files converted to TIF in Canon DPP, stacked in Astro Pixel Processor, GraXpert for gradient removal, Photoshop CS6 for stretching and other cosmetic adjustments.
Problems and learnings In a way, despite the more comfortable temperatures we would be working in, I was dreading the summer months when it came to prospects of astrophotography. I knew the scrambling that would need to be done to take advantage of the dark skies during the shortest nights of the year, but this isn’t what I am referring to. Since I use a non-cooled dSLR for this purpose, I was worried about sensor noise that increases dramatically as the temperatures rise. I knew this could be a significant issue, but wasn’t expecting the problem that it would bring.
I have now become aware of what is known as “Canon banding.” This problem manifests as broad horizontal bands of color noise that alternate in greens and magentas across the frame and is a well known issue with astrophotographers using older model Canon dSLRs. I couldn’t see this on the individual subs, but after stacking and just a slight amount of stretching, they became distinctly obvious and impossible for me to correct with my processing skills.
Up steps Miguel to save the day again. In PixInsight, the AP processing software Miguel uses, there is a script function that can reduce Canon banding dramatically. Miguel ran my unstretched stacked image through this and it made a world of difference. It did not eliminate the problem completely; I was still limited on how much stretch I could apply to this image because of it. But, with a little bit of touch up to the final stretched image, I was able to produce something I am happy to share.
Conclusion Overall I am very pleased with the final image, although it wasn’t exactly what I had in my mind’s eye when planning. Part of the problem was the banding issue, explained above. Additionally, I have come to realize that many summer DSO targets would greatly benefit from being shot on multiple nights. I think this would have come out more to my expectations if I had double or triple the amount of integration time. This simply isn’t possible in a single short night in summer months. I have never given the possibility of multi-night sessions much thought – one night’s sleep a month lost is enough I think. But, to do summertime DSO’s justice, especially nebulas, this might be worth considering when I have the opportunities.
I really do love this target. There are a lot of opportunities here that I look forward to trying in the future. I speak specifically to the different options of focal length. Using a longer lens (200-300mm) will focus in on the different great nebulas, bringing out more of their details, while using a wider lens, will show the dark river nebula flowing into the much brighter core of the milky way to the east.
If you made it this far, thanks for visiting and reading. I hope you liked this month’s AP image!
Markarian’s Chain – An interesting look into the Virgo Galaxy Cluster
Markarian’s Chain (NGC 4406) Since I picked up astrophotography, I knew I wanted to shoot some galaxy clusters. The first that comes to mind is Markarian’s Chain, a nice curved line of galaxies that lies amidst a large cluster of galaxies known as the Virgo Galaxy Cluster. The Virgo Cluster contains up to 2,000 different galaxies and Markarian’s Chain is an asterism-like chain that provides an interesting order to the randomness of the surrounding cluster. Typically, Markarian’s Chain is considered to be comprised of seven galaxies, all of which are moving in the same relative speed and direction with one another. The distance from earth to the galaxies varies from between 50 -80 million light years! Of course this means we are seeing them where they were up to 80 million years ago.
The galaxies comprising NGC 4406 are mostly elliptical and lenticular in type, but there are some fascinating details that can be found by taking a closer look. I’ve left the image above a bit larger than normal and invite the viewer to search within to see some of the different shapes and go galaxy hunting if you would like. I have counted about 35 galaxies in this frame. Most are quite small. Remember, if it’s a little fuzzy, it’s a galaxy. The stars are typically sharp in contrast to the dark background void.
Markarian’s Chain – annotated. Click for larger view.
Let’s take a look at some of the galaxies making up this frame. First, the two larger appearing galaxies that anchor the chain are M84 and M86. Just to the left of these are two interacting galaxies, NGC 4438 and NGC 4435, known collectively as ‘Markarian’s Eyes.’ I was happy to pick up enough detail to show how NGC 4438 is being distorted by the gravitational pull of it’s neighbor, sweeping out a lot of the gas, dust and likely stars from their normal placement.
Another prominent galaxy in this frame is found in the lower left corner. This is the supergiant elliptical galaxy, M87 (Virgo A, NGC 4486). M87 is one of the largest and most massive galaxies in our local universe, containing several trillion stars.
