Leveraging Starlight for Sharpening Planets

The field of digital planetary imaging is where art meets science, particularly in post-processing. After using our preferred tools to distill a video of several thousand frames into a stacked and aligned image, there is still much work to do. We need to refine it into a sharpened view of the target before applying some tweaks in a program like Photoshop. To achieve that sharpened image, we have two techniques at our disposal: wavelet sharpening and deconvolution.

Wavelet sharpening is a key feature of the freeware application Registax6, a staple of planetary imagers for many years. The author of the software, Cor Berrevoets, has not issued an update to the venerable program since 2011. He has, however, created a successor in the form of another freeware application called waveSharp. Both of these tools decompose the selected image into layers - from large-scale components of the image to fine scale. By adjusting the sliders, you can selectively enhance these aspects of your image. The finer scale adjustments must be done with a light touch to avoid introducing significant noise to the final result. Fortunately, one can combat the noise by suppressing the finer scale adjustment.

The ability to apply deconvolution is appearing in more tools for the planetary imager. One excellent new addition is the Lucky Stack Worker (LSW) freeware application (a video by the author, Wilco Kasteleijn, is on the ALPO channel). Another is AstroSurface, an application with extensive filters and functions for not only the planetary imager but the deep sky enthusiast as well.

So, what is deconvolution? In brief, it is using a contemporary representation of an Airy disk to help recover detail lost through atmospheric turbulence, soft focus, or optical issues. Under perfect conditions, when examining a moderately bright star, you would expect to see a small disk with diffraction rings emanating from it, known as its Point Spread Function (PSF). The interface on the LSW has two checkboxes - one for "Deconvolve" and one for "Sharpen" (i.e., wavelet sharpening). If we select the Deconvolve and select the "bullseye" adjacent to it, we see that LSW is offering us a synthetic PSF with sliders to allow us to adjust it.

Impacts when adjusting the Seeing Index slider

You could take a few minutes before or after your imaging run to inspect a nearby star and make a note of its Airy disk appearance to emulate it in the synthetic version. But why not record an image to capture the PSF for that particular imaging session? This is exactly the sort of thing that Wilco Kasteleijn advocates in the LSW manual and references a nice article by Marco Lorenzi on how to do this.

A couple of nights ago, Astropheric was displaying that the seeing would be "average" with temperatures in the 40s, so it was an opportunity to try this technique and maybe gain some experience acquiring a PSF image to leverage in my processing. Like a deep sky flat frame, the PSF image should be taken with the same imaging setup and without pointing the telescope too far from the target.

My first attempt using a star near Jupiter did not yield results, as it ended up being too faint and requiring a longer exposure. That, in turn, blurred the Airy disk by its scintillation. For Mars, I targeted a brighter star and had more success with a frames-per-second rate nearing 100. Even so, it is challenging to get it right; in retrospect, I should have lowered the gain further to avoid "blowing out" the Airy disk.

The PSF image taken during the imaging run

So, here are the results! Even with only a fair PSF image processed by Autostakkert, the LSW did a nice job of recovering the details from what turned out to be sub-par seeing. Applying sharpening and denoising to the image resulted in a reasonable, if not admirable, image showing albedo features, the polar cap, and likely cloud features.

To me, this technique of capturing a PSF image as part of the Lucky Imaging session holds great promise. As a final note, here is a Copilot-assisted comparison of how these two techniques help us achieve fantastic planetary images.

Chasing Planets: January's Observations and Challenges

The media has been hawking the auspicious "planetary parade" that allows an observer to see 6 planets during frosty January evenings. Of course two of those (Uranus and Neptune) are not naked eye objects. I do not mind articles that generate interest in our hobby, but my fear is always the "over promising and under deliver" risk.

However, January was indeed a fun month for us planet observers. Mars was occulted by the nearly Full Moon on the evening of the 13^th, and then two days later came to opposition for this apparition. Jupiter was positioned well and decided to throw a major eruption amid its North Tropical Zone southern jet stream on January 10^th, garnering a lot of attention. Venus also ascended the Zodiac after lying close to the southwestern horizon most of its current evening apparition, reaching greatest elongation on the 10^th heading for its highest altitude in the western sky on February 2^nd. The only downside has been the weather with classic winter turbulent seeing amid very cold temps.

