It has been a long 76 days since the last time I pointed a camera at the night sky. With the threat of possible rain later in the week, I decided to seize the opportunity last night to shake some rust off and get some practice under my belt. Only my second time out with the new monochromatic CCD, I was feeling the learning curve and ended up spending a lot more time on star alignment than I would have liked. The good news is, I remember going through a similar struggle when I started imaging with a DSLR off an equatorial mount too, so I’m sure this will pass with more practice. Another interesting challenge of using the CCD is the data acquisition time goes up by a factor of the number of channels you are integrating. To explain, on an OSC camera like a DSLR, your red, green, and blue channels are all captured at the same time. Let’s say you decide to capture an hour of data on a single target. To get “the same” hour of color data with a mono-CCD, you would need to capture an hour of red channel, and hour of green channel, and an hour of blue channel. There are a myriad of technical reasons to explain why those two images wouldn’t actually be the same, but for the purposes of illustrating time investment, you get the gist. The window between moonrise (1:17am) and when I finally was pseudo-focused and aligned wasn’t enough to really get what I needed on a target, so I just captured some Luminosity information on a well-known galaxy. I still struggle with focusing the CCD. Even with using TheSkyX focus tool and trying to be diligent and precise (visually) to get set up for an imaging run, I feel like the images are fuzzy or soft. I have questions like whether or not I need to refocus after changing filters and what is the best process for going about doing that without a RoboFocus. So the exciting part of the whole adventure was the location of the learning. Rather than drive an hour up to the HAAS (SHSU) Observatory in Huntsville or two hours to the Houston Astronomical Society Observatory in Columbus, I drove to the cul-de-sac in front of our new home location in Grimes county. There were a few active Chuck-will’s-widow, a Great Horned Owl, and various other critters weaving an ambient sound blanket under the stars. Depending on which LP map you reference, the area is yellow or green, but it is even still better than anything I see regularly where I currently live. I’m looking forward to being able to practice without the drive and to start accumulating some really deep data sets for creating (eventually) wall-hangers.
So here is the exact same data set of M81… dew and all. With the help of some kind folks over at the Cloudy Nights forums, I was able to reprocess with a little better results. I have a lot of work to do, but I’m really excited about getting out and capturing some better data to practice on… practice, practice, practice.
It’s been a few months since I’ve imaged anything. There are a number of factors that play into that unfortunately fact, but the main one has been weather. I believe last night was literally the first cloudless night without rain in nearly four weeks. I had ordered a monochromatic CCD back in October that took some time to fulfill and the camera (with accessories) arrived just when the poor weather hit. Coincidence? On a brighter note, this allowed me to figure out I should purchase a new laptop, install all my AP software, and check connectivity and camera control from my dry desk indoors before spending a night in the field. This entire shift away from my unmodded, Bayered, one-shot-color DSLR to a set-point cooled, mono CCD is quite the endeavor for me. It not only requires new workflow in both image acquisition (per-channel imaging with potential for narrowband) and processing (drastically different integrations and post processing sequence), but it also has introduced new software since my user-friendly and intuitive BYEOS doesn’t work with the CCD. I decided to go with the STF-8300M from Santa Barbara Instruments Group. Part of the decision was based around great “bang for the buck” in capability and features, but mostly it was based on reputation and proven track record as being a “work horse” in the field. There were/are newer and improved models, but I really felt this would serve me well as a first dedicated AP camera. So, back to last night… I arrived at the Observatory around 6pm with plenty of time to set up all my gear and get things balanced. As soon as Polaris was bright enough for my amateur seeingballs to make out, I quickly did a polar alignment and waited for enough high mag stars to facilitate a 3-star alignment. This is where the fun began. First off, I had no idea how to do an alignment with the CCD. In the past, I used Live View on the DSLR and more or less treated it like an eyepiece of sorts. In lieu of this, I used the focusing tool in TheSkyX’s camera plug-in (what I’ve decided to use for now) and attempted to align. I botched the first alignment and couldn’t get on target, so I started over from scratch and used a handheld 520nm laser to aid in locating my position when off at each step. The second time around, I got the alignment spot on and was quite happy except for the fact that the entire process had taken well over an hour… but I learned a lot for the next time around. I decided to shoot Bode’s Galaxy since that was the first DSO I ever attempted when I started this hobby about 10 or 11 months