One last galaxy to bring your attention to is NGC 4440. This is an interesting barred spiral galaxy that I was not expecting to see in such detail. This galaxy is located at the intersection of two lines in this frame. Draw a line going directly downward from the eyes and another starting at Virgo A going to the right. Where these two lines intersect you will be close to NGC 4440.
See the accompanying partially-annotated image showing the names of the more prominent galaxies in this frame.
Collecting the data I have made my bed as an astrophotographer that does not use “go-to” technology and I am frustratingly sleeping in it. This one should have been easier to find. It is literally between two mid-magnitude stars – Denebola, in the Leo constellation and Vindemiatrix in the constellation of Virgo. All I had to do is draw a line between the two and the target is in the dead center. Somehow, I did not take this literally enough and spent nearly an hour finding the target and composing the frame. I do have one excuse; this area is filled with galaxies, so every time I took a test shot, there were several galaxies in the frame and it took me some time to see if the pattern I was looking for was there or not. Other than this, the night went pretty easy. We had perfectly clear skies, cold temps and Miguel and I had extra company. We joined with an imaging party from the Astronomical Society of Eastern Missouri, who just happened to be at Danville C.A. the same night we were. It was fun watching the experienced imagers and viewers pulling out all sorts of big, pretty and expensive optics and mounts. Unfortunately, between trying to concentrate on what I was doing and the very cold temperature, I didn’t find the time to do much socializing.
Date and location Imaged on the night of 19/20 March 2023 at Danville Conservation Area in Montgomery County, Missouri (Bortle 4). Dark period: 20:45 – 05:42 Target period: 19:52 – 07:31; Zenith 01:42
Conditions Clear skies over the course of the session. Temperature in the mid 20’s F. Winds below 5 mph.
Equipment Astro-modified Canon 7D mkii camera, Canon 400mm do mkii lens, Skywatcher Star Adventurer tracker without guiding on a William Optics Vixen Wedge Mount. Gitzo CF tripod, Canon shutter release cable, laser pointer to help find Polaris and sky targets, lens warmer to prevent dew and frost on lens, dummy battery to power camera, lithium battery generator to provide power to camera and dew heater, right-angle viewfinder to aid in polar alignment.
Imaging details Lights taken (ISO 6400, f/4.0, 20 second exposure): 1,076 Lights after cull due to tracker error, wind, bumps, etc.: 912 Used best 90% of remaining frames for stack for a total of 821 subs used for integration (4.56 hours) Darks: 36 taken at same exposure time and ISO as lights
Processing RAW files converted to TIF in Canon DPP, stacked in Astro Pixel Processor, GraXpert for gradient removal, Photoshop CS6 for stretching and other cosmetic adjustments.
Problems and learnings Miguel had to save my bacon with this one. This was the “first light” for astrophotography for my Canon 400mm f/4 do mkii lens. I had been eagerly waiting to try this lens for this purpose and, as I feared, this longer focal length did not allow for the 30 second exposures I had gotten used to using the 300mm lens. Even though this combination was a bit lighter than the 300mm f/2.8 lens, the Star Adventurer tracker just wasn’t up to it. So, I was forced to go with 20 second exposures to limit star trailing and, consequentially, had to use ISO 6400 to keep the signal to noise ratio where I needed it. This ISO setting is really pushing it with the camera I use so I wasn’t at all sure that I would even have a final image worth sharing in the end.
Because I pushed the ISO, the noise was pretty awful. Following a very light stretch after stacking, huge bands of green and purple showed up against the dark sky. I was at a loss on what to do about this, having exhausted all of the tools I knew to use in my processing train. I knew Miguel was beginning to become quite proficient in PixInsight processing so I thought I would ask him to try and see what he could do with my stacked image. I was dumbfounded when he was able to fix my problem in about 10 minutes! The final image could still probably be stretched a little more to bring out further details, but considering the ISO I was using, I have to be satisfied with the end result. I can’t get myself to put down the purchase price for PixInsight anytime soon, but that is something I’ll be considering in the future.
Conclusion Spring is known as galaxy season in the astronomy world. Most of the popular nebulas are not as available as they are in the winter and summer. Unfortunately, I really don’t have the equipment to take closeups of the far off and very small galaxies so I will have to settle for a few of the relatively larger ones as well as the clusters like Markarian’s Chain. I am pleased with what I was able to create here. As usual, it was with some considerable struggles and frustrations but I am coming to find that I kind of like overcoming those obstacles despite what I feel at the time.