Mars Occultation

The skies were clear but quite cold for the occultation of Mars. I set up the 10" Cyrus telescope and verified its collimation. The Moon served as a convenient focus target as I set up about 20 minutes before the scheduled disappearance. I knew that the difference in brightness would be a challenge and thought I'd have time to fiddle with the gain setting right before the occultation, but it happened so fast that I really did not get a great capture with the Moon very overexposed. Still, it was a very cool event to watch the Moon relentlessly approach the red orb and cover it up with about 30 seconds.

The Moon ready to cover Mars

January 17th Session

The evening of the 17th was predicted to have average seeing and temperature right around the freezing mark, which is fairly good for this region in winter. I again set the Cyrus scope out early to cool and verified its collimation. As Venus emerged from encroaching twilight I set to work on capturing our sister planet. 

Starting with the Deep Red filter (642+nm) and no Barlow, Venus provided a bright target upon which to focus. Doing a 5 minute capture resulted in a nice image, showing the planet past dichotomy and a common cue-ball appearance. I have yet to truly discern any cloud details in IR light.

Swapping out the Deep Red filter for an IR-block and UV set, I retargeted the planet and adjusted the settings to bring up the brightness in the fainter UV light. I could make out even on the on-screen image that there was uneven brightness in the sunlight reflecting off the Venusian cloud tops.

Processing produced a nice greyscale image with a some cloud structure. Interestingly, a well defined cusp cap was not really seen, although you might argue one was around the south pole region. This is somewhat in agreement with the UV Venus images I have been seeing submitted to the ALPO for the current evening apparition; cusp caps are not as prominent as I believe they were during the last apparition.

By now Saturn was visible in the deepening twilight, close and to the left of Venus. I figured why not give it one last capture since the upcoming mid-March solar conjunction and my obstructed western horizon meant it would soon be inaccessible. I added the Barlow back into the imaging path and returned to the Deep Red filter. Seeing was not very good, and the rings had closed up again compared to a few months ago. I had enough juice in the laptop for two 2-minute captures, resulting in a sub-par image where it is hard to even detect the globe's shadow being cast against the rings. Au revoir Saturn - until we meet again in the late spring!

Getting the AC adapter hooked up to the laptop I next swung over to Jupiter. My hopes were to get multiple captures into the evening if the weather held, recording not only the very recent North Tropical Zone southern jet stream eruption but also that continually expanding disturbance in the South Equatorial Belt that started back in November.

The seeing ended up being fairly good over the course of about 5 hours, allowing me to capture a lot of interesting features, including that NTrZ outbreak. As we began to close in on midnight the gods conspired to end my run as the cirrus clouds began to thicken and the tracking on the Celestron mount suddenly had a stall (it is always amazing how quickly the planet exits the frame when this happens). Rather than fight to recenter and continue amid the deteriorating seeing and transparency I decided to wrap things up on Jupiter.

In the middle of my Jupiter captures I had to take a break due to the location of the planet. When an object is high and near the meridian, the Cyrus telescope tube runs up against one of the tripod legs. The resolution would be to raise the tube up off the saddle, somewhat like extending with a pier. But that would be a lot of effort and so is not likely to happen in the near future (if at all). 

But rather than waste the time I opted to do a run on Mars which had just passed opposition a few days earlier. While at only about 13" in size the disk was large enough to take in some nice albedo features such as Syrtis Major setting and Sinus Sabaeus and Sinus Meridiani on the central meridian. The NPC was also a brilliant white and was a good feature to leverage in trying to get the best possible focus. Hopefully I will get in a few more sessions with Mars for this apparition, but it's going to shrink in size quickly now that it is past opposition.

While I did not achieve all my goals for the evening (I missed seeing the SEB disturbance on Jupiter), it was quite a good night for the middle of January. It reflects why planetary observing provides such a rich experience for the amateur astronomer.

December Planet Parade

While it is nice to see a planet coming to opposition in the northern part of the zodiac given the much higher altitude it then attains in our skies. But while the planet heads north, our opportunities of good seeing go south. The heat of the day radiating into the atmosphere sets up turbulence and often results in poor seeing. It also seems that the winter months are more overcast. This year I went 51 days (late October to mid-December) between observations - not great! 

