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Starting summers observatory project


Magnus_e
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Hi.

Finally it's time to start a project i have been planning for a while. My remote Linux - INDI observatory :hello2:

Some info about the project. The observatory is going to be box style. I don't do any visual stuff, so i wont make room for myself. It is going to sit on a south facing second story balcony at my parents place. It's by a fjord near Drammen, Norway, so almost everything southbound is water and zero light pollution. The house itself sits on a spot with mostly green and yellow on the LP map, so beats my apartment where there is dark red LP as far as the eye can see (sadly)..

 

To start things off, I'm building the pillar. As it's on a balcony, there will be no way to dig and cast a base in concrete. However concrete (b30) will be used to make the pillar more substantial. I want it to be very rigid, and I guess by having some weight to it, some flex in the floor will be "pre flexed".

Any project starts with a good drawing :) so here is some cad. The outer tube is a cardboard casting tube. It sits on a wood plate with a total thickness of about 3.6 cm, has four m20 threaded rods that will be casted in with four 50x35 cm steel angels for stability. On top there is three steel plates connecting the base to three m20 bolts with mounts for the celestron avx. I will use the celestron's plate from the tripod (removing the legs) on top to mount the head on. The gap between plate one and two from the top is to be able to adjust and level the mount. I will have to get the three plates and three blocks on the right fabricated, but hopefully at a acceptable prize, hopefully...

This weekend was mostly drawing, but did get something started.

Let me know what you think about the design. More to come as project progresses...

Pilar-v1-with-parts.jpgPilar-v1-no-tube.jpg

DSC_0130.JPGDSC_0129.JPG

Edited by Magnus_e
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  • 4 weeks later...

Some progress at last :)

Just finished casting my pillar in b30 concrete.

The round plate on top is just a template for my drilling. Figured it was smart to leave it on while the concrete sets, so my threaded rods stays aligned.

DSC_0160.JPGDSC_0164.JPGDSC_0163.JPGDSC_0166.JPG

 

Not sure how long it will take to set. Does anyone know?

 

Have also come along on the observatory design. It's about 120x150x120 cm, so will fit nicely on the balcony.

Made the backside a double wall so i can house all the electronics, and have remembered to plan for air vents. Made everything as components i Sketchup, so i can use it as a builders manual.

Observatory-v1.2.jpg

Observatory-v1.2-no-parts1.jpg

Observatory-v1.2-no-parts2.jpg

Observatory-v1.2-no-parts-closed.jpg

Does llok like i have something to do on rainy days this summer :)

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Thanks for the kind comment Jim.

I don't want to use WiFi, and i am reluctant to drill a hole in the wall for TP cable, so i think i'm going to use a Powerline network.

The ones from Netgear looks to be the best ones. The Netgear Powerline 1200 has a theoretical max bandwidth of 1200 Mbs.

From what i read there are somethings that reduce the practical bandwidth, but i think it will be more than fast enough.

The Obsy location has 300/300Mbs fiberwire SDSL, and my home has 75/15Mbs ADSL, so remote connection should be OK :)

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Magnus, by coincidence I'm looking to install a similar Powerline adapter in my own obsy. I haven't yet installed any permanent electrical power or data cables (my job for the summer holidays).  However as part of my security measures I bought a IP security camera, only to find the obsy is just out reach of my home Wifi, the Powerlink should solve the problem hopefully.  What are your winter temperatures like, will you get away with insulating the box or do you think there may be a need for a small heater or humidifier to fight off any condensation?  I don't use any heating or dehumidifier myself, but I have a lot of fresh air circulating in my roll-off obsy, its been up for just over a year and so far no major problem with condensation.   What about the initial alignment once you have the scope installed, do you have the space for the usual polar scope alignment by eye or do you another method in mind?

 

Jim

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My winter temperatures are low. Often in -10 / 15 C range, and sometimes lower :help:

It's also a lot of humidity in my location, it's by a fjord leading out to the ocean. My plan so far is 100mm air vents with a vent fan. It will be on always to circulate fresh air.

I will also use (don't know name) blue dense styrofoame plates inside of the framing, and some water proof sheet between the framing and panel.