The Rosette, or Skull Nebula, one of the largest and spectacular star-forming regions in our sky. Can you make out the skull? It is looking downward around 8:00.
The Rosette or Skull Nebula (NGC 2237, Sh2-275) My February target was the fantastic and grand Rosette Nebula, also known as the Skull Nebula for hopefully obvious reasons. This nebula is a gigantic cloud of predominantly ionized atomic hydrogen that lies in the Monoceros constellation, not too far from the Orion Molecular Cloud Complex. This object has a number of different catalogue designations given to different regions of the nebula (NGC 2237, 2238, 2239, 2246) and associated star clusters. The primary star cluster being NGC 2244 – the most central cluster that provides most of the illumination and stellar winds and radiation that illuminate and disperse the gaseous clouds that form the nebula. X-ray imaging has identified approximately 2500 young stars in this star-forming complex.
Space is Big This nebula lies approximately 5,000 light years from earth and is roughly 130 light years in diameter. To get an idea how immense this nebula is, compare this to the Great Orion Nebula (M42), which is only 40 light years in diameter. With all this talk about light years, I wanted to explore this to get a better idea of what we’re talking about and try and wrap our heads around the scale of an object like this. A light year is roughly 5.88 trillion miles – the distance light travels in a year. Since I’m an American, I’ll keep everything in miles so that I can better understand. The diameter of this nebula is roughly 764 trillion miles. The fastest spacecraft ever recorded is the Parker Solar Probe, which reached a top speed of 364,660 mph. This comes to 3,194,421,600 miles this probe can traverse in a single year. Sounds like a lot, right? Well, to cover the 764 trillion miles to reach one end of this nebula to the other, it would take the Parker Probe 239,167 years! We probably don’t need to get into the amount of time it would take the Parker Probe to get to the nebula in the first place.
“Space is big. You just won’t believe how vastly, hugely, mind-bogglingly big it is.” Douglas Adams – A Hitchhiker’s Guide to the Galaxy
Collecting the data I had anticipated this one being a little difficult to find. IT is found roughly on the line between two stars of the winter triangle – Betelgeuse, and Procyon. But, there are really no large magnitude stars in close proximity to help get it in the tight frame of my 300mm lens. I was please that it took me only about 10 minutes to get it in frame. However, because I was hoping to grab some of the much dimmer gases that can make up a sort of stem of this rose, I spent another 30 minutes trying to frame it just so. This turned out to be time wasted. In order to get this dim gas to show, much more integration time would be necessary than what I was able to collect on a single night.
Date and location Imaged on the night of 17/18 February 2023 at Danville Conservation Area in Montgomery County, Missouri (Bortle 4).
Dark period: 19:10 – 05:19
Target period: 15:20 – 02:08; Zenith 20:44
Conditions Clear skies over the course of the session. Temperature: 31° – 27° F. Winds forecasted to be 6-8 mph but seemed lower than this.
Equipment Astro-modified Canon 7D mkii camera, Canon 300mm f/2.8 lens, Skywatcher Star Adventurer tracker without guiding on a William Optics Vixen Wedge Mount. Gitzo CF tripod, Canon shutter release cable, laser pointer to help find Polaris and sky targets, lens warmer to prevent dew and frost on lens, dummy battery to power camera, lithium battery generator to provide power to camera and dew heater, right-angle viewfinder to aid in polar alignment.
Imaging Details Lights taken (ISO 3200, f/2.8, 25 second exposures) 779. 61 frames dropped due to poor focus, 217 frames dropped due to tracker error, 10% frames dropped in stacking instructions. A total of 450 frames used in integration for a total of 3.13 hours. Darks: 39 taken at the exposure time listed above. Bias and Flats: Not taken. Removed most vignetting and some chromatic aberration while converting RAW images to TIF.
Processing RAW files converted to TIF in Canon DPP, stacked in Astro Pixel Processor, GraXpert for gradient removal, StarNet++ for separating stars from nebulosity, Photoshop CS6 for stretching, recombining stars and nebulosity and other cosmetic adjustments.
This one was a bit tougher than I expected, mainly due to the StarNet software not wanting to work the first several times I tried. I captured more of the hydrogen alpha in the surrounding regions than this image depicts but, because it was so faint, nasty artifacts appeared during the stretch. I was forced to leave much of this out of the final image due to this. I think in order to do this properly I would need much more total integration time.