Uranus - December 18, 2024

At the start of the year one of the astronomy goals I had set was to image Uranus with its moons. I tried a couple of times earlier in the fall without success, but finally on the night of the 18th I got the SharpCap stacking working with Uranus as the target. I had to keep the region of interest (RoI) wide because otherwise the software complained of not having enough stars to align. I played with the exposure and gain to finally generate a nice stacked image that clearly showed some of the moons.

Using some post-processing tools to enhance the raw stack resulted in a fairly satisfying result. The Sky & Telescope online tool that shows where the moons are in relation to the planet was helpful in orienting the shot. I ended up capturing 4 of them (Titania, Oberon, Ariel, and Umbriel) - Miranda was probably lost in the glare of the planet. Maybe next time I'll try to include the Barlow in the imaging train to gain some more space between the planet and moon.

After that success I decided to focus on trying to capture the planet without overexposing it. For this run I did WL with an UV/IR cut filter. Uranus is very difficult to pull out details, and those usually require an IR wavelength and larger aperture. The ending result was perhaps a bit more blue than I expected, but overall definitely the best image of Uranus I have been able to produce.

Jupiter - December 23, 2024 

Just a couple days before Christmas the evening sky was clear but cold, but with predictions of average seeing so I thought I'd set up the scope. I was amazed to find that the seeing was actually above average as I dialed in Jupiter. I started off with a series of WL runs using the Cyrus 10" f/6 and a 2.5x Barlow. 

In between Christmas Eve activities the next day I found a little time to do some processing of the captures and was quite happy with the outcome. Oval BA was almost on the meridian, far easier to see than last year with a pale tan coloration. Out ahead of it was long enduring oval A8. The SEB had some spots of darker material, but my general impression is that the belt is weaker than it has been the last couple of years. The EZ had a lot of material swept into it from both NEB and SEB, presenting almost like latte foam art crafted by a talented barista. The NEB had a small, intense outbreak midway between the following limb and central meridian. 

I also ran a set of CH4 captures since the seeing was above average. As to be expected, BA was the most prominent object at that wavelength.

Mars - December 23, 2024  

By this time Mars had cleared the neighbor's tree and was an enticing target. I did several runs in WL with high hopes of getting a good capture. After four 2-minute runs I swapped out for the R+IR filter, but the laptop unfortunately cut off due to low power after only one capture.

Processing after Christmas showed a well-formed NPC with a "Lowell Band" around it comprised of Propontis II and Utopia. There definitely were some clouds around the south pole, and M. Cimmerium was well placed. In the center was the Elysium area which seemed to show as an elevated area more strongly than I recall previously. The single R+IR shot was also worthwhile, demonstrating how the longer wavelength can sometime bring out additional details, such as the subtle Gomer Sinus extension off of M. Cimmerium.

Overall, quite a nice way to wrap up 2024. It was another enjoyable year with lots of activity, from a Total Solar Eclipse to a pretty good comet. Hopefully 2025 will bring more clear nights and interesting features to enjoy!

Occultation of a Sapphire

Out of the 12 zodiac constellations, only six stars shine at first magnitude. Of these, just four lie close enough to the ecliptic for the Moon to occasionally pass in front of them during its monthly orbit. Up until now I had been able to catch occultations of Antares and Aldebaran, but not Spica and Regulus. Lunar occultations of this stellar quartet is not routine. First, the Moon's distance from the ecliptic has to match that of the star when the Moon is swinging by it. Then you have to be in the right location on Earth. Due to the Moon's closeness to the Earth, parallax is in play so that an occultation in the US can easily be a near-miss in Canada. Add to this the need to have clear skies and it's easy to see why many amateur observers have not caught occultations of all the candidate bright zodiac stars.

This month in the pre-dawn skies on Wednesday, November 27^th, Spica was slated to undergo an occultation from my location. Some aspects of the event were very favorable. The Moon would be a fat crescent, making it easier to see Spica adjacent to it. The altitude would be at least 20° so that it would be above the tree line. On the downside, the reemergence from behind the Moon's dark limb would happen close to sunrise, making it impossible to see naked-eye but certainly doable in binoculars. 

