Full Frame Focus

We're getting close now to the big event - the April 8th Total Solar Eclipse! And as the days fly by I'm trying to finalize my strategy for getting some memorable shots while balancing my desire to also "be in the moment" during the 4+ minutes that are going to whip by in time-warp fashion.

For the 2017 eclipse I used our "family" camera - a Canon t6i - attached to my Vixen 600mm refractor. That particular model has an APC (or cropped) sensor, which has the effect of increasing the focal length. Per Fred Espenak ("Mr. Eclipse"), a cropped sensor will increase the size of the Sun in your photo by about 50%. And while I was blessed to get some very nice shots using it at the 2017 eclipse, I felt that I wanted to have a bit more space around the Sun to better capture the full extent of the corona. While the 300mm telephoto lens on the t6i would certainly do that (and worked well for the Albuquerque Annular eclipse), I like the sharp optics and higher focal length of the Vixen.

And so began my research into getting a "full frame" camera body. There are basically two options now - a standard DSLR that has a flip-mirror in the optical path, or a "mirrorless" design where the sensor feeds directly to the screen on the camera rather than looking through a view finder. The latter is still fairly expensive (IMO anyway) at over $1,300 for a decent quality unit. 

But with users switching over to the mirrorless format, I reasoned that their old cameras might be popping up on eBay. After an afternoon of evaluating the offerings I found a Canon 5D Mark II camera body for $350. Sold!

A few days later the camera arrived. The body cosmetically looked acceptable, so the next step was to charge the battery to verify it turns on and works. That test passed, but then the challenges of getting it eclipse-ready started. The first disconnect was the SD card I ordered did not fit - these older units take a much larger UDMA card. Fortunately I could find one with adequate capacity and good transfer rate.

With the camera charged and outfitted with a card I turned my attention to hooking it up to the Vixen to see if I could get some Sun pictures. While my existing T-ring that I use to hook up my Canon t6i fit the Mark II, I immediately realized that since it was a 1¼ inch design I was shooting myself in the foot by not having a 2" T-ring. A little internet searching turned up a great company, Telescope Adapters, that had just what I needed. A couple days later I had my adapter and was ready to target first Solar light for the full frame camera. On the 9th of this month that took place, and I was pretty impressed with the wider field.

The final hurdle was to integrate the camera with laptop software to automatically take a sequence of shots during the eclipse. In 2017 I had tried Eclipse Orchestrator but did not feel confident enough to let it run the session, and ended up manually taking shots via the Canon app on my tablet. That definitely impacted my ability to "be in the moment" for the eclipse (but it was still a riveting, surreal experience!) Additional research turned up the Solar Eclipse Timer and Camera Controller (SETnC) application. This seems a little simpler and hopefully will prove to instill greater confidence in turning the camera control over to it.

Last weekend I set the Vixen up again and played with the SETnC taking exposures. While setting up an exposure sequence and executing it went well, I did find that the best rate for snapping off shots is roughly 1 per second, even with the premium UDMA card. That is a bit of a disappointment as I was hoping to be able to click off at least 2 shots per second to provide some bracketing during the C2 and C3 events  (e.g., trying to capture Bailey's Beads or Diamond Ring). Given the age of the camera it is really not a surprise, but at this point I think I am going to let fate dictate the outcome and hope for some great souvenirs of my last Total Solar Eclipse. After all, luck is always a factor in any such endeavor (just ask someone who's been clouded out for their celestial event!)

Image of naked-eye sunspot AR3590
with Mark II and Vixen 80mm

Jupiter's June

With the exception of Mercury at only 0.03°, all the planets have some tilt to their axis. As any fifth grader should be able to explain to you, Earth has an inclination of 23½° and that is what gives us our seasons as we orbit the Sun. As amateur astronomers we can sometimes notice the tilt when observing some of our planetary neighbors. Mars' axial tilt is about a degree larger than Earth's and can present one hemisphere more favorably than another. For example, our best views of Mars are when it comes to opposition right around the time of its perihelion. As it turns out Mars is always close to its Winter Solstice at that point in its orbit, so we see  southern hemisphere features like Hellas and Syrtis Major better because they are tilted towards us while northern albedo markings such as Mare Acidalium are tough to discern (map). 