Problems and learnings This one went about how I had expected except for one thing. I was devastated to learn that I had not acquired critical focus for roughly the first 45 minutes of imaging. This was even more of a blow as this time coincided with the object being at or near its zenith, meaning I lost some of the best potential data gathering of the night.
I have also been collecting some data on how many subs I throw away due to errors in tracking. In this case, 35% of the subs I took were thrown away, which seems to be close to my average when using this lens at these exposure times. I dropped the exposure time to 25 seconds in order to help reduce this but I think this issue is mostly due to the tracker being at or above its limit in regards to payload and focal length. For this reason, I am investigating a new tracker that should meet my needs nicely for a 1-2 minute exposure with the above kit and a keeper rate of greater than 90%. Keeping my fingers crossed for that company bonus this year. 😉
Conclusion This is another very popular and relatively easy object that most astrophotographers tackle early on. Overall I’m pleased with the outcome. I like the detail and the colors but I think that better processing might bring these out better even with the data I have here. Always learning. This object is better imaged in December or January, when more time with it can be had in a single night. I look forward to trying this one again someday.
Comet C2022 E3 (ZTF) photographed on 21 January 2023
After M42 had began to drop to low in the western skies, making any further attempts at photographing it futile, I decided to try and find the newly discovered, long period comet, C2022 E3 (ZTF). I was unable to see it with my naked eye at my location, but with careful scanning using binoculars, I was able to find it. At 03:00, I was happy that getting it in the camera viewfinder wasn’t too difficult a task. I knew this wouldn’t be the best image of this comet, but I didn’t want to pass up the opportunity. This is a stack of 77 20-second images. You can make out the green color of the comet’s head, proposed to be due to the presence of diatomic carbon, along with two tails. The broader, warmly colored tail is the dust tail and the fainter tail below is the ion tail.
The comet’s closet distance to earth will appear on February 1st, where it will be close to the north celestial pole. The waxing moon will make it harder to see. So, if you plan on trying to see this one yourself, you should wait until the moon sets.
Located in winter skies of the northern hemisphere within the asterism of Orion’s Sword, The Great Orion Nebula (M42), and it’s smaller companion, The Running Man Nebula (M43) are the closest star forming regions to earth.
The Great Orion and Running Man Nebulas (M42 and M43) After trying for three months, we finally had a night of very good conditions to create the closeup of these two objects that I have been hoping to accomplish. The winds were low enough that I felt comfortable using the big 300mm lens. We had zero clouds the whole night and although this was the night before the new moon, the 3% moon that was left didn’t rise until after 05:00. Humidity was high, so seeing and transparency weren’t the best and the frost was building, but I’ll take a night like this anytime. In addition, since these objects set around 03:00, I had the opportunity to photograph a new comet in our sky, C/2022 E3 (ZTF). This comet appears to have an orbit that won’t put it back by earth for about 50,000 years, so I thought now would be the best time to try for a photograph.
A part of the asterism known as Orion’s Sword within the Orion Constellation, the Great Orion Nebula (M42) is an enormous cloud (~40 light years in diameter) of fluorescent gas, composed primarily of hydrogen, which lies approximately 1350 light years from earth. It also contains traces of helium, carbon, nitrogen and oxygen. M42 is a diffuse, emission-type nebula that is home to star formation. The bright nascent stars, primarily Theta Orionis – the four stars that make up the asterism known as the “Trapezium,” are found within the bright core of the nebula. Via a process known as photoionization, these stars provide the ultraviolet radiation that excites the hydrogen and other elements to emit the visible light by which we can see the fine, multicolored mackerel patterns throughout M42. There are thought to be about 2800 young stars, mostly unseen via visible light imaging, within the nebula.
The M42 nebula is both the brightest and closest such star forming nebula to earth, making it one of the most viewed, photographed and studied deep sky object. Evidence suggests that the current brightness (equivalent to a 4th magnitude star) may be a recent phenomenon. This is supported by the fact that M42 and M43 were not mentioned by the early astronomers (e.g. Ptolemy – 2nd century CE, al Sufi – 10th century CE, and Galileo – 17th century CE) despite their close observations and records of this area of the sky. The accepted first discovery of M42 was by the French astronomer, Peiresc, who first published his observations in 1619.