ago. Since everything was new, I had no idea how long to shoot each sub or how many subs would be sufficient. I mean, more is always better, but I had no reference point. I decided, which more or less was just a complete guess, to shoot 10 Luminance subs binned 1×1 and 5 each Red, Green, and Blue subs binned 2×2. At the end, I also shot 5 Hydrogen-Alpha subs binned 1×1, but ended up not using them for now. I have so many questions. Anyhoo, the night could be summed up in two words… cold and wet. The temp dropped dramatically after sunset and the air was thick with moisture. We are coming off a month of rainy and dreary days, so there was no shortage of dew forming on every surface imaginable. I had my dew heaters on 100% power from the moment I thought they were holding up well, but when I looked at my data this morning, it is clear that the dew won. I also had “checked” my focus in between each channel run, but apparently not well enough. I can’t tell if focus had drifted or if the star bloat is from dew. I am leaning toward the latter because of the chromatic artifacts that shouldn’t be there from anything in the optical path. The registration/calibration and integration workflow in PixInsight is very different when starting with individual channels. There were a lot of challenges with this bad set of data I managed to bunch up last night. The first thing I noticed was the challenge of integration of linear versus non-linear data. I am not quite sure where you have to have transformed the histogram to non-linear before combines and where you can get away with linear data. The second thing I noticed (other than the focus/dew problems) was that I seemed to have a ton of hot-pixel looking noise for the color channels, but not for the luminance channel after registering and integrating the subs. The only thing I can think of that would be different is that I changed the binning to 2×2 for the RGB channels. Since binning down should improve signal to noise, I am not sure I get why I introduced this artifact… or if that is even what it is at this point. Of all the “schtuff” that came up along the way, this question is the most pressing on my mind. I’m sure my inability to leverage the Hydrogen-Alpha data will get solved with experience in processing. Which was the third baffle… I could not get PixelMath to map the Ha data into the LRGB data. I honestly don’t know if it is my integrated subs, if I input wrong wavelength filter bandwidth in the expression, or if there was some mumbo-jumbo going on with linear versus non-linear working spaces. There was also the star-mapping step to upsample the RGB channels to match the Luminance for the LRGB combination, so I used the same star-mapping method on just the Red channel for the PixelMath operation and that might have jacked something up. I really don’t know, so I just shelved the Ha data for now. In retrospect, I probably won’t shoot a separated Luminance channel next target. I’ll just shoot RGB unbinned. I’m also going to try to find some public domain data sets to practice the integration steps on better quality data. The fact that I got dewed out is disheartening because I don’t know how to beat it. I suppose I could double up on the heater strips and take a hair dryer with me to zap the front element of the OTA every couple of subs. Overall, it was a good “first light” on the gear. I learned a lot about the minor steps that will save me time the next time around. I learned a few areas I need to be more meticulous about checking throughout the imaging run. It’s easy to get bummed out with poor results like this, but when I look back to last May and what I’ve learned, I’m really excited to see where my images will be with another 10 months of practice.
So despite the cloud cover, with it really being the only chance I would have for a few weeks to try, I loaded up the Tundra of Love and headed to the SHSU Observatory to take a run at Comet Lovejoy. It was patchy when I arrived, but promising. A large fire fueled by something unknown raged to the south. The light polluted skyglow from New Waverly/Willis/Conroe was punctuated at the treeline with an eerie orange glow and plume of black. The winds were favorable and Pleiades was near zenith, so I continued setting up my rig and performing polar and star alignment. Georgia‘s parents bought me an amazing zero-gravity field chair for Christmas, so I waited out the meridian flip and enjoyed stargazing with my hand-me-down binoculars through holes in the clouds. Since the comet was about 9 degrees or so off Messier 45, I knew that ones The Sisters had transited the zenith, I could start my data acquisition. In a serendipitous moment, the skies opened up and the blanket of stars seemed to brighten. It was a good night. Comet Lovejoy was discovered in August 2014 by an amateur astronomer in Australia named Terry Lovejoy. It’s actually the 5th comet he has discovered, so “Lovejoy” is more or less what people are calling it because it happens to be here now, but the actual designation is C/2014 Q2. I has already passed opposition (last week) and is headed toward reaching perihelion (closest approach to the Sun) on January 30. Once it begins the journey leaving our planetary region, it will have an orbital period of about 8000 years. So, if you think there is a chance you might not be here in 8000 years to check it out next time around, you may want to peek outside during this flyby.
