A Virtuoso Mini-Review

September 11, 2024Richard WrightEquipment Reviews

Sky-Watcher 25th Anniversary Limited-Edition SkyMax 127 Virtuoso GTI
$775.00

A complete and capable tabletop telescope.

One of the biggest problems with telescope ownership is many people often get a scope that is suitably impressive and capable but takes a bit of time to setup for use. The best telescope you have is the one you actually use right?

Telescope on a table
The Virtuoso GTI anniversary package comes with everything you see here and is ready to go.

I have a pretty impressive collection of telescopes myself, various optical designs, several different mounts, some even small, portable, and easy to setup. Yet, I will very often find myself taking out the trash or coming home from an evening engagement and noticing that the sky is clearer than I expected it to be that night. The Moon/Jupiter/Saturn/etc. looks fantastic tonight, it’s too bad I don’t have scope setup and ready to go. This happens more often than it should. Years ago, I bought a simple small tabletop Dobsonian, mostly for my children at the time, but unlike my current 14” dob, it didn’t track, didn’t have GOTO, and was unsuitable for astrophotography. I ended up giving it to my daughter when she got married and moved out. Occasionally, when my favorite visual target the Moon surprises me one night, I’ve missed that little scope. Well, I used to.

For Sky-Watcher’s 25 anniversary, they have released a limited number of SkyMax 127 telescopes with the Virtuoso GTI mount. They sent me one for review, and it’s a keeper. The included optic is a 127mm Mak-Cassegrain with a focal length of 1,500mm and a focal ratio of f/11.8. I love the Mak-Cass design and own the larger 180mm version myself. The optical design has many advantages for visual astronomy as well as astrophotography. In the many years I’ve had the larger one and transported it around, I’ve only had to tweak the collimation one time, and the truth is, I probably should have left it alone. It’s not quite as good as a refractor (sorry, I’m a bit of a refactor fanatic), but it’s close in terms of sharpness and contrast, it’s far more portable and provides superior views of the Moon and planets to a Schmidt Cassegrain for its size. For the anniversary edition, the 127 OTA has a special insignia on it and each one is numbered as well. Fancy.

Scope on a tripod
Quick and easy setup in my driveway on a tripod!

Although, the Virtuoso GTI is a tabletop mount, it also has a 3/8” threaded block on the bottom for mounting on a tripod if you want it elevated. I found this to be a surprisingly useful feature. The whole thing weighs just 21 pounds too. The Virtuoso is an Alt-Az mount with a Vixen style dovetail clamp. You could easily remove the SkyMax OTA and put on another telescope as long as it was short and lightweight (10 pounds or less). A small refractor for example would do nicely here. The GTI creates its own WIFI hotspot and can be controlled with Sky-Watcher’s free SynScan app, which is available for both iOS and Android mobile devices. If you have or purchase separately a SynScan hand controller, there is also a port for that as well. I do confess, I sometimes prefer to have that tactile feel of real buttons while I float above the Moon with my eye glued to the eyepiece, and I’m pleased this scope offers that option.

Side view of Virtuoso
Like most Sky-Watcher mounts, the Virtuoso GTI sports a hand controller port, power port via batteries or an AC power brick, and has a snap port for controlling a camera.

It’s a tracking mount, which means it needs power. There’s the ubiquitous 2.1mm power port for a 12v power supply, or you can add eight AA batteries for a more cord free experience. I found alignment to be trivially simple. There are clutches on both axes you can loosen for easy OTA positioning. Just level the mount, point the OTA north, and connect with the SynScan app or hand controller. I most often use it for a single target opportunity, and the one-star alignment gets me close enough to the Moon for example that I can find and center it up well enough with the included 9×50 straight-through finder scope. Tracking is good, and there are options for setting both lunar and solar tracking rates (be sure and use a FRONT MOUNTED SOLAR FILTER). I appreciated the 2” diagonal and back on the 127 SkyMax as I can use it with my entire eyepiece collection.

Some of my finer scopes I keep indoors, but I can’t just take them outside and use them on a spur because in Florida the optics will immediately gather condensation in the warm humid air outside after being in my air-conditioned home. This setup however, I keep in my shed and have been up and running and exploring the Moon in literally under 5 minutes. There is an included 28mm eyepiece in this package, but I also found the views are quite nice with my Takahashi and Brandon eyepieces, and when seeing conditions are good, I’ve pushed the magnification up to over 300x. Yes, I know that exceeds the maximum recommended for an optic this size, but your brain is an amazing image processing device too, and you’d be surprised what you can see sometimes.

