Astro Cat: Raspberry Pi Telescope Controller

When somebody tackles an engineering problem, there are two possible paths: they can throw together a quick and dirty fix that fits their needs (the classic “hack”, as it were), or they can go the extra mile to develop a well documented solution that helps the community as a whole. We cover it all here at Hackaday, but we’ve certainly got a soft spot for the latter approach, even if some may feel it falls into the dreaded territory of “Not A Hack”.

When [Gary Preston] wanted to control his telescope and astrophotography hardware, he took the second path in a big way. Over the course of several posts on his blog, [Gary] walks us though the creation of his open source Raspberry Pi add-on board that controls a laundry list of sensors and optical gear. Just don’t call it a HAT, while it may look the part, [Gary] is very specific that it does not officially meet the HAT specifications put out by the Raspberry Pi Foundation.

Even if you aren’t terribly interested in peering into the infinite void above, the extremely detailed write-up [Gary] has done contains tons of multidisciplinary information that you may find useful. From showing how to modify the Pi’s boot configuration to enable true hardware UART (by default, the Pi 3 ties it up with Bluetooth) and level shifting it with a ST3232 to a breakdown of the mistakes he made in his PCB layout, there’s plenty to learn.

Astro CAT is a completely open source project, with the hardware side released under the CERN Open Hardware License v1.2, and the INDI driver component is available under the GPL v3.

If this looks a bit daunting for your first stab at astrophotography with the Raspberry Pi, fear not. We’ve covered builds which can get you up and running no matter what your budget or experience level is.

A Giant Magellan Telescope Needs Giant Mirrors

The Giant Magellan Telescope doesn’t seem so giant in the renderings, until you see how the mirrors are made.

The telescope will require seven total mirrors each 27 feet (8.4 meters) in diameter for a total combined diameter of 24.5 meters. Half of an Olympic size pool’s length. A little over four times the diameter of the James Webb Space Telescope.

According to the website, the mirrors are cast at the University of Arizona mirror lab and take four years each to make. They’re made from blocks of Japanese glass laid out in a giant oven. The whole process of casting the glass takes a year, from laying it out to the months of cooling, it’s a painstaking process.

Once the cooling is done there’s another three years of polishing to get the mirror just right. If you’ve ever had to set up a metal block for precision machining on a mill, you might have an idea of why this takes so long. Especially if you make that block a few tons of glass and the surface has to be ground to micron tolerances. A lot of clever engineering went into this, including, no joke, a custom grinding tool full of silly putty. Though, at its core it’s not much different from smaller lens making processes.

The telescope is expected to be finished in 2024, for more information on the mirror process there’s a nice article here.

Hackaday Links: đŸ‘» 🎃 Spooky Edition, 2017

A few links posts ago, we wrote something about a company selling huge LED panels on eBay, ten panels for $50. Those panels are gone now, but a few lucky hackers got their hands on some cool hardware. Now there’s a project to reverse engineer these Barco NX-4 LED panels. Who’s going to be the first to figure out how to drive these things? Doesn’t matter — it’s a group project and we’re all made richer by the contributions of others.

Prague is getting a new hackerspace.

A year and a half ago, a $79 3D printer popped up on Kickstarter. I said I would eat a hat if it shipped by next year. Seeing as how it’s basically November, and they’re not selling a $79 printer anymore — it’s $99 — this might go down as one of my rare defeats, with an asterisk, of course. I’m going to go source some very large fruit roll-ups and do this at Supercon. Thanks, [Larry].

Speaking of bets, this week Amazon introduced the most idiotic thing ever invented. It’s called Amazon Key. It’s an electronic lock (dumb), connected to the Internet (dumber), so you let strangers into your house to deliver packages (dumbest). CCC is in a few months, so I don’t know if Amazon Key will be hacked by then, but I’m pretty confident this will be broken by March.

The Lulzbot Taz is one of the best printers on the market, and it is exceptionally Open Source. The Taz is also a great printer for low-volume production. It was only a matter of time until someone built this. The Twoolhead is a parallel extruder for the Taz 6. Instead of one extruder and nozzle, it’s two, and instead of printing one object at a time, it prints two. Of course it limits the build volume of the printer, but if you need smaller parts faster, this is the way to go.

Hey, did you hear? Hackaday is having a conference the weekend after next. This year, we’re opening up the doors a day early and having a party at the Evil Overlord’s offices. Tickets are free for Supercon attendees, so register here.

At CES this year, we caught wind of one of the coolest advances in backyard astronomy in decades. The eVscope is ‘astrophotography in the eyepiece’, and it’s basically a CCD, a ton of magic image processing, and a small display, all mounted inside a telescope. Point the scope at a nebula, and instead of seeing a blurry smudge, you’ll see tendrils and filaments of interstellar gas in almost real-time. Now the eVscope is on Kickstarter. It’s a 4.5 inch almost-Newtonian (the eyepiece is decoupled from the light path, so I don’t even know how telescope nomenclature works in this case), an OLED display, and a 10-hour battery life.

Is the fidget spinner fad over? Oh, we hope not. A technology is only perfected after it has been made obsolete. Case in point? We can play phonographs with lasers. The internal combustion engine will be obsolete in automobiles in twenty years, but track times will continue going down for forty. Fidget spinners may be dead, but now you can program them with JavaScript. What a time to be alive!

Audio tomphoolery even an idiot tech blogger can see through! I received a press kit for a USB DAC this week that included the line, “…low drop out voltage regulators running at 3.3 V, meaning the 5 V USB limit is well preserved.” Yes, because you’re running your system at 3.3 V, you won’t draw too much current from a USB port. That’s how it works, right?