The weather prediction on the evening of the 26th was very guarded. Depending on the source, predictions were for anywhere from 20% clouds to 70% clouds with a storm system heading our way for the holiday (Thanksgiving). Given the uncertain weather, I opted not to set up my telescope. Instead, I relied on my binoculars and camera with a telephoto lens for a simpler approach.

I got up around 4:30 a.m. and peeked out the window to see a fair amount of clouds, but a few "sucker holes" thrown in just enough to entice me to getting dressed and going outside. A little before five I was outside and could see the Moon rising through the denuded tree across the street from my driveway. Spica was visible as well, and its blue color evident nicely in the binoculars. But the clouds, not so thick as to obscure the Moon yet heavy enough to degrade the view, were passing by frequently. It'd be a matter of luck as to whether I'd catch anything.

Crescent Moon, Spica clearing tree line

In the back yard I positioned myself where the Moon would be above obstacles and worked on the camera's focus at 300mm. I snapped a few shots and examined them to verify that I had a reasonable focus. As the minutes ticked down to the anticipated disappearance at 5:34 a.m., I alternated admiring the view with just my eyes and then with the binoculars, all the while grabbing a few shots to document the approach. Part of what makes an event like this so suited for visual observation is the ability of our eyes to handle a wide range of brightness. I could appreciate the bright star hanging below the even brighter crescent which then gave way to the dark side of the Moon illuminated by earthshine. It is very hard to recreate that visual experience in a photo.

Finally with one minute to go I switched the camera to record video and inspected the view in my 7x50 binoculars. The task of witnessing the coup de grâce was challenging. My hands were not steady enough to get anything but a fleeting, occasional sighting of the star adjacent to the bright lunar limb. Within a few moments it was gone from view, and I halted the recording and went inside to warm up.

With about 70 minutes to go until reemergence of Spica I had to decide how to document that event. With the clouds continuing to hang around I didn't feel it was worth the effort to set up a telescope to capture it. The camera with its lens would hopefully be able to pick out Virgo's lucida when it popped into view. 

I took my position a little before quarter to seven o'clock and focused the camera on the Moon. As fate would have it there were actually very few clouds now, making me wish I had set up the Vixen to observe the reemergence. With about a minute to go I turned the video on and began targeting the Moon in my binoculars, trying to steady them by resting my elbow on the fence. Suddenly there it was, a shining dot backlit by a strong twilight sky. The show was complete and I brought the camera inside.

Spica's Reemergence

Reviewing the captures revealed the shots leading up to the disappearance went well for the most part, but the last few seconds on video are quite hard to discern the moment the star winks out given the brightness of the lunar limb. The reemergence video is better in documenting how Spica suddenly appears in the pale blue sky. Undoubtably there's much opportunity to massage the digital data on upcoming cloudy evenings into something that more closely represents what was seen by the human eye.

While conditions were not perfect, they were good enough that I’ve now witnessed three out of the four first-magnitude stars in the zodiac disappear behind the Moon ‐ only Regulus remains! This occultation, with Spica glowing like a sapphire alongside the Moon’s western limb, is now one of the highlights of my astronomical year and a reminder of how the cosmos never ceases to delight me.

A Charming Comet

There was the standard hype and hope surrounding Comet C\2023 A3 (a.k.a. Comet Tsuchinshan-ATLAS) as it closed in on perihelion last month. Discovered some 18 months earlier, it had seemed to stutter on its brightening curve over the summer, leading some to wonder if it'd be only a 3rd-4th magnitude object. Others fretted that the comet was not even going to survive buzzing the Sun and would go the route of Comet ISON in 2013 and disintegrate.

However, by early October it became apparent that the comet had survived and was poised to put on a nice show in northern skies around the 2nd week of October. The window of opportunity would not be very long as the Oort visitor would be quickly heading outbound and fading with each passing day. Would it be something I could see with my naked eye? And would nature cooperate with some clear skies?

Comet C/2023 A3 on Oct 15th

The evening of October 15th had beautifully clear skies so I grabbed the camera and walked up the street a little to get the best possible western sky view. I started around 7:20 pm and continued looking for the comet for about 25 minutes. I had no luck with either naked eye or using my 7x50 binoculars, which I attributed in part to being quite literally 20 yards from a street light. I kept snapping bracketed images of the sky in hopes that maybe I would pick up something.