Another reason I’m so fond of this setup is that there’s very limited sky from my back yard. When the Moon is behind the neighbors’ trees, I can pop this on a tripod in my driveway, spend a few minutes lost in the Moon’s terrain, and then put it away quickly before bed. I can even extend setup time to a whopping 10 minutes<g>, by grabbing my laptop and a high-speed camera to do some lucky imaging since it’s a tracking mount.

Some quick lucky imaging has never been more convenient than with a ready to go system that I can plop down anywhere.

I really have no critique of this package. It’s small, light, fast to setup, and it’s bringing me back to my favorite target the Moon when the opportunity strikes. Sure, I can do a little better with one of my larger scopes, but “more frequent” is also a pretty compelling feature! It’s also a great scope for the planets, and brighter deep sky objects, but for me it’s going to primarily be my “Moon Ship”. I name all my scopes, and this one I’ve christened as “Artemis”. You can probably guess why.

Richard S. Wright Jr. does not have more telescopes than he needs, no matter what his friends and family says. He also does not have too many books on the Moon, and is always looking for more at used book stores.

Solar Nirvana?

July 28, 2024Richard WrightAstrophotography, Solar Imaging

The weather for astrophotography in Florida is so dismal in the summer, or rainy season as I call it. Even when it’s bright and hot outside, there’s a haze of moisture and thin clouds most days, and the nights are quite opaque. We had a break the other morning and I had a chance to get out some new gear I’ve been curating. I think my solar rig is “almost” as good as I can hope for, and I captured a nice view of the Sun the other morning (7/26/2024) and Active Region 3762.

The Sun in Hydrogen Alpha light and my rig used to capture it.

I have a DayStar Quantum 0.5 Angstrom Ha filter. This is a very specialized filter for capturing light just from glowing Hydrogen in the Sun’s atmosphere. It reveals an amazing amount of surface details, and it works on the back of most any refractor as long as it isn’t too big. I will be honest, it’s an advanced piece of astro-gear, and I struggled a bit to get the tip top performance out of it for a while. Focal ratio matters, sort of. What really matters is nice parallel rays of light coming into it, and certain optics technically change the focal ratio, but don’t necessarily produce the most parallels rays. I also have found, despite my earlier confidence, that a front mounted energy rejection filter helps a great deal (ERF). I bought an 82mm Lunt ERF second hand in a custom 3D printed cell that fits my Astrophysics Stowaway telescope. I use a TeleVue Powermate or a Baader 4X Telecentric on the back to get the focal ratio/parallel light rays going.

Other luxuries in this photo. A Paramount MYT with absolute encoders, which is an absolute joy to use. Already aligned and ready to go, you just flip a switch and go. The scope is an Astro-Physics Stowaway refractor, there’s a waiting list and/or lottery to get  these fine refractors. I really think Roland Christen is the modern Alvan Clark. There’s a top of the line Feather Touch focuser on the back, and an Optec QuickSync motor on it. Finally, a Player One Apollo Max on the back is taking the images. One further improvement is a cooled camera. There’s some debate as to if this really helps with solar imaging, but I do find that the fact that the temperature is regulated does make a big deal. Not so much that it’s “reducing noise” in the raw images, but calibration frames need to be at the same temperature if you you want the flat frames to work properly. Nine times out of ten, it doesn’t seem to matter, but occasionally, I’ll end up with flats that won’t work, and this is the reason why. Some helpful advice… “Just keep your optics clean”… makes me laugh.

I think this is just about as good as it gets for a high quality solar rig for myself. I might have to get a 3D printed cell for that ERF to fit my Esprit 150 though. It’s only taken some 30+ years of wheeling and trading up to get here. As Ferris Beuler says, “If you have the means“… maybe you won’t have to wait 30 years 😉

Now… how about some clear skies?