I also have dew heaters for main optics, field flatener and guide scope.

 

Initial polar alignment will be done with a old fashion magnetic compass and a bubbleleveler. Then i have a red dot sight attached to the scopes clamshells. I have used it with great result this winter to find the alignment stars.

It will be difficult to get a view trough the sight with the scope in the box, but by selecting stars near the horizon for PA i will manage to get a good enough view to find a couple of them, i hope.

Ekos have built in plate solving with astronomy.net so finding stars is no issue, the issue is when doing polar alignment. When aligning to a star the scope moves to where the star should be and i have to find it. If i remember correctly Ekos gives the PA error in angels by using the plate solver, so i get some help.

A couple months ago i pointed my scope on the wrong star to test, and Ekos alignment module iterative moved my scope ~15 deg RA to the correct star using the astrometry solver :)

 

Here's a picture from a cold humid night this winter. Thankfully the mount does survive some moisture.

DSC_0013.jpg

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I struggled with powerline adaptors, kept unpairing and that was after I researched for the best adaptors for my situation,  working at a 40 metre distance. I eventually hardwired with cat6 and haven't had an issue since. 

Steve

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Thanks for the heads up Steve.

I will check what is the best distance for powerline adaptors. As my obsy will sit on the balcony and the switch i will be connecting to is in the room that opens out to it, i will only have a distance of about 5 meter between the two adaptors. (Assuming it's the same circuit indoors and outside.) Will have to double check that.

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So, no progress for a while. I hit a snag when it came to the custom parts for the pier.

The first mechanical workshop i contacted, have not managed to give me a quote for the price of the parts in over a month. Contacted another CNC shop. They were polite and fast to answer, but then there was the price!! For the three plates with various unthreaded holes, and three blocks with threaded m20 holes they wanted 377 - 460 GBP! They also wanted 42 GBP for retracing my drawings so they would work in the CNC. I could not risk paying ~500 GBP for those parts, so change of plans.

Ended up ordering from Dan's Pier Top Plates :icon_biggrin: . Ordered the 8" version. It originally has 3 holes to connect to the pier and 3 threaded holes to connect to the Celestron AVX adapter. He customized it to a 4x4 pattern to fit my pier for ~20 GBP, and it all ended on 270 GBP shipping included. I do have to pay taxes when it arrives, but its a huge prize difference, and i think i will end up with a better result. I also don't have to use the connecting plate from my AVX's tripod, so i can use it if i want to pick everything up and go on a road trip.

 

Of course i had to check in sketchup that i will still get the required height.

Pier-8in-top-plate.pngPier-8in-top-plate1.png

 

Next is mount my equipment on the tripod and make a mock-up observatory. Don't want to risk building it and find out i have clearance issues.

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Are you talking about the four threaded rods? If so, they are 4x 20mm rods that passes trough the pier and attaches on the underside of the base.

The plates attaches like this. http://www.pierplates.com/image/Index 2.JPG

Not sure what you mean about weakness? Are you thinking about vibrations, or structural. I'm quite shure it will hold the weight, and they are werry solid as they are casted in to the pier.

Also, the center pin to attach the AVX needs a minimum gap of 2.5". Preferably 4" according to spesifications. The gap i need to get my required heigth is about 3,25". I could add something to stiffen it up, not sure what thoug?

Edited by Magnus_e
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I'm thinking vibration mainly. From your sketch it looks like you've 4 studs from the pier to an intermediate plate then another 3 or 4 studs to the top plate, all of which can vibrate, and the intermediate plate can flex as well.

Can you at least cut out the intermediate plate and bolt the pier to to the pier with the shortest length of stud you can get away with?

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Hi. Thats correct.

I do need the intermedeate plate, as it connects to the top plate with 4 threaded 3/8" bolts. However they are encaptulated in 1" high aluminum sleves http://www.pierplates.com/products_8564.html The intermedeate plate is 1/2" thick aluminum, so doubt my 4" refractor will be able to flex it, even with camera and guider.