Hubble captures Titan's Transit - Feb 24, 2009

Saturn, with an inclination of 26¾° is the easiest example of noticing the affect of axial tilt. At its spring and fall equinoxes the rings all but disappear as we view the planet's equator straight on. At its solstices we are treated to the full grandeur of the ring system during maximal display. Another aspect is that only when Saturn approaches its equinoxes will the orbital planes of its moons begin to intersect the globe of the planet from our vantage point. It is only at those points in its ~29-year orbit that we get to see Titan transit and cast its large shadow upon the clouds below. While not as rare as a Venus transit, seeing our Solar System's largest moon cut in front of its home planet is an infrequent event (and one that is on my bucket list for the upcoming equinox!)

And where does Jupiter lie on the axial tilt spectrum? It comes in at a mere 3°, barely tipping towards or away from our view. We never get a nice look at its polar regions as with Saturn, it is consistently featuring its full-on view. Despite Jove's stingy axial tilt, the observant amateur astronomer can still discern evidence of the inclination, even with a modest telescope, by studying the Galilean moons. 

Yesterday (January 20, 2024) on Jupiter the Druids assembled at their Stonehenge to celebrate their Northern Summer Solstice, the maximal tilt of the planet's north pole towards the Sun. About a week earlier I was out imaging Jupiter (under very poor seeing) with a serendipitous alignment three out of the four Galilean moons. Io was about to slip behind the planet, while Europa had just start its trek across the planet's face. Ganymede stood nearby just off the limb awaiting its turn to begin transiting the planet.

Jupiter on Jan 13, 2024 7:39 p.m. EST

Like most planetary moons, the Galilean quartet have their orbital planes roughly aligned to Jupiter's equatorial plane (i.e., if we could see those planes it'd be similar to seeing Saturn's rings). But in my capture we note that despite having orbits lying in that equatorial plane, none of them appear near the planet's equator as they approach Jupiter. We see that the two that are about to cut in front of the globe will do so across Southern hemisphere cloud tops, while the one that is about to duck behind the planet appears at a northern Jovian latitude. This let's us know that Jupiter's northern hemisphere, and by extension the orbital planes of these moons, is currently tilted towards us.

There's another piece of information to be gleaned from the image taken on the 13th. If we use WinJUPOS to apply a grid overlay on Jupiter, we can more easily see that the distance the moons lie from the equator varies. Io is closest to the equator at roughly 20°, Europa is about double at ~38°, while Ganymede is doing a more polar crossing at about 55°. If we consider the schematic below that approximates how a set of orbits lying in the planet's equatorial plane might appear with a north-leaning planet tilt, we can see the significance of this. Io must be orbiting closest to the planet since it is nearest the equator. Europa must lie (very roughly) twice as distant. and Ganymede is orbiting at a distance perhaps some 2½ times that of Io. When we check our hypothesis we see that our analysis was an acceptable swag: 

• Io: 422 km
• Europa: 671 km
• Ganymede: 1,070 km

But what about Callisto, the farthest out of the 4 Galilean moons at 1,883 km? If Callisto had been in the frame we would have seen it floating above or below Jupiter given the combination of the moon's more distant orbit and the planet's current maximum northerly tilt (much like the green orbit in our schematic above). 

Of course now that Jupiter has passed the Northern Summer Solstice in its orbit it will be moving towards an Autumnal Equinox roughly 3 years from now. As we head there you'll see the moons gradually fall back towards transiting the planet along its equator, and Callisto will once again join her siblings in crossing the Jovian cloud tops from as seen from our home planet. 

