Mars on 12/25/2022

 The Christmas skies were clear this evening, but the cold wave that passed through Charlotte from the Midwest gave us very transparent but unstable skies. Mars was difficult to image; the planet appeared to be under rippling water, with surface details appearing and disappearing every few seconds. 

This image shows the planet with linear wavelet processing. I pushed the processing as far as I could to enhance albedo features, while trying to perserve a "natural" image of the planet. The visible features can be identified from the Mars map of the area (below).

Is More Better? Mars on 12/18/2022.

Seeing was below average this evening, but I decided to see if stacking significantly more images of Mars would produce a better picture than a large, but smaller number. The “lucky imaging” approach captures many frames at tens of frames per second. These frames are then stacked using packages such as AstroSurface, Registax, Autostakkert, etc,. Each of these packages ranks the captured frames by quality. The user then selects the percentage of the frames they wish to stack and process. However, the benefits of stacking decline as the number of frames increases. Stacking 1000 frames rather than 500 makes for a much higher quality image, but as the number of frames increases, the incremental improvement (i.e., the impact on the final image) shrinks.

The first image is from a large stack. I combined several AVIs captured sequentially to produce a large stack of almost 70,000 frames. I selected 45,000 frames for stacking. The second image is derived from 14,000 frames selected from a stack of 25,000 frames.

The differences between these images is subtle. The saturation of the first image (after color balancing), is a little more accurate. Moreover, subtle atmospheric limb clouds (the blue-white haze) are visible. These are missing from the second image. With more frames, I was able to back off wavelet adjustment and reduce the edge “rind” on the left limb of the planet. Achieving similar detail levels on the second image emphasized this rind.

My conclusion is that more is very subtly better. Would this conclusion be the case with a bigger aperture? I hope to test that out next year.

Images captured with a 5 inch Mak and Mallincam SkyRaider SLP.

Jupiter on 12/17/2022

Seeing was slightly below average tonight after a cloudy day. Jupiter is close to its highest point in the sky by 6:30 local time, so it is ideally placed for imaging. 

The Great Red Spot (GRS) features prominently in this image. The GRS was likely discovered by Giovanni Cassini in 1665. This spot was observed until 1713, but then there is an observational gap of 118 years before it was again observed on September 5, 1831, with some 60 observations by 1879.. Since 1879 it has been continuously observed. 

There was a great deal of conjecture as to what the GRS was. We now know it is a massive, anticyclonic storm in Jupiter's atmosphere. If the early observations mentioned above are accurate, then it is a strom that has been raging for 357 years, with wind speeds as high as 432 km/h. 

More recently, in this century, the spot appears to be shrinking, with reports of the clouds at the edge shredding into the atmosphere. However, many astronomers believe the Spot's size is just a reflection of total cloud cover in the area, and not the actual size of the vortex that is creating it. The cloud shredding is, similarly, not related to the Spot. If this is the case, the Spot will be with us for many more years.

Mars with 5x Barlow on 12/17/2022

 Conditions tonight were better than yesterday and I decided to try some imaging with the 5x Barlow. This is a little crazy in the 125 mm f/15.3 Mak. The resulting focal ratio is f/76.5, for an effective focal length of 9,500 mm -- a little more than 31 feet!

The dim image meant I had to use a high gain setting to achieve a decent (47 fps) frame rate. Noise was high, but as I stacked about 13,000 of 26,000 captured frames, it was not an issue for the final image. The improved image size brings out some subtle detail on the disk which is missing on the 2x Barlow images.

Here is the Mars map for this image:

Mars on December 16, 2022

Despite less than average seeing, I imaged Mars twice tonight; once, when it was relatively low in the sky, and again when it was near the zenith. The images were passable, but definitely compromized by seeing. Before beginning the second imaging session, I had to clear dew off the scope corrector with a hairdryer. I've included Mars map comparisons for each image.

 

Jupiter on December 16, 20200

Conditions were a little more challenging for imaging tonight, with haze and dewing. Neverthess, I was able to get a usable image of Jupiter which shows some nice detail on the cloud belts. This image was taken with the 125mm Mak and 2x Barlow and the Mallincam Skyraider SLP. This image is from a stack of 15,000 images, with 12,000 stacked in AstroSurface; wavelets in Registax.

 

Mars on 12/13/2022

Later the same evening I imaged Jupiter (last post), I also imaged Mars. The planet is close to the zenith around 9:30 local time here in Charlotte. Conditions were not as favorable as they were the last time I imaged the planet (I had to remove heavy dew from the corrector using a hair dryer), but I was able to capture a usable image using the 5 inch Mak and SLP imager (this is a stack of the best 40% of 15,000 frames).

Looking at the Mars map below the image, it’s not as easy to align the features with the map as it was in the previous image. Even early Mars observers noted that dust storms and weather on the Red Planet can make significant differences to surface features, and this appears to be the case with this image.