The Running Man Nebula (M43) is so named for the vague specter that can be seen sprinting across this gaseous body. It is a wedge of nebulosity located northeast of the Trapezium and primarily illuminated by the 7th magnitude “Bond’s” star. I find that M43 is a perfect bit of color and contrast that tops off M42 very well.
Collecting the data (20/21 January) Having had imaged this section of sky in December, I gained experience in collecting image data and processing using multiple exposure lengths. This is important for M42 particularly in collecting fine details in the outer dim gas and dust clouds while also capturing the details in the bright hot core. Overall, imaging went as I anticipated with the exception of a couple new issues that I explain below.
Substantial frost developed on all exposed equipment during this night’s session.
For this session, Miguel and I setup at Danville C.A., as usual, and Miguel brought along his partner, Leela. Miguel wound up collecting the data he needed earlier than I did, and he and Leela were on their way home before 01:00. The forecasts were mostly correct. There was a chance of clouds developing over us around 03:00 but when I was on the road home around 05:00, the skies were still clear. I want to thank my friend, Pete Kozich for his assistance in meteorological forecasting for this and past projects. That is always a big help and much appreciated.
One anecdote to share was something I expected to happen sooner or later. Miguel and I had just started our imaging when a pickup truck pulled into the parking lot, with the driver placing its beams down the road to where we were setup. I immediately thought this was going to be another meeting with a Conservation Agent. When it was obvious they weren’t going to pull out and head off, I stopped the camera and headed over to the parking area. When I arrived, I was met by a group of friendly hunters and their dogs who shared that they were hoping to do some coon hunting. They asked what we were doing and I told them, mentioning that their headlights and any additional lights would be detrimental to what we were trying to accomplish. Thankfully, this C.A. is pretty large with a few different access points. When they understood the situation, they graciously decided to allow us to continue without further disturbance and headed to a different location. I understand these areas are used by different folks with different purposes in mind and was thankful they didn’t try and push the point.
Conditions Over the course of this imaging session, skies were clear of clouds. Winds started at 6 mph and wound up around 2 mph by the end of the night. Temperature ranged from ~34 – 23 °F over the course of my imaging.
Equipment Astro-modified Canon 7D mkii camera, Canon 300mm f/2.8 lens, Skywatcher Star Adventurer tracker without guiding on a William Optics Vixen Wedge Mount. Gitzo CF tripod, Canon shutter release cable, laser pointer to help find Polaris and sky targets, lens warmer to prevent dew and frost on lens, dummy battery to power camera, cart battery to provide power to camera and dew heater, right-angle viewfinder to aid in polar alignment.
Imaging details Lights taken (ISO 3200, f/3.2): 32 seconds (492 taken, 412 used in integration); 16 seconds (165 taken, 148 used in integration); 8 seconds (112 taken, 106 used in integration); 4 seconds (56 taken, 54 used in integration); 2 seconds (63 taken, 61 used in integration); 1 second (61 taken, 60 used in integration). Darks: 30 taken at each of the six exposure times listed above. Bias and Flats: Not taken. Removed most vignetting and some chromatic aberration while converting RAW images to TIF.
Processing I admit, this one was a chore. Almost 15 hours in total, most of this in the stacking at the six different exposure lengths. I’m not completely satisfied with my compositing for the core of M42. Even though I’ve gotten a lot of experience with doing this in Photoshop, I still don’t have the skillset to combine the different stacks into something I picture in my mind.
I think I may be finished with Deep Sky Stacker (DSS). When attempting to stack the 32-second frames, DSS would only accept about half of them. Digging into the reasons for this, I found that DSS is particularly picky about only accepting subs that are above a threshold of star quality. Because I shoot with fast lenses, opened wide, and because I am using an entry level star tracker, my stars would not be considered top quality by any serious astrophotgrapher. I don’t particularly care about this. I’m focusing on the DSO, not taking pictures of fine, perfectly round stars. Wanting to use every possible frame that I deemed useable, and not able to find a workaround in DSS, I needed another option.