As it turns out, this data was a lot trickier to integrate than DSOs like galaxies or nebula. We are still spinning and orbiting… none of that has changed… but the comet is moving quite rapidly through space (relative to the perspective of massive celestial bodies thousands, if not millions, of light years away). This actually requires the data to be processed in two parallel paths and then merged at the end. The comet and it’s ion tail are stacked “at their speed” and then a linear fit and starmask is used to map in the background field from the same exact frameset. I know there is a ton of room to improve, but it isn’t too shabby for my very first comet… imho.
“The green glow comes from molecules of diatomic carbon (C2) fluorescing in ultraviolet sunlight in the near-vacuum of space. (In addition cyanogen, CN, can add some violet to the green, but our eyes are fairly insensitive to violet.) By contrast, a comet’s ion tail (gas tail) — the narrow, often detail-filled part of the tail that points directly away from the Sun — is tinted blue. The ion tail’s color comes from fluorescing carbon monoxide ions (CO+). Dust in a comet’s head and tail simply reflects sunlight, so it appears Sun-colored: pale yellowish white. The greatest comets tend to get that way by being very dusty, so the most memorable naked-eye comets are usually remembered as white. Examples were the spectacular Comet Hale-Bopp of 1997 and the grand sungrazing Comet Lovejoy of 2011, C/2011 W3. But the current Comet Lovejoy is producing very little dust.”
It’s been a quick minute since I’ve seen dark skies that weren’t on the way to sleepytime. Honestly, between weather and business travel, I haven’t been out since October 26. It is only fitting that my first venture into the starlight since was last night… November 26. This past month, when I’ve had time to think about astrophotography, has been a lot of me reflecting on the simple mistake I made at my run at Barnard 33 (the Horsehead Nebula). I had adjusted the prime focus on the Crayford and didn’t tighten the tensioner well enough before slewing to Alnitak. It wasn’t until I’d captured a couple hours of data before I realized my mistake. I did get a few subs on a subsequent night to pad the error in integration, but the result was still soft. This past month, I visualized going back and doing it better… paying closer attention. In the last minutes before packing up my gear for the hour-ish drive to the dark site, I called an audible and left my APO at home. I thought (incorrectly) that if I re-tooled my setup back to the side-by-side saddle and shot through the 600mm native lens that I would be able to capture the great nebula in Orion and the Flame in the same frame. As it turns out, you need around 400mm of FoV to make that happen on my DSLR, so I had to choose. The choice was obvious and easy. I had to take another run at the Flame and try to make amends for my rookie fumble last month. I ended up without about 3.4 hours of data pre- and post- meridian transit… which cost me some edges because I didn’t compose well enough after the flip, so I trimmed the messy off before processing with a quick crop. There is some minor vignetting that I’m not 100% sure I understand given the imaging train (there should be no light loss at the edges), but I’m ok with leaving it because I didn’t want to lose any of the nebulosity exposed in the bottom center of the frame. Over all, I think this makes a good web redemption. I’m really looking forward to growing into narrowband acquisition and some improved full-spectrum sensitivity with a monochromatic CCD, but all things in time, right? I did place an order with Santa Barbara Instruments Group for an STF-8300M, but there has been no word in over a month on estimated ship date. I also have elected to start with The Sky X (w/camera plug-in) as I transition to CCD, but more on that later… after I make the switch. Happy Thanksgiving everyone.
I shot a few subs of the deceptively small Crab Nebula (Messier 1) last night before realizing that the seeing just wasn’t where it needed to be for me to get that target under my belt. It will have to wait for another time. So, after calling that audible and knowing that I had let my focuser gravity drift the night before on my Flame attempt, I decided to grab a few more subs and see what happened when I integrated both nights (which I had never tried previously). The result was about 2.7 hours worth of data that looked like a train wreck when I stacked it, but after cropping off the tattered edges, there was some good in the middle… even if still out of focus. Live and learn. I will definitely put more time into this DSO in the future!
