Hiking with SeeStar S50

 Tripod can be ditched.

Ultralight base: 

SeeStar S50 trick: No leveling nor compass ever?

Being working on the Plate Solving project myself in the past, I've figured that SeeStar firmware implementation might follow a similar math for its functionality.

That led to a few simple experiments confirming that initially. After a few software updates from ZWO  rendering my initial findings obsolete I now have reworked my quick guide below.

ZWO SeeStar S50

I have decided to get this minimalistic but full fledged robotic astro-photo rig for occasional near zero effort sky events documenting and possibly astro-photometry, some astronomy apps development ideas benefiting my main aperture (Portaball 12.5), and remote terrestrial imaging.

Zero regrets! I believe it's on par with the venerable 100% manual AstroScan ball scope in the engineering ingenuity.

PORTABALL

 1. From under UTA with (L to R):

A. 3D printed Secondary Mirror in Snap-on rigid protective dust cup (bottom).

B. 3D printed oversized starpiece in the focuser for RLC/BRLC (laser collimator) dual-side projection screen with Cheshire center hole. 

Orion 70mm Multi-Use Finder Scope

Just would like to share my impressions with this simple purchase.

At $100 it's somewhat overpriced for what it is indeed, as at the close inspection I have figured it's just the front piece of the Orion's 70mm binoculars plus the 6 adjustment screws shoe mount stalk and some threaded adapters. But overall it might worth it in the long run.

Internet of Things for amateur astronomy.

or The ultimate Telrad / QuInsight USB Power / Blinker Mod

Every light-producing telescope sighting device for astronomy use could benefit from the so called "Blinker" feature, which helps the observer to maintain the eyes darkness adaptation as much as possible during the telescope pointing flow with that type of finders simply reducing the light exposure. That allows to point with such a device using much fainter stars than with the reticle constantly shining into observer's eyes.

I had that "blinker mod" implemented over a decade ago using the trivial LM555 timer IC for my Telrad (you can easily google for that circuit and Telrad integration guides, there are plenty online). But as I have recently acquired the more advanced collimator sight the QuInsight I decided to make a more advanced blinker as well. But it turned out so advanced that I see it frankly opening the IoT era in amateur astronomy!

TPM Telrad Pattern Matching

Another write-up on the subject, which is so trivial that it deserves a detailed explanation! How to use the Telrad properly? Many people use it as just a glorified red dot finder, which is sad to see, knowing its potential rivals even the most advanced GoTo systems... But let's start from afar with the most frequent question a beginner or mature amateur astronomer is constantly concerned about: How to point a telescope to an invisible deep-sky target to the naked eye? I mean, in a reliable way? [The write-up is still under development]

Photo by Guillermo Ferla on Unsplash

I bet you have already heard dozens of answers to that. After asking that question for over 40 years myself and trying what others are doing to solve that problem, I have finally found the definitive answer: the TPM. Which stands for "Telrad Pattern Matching".
Back to our question. What is the formalized goal of all celestial target pointing methods? Surely is to get the object you want to observe into the field of view of your telescope eyepiece (into the magnified and enhanced circular portion of the sky you see when looking into the telescope).

How can we make that task so trivial that there is no question of how to do that, even for a little kid? Think about the Moon, for example. Obviously, as soon as you can see its shiny disk or sickle in the sky, you can raise your hand and point at it with your finger immediately. What could be more trivial than that?
Lets "dissect" that process to its components which we apply nearly unconsciously:

1. Find the moon in the sky by moving your head and eyes around until you see its edge.
2. Move your index finger toward it until it is under the edge (or at its center).
3. Done. You can be sure that you are pointing your hand at the moon.

 
But is it at all possible to point a real telescope to, let's say, the Horse Head Nebula, which is hard to see even through a decent telescope, with the same ease and triviality? Yes, it is! By using the Telrad Pattern Matching (TPM) method.

Okay. So what the heck is that TPM after all? Almost exactly the same thing as pointing with your finger! But:
 

1. Instead of the easy-to-recognize limb of the Moon in the sky, you are pointing at multiple naked-eye stars in the close vicinity of your invisible target. These are still easily recognizable stars of constellations. You can call it an asterism, as in the star-hopping pointing method. However, the difference is that it's a dynamic thing; you can add or remove stars (or even bright DSOs) to or from it as needed or desired.
2. Instead of the finger's contour (which you move in the sky toward the Moon's limb), you are pointing with the special reticle "projected" in the sky. The primary difference from the fingertip is that it's a bit larger and has more features in it to catch your attention when deciding if you have your "finger" pointing "at the Moon" already or if you need to move it a bit more in a certain direction.
3. Done. As soon as you can tell that the "finger" ring is exactly on the "limb" asterism, you can tell for sure that the telescope (aligned with the rings) is pointing to the target you want.