Nevertheless, some features identifiable: the north polar cap, and, at the top of the globe, Mare Sirenium, Mare Cimmerium, and Solis Lacus. The lighter, circular feature below center left is Amazonis, part of the Tharsis bulge, with its massive volcanoes, including Olympus Mons, the largest known volcano in the Solar System. Adjacent lighter areas,A rcadia, and Elysium, are also visible.

Many of these names originated from the observations of Percival Lowell. Lowell was a businessman, as well as a brilliant mathematician and avid astronomer. From 1893 to 1908, he studied Mars from his well-equipped private observatory in Flagstaff, AZ. Using his 24 inch Alvan Clark and Sons refractor, he noticed what he called “non-natural features” on the planet—the famous (or infamous) canals.

Lowell's canal map--1905

Lowell was consumed by the romantic vision of a mighty civilization struggling to survive as their planet slowly withered around them. The canals formed a vast transportation network, moving water from the polar regions to the dry deserts in temperate and equatorial regions. He also gave features on the planet romantic and evocative names (Arabia, Amazonis, Elysium, etc.), which created an exotic image of Mars in the popular imagination. The Barsoom novels of Edgar Rice Burroughs echoed this sentiment, while H.G. Wells explored its darker side in War of the Worlds.

But even in Lowell’s time, there were many who doubted the existence of the canals he so carefully mapped. The great astronomer E.M. Antoniadi reported seeing canals occasionally, but he believed they were an optical illusion caused by the brain joining up fleeting, fine details into linear features (I have, myself, seen linear features when visually observing Mars, only to have them break up into a complex of fine detail in moments of good seeing). Others criticized the whole idea of using open canals to transport water as preposterous, as evaporation would consume any water long before it reached lower latitudes. The overwhelming consensus was that the Martian climate was too hostile to support the development of complex life forms such as those Lowell envisaged. But despite this, the idea of a Mars with some sort of life persisted—I have a 1960s astronomy book which says the scientific consensus was that the dark areas on the planet were evidence of hardy, lichen-like plants.

The probe Mariner 4 put the final nail in the coffin of this belief. Its pictures showed a cratered, dry, moonlike world with an atmosphere far thinner than had been previously thought. However, these images resulted in an overcorrection of our perception of Mars. The track of the probe took imaged, by serendipity, the most moonlike areas of the planet. Future probes, such as the Viking landers, showed a much more Earth-like planet with bright skies and a landscape not unlike the US desert southwest.

Now, we know Mars is a dynamic world of winds and storms, of cratered plains and sand dunes. It is indeed an alien place, but our perception of it is still colored by the romantic imagination of Percival Lowell.

 

 

 

 

Jupiter and Europa (did I capture surface detail on the Galilean Moon?)

Last night was cold and a little hazy, so I decided to do some planetary imaging. Jupiter was high in the sky at 6 pm Eastern when I began imaging. Haze can sometimes benefit planetary imaging but seeing did not seem to be particularly good. Capella was twinkling low on the horizon in unsteady air. I took a quick peek at Mars (also low on the horizon), but it was scintillating, and no detail was visible. However, conditions were better towards the zenith, and Jupiter’s image indicated average seeing conditions. I took some test frames with the 5 inch Mak and Skyraider SLP imager. I was puzzled by the low framerate (about 12 fps), when I noticed I was running at 2048 x 1536. I reduced the resolution to 1024 x 768 (my usual imaging resolution with this camera) and achieved about 48 fps.

The Jupiter image below if about 45% of 15,000 captured frames. The quality graph in AstroSurface was surprisingly flat, and the resulting image of Jupiter (wavelets in Registax) showed unexpected detail. Textures are visible in the north Polar Region and North Temperate Belt. Loops and eddies of gas can be see in the North Equatorial Belt, with swirling clouds in the Equatorial Zone. In the Southern hemisphere, one of the 3 white storms in the South Temperate Zone/Belt is visible (the white oval). Two moons are also visible in the image—Callisto (nearest Jupiter on the lower left) and Europa (further to the left and higher in the image). These moons appear irregular when zoomed, which is an indication of the quality of seeing when they were imaged.

Out of curiosity, I processed an image of Jupiter captured at the lower frame rate (750 of 1500 frames) and I noticed that the moons appeared round. I zoomed in on Europa and was surprised to see what looks like albedo detail. The image below shows this zoomed image. My quick, back of the envelope calculation, indicates that Europa’s angular diameter is 1.04 arcseconds. Given that the 5 inch scope can resolve about 0.9 arcseconds, that’s remarkable (unless it’s an illusion!). The color does seem to match that of Europa’s dark features.

NGC 7822

 My last post for NGC 7822, a star forming region in the constellation of Cepheus, was on October 26 of this year. The image I posted was a short integration of 33 x 45 second subs (a total of about 25 minutes). The resulting image needed significant noise reduction in Topaz DeNoise, but the result was worthwhile. Last night, I decided to add to this data. Before clouds rolled in, I was able to capture an additional 200 subs. The image below is a stack of 233 x 45 second integrations, for a total integration time of about 3 hours. The result shows a much better contrast balance and more detail in the surrounding nebula. Click and zoom for more detail. The second image is a crop of the core region of the nebula, showing its "Pillars of Creation" features.