So often we set up the telescope and take a just a quick peek at our target, not tarrying to inspect the view in the eyepiece nor record what was seen. So here's a challenge for you to do something more. Observe Jupiter when a Galilean moon event is set to occur (S&T has a great online tool to predict when these occur, with three opportunities this coming week on the 22nd, 24th, and 29th). In a notebook sketch what you see (and you do not need a large scope to see these events). Continue to do this over the next three years and you'll have a cool record that shows the shifting tilt of the planet as evidenced by the changing appearance of the 4 brightest moons when near or in front of the planet. While you won't get an award for your effort, I bet you'll feel a reward for being able to demonstrate some of the mechanics of our Solar System through a patient recording of what you've seen first-hand.

Tovala Telescopes?

Did you feel the amateur astronomy ground shift under your feet last year? While in the making for decades, AI exploded and took center stage in 2023 with the promise (or threat) of doing things for us. And while we have had "smart telescopes" such as the Unistellar eVscope since about 2020, the entry of products such as ZWO's SeeStar and Dwarf2 with a much more affordable price point of about $500 promises to be a game changer to our hobby. 

For those unfamiliar with these instruments, they abstract away most of the challenges in acquiring images of deep sky objects. Their refractor design means no worries collimating anything, and their stacking using short ~10-second captures means minimal tracking snafus. Plate-solving ensures your target is centered in the field. Polar alignment isn't required. It seems the most challenging part is just getting the unit level. The end result is that what used to be a significant threshold in terms of time and money to produce beautiful images of deep space objects has been dramatically lowered. And for those who want to refine the tiny scope's output there's the potential to download the individual subs to play with in your favorite photo processing software. The outcome - as seen here in this example from a photo Ken Sall forwarded from a FB group - is pretty astounding. 

I always grow a bit philosophical when confronted by these sort of advancements to our hobby and their impact. Progress is inevitable (especially if a profit is to be had) and often a boon to us. GoTo technology allows one to be far more efficient in an observing session and obviates the need to employ star-hoping skills. And who would want to go back to capturing photons on film save for the nostalgia of it? (I can smell the pungent aroma of the darkroom's stop-bath  as I typed that...)

And yet - does this sort of quantum leap remove some of the essence of why we take those photos? What is it that pulls us out under the stars in the first place? One approach to answering that question might be to consider Maslow's Hierarchy of Needs in which the 20th century psychologist postulated what makes us tick. The hierarchy is often shown as a pyramid in which a person works their way up from the bottom towards the top. The base of the pyramid deals with one's physical needs - food, shelter, safety. Once those are met we are free to move higher up to psychological needs of friendships and esteem. At the pyramid's pinnacle we have creative activities. Certainly it is in those areas that we find the impetus for people joining our hobby. 

Like most hobbies, astronomy certainly offers the opportunity for community and friendships that often accompany it. That is the raison d'etre for HAL. And, at the moment at least, there is a bond among SeeStar owners as they share their experiences using the scope that isn't seen for most other types of scopes. 

But how do the EAA telescopes fare in terms of fulfilling the esteem and creativity motivators within us? Their popularity would argue they indeed can provide their owners with a sense of pride and spirit of creativity as they image the wonders of the universe. That image of M42 demonstrates that. But over the long haul will that hold up? Those who delve into the processing of the little scope's stack of images to enhance and amplify the resulting photograph will likely continue to have those esteem and creative itches scratched. But for the person whose input is mostly just telling the machine what to target, I suspect that their initial psychological rewards will fade once the sky has done a full turn. Will we see a plethora of eBay listings of these scopes in a couple years?

There is another aspect that is, to me, a little unsettling. How ironic that a telescope calling itself SeeStar actually doesn't allow you to peer through it! There is a wonderful sense of awe peering through the eyepiece at the universe. Some targets, such as Saturn, need no introduction and can become an experience you'll always remember. Others, like seeing the stellar point of light at the center of galaxy M77 and knowing it represents an active galactic nucleus powered by a black hole, are more subtle but just as profound. Many of us also delight in the success of catching a glimpse of a challenging object such as discerning the active star forming region NGC 604 within the Triangulum galaxy or sleuthing out which faint star is actually distant Pluto. I suspect that we can thank another form of progress - light pollution - for the making such things more difficult and fueling our desire to swap out our eyes for the CMOS photon sponges.