As your memory is not yet familiar with your new "finger" and the new "Moon limb" shape (which is also unique for every real target), let's add exact virtual copies of them (the Telrad reticle and the asterism, respectively) to the star chart (on the handheld digital screen). In a way, showing you the precise example of how these two subjects should look perfectly aligned in the sky when your telescope is pointing exactly at your desired but yet invisible target at any given moment (i.e., centered in the Telrad reticle like the Moon on the tip of your finger).

The TPM could also be conceived of as a way to enhance the visibility of the deep sky target location as needed to point at it directly (the target was invisible, now it is clearly visible by surrounding it with "proxy" stars), then as the "pointing finger" enhancement (it was small, dark, and featureless, now it is large, well lit, with many features to align, and even semi-transparent), and finally as the human brain enhancement (with the easy-to-see and comprehend cheat sheet right in front of your nose and possibly even side by side with the "Moon" and the "finger" clearly visible), all the way to making our ultimate task as easy as finger-pointing at the Moon.

That's all.

The TPM is as natural as pointing with your finger at the moon because, in your brain, the procedure of finger-pointing at the moon means moving your outstretched arm until the contour of your index finger is aligned with the moon's limb's shape in a certain way. Sounds complex? But that's just a strange way the "human's finger-pointing process" could be described to, let's say, an alien life form. For the typical human brain, it's completely natural! Got a tough target to see? Just enhance what you are naturally using for pointing to a certain level and allow the brain to do the work you have been perfecting since the time you first opened your eyes: recognize and match visual patterns around you to survive by solving problems and moving your body accordingly! Weirdly put? Indeed. But it works..

A typical question: Why can't we point a telescope just by a "small finger" like a red dot or a laser beam's end? Because the target is invisible to you; naked-eye stars around it are usually far apart. Thus, any single dot positioning will mostly be just guessing the invisible object's location between them, not pointing at it. The guesswork reduces the chance your target will be close to the center of the FOV due to a plethora of natural factors (physiological, psychological, optical, perceptual, atmospheric, etc.) as well as artificial factors (the chart orientation, chart projection, RDF mount angle, RDF aberrations, etc.). So, if it's not a bright and familiarly shaped object obvious in the EP FOV, you may spend hours hunting for your target around that guessed spot again and again.

Due to the large size and multiple alignment points in the Telrad reticle, instead of guessing you are aligning these points with multiple clearly visible stars and thus automatically triangulating the target's position from most reliable matching points close to each other or aligned with each other in a clearly visible way which helps with the precise matching of views a lot even just from your visual memory. Each parameter your brain is taking into the account automatically while matching these views feature by feature adds to the accuracy of pointing. And that's not by tedious measurements from multiple points (a well known geometric method of using Telrad or RDF), you are matching the entire pattern unconsciously, with the goal of making it look exactly the same as on the chart's screen. That "the same" is based on zillions of factors catching in your neurons, not just a single dot far away from any visual anchors as with the RDF.

There are some caveats, though, which many who have heard about the Telrad and even the TPM method might overlook when trying to understand or practice it. So, let's polish your understanding of the TPM a little more before getting into the actual step-by-step flow example:

Prerequisites

1. A telescope you can move manually when pointing (even if using an electronic remote control device or technology).
2. Telrad or QuInsight collimating pointing device. The Red Dot, Green laser, or optical finders with more than 1x magnification would not work. Its mount must hold the alignment with the telescope's optical axis while you are moving it.
3. Digital star chart capable of displaying a precise model of Telrad or QuInsight rings pattern on the star chart as a live overlay image. The only digital star chart in existence that natively supports both Telrad and QuInsight reticles' precise models is DSO Planner. As of 2020, other apps have rudimentary support for Telrad only (see "Before you start" #4 below why), but some apps have a feature that allows showing multiple eyepieces FOV rings, which can be hacked together to mimic Telrad or QuInsight rings in a totally usable way (see User Note 6 below).
4. Either a good knowledge of constellation stars or the digital star chart app feature that shows the chart of the sky region behind it on the screen when you hold the screen up to the sky (often called Digital Compass or Augmented Reality Mode). Such a feature will help you distinguish bright stars in the sky until you memorize them well enough. The DSO Planner app is one step ahead by providing that feature along with the additional Digital Horizon feature, which also levels the horizon line on the chart with the real thing. So you can distinguish constellations easier from a possibly awkward posture behind a Telrad or if you have the smartphone mounted (at a fixed angle) on the OTA.
5. Enough stars that you can see with the naked eye. If you are in an urban area where you can barely see two or three stars, even after prolonged dark adaptation (which is another vast and controversial subject I'm leaving for a separate write-up in the future), you are in trouble. Though, with experience using TPM and having the QuInsight device (versus Telrad), it might become possible too. Because as you master the method, you could do well with just a single star visible close enough to the rings pattern.

Before you start

1. While you are a beginner, ensure you are using the widest FOV eyepiece available for your telescope, as initially your target may end up within 0.5-1 degrees from the FOV center after using the TPM. Give it as much slack as the telescope permits.
2. Make sure the Telrad/QuInsight is precisely aligned with the center of the eyepiece's field of view (you may want to temporarily install a higher zoom eyepiece to double-check for that or use a "crosshair" eyepiece).
3. Using your star chart app, find a region of the sky abundant with stars at a convenient altitude for Telrad viewing (but no lower than 45 degrees to minimize the refraction distortion of the field of view). Center a star in the Telrad rings. Center that same star on your star chart with the Telrad overlay turned on. Observe the stars behind the Telrad rings and compare the view with the chart (you can move the OTA around the location to have stars touching the rings, just adjust the star chart accordingly too). I bet you will immediately notice that:
1. A ring's Size (diameter) doesn't match the rings on the chart.
2. The Angle of gaps markers in the rings doesn't match the chart markers for them.
3. The Width of the rings overlay doesn't match rings width on the chart.
4. You want to fix that. So, go to the app settings and change the parameters used to draw Telrad rings on the chart. Adjust them until everything you see in the sky on that "test star pattern" (asterism) precisely matches the star chart's image, or you know where it is different and how exactly. You might need to revisit these settings multiple times, including as you gain experience with the TPM, because you will notice more and more tiny mismatches that are possible to correct. That's the key to the ultimate success of the TPM in any practical situation, from the lack of visible stars to horizon features blocking an open view of a pattern. And that's what all other apps on the market are severely lacking.
   
   NOTE that you will need to recalibrate your Telrad (as described above) after refocusing the reticle again (the Telrad reticle must be refocused after a while, as it often drifts out of focus after multiple axis alignments performed unconsciously in the same direction; the QuInsight design, on the other hand, is free from this defect as it adjusts the collimated beam direction). So consider refocusing it first if it is not already ideal.
   
   
5. Make sure the app is showing the star chart for your actual local time and geographical location, and that its real-time clock is ticking (so the chart is updated to the real sky view position at least every minute).

The TPM flow

1. On the star chart, select the object you want to see in the telescope and center it in the simulated Telrad rings overlay on the chart. (Some apps may require special measures to be turned on to keep the object always centered on the chart as the stars move with time, so the app might move them away from the Telrad's center eventually.)
2. Using a low star chart zoom, figure out what constellation or/and bright stars surround your target.
3. Find these constellations/stars in the sky (use the app’s digital compass for assistance with the general direction).
4. Point the telescope in that direction roughly.
5. Prepare to work with Telrad (e.g., move your chair, drop your knee pad, and don eyeglasses).
6. Zoom the chart so that the Telrad rings fill as much space on the screen as needed to show at least two bright stars that you can clearly distinguish in the sky AND on the chart in a favorable pattern inside and/or close around the rings overlay. Ideally, you want stars touching one of the rings or nearly precisely between two of them. Later, as you get a certain "spatial feeling" in the sky, you would do very well with almost any pattern.
7. The final step is to look through the Telrad and move the telescope until the real Telrad rings and corresponding real stars you see in the sky are creating the exact same pattern that you see on the star chart.