I decided to download a trial version of Astro Pixel Processor (APP) because I read that this software works very well, and it allows the user to set the threshold for the acceptability of the frames it uses. This seems to be a nice way to run stacks. APP can analyze every frame and then provide you scoring data for each frame on a few different parameters. It is then easy to set a threshold, letting the software pick the top 90%, for example, or selecting and removing the frames yourself based on your own judgements about what the rating data provide.
APP is definitely more complicated than stacking software I have previously used, but not nearly as complicated as something like PixInsight. Much of what APP offers I won’t have any use for, but, because it gives you the option for doing things either mostly automatically or picking and choosing the settings yourself, I think I have found my new choice for stacking.
A note about colors. I encourage the reader to look up images like mine to see the wide array of colors with which these objects are depicted. There are a few reasons for this. First, subjective decisions. Some imagers just like to play with colors and saturations to create what they like. Another reason is improper color balance choices. These are cases where the colors are not true to what you would see in visible light but were not necessarily the choice of the photographer. The equipment used is another reason for the color variation seen in different images of these nebulae. Some photographers use filter systems designed to pick up enhanced light coming from the specific elements, e.g., using filters that pick up more blue or green light emitted from oxygen or red light from hydrogen. When these frames are put together, there is always going to be differences between any two images and not necessarily like what the human eye perceives. It is my goal to create images that are as close to neutrally balanced as possible. But much like the question of what the proper pronunciation of Latin should be, there simply is no agreed upon answer for what are the trues color of many of these objects.
Problems and Learnings It seems I can’t get through a session without a lesson or two to learn. I had three from this night’s imaging, but I am pleased that none of these wound up ruining my efforts for this evening and that I was able to diagnose the issues to avoid making these mistakes again.
During this session, the 300mm f/2.8, which until this night, had never had much of an issue with losing focus over the course of a night, began exhibiting this problem quickly. For the first couple of hours, I found I needed to check and reacquire focus nearly every 30 minutes. Then, it seemed to level off and hold focus for the rest of the night. The outside temperature was not changing rapidly, and I had the rig exposed to the elements for close to two hours before beginning imaging, hence my perplexity. I think I figured it out. I had setup everything and had it ready to go about an hour before sunset but did not turn on the dew heater until shortly before beginning imaging. The lens, having already acclimated and reaching the same general temperature as the air, began changing temperature when the lens heater was powered up, and therefore, began losing focus due to this change in temperature. I now realize that in the future I need to turn on the lens heater immediately after setting up, so the lens reaches its steady state before imaging starts.
My next lesson learned was even more perplexing. Early on, when beginning to take the 16 and later the 32-second exposures, I noticed a faint glow on one of the long sides of the frames. I knew that there was nothing in that portion of sky that should show up so profoundly in that area of my composition and that it must be something of external origin. I checked and made sure there was no light pollution center in that direction of the sky. I then thought it must be some stray light entering the imaging path somewhere. Maybe the lens hood wasn’t installed correctly and allowing light to “leak” in? During the night, I couldn’t figure it out. But, because it was relatively minor and did not directly affect the main objects, I put it out of mind, figuring I could probably fix it in post processing using the gradient removal software. Then a more worrisome development came to my attention. When looking at my dark frames, which are taken in near completely dark conditions, I saw the exact same glow in them! What was going on here? Now I was concerned. Was there a problem with my newly converted camera? Did they not seal something correctly when they put it back together?
I had to wait until I got some sleep before getting into this research and giving this issue some serious thought. I decided to try taking some dark frames in as dark of conditions that I could possibly make. The glow was still there. I felt I could safely eliminate the possibility that this was due to a leak in the body that was letting light in. Another factor that added to this mystery is that I used “Bulb” mode in my camera to take the 16 and 32-second exposures. I then thought this might be the issue. I noticed that while using continuous shooting while taking my light frames, the camera behaved and sounded a bit different that when I normally shoot this way in “Manual” mode. This must be the cause! But that wasn’t it either. I then tried a series of 30-second dark frames in “Manual” mode and found the glow in most of these as well.
An example of a single, unprocessed 32-second light frame showing amp-glow – the light seen at the top of the frame. This was caused by shooting my astromodified dSLR in live-view.