The Flame Nebula (NGC 2024) is an emission nebula in the constellation Orion. It is about 900 to 1,500 light-years away. The bright star Alnitak, the easternmost star in the Belt of Orion, shines energetic ultraviolet light into the Flame and this knocks electrons away from the great clouds of hydrogen gas that reside there. Much of the glow results when the electrons and ionized hydrogen recombine. Additional dark gas and dust lies in front of the bright part of the nebula and this is what causes the dark network that appears in the center of the glowing gas. The Flame Nebula is part of the Orion Molecular Cloud Complex, a star-forming region that includes the famous Horsehead Nebula (Barnard 33). It is one of the most identifiable nebulae because of the shape of its swirling cloud of dark dust and gases, which bears some resemblance to a horse’s head when viewed from Earth. This stellar nursery, as it is known, can contain over 100 known organic and inorganic gases as well as dust consisting of large and complex organic molecules. The red or pinkish glow originates from hydrogen gas predominantly behind the nebula, ionized by the nearby bright star Sigma Orionis. Magnetic fields channel the gases leaving the nebula into streams, shown as streaks in the background glow. A glowing strip of hydrogen gas marks the edge of the massive cloud and the densities of stars are noticeably different on either side. The heavy concentrations of dust in the Horsehead Nebula region and neighboring Orion Nebula are localized, resulting in alternating sections of nearly complete opacity and transparency. The darkness of the Horsehead is caused mostly by thick dust blocking the light of stars behind it. The lower part of the Horsehead’s neck casts a shadow to the left. The visible dark nebula emerging from the gaseous complex is an active site of the formation of “low-mass” stars. Bright spots in the Horsehead Nebula’s base are young stars just in the process of forming.
This is a very short 5x180s integration with no noise reduction applied. I want to come back to this target when I have some time to spend with it. It is much brighter than I expected!
Messier 16, the Eagle Nebula (NGC 6611), is a young open cluster of stars in the constellation Serpens. The Eagle Nebula is part of a diffuse emission nebula. It contains several active star-forming gas and dust regions, including the famous “Pillars of Creation” region. This region of active current star formation is about 7000 light-years from us and the tower of gas that can be seen coming off the nebula is approximately 9.5 light-years or about 90 trillion kilometers long.
Back to back nights with new moon darkness have been a real treat. I learned a lot… like not to try and clean my sensor when there is a caliche road anywhere within 500 miles and that you can never check your focus too often. This image of the Eastern Veil nebula suffers from some focus drift because I didn’t have everything nice and snug on my Crayford. Some of the images from this weekend are plagued by the mound of dust I introduced into my sensor. I started dithering for the first time. I am getting better at using FWHM (full width half maximum) focus… especially after losing hours of data to my inattention to this gremlin. Overall, it was just great to be out under the stars and feeling like I’m making progress. I’m grateful.
The Veil Nebula is a cloud of heated and ionized gas and dust in the constellation Cygnus. It constitutes the visible portions of the Cygnus Loop, a large but relatively faint supernova remnant. The source supernova exploded some 5,000 to 8,000 years ago, and the remnants have since expanded to cover an area roughly 3 degrees in diameter (about 6 times the diameter, or 36 times the area, of the full moon). The distance to the nebula is not precisely known, but Far Ultraviolet Spectroscopic Explorer (FUSE) data supports a distance of about 1,470 light-years. The analysis of the emissions from the nebula indicate the presence of oxygen, sulfur, and hydrogen. This is also one of the largest, brightest features in the x-ray sky. This particular image is of the Eastern Veil (also known as Caldwell 33), whose brightest area is NGC 6992, trailing off farther south into NGC 6995 and IC 1340.
The Helix Nebula (NGC 7293) is a large planetary nebula located in the constellation Aquarius about 700 light-years away and spans about 2.5 light-years. Gases from the star in the surrounding space appear, from our vantage point, as if we are looking down a helix structure. The remnant central stellar core, known as a planetary nebula nucleus or PNN, is destined to become a white dwarf star. The observed glow of the central star is so energetic that it causes the previously expelled gases to brightly fluoresce.
Sweet, dark skies. Last night was my very first imaging session during a new moon and the skies were glorious… well, relative to normal for this neck of the woods.
I’ve been wanting to shoot the Bubble Nebula for some time now. I know I’ll come back to this target after I get some better Ha response in my imaging rig, but here is a short integration first attempt with poor tracking. I opted to not crop out Messier 52 because it gives a neat perspective.
The Bubble Nebula (NGC 7635) is a Hydrogen emission nebula in the constellation Cassiopeia. The “bubble” is created by the stellar wind from a massive hot central star about 10 to 40 times larger than our own. The nebula is near a giant molecular cloud which contains the expansion of the bubble nebula while itself being excited by the hot central star, causing it to glow. It was discovered in 1787 by William Herschel. You can also see Cassiopeia’s open cluster, Messier 52 (NGC 7654), in the upper right of the photo.