As soon as the pattern is matched, you can be 100% sure your target is in the field of view of your eyepiece, even if you cannot see it there at first glance! Many tough deep sky objects require field identification to locate the exact spot where the object or its edge sits between the faint stars you see in the eyepiece. And for that, you need a really good digital star chart again, capable of showing you ALL the stars you could reliably see with your telescope and eyepiece, so you could match the chart content with the eyepiece view as well. Try that with a paper star atlas!

An avid TPM user's notes

1. Ideally, as a beginner, you want to compare the sky view and the chart side by side. That way, you can get used to how the star chart app abstracts reality. Obviously, there will never be an exact match between the screen and the sky, so you need to adjust your "pattern matching brain algorithm" to the same level you have it adjusted for matching, let's say, an animal you saw in a painting with the one hiding in the bush. To do that, you need the Telrad (or QuInsight) mounted in a way that makes that easy. For over a decade, I've been using my Telrad on the side of the 12" Dobsonian. Yes, under the eyepiece, not above it as most everyone else does. So the pointing looked like targeting with a shoulder-mounted bazooka! I understand that it's not for everyone's knees, but it's extremely convenient for side-by-side comparison and study of the handheld screen and the Telrad views.
2. To compare by memorizing the pattern (when side-by-side placement of the view is infeasible), use gaps in Telrad rings. I have my Telrad oriented so one of the gaps is clearly on top of the view; that's considered a 12 o'clock orientation. You've got the idea already? Now, I can remember the pattern as "the top star is within ring 3 and 2 at 1:30 o'clock, the lower star is at 7:45 outside of ring 3 for a bit less than a degree." That's enough for better than 0.5 degrees of pointing accuracy, which is all I need to go straight to my main eyepiece at 90x magnification after sweeping my Dob in a fluid, wide arch with a brief kneeling at the end of it (in about 5 seconds). The only app supporting Telrad gaps angle adjustment is the DSO Planner.
3. Ideally, you want that "pair of stars to match" to land on opposite sides from the target (to "counter-cancel" various hard-to-avoid errors of the entire setup). But as your experience grows, stars on one side and even a single star away from the rings could work in a pinch. That allows you to point in an urban environment with much of the sky obscured by the environment or hidden by light pollution.
4. Don't forget about atmospheric refraction. It distorts star patterns relative to the unchanged Telrad rings drawn by the app as ideal circles. The error is not very significant but might create confusion. Especially when you have your rings calibrated in the app conveniently pointing at some stars close to the horizon on a warm night (high refraction). 
5. All other pointing methods available to amateurs that I have ever tried or know about (except for the ancient star hopping and the 2020s high-tech Celestron Star Sense Explorer) cannot match the TPM in simplicity, reliability, and pointing speed. All of them are either relative to some initially calibrated point and thus prone to mechanical failures or deficiencies or incapable of compensating for ever-changing conditions and user errors. Others are simply too slow either in preparation or application (I'm leaving the side-by-side comparison to a later write-up, maybe).
6. If you have a star chart app that doesn't have adjustable Telrad rings, see if it has the option to show multiple eyepiece FOV rings instead. In that case, you can try modeling Telrad rings one by one by adding special "ultra-wide" fake eyepieces and tweaking their parameters until the EP FOV ring matches one of the Telrad rings you see in the sky. You want to match Telrad rings by the same edge (e.g., outer) for each ring to avoid introducing a ~0.1-degree error, as the width of these EP FOV rings is usually not adjustable. Sadly, you can't adjust the gaps angle that way either, so you will lose quite a bit in pointing accuracy, speed, and convenience due to the inability to leverage 8-16 gaps markers in the TPM.
7. The nearly religious care of your eyes’ darkness adaptation is key for any astronomy observations of deep sky objects’ success. The same is true for the TPM’s success, as even though you are starting from very bright stars, the background view full of faint stars makes the procedure more accurate, intuitive, and quick as it becomes a natural habit. Study proper techniques for darkness adaptation, its preservation, regaining, and maintenance. They are especially crucial in a light-polluted observing location. Improve your observatory equipment and location to help with that as much as possible too. Also, it is possible to modify Telrad and QuInsight with the blinker circuit, which is a huge help with adaptation maintenance.

In addition to simple and reliable target-pointing benefits, the TPM allows you to focus on the sky more than on pointing aids. For a newbie, it's a great way to learn the sky, so at some point, all you need to point at some faint goodies is the Telrad and a couple of patterns you recall from your good times under the starry sky memories.