 

Montes Apenninus

May 18, 2024Richard WrightAstrophotography, Lunar Observing and Imaging
The Apennes Mountains on the Moon
Montes Apennius bisects Mare Imbrium and Serenitatus

As a child, my family would visit the Great Smoky Mountains in Tennessee, often multiple times a year. I imagine future lunar citizens might vacation in the Apenninus mountains, a beautiful chain of mountains that curves along the edge of Mare Imbrium on the left side of this image. Named after a mountain range in Italy, it has a small gap (perhaps analogous to the Cumberland gap of my childhood home) that opens the way from Imbrium to the sea of Serenity to the right. Were the lunar maria actual oceans, there would for sure be a vibrant trading city located here as the most practical passage between these two great seas.

Alas, this is the Moon, and the Maria are indeed not waterways, but vast plains of cooled lava… well… a sea of frozen lava is still a sea, isn’t it?

Taken on the night of May 16, 2024, the lighting here is really quite outstanding for great views of a number of prominent features in this area of the Moon. At the upper left we see the crater Plato, which often looks quite shallow and flat. Due to the Sun’s angle at this time however you can see the highly detailed walls of the crater rising high above the smooth surface of Mare Imbrium. To the upper left of Plato, you can see a small ring of light that is the crater Fontenelle. Through the eyepiece this night, that ring was glowing in the darkness of the terminator like the lights of a great city in the night.

Midway down and to the left of the Apenninus mountains is another flat and smooth crater Aristarchus. Like Plato this crater appears to be older than the Mare Imbrium as its floor is flooded with the same cooled lava that surrounds it. A younger crater at the southern tip of the mountain range is Eratosthenes. There is no smooth floor here, and in the center, you can see a tiny dot of light that is the central peak of a mountain of material that was rebounded when the impact crater was formed.

While the Moon is not quite as dynamic as the Sun, it is different every night, and even every hour you can see changes in the surface as the light and shadows dance across the lunar day. Even the smallest telescope or binoculars will reveal this world to you, and I encourage you to go take a look as often as you can.

Just One Hour

May 5, 2024Richard WrightAstrophotography, Basic Photography

The August, 2024 issue of Sky & Telescope has an article by me about shooting star trail images. It’s too bad I didn’t have this shot before because it’s my favorite star trails image to date. I setup my camera behind an equatorial mount (I was shooting M106 at the time), and set my canon EOS Ra to take 30 second exposures repeatedly. Then, as I describe in my afore mentioned article, I loaded all the images as layers in Photoshop and set the blend mode to “Lighten”. I did paint out a few airplane trails in the individual layers, but otherwise the image is accurate. There are even a few short meteor bursts if you look carefully for them.

Star trails over a telescope
One hours worth of star trails show just how much the stars appear to move in such a short amount of time.

This image shows why we use an equatorial mount for long exposure astrophotography. As the Earth spins, the stars move considerably, and in this case you can see exactly how much in only an hours time. An equatorial mount works by aligning it’s axis of rotation with the Earth’s, and then rotating in the opposite direction of the Earth’s motion. It’s like being on a merry-go-round, and you have to turn your head to keep looking at someone or something off in the distance. Without an equatorial mount, objects zip by in the eyepiece or camera pretty quickly. There are also alt-az mounts that track objects in the sky without having to do much alignment work, however, because of the way they move, objects in the camera will rotate in place as you track them across the sky. This makes long exposures a bit more challenging 😉

For context, I’ve added just a single 30 second frame as well. As a stand alone image, it’s not too bad either IMHO.

Richard

A telescope against a starry sky
Here’s just one of the 120 frames used to create the star trails image.

Totality at Last!

April 23, 2024Richard WrightAstrophotography, Eclipses

Total Eclipse SequenceYou’d think given my years of astrophotography (if not just my age!) that by now I’d have seen a total eclipse. The total eclipse of April 2024 that crossed North America was not my first attempt at a total eclipse, but it was my first successful attempt at witnessing a total eclipse! I can now tell you; the hype is real.

The Diamond Ring Effect
The Diamond Ring at the beginning of totality during the 2024 total solar eclipse.

I went to the Texas Star Party, which was moved both in location and time to coincide with totality and we were nearly right on the center line for nearly four and a half minutes of totality. That was the fastest four and a half minutes of my life. I can now understand why people tell you that you should not “focus” on astrophotography at your first totality. Of course, that advice is lost on me (and probably some of you) because photography is in our DNA. I did not however completely ignore the advice. My photography rig was 99% automated. All I had to do was remove the front white light filter at totality and put it back on after totality.