Stumped, I began a conversation with Miguel and fired up the Google machinery. I’ll save you the rest of the unimportant details and let you know that with the help of Miguel and some experienced folks in the proper online forums, I discovered the cause of the glow. It was caused by something called “amp glow.” This is the term for the glow that is produced by the heat of the circuitry inside the camera and, as it turns out, is a common occurrence when shooting with “live-view” enabled with moded dSLR bodies. Using live-view for astrophotography with dSLRs is almost a necessity as it makes it much easier to find your target and obtain critical focus on the distant stars. Why had I not noticed this earlier in my previous sessions in which I also used live view? I am not certain. Maybe it was the combination of using ISO 3200 over the course of a longer evening, allowing for the buildup of heat?
To ensure this was indeed the cause of the glow I was experiencing, I performed some tests, taking 60-second dark frames with and without live-view engaged. Just as I expected, those without live-view engaged had no glow and those with live-view turned on showed it in every frame. Thankfully, this wasn’t a major issue with this project. Using the dark frames at these exposures, which also had amp glow, was supposed to result in the removal of the glow during the stacking process. This was not the case, unfortunately. Even though I had what I believe were the correct settings for this glow to be removed, that didn’t wind up working. I assume the fault lies in me not doing something correctly, but I don’t know how to fix this. The glow following the stack was so substantial, that gradient removal couldn’t do the trick in this case. This forced me to crop the final image more than I had originally designed to remove the area most affected by the glow. To avoid this problem in the future, my new imaging process will now be to use live-view only for acquiring the target and acquiring/checking focus. I will then turn this off and let the mirror slap away when taking my light frames.
The third issue, and simply a mistake in my strategy, is that I was unable to properly resolve the Trapezium. I had thought 1-second exposures would be good enough to allow me to properly resolve the four bright stars located in the center of M42, but these wound up being a rectangular blown out blob. I suppose that 1-second is still too much at ISO 3200. I should have checked these shorter exposures more closely so that I could have adjusted for this. Oh well, a reason to shoot this one again someday.
Conclusion I have wanted to make this image since I first began thinking about getting into astrophotography. These paired nebulae are most astrophotographers’ first object chosen to image and, most likely, the most photographed DSO of all time. This isn’t quite the image I had envisioned in my mind, but it comes reasonably close. I think the primary reason it doesn’t match my expectations is my limited skillset with making composits in Photoshop. I also need to rethink my strategy in shooting high dynamic range objects. Maybe it’s a good thing not to have nailed it on my first try. This gives me the impetus to try again in coming years.
The aptly named Witch’s Head Nebula (IC 2118, NGC 1909) gazing towards the star, Rigel, which gives this nebula the light that we can see her by.
Witch’s Head Nebula (IC 2118, NGC 1909) IC 2118 has been on my list of potential deep sky objects to photograph since I first hear about her. I didn’t think I would have the skills or techniques to do her justice so soon but my plans for shooting M42 with the 300 mm lens were dashed again because of high winds. I studied the area and figured out my desired composition using a 200mm lens and a 1.6 x crop body camera and this is pretty much the result I was hoping for.
Why is this target so difficult for photographing? IC 2118 is known as a reflection nebula, meaning that there aren’t a lot of highly illuminous stars or star formation occurring within this collection of dust and gas. This very dim (apparent magnitude of 13) reflection nebula is primarily illuminated by the 7th brightest star in our sky – Rigel, the left foot in the constellation of Orion. Rigel, located 2.6 degrees to the east of IC 2118, is actually a system of four stars in close proximity. Rigel A is the primary star and is measured to be approximately 120,000 times more luminous than our sun, with an apparent magnitude of 0.13. It is a young star, approximately 8 million years old and has already burned through the hydrogen in its core. It is now burning heavier elements and will one day go supernova – one of the closest stars to us that will do this. When this happens, it is estimated that it will be as visible to us on earth as a quarter moon!
Back to the oh-so-appropriately named Witch’s Head. Due to the blue color of Rigel and the properties of this light scattering off of the gas and dust, this nebula appears blue in color, similar to the reason why our sky is blue on earth. Astronomers are unsure if the nebula is the remnants of an ancient supernova itself or just a collection of dust and gas. Although being close to, or perhaps a part of, the Orion molecular cloud complex, IC 2118 officially lies in the constellation Eridanus. This nebula is approximately 800 light years from earth and of course is absolutely huge. IC 2118 is roughly 1 x 3 degrees in our night sky and roughly 50 light years long. It is not visible to the naked eye from earth, but to give a size comparison of the amount of sky this object would take if we could see it, it would roughly be equivalent in length to six full moons in our night sky.