After your last post i mesured my pier again, and it seams like i will be able to cut down the struts, so the intermedeate plate will sit at it's minimum height of 2.5"

I'm feeling confident, but time will tell. Wont cut anything before i get the parts and everything is mesured twice. Hard to uncut something :)

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A little panorama 180° east -> west from observatory location to be. Had to document the nice summer weather :)

The powerlines is not pretty, but not a big issue for imaging. When the Orion nebula is on it's higest ark in the sky it hits the powerlines almost on the higest point, so it's mesured to 19° altetude. Not any point to image below 19° anyways.

DSC_0190.JPG

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  • 1 month later...

Summer progress can be a bit slow, but I'm still going on with my obsy plans, and changing them on the way.

 

Since my last post I have collected almost all of the remaining electronics, minus the linear actuators and a ventilation fan. I'll probably need a small heater to :)

After reading quite a few writeups i realized that the Netgear Powerline 1200 was not a particular good choice. It has a great theoretical bandwidth, but is outperformed by many others in real life testing. One of the better test I read was this http://www.techhive.com/article/2868314/home-networking/the-essential-guide-to-buying-a-homeplug-ethernet-adapter-including-6-hands-on-reviews.html On a shared first place was the Zyxel PLA5456 with a theoretical bandwidth of 2000mb/s and tested to 350mb/s (yes big difference!), it's one of the fastest out there. I tested it from my router and out to the observatory balcony and got a great connection. I also tested it from my router and down to the garage, and still stable connection. My Odroid and RasPi now lives in my parents garage being subjected to simulated imaging sessions :)

 

I also want to have a view of the obsy from my home, so I ordered a D-Link DSC-4701E outdoor IR camera. It can see in total darkness about 30 meters, and with the motion detection it doubles up as security. With the configurable events it now sends me a mail with a 100sec movie every time a motion is detected. When the obsy is tested 100% and working, and I start using the EKOS scheduler, it will send me a mail when conditions is ok, and the roof opens. http://www.dlink.com/uk/en/support/product/dcs-4701e-hd-outdoor-mini-bullet-camera

 

By friday I will collect my order from my local buiders shop and start building the frame for the obsy, and I have got confirmation that my Pier Plates will be shipped late this week. Just have to decide on linear actuators. Will have to consult my CAD to see what stroke length will work, but think it will be one of these. https://gimsonrobotics.co.uk/categories/linear-actuators/products/gla600-s-12v-dc-long-stroke-linear-actuator Scrolled trough @Gonzo post about building the unmanned pico observatory to see where he got is actuators. I have got a lot of inspiration from (ripped off) that build :)

 

The pier is at least spackled and spraypainted matt black.

DSC_0219.JPGDSC_0223.JPG

Edited by Magnus_e
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  • 2 weeks later...

Hi. Probably should not post three post in a row, but I hope you'll forgive me :)

 

So no my project is in full momentum, gaining some progress every day.

I started out building to the drawings, but soon saw that it was slightly bigger than I imagined. Did some more measuring , and removed a few eye-balled safety margins. I also made the room for the electronics shorter. So I managed to save 22cm in the depth of the obsy and 12cm in width. As it is now, it spans a area of 122cm x 137cm.

The next thing on the // TODO list is to build the framework for the roof, and figure out how to mount the linear actuators. The ones i got is 505 mm when closed and 905mm when fully opened. So what should I consider when mounting them? Should I mount them as high as possible in the obsy, and as far out as possible on the roof, so the the roof mount point is as far away from the hinges as possible? Or should I mount them so they do more of a lifting rather than pushing action? I also have to mount them so the roof is fully closed when the actuators it fully closed, and the roof at it's highest when the actuators are fully opened. (the actuators have cut offs in fully opened and closed position, so I can use that to avoid binding) Any ideas on how to estimate the mount points easiest? I could use paper and a ruler to test gestimates, but there should be a better way?

 

Some pics of the build so far.

DSC_0256.JPGDSC_0257.JPG

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That's a very competent design Magnus. Will follow this thread with interest.

I'm part way through building a remotely operated observatory myself. May I ask a few things:

What does "INDI" mean in your opening post? & How exactly will you be performing precise accurate polar alignment; I assume you'll need to still be present twiddling alt. and az. knobs? That "Ekos" sounds interesting what is it exactly (I am not very clued up about the software side of things!).