My gear choice was pretty much ideal. I used an equatorial mount to keep the Sun’s orientation constant throughout the eclipse (Sky-Watcher Az-EQ6 in EQ mode). I polar aligned it on a previous evening using the integrated polar scope. For optics, I used an Astrophysics Stowaway 92mm refractor with the f/7 flattener. I had made a front mounted white light solar filter from Baader solar film for the 2017 eclipse that I reused this year. I

Total Eclipse
The Sun and Moon during totality. Note that bright prominence at the bottom just peeking through low areas on the lunar limb.

removed it during totality, and thus got nice safe images of the partial phases, and when it was safe (for the camera) I got Baileys Beads, the Diamond Ring, and some great prominence and corona images during totality. The camera was a Canon EOS Ra mirrorless full frame camera. The “a” means astronomical as it is slightly more sensitive to the hydrogen alpha wavelengths of emission nebula… and as it turns out, solar prominences!

Finally, the software the drove the sequence on my MacBook Pro was “Capture Eclipse”, which is a great program I can’t recommend enough. I rehearsed at home of course, and I focused using the @focus3 algorithm in TheSkyX Professional (which I wrote btw) on the sunspots right before the eclipse started. The telescope was already at equilibrium, so there was no focus drift during the eclipse.

Prominences on East side
Prominence’s on the Eastern limb of the Sun. Note the rather large triangular prominence at the bottom. This was visible to the naked eye during the eclipse.

I must say, I really lucked out. Sure being prepared helps, trying repeatedly helps, but the weather forecast shifted from seasonal norms to mostly cloudy for eclipse day. We got fortunate that the clouds parted for us and although we had a few thin clouds and the occasional thick cloud, we were rewarded with a glorious view of totality. While I’m very pleased with my images, there is absolutely no comparison to the view naked eye. If you can possibly make it to center line for a total eclipse, I highly recommend you make the effort. I know my passport will be ready for some future eclipses…

Additional and larger versions of these photos are available in the Sun gallery. My favorite shot of Baileys Beads is below!

 

Baileys Beads just before totality ends. These are caused by sunlight filtering through gaps in the lunar terrain like mountains, valleys, and craters.

Photoshopped!

March 26, 2024Richard WrightBasic Photography

Forgive a departure from astrophotography please. I’d like to drone on a bit about photography, imaging ethics, and “fake” stuff if you’ll humor me. There’s a pretty transparent correlation to astrophotography if you’ll read to the end, I think.

Red barn on a pond
A beautiful foggy morning in contemporary rural America.

While looking through my archives for something else, I came across this image I took from my hotel room near Cherry Springs Pennsylvania several years ago. I remember the moment quite well. It was a cloudy morning with lots of fog. Even though completely overcast it was still somehow bright, the green was so vivid, as was the red of this barn. This isn’t “how it came out of the camera”, cameras are linear sensors and very unlike the human visual system. I “Photoshopped” it of course. I cropped the image some, applied some curves for tonal adjustments (again, the camera/display has nothing on the human visual system), and color saturation. This is what I remember seeing, and despite my adjustments, the image is actually far more faithful to the actual scene than my memory is. It is in my opinion, a very nice record of a nice moment in time that I was privileged to experience. Through the medium of photography, I can even make a meager attempt to share it with others.

A few years ago, I joined the local camera club, hoping to perhaps become a better photographer of the terrestrial kind. They had great guest speakers and had regular contests. Contests are a great way to measure yourself against yourself and others, and the judges gave detailed and useful critiques of the images submitted. It was a good way I thought to get advice from “really good actual photography experts”.

This image would never have won, and I’ve watched enough images of others get judged that I can easily tell you how to fix this photograph and turn it into a winner. Start with clone brushing those distracting poles and power/telephone lines away. They take away from the natural beauty of the landscape. Next is that white building and little house to the left that draws the eye away from the barn. Easily removed with content aware fill. At least one in four judges would replace that large blank expanse of sky with blue and puffy clouds. Perhaps sliding that “temperature” slider a bit more to the warm to compensate on the landscape.

Congratulations. However, it is no longer a photograph. It is no longer a record of an amazing moment in time. It is something else now. It is an image, but not a photograph. (I did in time drop out of that camera club as I am already sufficiently skilled in Photoshop.)