All this being said, I need to disclose I've never used one of these scopes - perhaps I'd become their evangelist upon using one! I do sincerely hope that they bring hours of enjoyment to their owners and help grow the ranks of our amateur astronomy community. In our recent HAL board meetings discussing whether we should acquire a unit for club use, I was a solid "aye" vote in the matter (and my thanks to Grace Coventry for her efforts on making that a reality for us). If EAA entices people away from mindless scrolling on social media and brings them out under the night sky for a semi-virtual exploration of the heavens, then it is a huge win - not only for the hobby but for that individual as well.

When Smaller Is Better

Venus is a notorious tease. Her brilliance in the deepening twilight sky is a lure to any beginning astronomer, yet nearly all come away disappointed after centering the planet in the eyepiece. No details are to be had (at least none to an untrained eye without the aid of a filter) other than the changing phase of a featureless cue ball. 

The exception is when we view Venus in UV light. Thanks to an as yet unknown compound in the Venusian atmosphere that absorbs ultraviolet light the planet shows structure in its omnipresent cloud deck. As we know, UV is not something our eyes can discern. The best we can do visually is to apply a violet filter such as a Wratten #47 that reduces the glare a teases out a tiny bit of that structure as low contrast shadings. Most common of these (and with a scientific rationale for their existence) are the "cusp caps" seen at either or both poles.

All is not lost, however. The amateur who has outfitted his rig for planetary imaging can take advantage of the fact that the camera's sensor can record in UV. Some cameras are better than others in terms of their sensitivity in the UV portion of the spectrum, but even if you do not happen to have one of the more UV friendly models the odds are good that with the addition of an ultraviolet filter you can capture some details. A little over a year ago I purchased an Astrodon UVenus filter to pair with my ZWO ASI178MC (color) camera to see if I could capture the cloud patterns, and was delighted to have success earlier this year.

In researching the best approach to obtaining a good image of Venus in UV one of the tips that I ran across was to avoid lenses in the optical path. The anti-reflection coatings on them can apparently cut down on the UV transmission, making the image dimmer (and consequently requiring a lower frames-per-second rate that introduces atmospheric smearing). It has also been noted that the corrector plate on an SCT is not designed to provide correction in the UV range, so that design may be a bit handicapped when attempting UV capture.¹

Another factor I have noticed is that while you can detect cloud markings when Venus has become a large but slender crescent on either side of an inferior conjunction, the results seem far more interesting when the phase is somewhere greater than 35%. Enough of the disk is presented to allow one to often capture cups caps/collars as well as streaks in the middle of the planet that a crescent won't show.

My recent session a couple weeks ago was under average seeing with only fair transparency. Our sister planet was sporting a 70% phase and a diameter of only 16" as the planet continues to pull away from us following last August's inferior conjunction. Having to forego the 2.5x Barlow means it is a small image that one gets to work with, but it was clear even on the laptop screen during capture that the cusp caps were visible. Post processing can afford some help in enlarging the image (such as adding drizzle in AutoStakkert3!, leveraging the resizing functionality in Registax, or even using a custom resizing application like Topaz's GigaPixel product).

Since I had the time I decided to do a second capture, but this time with the Tele Vue 2.5x Powermate Barlow in the imaging train. I could immediately see the impact in terms of a dimer image, dropping my fps from 32 down to 9. This of course allows more time for atmospheric blurring to occur, reducing the number of frames of steady seeing that can be harvested. 

So while the image was certainly larger, the attenuation of UV light by the Barlow gave an image with far less clarity. Yes, the cusp caps are there, but the details in the smaller image, even after undergoing enlargement, were far superior. The verdict was clear - leave the Barlow in the box and work with whatever size we have to get the best UV image of the elusive Venusian cloud details.