Once inside with the images downloaded to the laptop it was quite apparent that I had been scouring the area a little south of the comet's position, because it was there quite clearly in the 4-second exposure. Sigh - a missed opportunity yet again due to Towson's light pollution!

Fortunately the weather was in one of those fabulous fall runs of clear, dry skies. So the next day I used Google Maps to identify a location in Hereford that appeared to have some parking as well as a nice western horizon. Shortly after dinner I set off with camera and binoculars to the Gunpowder State Park Trails off of Mt Carmel Rd. Twilight was fading when I got there and I was a little surprised at the number of people who were already there in the tiny parking lot. I grabbed the camera and walked across the road to keep the overhead power lines out of any picture.

It took only seconds to sweep up the comet in the binoculars sporting a beautiful coma of about 2nd magnitude with a tail fanning out behind it for several degrees. Lowering the binoculars and using averted vision I could definitely make out a streak in the western sky. There'd be no way to discern that from home, but out here, even with the automobile lights on this heavily traveled road, it was clearly naked-eye visible. I did a quick look in the glove compartment for my distance glasses but alas they were missing.

I started clicking off shots of Tsuchinshan-ATLAS as quickly as I could as some malingering clouds threatened to get in the way. I bracket exposures as well as focal length to hopefully get a wide angle and then a closer shot of the beautiful visitor. The rising full Moon over my shoulder served as a good test of focus to ensure I did not mess that up. I kept taking occasional breaks to admire the comet in the binoculars, admiring the gossamer tail trailing the star-like coma. 

While Tsuchinshan-ATLAS was certainly a pretty sight, it made me appreciate just how amazing the late 90's had been with Hyakutake and then Hale-Bopp. Those were truly spectacular comets that graced our skies back then, setting the benchmark against which all other icy interlopers are measured in my mind.

19 stacked 2.5 second frames at ISO 800

All too soon the comet lost altitude as it parachuted towards the horizon. Venus had set and Boötes with his lucida of Arcturus was struggling to stay above the horizon, signaling it was time to wrap things up. I grabbed the camera & tripod and carefully crossed the road to the parking lot (as one gets older it's critical to move carefully in the dark to avoid a fall!)

As I reached the car I chatted with a couple of folks who were also enjoying the spectacle. One of them had brought a Seestar and was getting some very impressive shots with that. And as it turned out one the guys was John Rose, a high school friend who had been in the Boys' Latin Astronomy club with me some 50 years earlier. I couldn't help but think how very cool it was that here we were a half century later, still being lured out under the night sky to witness its wonders! 

Planetary Potpourri

August finally brought Jupiter and Mars above the tree line for me in the pre-dawn skies. The classic humid skies under a dome of high pressure that is typical of summer around here have the one advantage of often providing some steady skies. 

Saturn
Aug 1, 2024

The month kicked off with the final transit of Titan across the far southern Saturnian cloud-tops for the current apparition. From here on out the massive moon will skim across the south pole until our geometry brings it back across the planet again. Arising at 2 a.m., I was blessed with very fine seeing (9/10) and started with captures in WL with a UV/IR block, resulting in the color image shown above. The low albedo of Titan compared to the planet's clouds yielded a dusky silhouette of the moon just skimming across the SPR. On the planet there are multiple bands in the N. hemisphere while the S. hemisphere is a bit more homogeneous and bluer in appearance. The shadow of the rings on the globe is easily seen, as the globe reciprocates with its shadow on the rings. Some vague hints of Cassini's division are seen. While I did not discern it while doing the imaging run, upon processing I found that if you look closely, you can also make out the tiny shadow of Dione which was in transit at the same time, lying just preceding the CM and at the latitude of the southern edge of the SEB.

Switching to the R +IR filter yielded the greyscale image above as Titan started its egress from the planet's disk. Between the different wavelength and the limb darkening, Titan appears white rather than its dark silhouette earlier in WL when over the SPR. In this view the planet itself shows multiple bands and bright EZ. The banding striations in the Southern hemisphere are much easier to see in this wavelength compared to the WL, and while not obvious the Cassini division is also a tad easier to pick out. And as with the WL capture, you can catch Dione's shadow just past the CM and at the southern flank of the SEB.