Don’t get me wrong. There is absolutely nothing intrinsically wrong about creating such an image. It might go on a billboard for the dairy farmers association, perhaps with some AI generated cows, or be the cover of a novel about how Jim Bob Walton’s life turned out in the 1960’s, etc. There is pride and perhaps a living to be made creating such images. Doing it well requires considerable artistic and technical talent to be sure and there is nothing unethical or bad about it at all, but it’s not photography anymore, is it?

We need a word for this other thing. “Imaging” comes to mind and is often the choice of others, but I hate using it that way. I’ve always used imaging as a verb, the acquisition of data, the result of which was a photograph, be it a single image such as this, or many hours of data for an “image” of a beautiful astronomical object. These objects are “photoshopped” to be sure, but true to the object’s essence. Colors can be over amplified certainly, even substituted. No two people actually see colors the exact same way, so please don’t get on a high horse about what something that can’t actually be seen actually should look like. However, that galaxy with four arms really has four arms, and the stars you see are really there, and sure under the right circumstances they may even look purple. Why so many people make hydrogen nebula orange, I’ll never understand… but if you think color is an objective reality, you should read some books on color theory and human perception. I digress. (Orange is still hideous to me, but if it suits you, you don’t need my blessing.)

Space art, like the hypothetical heavily altered imaginary barn image is not just art. Art is a beautiful and necessary thing in the world. It has utility, regardless of whether some of us care for it or not and is appreciated by at least it’s creator if no one else. If you have any understanding about the human condition at all then you will also truly understand that meeting the needs of the artist alone is all the justification required. Yours or my approval is not required.

Technology is moving forward so much faster than our ability to adapt and I look forward to getting past these growing pains… if I live that long. Recent advances in AI have made a great deal of artistic license available to a greater number of people than ever and made it even easier to wield. Synthetic images are hard to distinguish from photographs, and it’s been this way for a while now already. I often see the word “imaging” attached to this craft, and I may have to abandon my accustomed view of the word. Still, I hope we can find a way to recognize that photography still has its place, and more people will have an innate knowledge and respect to know the difference, and not mistake or substitute photography with… well, I still don’t know what the right word should be. I’m sure we’ll figure it out in time.

A Tale of Two Filters

March 2, 2024Richard WrightAstrophotography, Solar Imaging

Like a lot of photographers in North America, I’ve been making preparations for the total eclipse coming up in slightly over a month now from the time of this writing. I’m planning to take an arsenal of solar gear and spend a couple of days doing solar imaging with a variety of gear and techniques, and fleshing out some software I’m working on for lucky imaging to boot. This means I’ve been doing a lot of solar viewing and imaging in my back yard, and cycling through gear to make sure I have all the right adapters, spacing, etc. There was a very active region on the Sun (AR 3590) on the clear afternoon of February 27th and I had a chance to image it in white light and then just a few minutes later in Hydrogen Alpha. The difference is quite stark and I thought very illustrative.

Two images of AR 3590
Active Region 3590 in Ha and white light.

The telescope was a Sky-Watcher Esprit 150 (still my favorite optic for just about anything), which I had on my Paramount MX+. The Paramount’s have the smoothest motion of any mount I’ve ever used for any kind of high resolution Solar or Lunar work, but back to topic. The top panel at right was taken with a 4x Powermate to get the image scale and focal ratio higher for the Daystar Quantum hydrogen alpha filter. I used a Player One ERF (Energy Rejection Filter) in front of the PowerMate. I don’t use a big ERF in front of the 6″ objective, but 6″ is about as large a refractor as anyone should dare use for solar without a larger ERF in front of the aperture. The camera on the back was Player One Apollo Max, and I shot about 5,000 frames, of which I used 20% for the final stack. The original image was monochrome, but I colorized it as most people (my wife especially) prefer to see a nice color image. The mad truth is the single wavelength of Ha is an electric pink, but the convention is to make these images yellow to conform with the public’s perception of what color the Sun should be.

Ha images are stunning. They show in stark relief how the gasses are flowing along magnetic field lines on the Sun’s surface. The darker areas are still quite hot and blindingly bright, but they are just ever so cooler than the surrounding areas, and the white areas are as you’d expect super hot and bright.