¹ https://www.thefreelibrary.com/Imaging+Venus+in+the+ultraviolet%3a+a+new+development.-a0357147028 

Heavenly Symmetry

A first impression the prospect of traveling halfway across the country to catch an annular eclipse seemed extravagant to me. After all, we do not get to see the ghostly corona and fiery prominences during that period where Moon occults Sun. The stars do not come out and nature reacts far less confused when the Sun, even a small amount of it, remains exposed. You might be tempted to equate it with seeing a 99% partial eclipse of the Sun. 

However, the facts were that witnessing an Annular Solar Eclipse was an unchecked item on my astronomy bucket list, and the one this October was (given my age and location) very likely my last opportunity to catch such an event. What the heck - YOLO, right?

The first step in the journey was selecting a location. Studying the path and the weather prospects I decided to target New Mexico for a long weekend. The path crossed two interesting cities - Albuquerque and Roswell. Given the almost legendary dark skies of the southwest I felt that spending a couple evenings at an Airbnb outside Roswell might offer the additional perks of checking out the UFO/Alien scene in Roswell by day and then enjoying a star-studded sky in the evenings. By the end of March I had my flight, rental car, and accommodations all set. 

Practice Run Capturing Clouds & Sun

Discussing my plans over Labor Day weekend with my son Dave I was delighted that he took me up on my offer to come along. We edited the itinerary a bit so that we'd be at the Albuquerque Balloon Festival to witness the eclipse rather than Roswell. With the venue change I pondered whether I might get a unique photo opportunity since there were plans to launch balloons during the eclipse. I spent the next several weeks researching how to filter the Sun sufficiently while still getting some of the background in the picture, something I've seen before that make annular/partial solar eclipse photos interesting. In the end a set of neutral density filters (one of them variable) and an IR/UV blocking filter seemed to offer the promise that if a balloon floated by the eclipsed Sun I could hopefully capture that bit of serendipity.

Travel day - Friday the 13th - started off with a curveball. Southwest texted me at 6 a.m. that they had cancelled the first leg our flight and rebooked us to a direct flight that was departing a half hour earlier. We hustled along to get to the airport to allow enough time to check bags and clear security (I was happy that my long rectangular box holding my tripod was not any issue getting checked in). Several hours later we were in Albuquerque and scouting out online reviews for a good Tex-Mex lunch.

The next morning as we stepped out from the room we could see a host of colorful hot-air balloons hanging off in the distance. The weather, despite forecasts for 80% clouds at the start of the week, looked promising with some scattered, high cirrus hanging around. We Ubered to the Balloon Festival field with camera, tripod, folding chair, and filtered binoculars in tow by 8:15. It was packed, but fortunately the field was quite large and accommodated the tons of people who had assembled for a good time. We found our plot of land and set up our little camp.

The first 45 minutes we enjoyed seeing some of the colorful and fanciful balloons taking off. A pretty steady breeze out of the north was making it a chilly fall morning, and unfortunately it soon caused the event planners to put a hold on launching any more balloons. The field MC was providing a running commentary of what was going on interspersed with some music.

8:38 a.m. MDT

I strap on the mylar solar filters to my 7x50 binoculars and check out the Sun. No major sunspots are present but a couple can be made out when I steady my hand. I fire off a couple of shots to refine the exposure settings and await for the action to begin. 

9:15 a.m. MDT

The announcer tells the crowd that the eclipse has begun, and a bit of a cheer goes up as everyone sees the tiny, initial bite taken out of the top of the Sun using our solar safety glasses that were being passed out upon entering the field. Which makes me wonder - how disappointed were the vendors that were trying to sell them? 😏

Moon marching across the Solar disk, ready to cover AR3465

The field MC provides updates on the eclipse's progress between the songs being played, and in a moment of bad science around quarter after 10 he mentions that people with good eyesight might see that the edge of the Moon has crept up upon the sunspot and will be covering it soon. While AR3465 is clearly the largest sunspot on the face of ol' Sol today and easily seen in my binoculars, it would be impossible for us to see it naked eye.