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Hi. And thanks for the nice coment :)

INDI is a protocol for device drivers. It comes with drivers for a lot of astronomical equipment, and there's even a lot of 3rd party drivers. I have made two drivers i will be using myself, as it's open sourced and well documented http://github.com/magnue

As for EKOS it is a client software for indi, with an imaging module, a module for alignment (using plate solving), a guide module, and more.

The alignment module is one of the nicest parts. As it uses plate soling to find your polar alignment error, it will also give you the error in degrees. So it's possible to (with some patience) move the alt az knobs, and iterative re run the plate solving until there are no alignment error. The same alignment module is also used when slewing to a target. It slews, then platesolve, then slews until it's dead on target. I actually tested It late spring. I just assemeled my mount, using a phone compass as alignment, used quick align, and slewed to target. I was about 15deg off target, but the alignment module got me on target after a couple iterations.

Check out the INDI forum http://www.indilib.org/forum/general/210-howto-building-latest-libindi-ekos.html

The maintainer of INDI also has a youtube cannel, with a lot of demos using INDI and EKOS https://www.youtube.com/user/QAstronomy/feed

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So after changing my design a bit, whit the obsy being larger than i expected, and the roof looking like it would end up being unnecessary heavy I have been updating my cad.

Before I try to make the roof lighter I want to wrap my head around some geometry. The issue I'm having is probably obvious, but I thought i would ask.

At the moment when I attach the actuators in it's current location, the stoke length is about 6cm to long for when the roof is fully opened. The driver I will be using has the possibility to calibrate travel, so it's not a huge issue, I just wonder if I move the mounting location, can I manage to get the roof closed at 0% travel and fully opened at 100% ? It does sound obvious that the stroke length will be 6cm to long no matter where I mount them? Does it not? Or wold mounting them higher or lower help?

 

Images to show what I mean.

Observatory-v1.3-lin1.pngObservatory-v1.3-lin2.pngObservatory-v1.3-lin3.png

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Well, to answer my own questions none of my assumptions where correct. It does matter if it's mounted high or low. After some doodeling on paper with proper tools, testing the edge cases (and the middle). It seems like mouting the actuators so it starts out in a 45deg angle gives the best "fit". In this config the 100% stroke is only about a cm to long. I'll use the limits in the driver to avoid binding.

Time after time i learn that I'm not to assume anything, not cut out for that :) Thankfully I can test my assumptions, and disproove them.

 

Sent from my phone with no spellcheck, so apologize for my english.

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So just because I like posting progress especially images, here is some progress from this weekend.

On friday i finished the pier, added the 2x4" to mount the linear actuators, and the separator plate between the electroniks and the scope 'bay'.

Today I finished the framing of the roof and started cutting out some isolation '3cm thick styrofoam'. Got the mountings for the actuators finished on the right side of the roof, but a miss calculation left me an inch short of 2x4".

Jim, hopefully I will start wiring and testing my servers sometime next weekend. I have tested everything in simulated imaging with the AVX and the roof / power relays, and have one image imaged with indiserver and my equipment so hopefully everything will work :)

 

So first image is the scope in park position. When parked it will point at alt / az 181 / 1. I made the pier tall enough so the scope will have unobscured view to the horizon. By moving my red dot finder to the other side of the scope I will be able to use it on most of the stars S -> W, making the initial polar alignment easier.

DSC_0275.JPGDSC_0279.JPGDSC_0284.JPGDSC_0286.JPGDSC_0287.JPG

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  • 2 weeks later...

Finally 'alive'. Wiring is all done and I'm testing the drivers.

My home built indi roof driver is working as expected. Had a issue with parking the AVX, but the mount works, and I can power on / off camera, mount and dew heaters.

Managed to get most of the wires in a wire collector, and oriented so it will not bind in any way. All that's left is to test with the roof on, add water resistant film to the outside and add panel. Will also have to figure out how to make some inspection hatches in the panel for the electronics. Anyone know what I can use as a hatch that will be water proof, and attachable to the outside panel? Have not figured out what I can use yet. The only unknown left.

 

Made a little video of the scope slewing to the park position, and the 'unattached' roof closing.

 

 

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