The bottom image was taken with a Starfield Herschel Wedge. A Herschel Wedge is a lot like a normal star diagonal you see on many telescopes, but it let’s the majority of the Sun’s light pass through it out the back. A tiny portion is reflected up towards an eyepiece or camera for viewing. It simply dims the Sun, so you see the Sun as it actually appears, just a lot less bright and hot. Not using a filter like this would blind you instantly, or melt your poor camera before you could hope to get a shot off.

I still used a 4x PowerMate and the monochrome Player One camera, but replaced the Player One ERF (which is tuned for Ha imaging) with a standard UV/IR filter. The Herschel Wedge does not need this normally for visual work, but when doing photography, it eliminates some of the stray light that would be out of focus. The result is a “White Light” image of the same region. You can still see some of the same overall structure of the region, but you are not seeing the effects of the magnetic field lines that are more pronounced in the hydrogen bandpass.

The true color of the bottom image is actually… white. The Sun appears white in space, and even on Earth when directly overhead. It’s hard to tell of course because well, looking at it long enough to study it’s color would of course blind you! Still, I chose to colorize it for aesthetic purposes to match the image above. Scientifically, the images represent the structures accurately (even the limb darkening at upper left is real), but the colors are for taste alone.

I hope you can forgive my creative license (or shameless conformity), and enjoy seeing the difference between these two common ways to filter and view or photograph the Sun.

Bernard’s Merope Nebula

January 1, 2024Richard WrightAstrophotography
Merope Nebula image
Bernard’s Merope Nebula

This was a challenge target for me. Last month I was writing my monthly astrophotography target of the month column for Sky Safari (you will need a subscription to see it in Sky Safari Pro), I realized I did not actually have a good image of the Pleiades that featured this tiny jewel (cataloged as IC 349). I love to shoot the larger reflection nebula with a newtonian reflector because it makes beautiful diffraction spikes, but the spikes would obliterate this tiny little interloper to M45. Same with other refractors (or my Officina Stellare RH-200) I had used with longer exposures – the star Merope would swell up and swallow this nearby nebula, which physically is only 0.06 light years from the star!!

The Pleiades are a relatively bright group of stars and nebulosity, so I went for a short run under somewhat light polluted skies. I used 111 good 30 second exposures stacked for this image, and stretched VERY gently with the histogram and curves tools. The seeing was not super great that night with my Espirt 150 refractor and a Player One Ares-C Pro cooled color camera, so I confess as well I used the very nice Blur Exterminator to tighten the stars a little bit.

An interesting personal experience about this image. This is the first time since I’ve started wearing glasses (none of us are getting younger!), and just like a star test is a good way to test optical flatness, I found that when judging my star field on the computer screen, I could see… and DISTRACTINGLY SO… distortions in the star field that aren’t actually there. This can make it very hard to judge an astro image, and I now have TWO pairs of glasses. One for “most of the time”, and one for when I’m using my computer or working… um… well, truthfully that IS most of the time – LOL.

P.S. Happy New Year and Clear Skies!

Purple Haze

October 15, 2023Richard WrightAstrophotography, Solar Imaging

The great annular eclipse of 2023 has come and gone. The internet and social media are flooded with amazing shots of the Sun. Most are red or orange, and there are a few white light images taken with white light filters or solar wedges. “The Ring of Fire” was not in the cards for me this year, and I had to be content to observe and image the event from my driveway in Central Florida. I shared the event with neighbors and gave away some solar glasses from DayStar filters. No eyepieces though, I had a camera on the back of the telescope (oh, did this require some “explaining” and warnings), and a black and white image of the Sun was displayed on my laptop, cleverly shielded from the hot bright sun by a cardboard moving box.

Solar Eclipse in Calcium Light
Maximum Eclipse from Central Florida in Calcium-H light

My processed images though are Purple. Whaaat?!

I used a Daystar Calcium Quark, specifically the Calcium-H line. Some of you know this, but many people do not know that much of what we know about the Universe and what things that are far away are made of, is done by studying the light we receive from them. Here’s a great article on the Hubble Space Telescope web site that explains some of how this works: What is Spectroscopy.