With about 20 minutes before 2nd contact we're also told that there won't be any balloon launches as we approach maximum. It's a disappointment but understandable as the winds have been constant since our arrival and would likely make it too dangerous. They still hope to do a "balloon glow" on the field during the time of greatest eclipse where the balloon is inflated but tethered to the ground.

10:20 a.m. MDT

I stop for a moment to look for Venus, and it takes very little time for me to pick it out high above us in the deep blue desert sky (even without my "distance" glasses). Once I point to it Dave can also quickly see it, although at first is not sure whether it's a plane at high altitude catching the glint of sunlight. The binoculars quickly resolve the question as I can see a disk exhibiting a phase to it. I try to grab a picture of it but the camera cannot do it, yielding only an overexposed sky, yet again demonstrating the amazing ability of our eyes to take in a logarithmic range of brightness that a CMOS sensor cannot.

By 10:25 the field has taken on that odd late-in-the-afternoon light that seems surreal for the hour of the day. There is not any wildlife in the area to observe, but given how my human instinct tells me the Sun should be close to setting I strongly suspect that our fellow animals are likely reacting to the change in light, albeit not as profoundly as in a total eclipse. 

This is the first eclipse I have experienced without any of the "pinhole projector" effects. Normally there are some deciduous trees around and they provide the multiple crescent images at this point, but in a wide, empty field suited for hot-air balloons there are none. The field announcer mentions that if you have a Saltine cracker, the dozen or so holes that perforate it will serve nicely as a makeshift projector. Perhaps that should have been part of the handout along with the solar eclipse glasses? 😄

With less than 10 minutes to go we are told that even the balloon glow cannot take place due to the winds, and instead the best that can be done is a "candlestick", where the propane burner is fired to create a tower of flame sans balloon. 

And finally we are at the moment we've waited for!

10:34:41 MDT

Second contact is announced and the crowd cheers as people begin to make out the off-center unbroken ring of light encircling the Moon.

10:37:12 MDT

We've reached the climax of maximum eclipse. To the unfiltered eye the Sun is still glaring and without hint of being 90% covered, but with eclipse glasses, and especially in the binoculars, there is this amazing alignment to behold. A perfect glowing circle of bright light that seems like it is a Hollywood special effect made for Lord of the Rings stands before us. Lots of cheers and the roar of the hot-air balloon burners lighting up the field makes the entire experience unique and unforgettable. This is what I came for - that incredible, visceral connection that an eclipse can provide during those brief seconds of totality/annularity. While I wondered if the annular version would come close in that impact, the stunning symmetry in the sky does not disappoint!  

Facebook Livestream:

10:39:35 MDT

All too soon Luna has crept to the eastern solar rim and prepares to exit. Dave is using the binoculars as we head to 3rd contact and - without any foreknowledge of the Baily's Beads effect - mentions to me that he sees the brief sparkling of the sunlight along the Moon's limb as it exits. My constant firing off shots allows me to also capture the phenomenon digitally.  

As the Moon begins to retreat from the face of the Sun, many of the folks assembled on the field begin to head out as well. It really has become noticeably cooler, and judging from the comments I overhear I am not the only one wishing I had brought a heavier jacket. While it is a bit anti-climatic it seems that it would be almost rude for me to break down the modest equipment and hail our Uber. Dave takes the time to explore the long line of vendors' tents in search of some souvenirs for us to remember the day while I continue to document the egress towards 4th contact. 

By noon we collapse the tripod and camp chair and place the request for our ride. With only a few more minutes left I take my final shots of the Moon departing the Sun in hand-held fashion as we make our way out. While not the epic traffic jam that I encountered following the 2017 total eclipse, the wait and fees for the Uber tell us that a lot of people have participated in this annular eclipse. While a bit tired I am joyful at what God granted me in witnessing this eclipse with my son and checking off another of my astronomical bucket-list items!