Collecting the data (27/28 December) It was nice having two opportunities in December to work on astrophotography. Like I mentioned above, I was hoping to do a closeup of Orion and Running Man nebulas but with 10-12 mph steady winds with gusts above 20 mph, I knew I better not shoot with the 300 mm lens. IC 2118 was definitely on my list and could be captured with the much smaller 200 mm lens. The weather forecast was tricky and one of four weather apps suggested that clouds would ruin my night starting around 01:00. Even if so, which it did, I could still get up to six hours on the target.
I was by myself for this session, Miguel having something else, like sleeping I guess, going on this evening. And I setup at the usual location – Danville Conservation Area. It was truly windy and the temps hovered around the freezing point, which was warmer than the last time we went out.
An individual, unprocessed 30 second exposure. Looking closely, you can just make out the witch’s head on a computer monitor. I could not on the back of my camera!
Being such a dim target presented a significant challenge. Primarily, with a 35% luminated moon, I struggled a bit with getting exposure where I wanted. I would have liked to use ISO 3200, but when I started, this put the histogram peak above the 50% line. So I decided to use ISO 1600 using 30 second exposures. When the moon set at 22:04, I knew the histogram peak would drop and it did to a little less than the 20% mark. This was concerning because I knew this would be too close to get the signal to noise ratio I needed, especially with such a dim target. I contemplated changing the ISO up to 3200 but then I wouldn’t be able to stack the two sets taken at different ISOs with my dark frames while being able to use the process to remove satellites and plane trails. Instead, I opened up the aperture from f/3.5 to f/3.2. This gave me a third stop more light for each sub. I wasn’t sure if this was going to work, especially not being able to see the target in an individual frame!
As I feared, clouds came in heavier than 3 out of 4 weather apps and a meteorologist predicted! So, I shut down around 01:45 and made it home by 03:30 – an early night!
Equipment Astro-modified Canon 7D mkii camera, Canon 200mm f/2.8 lens, Skywatcher Star Adventurer tracker without guiding on a William Optics Vixen Wedge Mount. Gitzo CF tripod, Canon shutter release cable, laser pointer to help find Polaris and sky targets, lens warmer to prevent dew and frost on lens, dummy battery to power camera, cart battery to provide power to camera and dew heater, right-angle viewfinder to aid in polar alignment.
Imaging details Lights taken (30 seconds; ISO 1600; f/3.5 and f/3.2) 671 taken, manually removed bad subs due to tracking errors, winds and clouds for a total of 433 used in integration. Darks: 49 Bias and Flats: Not taken. Removed most vignetting and some chromatic aberration while converting RAW images to TIF.
Processing Not knowing for sure if my individual sub-exposures were going to be accurate, I was eager to get to the processing. After removing obviously bad sub-exposures, I plugged the 433 photos into Deep Sky Stacker and told it to use the best 90% of those, giving me a total of 3.25 hours of integration time.
It’s amazing how I can get sucked into processing these DSO images. This one only took me about four hours from start to finish but it seemed like no time at all. I also used GraXpert to remove gradients and various steps in Photoshop CS6.
Problems and learnings This is definitely an object you want to shoot without light pollution and with as much time as you can possibly get on her. With roughly half my night lit by the moon and not getting as much time as I had hoped for, I am very pleased with the outcome. I hope to try this one again someday. Being a winter target, it is possible to get 8-10 hours on this target in a single night. This would help bring out the surrounding dust and provide better definition of the target herself. I did wind up using some subs that had light clouds, providing the halo around Rigel that normally wouldn’t be there. I don’t think this hurt the image, however. I could also shoot her with the 300 mm lens but this would eliminate Rigel in the frame and I don’t think would be nearly as interesting.
Conclusion This is the second image of five I hope to make around the Orion molecular cloud complex. I did not expect to shoot the witch this soon but I am pleased that I have learned enough to make a competent image of this dim and challenging subject. After doing this a few months in a row, I am much more confident in what I am doing and using my kit has almost become old hat. As long as the weather gods bless me, I am feeling much more confident in being able to capture and process the targets that are within my capabilities. I hope to upgrade my tracking mount within the next year or two but I will continue with what I have at the present.
A Thousand Acres of Silphiums 