Jupiter
Aug 23, 2024

Some above average seeing greeted me again on Friday morning the 23rd (seeing 8/10, transparency 7/10) for a Jupiter session. Started off with Great Red Spot near CM, followed by a very chaotic section of the SEB punctuated by a strong rift. Given that white clouds are higher in the atmosphere, it makes me speculate that perhaps this could be the beginning of an SEB fade? Time will tell. The images also allowed for a rough estimate of the GRS's size, which came out to roughly 13,100 km - a new low. For decades the boast has always been that you could fit 2-3 Earths inside the massive storm, but with our terrestrial diameter of 12,750 km it may soon come to pass that it won't be large enough for even a single Earth.

The South Temperate Belt, home to the long-enduring anti-cyclone "A" storms, was featuring 3 of them at this longitude. I believe from left to right we are looking at A4, A3, and A2. The North Temperate Belt also features a chronic storm, NN-WS-4, just trailing the GRS's latitude a bit.

The image also displayed some intense "hot spots" along the southern edge of the Northern Equatorial Belt, spawning blue festoons trailing down into the EZ. The NEB is now back to its dominant self, having extended northward to reclaim its girth. Along its northern edge we have some ovals. These appear to be the long enduring "White Spots" (such as WS-E, WS-Z) that have been surrounded by the expanding NEB, making them far more conspicuous than in recent years by the added contrast.

Mars
Aug 23, 2024

With power still remaining on the laptop after my Jove captures I swung over to Mars to see what was up. At just a little larger than 6", I am always amazed that the SPLICE process can pick up any features at all. Sinus Meridiani and a little of Sinus Sabaeus are seen as well as Margarifiter Sinus and M. Erythraeum. There is no sign of a South Polar Cap which has dissipated as winter retreats in the planet's Southern hemisphere. But the northern chill has begun as evidenced by a North Polar Hood beginning to form. Niliacus Lacus also can be seen extending out from under the hood. While this won't be a great apparition with Mars' size topping out at a little above 13" in January, it still promises to be fun imaging our mysterious neighbor.

With Saturn hitting opposition in a few days and Jupiter nearly at western quadrature, the 2025 planetary season is definitely upon us. Here's hoping for lots of opportunities to check in on them under clear and steady skies!

Orion Obit

It's been a couple weeks now since the news broke that Orion Telescopes & Binoculars, a well known and loved retailing resource for the amateur astronomy community, had shut the doors to its California brick & mortar store. It some ways it came as a shock - how could such a giant and long established vendor go under? And yet there seemed to be signs along the way that this was a possibility.

A couple years ago Orion successfully sued Meade for price fixing, driving them to file for bankruptcy. On the heels of that Orion opted to buy the company and bring it under their umbrella, setting up a manufacturing plant in Tijuana, MX. While that was certainly a boon to Meade owners (no one wants to see their warranty dissolved or not able to obtain support), I have to wonder how good of a fit that was for Orion. It can be challenging to be competent at both being a vendor of astronomical products as well as a manufacturer of a large line such as Meade.

I have bought items from Orion for probably the better part of three decades. They had good prices, shipping that was very reasonable, and a solid inventory of desirable products. If I ever had a problem or question they were able to help. As recently as last year I purchased an extended Wratten filter set that I have been very pleased with.

I suspect that part of the problem was that Orion increasingly only sold Meade and their house brand. As a result, when I wanted to purchase a new planetary camera I spent time on Agena and Highpoint Scientific websites because they offered a range of products from which to choose. And both of those vendors also were very good about shipping my products and standing behind them. I also especially liked Highpoint's offering of very reasonable financing of more expensive items. In short, being exposed to alternative vendors with a wider variety of offerings did change my habits, causing me to check their online store first when looking to make a purchase.

Perhaps Orion is planning to go the way of Bed, Bath, & Beyond and convert to a strictly online outlet. I have not heard anything definitive in terms of the plant in Tijuana. If that has been shuttered as well then there will be no new Meade telescopes rolling off the assembly line and some orders might go unfulfilled. Then again, we may see a "fire sale" of Orion's inventory or (more likely) it may be acquired by a competitor. 

It is sad to see such a storied entity in our hobby go under. And I do feel for Meade owners who now may have trouble getting support. While the good news is that we have other vendors available to take our orders, I personally will always have fond memories and an appreciation of purchases from Orion that furthered my exploration of the heavens.