Not Feeling Lucky

"Diligence is the mother of good luck." - Ben Franklin

I guess it's been the better part of a decade since I first encountered the term "lucky imaging" that is used in amateur astronomy to characterize the technique of stacking and enhancing video frames to produce the stunning planetary, lunar, and solar images that we see so often today. The moniker derives from the fact that we are able to extract those brief, "lucky" moments when the seeing has steadied for a split second to create a photo that reveals details the eye could never behold. Indeed, not just our eyes, but those of us old enough to have tried capture using film greatly appreciate the superior results (and in many ways the simplicity) of using this digital video approach.

While the term has a rational basis for its origin, I have to confess it has never sat quite right with me. Using it connotates that I pointed my telescope at my target, yelled "action!" and hoped for the best. If the imaging gods smiled on me then I was rewarded with a detailed image of  Mars revealing Olympus Mons or kilometer-sized craters on the floor Plato. If they did not I was left with a fuzzy outcome that no amount of post-processing could salvage. Better luck next time kid! 

Of course, any serious solar system imager knows that aside from decent seeing, luck is a rather small component of creating a nice capture of your target. There is the research into what equipment to use and the financial investment in acquiring it. That equipment then often needs a knowledgeable and skilled hand for optical alignment (collimation) to wring every last sub-arcsecond detail from our quarry. Once that is checked one needs to engage in a successful polar alignment to enable tracking of the object at high magnification. If an Atmospheric Distortion Corrector (ADC) in your imaging train then that, too, must be adjusted throughout the imaging session to combat the subtle smearing that occurs when light travels through our home planet's blanket of air. 

One of the biggest challenges is achieving a sharp focus. "Lucky" imagers do not get the benefit of a Bahtinov mask to provide the assurance that they have a crisp image. The user must study the image on the screen to identify a high-contrast feature to zero in on and then twiddle the knob incrementally back and forth while evaluating the outcome after each minute adjustment. If being done by hand that means waiting a few moments after each tweak for the target to stop dancing around the field. (Those of us who have outfitted our scope with an electronic focuser would never part with it!) 

Once collimated, polar aligned, and focused it's on to setting up the gain and exposure in the software's capture interface. Having the fastest possible shutter speed while holding the graininess of the capture at bay is another balancing act that the imager has to perform. Finally, we're ready to capture some video!

With gigabytes of data safely stored on the hard drive you're halfway home. Next comes the post-processing effort where we transform those thousands of frames into a single thing of beauty. But between those two points lies a bevy of software products to perform that magical massage, and the time to learn how to use them. One of the most critical stages, the wavelet sharpening, is part science but very heavy on art. Here the observer must use their skills to sharpen the stacked outcome in such a way as to provide the clearest view that does not introduce artifacts into the final product. Only after all this effort based upon investment in equipment, study, and experience does the reward of a detailed photograph of a member of the solar system emerge. 

Lucky? Really? 

I may be tilting at windmills here, but I am launching a campaign to retire the "lucky imaging" description for a more appropriate acronym. I asked the question on the Cloudy Nights forum and got some interesting (and humorous!) suggestions along with pretty universal support to call our technique something else. Some of them contained the word "planetary" in the acronym, which would describe most of my personal effort but snub the amazing work done by Solar and Lunar imagers. After collecting descriptive terms and jockeying them around I think I finally have the replacement acronym:

Solar, Planetary, and Lunar Imaging Capture & Enhancement (SPLICE)

Not only does it cover the targets for which we most often apply the technique, the "splice" has a slight double entendre in that in many ways that is at the heart of what we do - gather the best parts of our movie and then splice them together for our finished product. 

Coming up with a suitable acronym is certainly the easier part of this effort. The real challenge will be to get our favorite print publications (and other influencers such as podcasters and YouTube creators) to adopt it. It's up to us to ask them to remove "lucky imaging" from the amateur astronomy lexicon!

An Autumn Grab Bag

Overall the past 4+ months have not been kind to amateur astronomers in my area. There seemed to be an above average number of cloudy evenings, and those that were clear often had a haze triggered by smoke drifting down from Canadian wildfires. So to say that the return of some cooler, crisp fall evenings was most welcome is probably an understatement. 