[Peter Sripol] is building an ultralight in his basement. The last few weeks of his YouTube channel have been the must-watch videos of the season. He’s glassed the wings, installed all the hardware (correctly), and now he has the motors and props mounted. This is an electric ultralight, so he’s using a pair of ‘150 cc’ motors from HobbyKing. No, that’s not displacement, it’s just a replacement for a 150 cc gas engine. On a few YouTube Live streams, [Peter] did what was effectively a high-speed taxi test that got out of hand. It flew. Doing that at night was probably not the best idea, but we’re looking forward to the videos of the flight tests.

World’s Largest Telescope Stopped by LED

Earlier this year a simple indicator LED brought the Keck 1 telescope, a 370 tons mass, to a halting stop. How exactly did an LED do this? Simple: it did nothing.

As it so happens, [Andrew Cooper] was just about the leave the summit of Mauna Kea (in Hawaii) when his radio instructed him otherwise: there was an issue. Upon returning, [Andrew] was met by a room of scientists and summit supervisors. “Yeah, this was not good, why are they all looking at me? Oh, h%#*!” The rotor wasn’t moving the telescope, and “no rotator equals no science data.” After being briefed on the problem, [Andrew] got to work. Was it a mechanical issue? No: manual mode worked quite fine, also indicating that the amplifiers and limit switches are functional as well.

Jumping from chip to chip, [Andrew] came across an odd voltage: 9.36V. In the CMOS [Andrew] was investigating, this voltage should have High (15V) or Low (0v) and nowhere in between. Judging by the 9.36V [Andrew] decided to replace the driving IC. One DS3632 later, nothing had changed. Well, maybe is one of the loads pulling the line low? With only two choices, [Andrew] eliminated that possibility quickly. Likely feeling as if he was running out of proverbial rope, [Andrew] remembered something important: “the DS3236 driving this circuit is an open collector output, it needs a pull-up to go high.”

Reviewing the schematic, [Andrew] identified the DS3236’s pull-up: an LED and its current limiting resistor. While the carbon composition resistor was “armageddon proof,” [Andrew] was suspicious of the LED. “Nick, can you get me a 5k resistor from the lab?” Hold the resistor on the pins of the chip and the amplifiers immediately enabled.

[Andrew] summarizes things quite well: “yes
 One of the world’s largest telescopes, 370 tons of steel and glass, was brought to a halt because of a bad indicator LED”. It stopped things by doing nothing, or rather, by not turning on.

We love it when we get troubleshooting stories, and if you share our interest in problem-solving, check out this broken power supply troubleshooting or learn what could go wrong with I2C.

Edit: Keck 1 is one of the largest optical telescopes in the world. Thanks to [Josh] for noticing our error.

Embiggen your Eclipse 2017 Experience with a Sun Funnel

As exciting as Eclipse 2017 is going to be this Monday, for some folks it might appear a bit — underwhelming. Our star only occupies about half a degree of the sky, and looking at the partial phase with eclipse glasses might leave you yearning for a bigger image. If that’s you, you’ll need to build a sun funnel for super-sized eclipse fun.

[Grady] at Practical Engineering is not going to be lucky enough to be within the path of totality, but he is going to be watching the eclipse with a bunch of school kids. Rather than just outfitting his telescope with a filter and having the kids queue up for a quick peek, he built what amounts to a projection screen for the telescope’s eyepiece. It’s just a long funnel, and while [Grady] chose aluminum and rivets, almost any light, stiff material will do. He provides a formula for figuring out how long the funnel needs to be for your scope, along with plans for laying out the funnel. We have to take exception with his choice of screen material — it seems like the texture of the translucent shower curtain might interfere with the image a bit. But still, the results look pretty good in the video below.

Eclipse 2017 is almost here! How are you planning to enjoy this celestial alignment? By proving Einstein right? By studying radio propagation changes? Or just by wearing a box on your head? Sound off in the comments.

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Eclipse 2017: Was Einstein Right?

While most people who make the trek to the path of totality for the Great American Eclipse next week will fix their gazes skyward as the heavenly spectacle unfolds, we suspect many will attempt to post a duck-face selfie with the eclipsed sun in the background. But at least one man will be feverishly tending to an experiment.

On a lonely hilltop in Wyoming, Dr. Don Bruns will be attempting to replicate a famous experiment. If he succeeds, not only will he have pulled off something that’s only been done twice before, he’ll provide yet more evidence that Einstein was right.

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Best Product Entry: Telescope Control With RDuinoScope

The Hackaday Prize is more than just giving tens of thousands of dollars to hardware hackers. It’s also about funding the next batch of Open Source hardware products. Alongside The Hackaday Prize — the contest where we’re funding hardware that will change the world, — we’re also giving away $30,000 to the project that will best become a product. It’s almost like we’re funding hardware startups here.

[Dessislav Gouzgounov] wanted to build a small piece of hardware — a GoTo for his telescope. This handheld controller would allow him to use software to align the telescope with whatever celestial body he’s checking out.

Many GoTos simply interface with a laptop, but [Dessislav] built a standalone system centered around an Arduino Due and 240×400 touch screen, with GPS, RTC, and Bluetooth under the hood. It works on both hemispheres and contains a database of 250 celestial objects, features different speeds for time-delayed tracking of celestial, lunar, and solar phenomena, and it can work with any stepper-equipped telescope.

We covered [Dessislav]’s previous version of the RDuinoScope, but he’s improved the project considerably with over 2,400 lines of code including a new menu system and added a star atlas showing the location of the sky at which the telescope is currently pointed, among other improvements. The project is open source and you can learn more about it on [Dessislav]’s project page or check out his code on GitHub.

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