Tech card: RASA 8, NBZ filter, DS10C camera. 233 x 45 second integrations.

Mars Reprocessed

 I decided to try a slightly different approach to Mars processing. I captured 2 AVIs last time I imaged Mars and I decided to combine them in PIPP, a free software package that allows pre processing of planetary video captures before stacking with separate software (like AstroSurface).  One option is a "join" function for video files. Using this function, I combined the two separate SER files into one AVI with just over 23,000 frames. I then stacked the image in Autostakkert, selecting the best 50% of the frames.

Although the images of Mars in the last post look very like the Martian map in terms of color, etc., they are not an accurate representation of the way the planet looks through the eyepiece. Visually, Mars is not deep orange, but is more of a pale ochre color. The dark areas are not black, but have a bluish cast to them. In addition, the images have a prominent ring, or "rind" to them--it can be seen close to the edge of the planet. The rind has a number of causes, but is primarily an artifact of wavelet processing. Fixing the problem is also complex and challenging, but one way is to minimally process the image to reduce (but not eliminate) the effect.

I processed the large image stack mentioned above in Registax using this more minimalistic record. The result is a more natural looking image of the red planet that still shows some subtle detail, including some edge haze missing from the previous images.

Mars Under Good Seeing

The same evening I imaged Jupiter under good seeing conditions, Mars was also favorably placed for imaging, but not until much later. Mars’ oppositions vary in quality. In favorable oppositions—like that in 2020, Mars is relatively close to the Earth. Its disc has a relatively large angular diameter and lots of detail is visible. In less favorable oppositions, the planet is further away from Earth, with smaller angular diameter and much less detail visible. In 2018, the planet had an angular diameter of 24.2 arcseconds. In 2020, it was 22.4 arcseconds. In 2022, it is only 17 arcseconds. 2025 and 2027 will be even worse, with 14.5 and 13.8 arcseconds respectively.

While I can image Mars early in the evening, it is currently low in the sky and detail is lost in the thicker atmosphere the light passes through. It is not until 11 pm that the planet rises above blocking trees and offers an optimal imaging target. The image below is the best 30% of 15,000 captured frames. Given the angular size of the planet and the small scope used, the captured image is quite decent. I have included a map to show the features captured, including (most obviously), Syrtis Major, the North Polar Cap and a suspicion of the South Polar Cap at the 2 o’clock position.

Tech Card: 5 inch Mak, SLP imager, 2x Barlow. Best 30% of 15,000 frames stacked in AstroSurface with wavelets in Registax.

Jupiter Under Good Seeing

When I lived in Indiana, sky conditions were rarely favorable for planetary imaging. Skies were either hazy and stable, masking detail, or transparent and unsteady, making the planets shimmer as though under rapidly moving water. Here in North Carolina, conditions are frequently favorable for imaging planets, and last night proved to be the case.

Shortly after sunset, Jupiter is approaching its maximum altitude in the sky, making circumstances ideal for imaging. I set up the 5-inch Mak with a 2x Barlow and the Mallincam Skyraider SLP camera. The SLP is an excellent camera; its small pixels (2.5 um x 2.5 um) support the capture of fine detail. Even though it is only a USB 2.0 camera, it can capture at nearly 50 fps, which is adequate for “lucky imaging” under good seeing. Lucky imaging is a technique where large numbers of images are captured rapidly, and the best of them are stacked and processed. Such an approach minimizes the effects of short-term variations in the Earth’s atmosphere and helps to ensure a high quality result.

This picture of Jupiter was captured using this technique. Of about 5,000 captured frames, 2,500 were stacked and processed to produce the final image. Given this image was taken with a very small (but high quality) telescope, the result is a tribute to the excellence of the seeing and the effectiveness of the lucky imaging technique; a great deal of detail is visible on the planet, including white oval storms. The moon visible in the image is Io.

Tech card: 5 inch Mak, SLP imager, 2x Barlow. 2500/5000 frames stacked in AstroSurface with wavelets in Registax. Color normalization in Nebulosity 4.

The California Nebula--NGC 1499

 NGC 1499 is a large emission nebula in Perseus. Its low surface brightness makes it a difficult object to see visually, despite its magnitude of 6, but it is relatively easy to image with a narrowband H II filter. At 2.5 degrees in length, it is a good object for imaging with the RASA 8. The bright star in the image is Xi Persei. Also known as Menkib, Xi Persei is a blue star 12,000 times brighter than the sun; its radiation ionizes the hydrogen in the nebula and creates the object we see.

The California Nebula is a difficult object for me to image. I have only a 45 minute window from when iot emerges from one set of trees and disappears into another. Despite that, the F/2 ratio of the RASA was able to pull out some decent detail.

Tech card: RASA 8, DS10C, NBZ filter. 60 x 45s integrations.