Jupiter and Saturn took some of my attention, but I also made time to check in on some targets among the Astronomical League's Urban List in my ongoing assessment of how easily they can be spotted from suburban skies that suffer from significant light pollution.

August 19, 2023 
Sky: Mostly clear, temps ~65° F, light winds
Transparency: 7/10    
Seeing: 5/10
Limiting Magnitude: 3.2

NGC 6818 
Planetary Nebula in Sagittarius
10” f/6 Newt   15mm Plossl  CGX-L Mount  

It took a 4-star alignment process to get the mount's GoTo working accurately enough to ensure that it was landing on targets with good accuracy, but that was a prerequisite given the light pollution in the southeast where my chosen target lies. But it was worth it, as once I peered into the 25mm eyepiece it was apparent as a small, uniformly round orb with perhaps a slight blue tint to it amid a handful of field stars. Popping in the 15mm enhanced the view of the planetary. There was no structure such as an annulus that I could discern, and it sported an even distribution of light. While a little faint, it bore direct vision well, even without a UHC filter. Alternating between direct and indirect vision yielded no evidence of the central star.

NGC 6934
Globular Cluster in Delphinus
10” f/6 Newt   15mm Plossl  CGX-L Mount  

I know that I have seen this DSO before with my 6” RV-6, but that observation is lost among the many that have gone by the wayside. I wish I had been better about archiving them for later access.

When inspecting the field with the 42mm once the scope completed its slew there was no sign of the globular. I did not tarry long before switching to the 25mm eyepiece with the Baader Moon & Skyglow filter, which revealed it immediately. I followed up with the 15mm which gave a good view of this globular. The field has stars that form roughly an “arrow” asterism pointing to the east. And the globular lies along the shaft of the arrow on the side closest to its apex. It is perhaps 4-5’ in size and can take direct vision but is improved with averted. No resolution of the member stars was noted. The globular is circular and has surprisingly even illumination – no sign of a brighter core discerned in the observation this evening.

September 3, 2023 
Sky: Thin haze, temps ~85° F, calm
Transparency: 7/10    
Seeing: 7/10
Limiting Magnitude: 3.2

IC 4756
Open Cluster in Ophiuchus
6” f/8 Newt  TV 25mm Plossl  HEM27 Mount

Once I verified the HEM27 was working well I decided to target this open cluster. I slewed to Rasalhague and then did a center operation to ensure the hop over to the cluster would be on target. And indeed, as soon as I peered in the eyepiece with the 42mm I could see a loose, large cluster of stars.

Bumping the magnification up to the 25mm came close to filling the field, implying the cluster size at about ¾ degree. There is one bright anchor star, perhaps 7^th or 6^th magnitude, in the south of the cluster – no color noted in it or any of the other members of this cluster. The other members range in brightness from about 8^th magnitude down to limit of visibility. All told about 40 stars are seen, but there is no nebulosity hinting at any mass of unresolved members. Very nice cluster and would be worth checking again under darker skies.

NGC 6709
Open Cluster in Aquila
6” f/8 Newt  8mm TMB  HEM27 Mount

Once the scope finished its slew I checked the area with the 25mm TeleVue Plossl, and my attention was drawn quickly to an eye-catching triple set of stars. West of it seemed to have a slightly above average number of stars, but nothing that screamed “I’m a cluster”!

Dropping in the 8mm TMB I see a few more stars and a dim fourth sun joins that pretty trio. I do a quick online check to verify that I am on the cluster, easily confirmed by the trio-plus-one showpiece of the field. As my night vision adapts, I see perhaps about 15 stars that may be cluster members in what is a coarse and not very rich offering. No hints of any nebulosity, and none of the stars depart from the standard white color. It is small, perhaps 10-15’ in size. While it may be really nice in darker skies, I'd be inclined to drop this one from the Urban List.