So, back to the Wright Earth Telescope(s). The filter I used on the eclipse is what we call a “narrowband” or “Line” filter. It only let’s through a very specific wavelength of light, and this filter is tuned for the H line of Calcium (396.9nm), which if you had looked at it through an eyepiece, would have been a deep purple! I once had a similar dedicated telescope that was for the Calcium-K band, which also appears Purple, but is so deep that many people cannot actually see the details on the Sun’s surface. I’ve heard various explanations about genetics, and “old people”. My own experience is that I could see it years ago, and now when I first look all I see is a smooth purple disk. Then as I fish around, my eye will suddenly focus and I can see it for a few seconds, and then it’s lost. I don’t think it’s so much “detecting” the wavelength (which is very far towards the violet), as your eye loses the ability to focus on it. Maybe that’s the same thing. We’ll see if in another few years if I can ever catch the surface details any longer.

But this is why the Calcium-H line is very popular for visual solar observing. It reveals a very similarly detailed image and can be more easily seen visually in an eyepiece. Since it’s monochromatic light (just a single wavelength), typically what imagers do is use a more sensitive monochrome camera, and then colorize the image after they are done processing the image for sharpness and contrast.

The Gear

Telescope pointed at the Sun
Driveway Solar Astronomy. Be sure and share with your neighbors

I used a Sky-Watcher AZ-EQ6 mount in Alt-AZ mode. That was more mount than needed for my tiny Takahashi FS60-CB telescope. It has a fluorite lens, and many people worry about damaging fluorite with solar observing. It is true, fluorite lenses can be damaged by sudden temperature shifts, but here’s the thing about glass lenses… light passes through them. They don’t really absorb much heat. If your optic however gets too far off the Sun, and the concentrated light starts hitting your baffles or the edge of the tube, you can superheat the inside of the OTA, and bad things can happen. Bad things. I do understand some older oil space lenses can be problematic for solar though, so check with your manufacturer before you start tinkering with hot sunlight.

Inside the tube, I had an IR/UV filter, which reflects a great deal of the Sun’s invisible, but heat bearing wavelengths right back out the front of the telescope. Behind that was an Astrophysics 2X barlow. I love this barlow because it also acts as a flattener. If you are doing full disk solar work, or even high resolution solar or lunar work, it annoys me terribly when I use a large sensor and only the middle of the image is really in focus. The solar filter was the Daystar Calcium-H Quark and the camera was Player One Ares-M (IMX 533 monochrome) that I ran cooled to zero degrees C. This was a lot of fun to explain to the neighbors. Concentrated sunlight is going through a filter heated to a specific temperature, that then reaches a camera that is cooled and kept at 0 degrees Celsius. I’m just your average mad scientist working in his driveway…

Clear skies, day or night friends!

A Celestial Dolphin

July 28, 2023Richard WrightAstrophotography

Here’s a “cool” looking image for all the hot summer days we are having right now! A really amazing object in the southern sky in the constellation Canis Major (the Big Dog), is a big gas bubble cataloged as Sharpless 308. It has a popular (but unofficial) name of the Dolphin Nebula. It’s in the Sharpless catalog because of it’s Hydrogen Beta emissions, but it is especially bright in ionized Oxygen III. This image is about two hours of exposure time through a 3nm Chroma OIII narrowband filter. It’s amazing that we can photographically identify elements this way, but the OIII atoms emit a very specific wavelength of light, and this filter let’s only that wavelength through (well, plus or minus 1.5 nanometers!).

The Dolphin Nebula
Sharpless 308, or the Dolphin Head Nebula

The central star is pre-supernova and is responsible for blowing off all this gas, and is about 4,530 light years from Earth.

Artistically, this was a tough image for me. I took it back in February of 2023 at the Winter Star Party and only now (late July) am I satisfied to publish it. I did take about 1/2 hour of RGB data to give the stars color, but this is basically just an Oxygen emission image of this target. I went back and forth on the coloring. OIII is Cyan (blue/green), but of course the light is far too dim to see. What color is something that’s invisible? I settled on this, and finally even decided I liked the smoky background oxygen that is glowing around/behind the main focus of the image.

Gear used:
Sky-Watcher Esprit 150 refractor
Night Crawler Focuser
Player One Poseidon-M Camera w/Phoenix Filter Wheel
Chroma 3nm OIII narrowband filter
Software Bisque Paramount MYT
30 minutes RGB exposure time
2 Hours OIII exposure time