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dmahon

Pulsar Observatories 2.2m Dome and Shelyak Dome Tracker

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Like many of us, I was a little bit peeved at the time it takes to move about 50-100Kg of kit, set it up, make all the electrical connections, polar align, calibrate the GOTO system and fix anything that has gone wrong (it always does) prior to starting out a session - and that's if it's still clear. And then there's the packing it away again at the end of the night. It was such a chore that unless the forecast was clear all night long I tended not to bother.

To make my hobby enjoyable again, I needed an observatory. There are a number of options:

1) Roll-off roof

2) Roll-off shed

3) Clamshell

4) Dome

These all have their pros and cons. 1 & 2 are cheap, but need additional garden space to roll them off. The way my garden was set up, and the location I wanted the observatory, meant that I discounted them. The only clamshell easily available in the UK is the SkyPod, and whilst I considered it for some time, I finally got put off by the trouble imaging straight up and the reports of leaks. So that left a dome. The problem with a dome is that they are expensive - and for imaging they need automating (even more expensive). Still, that seemed like the best solution for me. In The UK, the dome that is most easily available is the one from Pulsar observatories. It is available in 2.2 and 2.7m sizes and can be made in white or green (possibly other colours too, white and green are the only ones I have seen). I had seen a dome at a fellow astronomers house - and he had successfully motorized it which meant that I could follow his plans. I'm, OK at tinkering with things, and can actually even be good at it, but for expediencies sake I'd rather get something off the shelf and I'd be rather upset if I found that I couldn't motorize it as I wouldn't be able to image which is my only interest in the hobby. So when Pulsar adjusted their design (see later) and made a fully motorised observatory "off the shelf" an option I decided to go for it. I bought a dome, dome controller, shutter controller and a Shelyak Dome Tracker.

Pulsar 2.2m Dome Oberservatory

Shelyak Dome Tracker

dome.jpg

rotator.jpg

shutter.jpg

shelyak.jpg

I took a while building the base in my garden - there's a separate thread for that. It needs at least a 2.4m circular or square concrete slab. I went the circular route as it's much harder to build. They suggest a 1m square base for the pier, but I decided 75cm would be more than enough.

base.jpg

I made a £500 deposit by credit card (for the protection it offers) and then the rest was paid by bank transfer 3 months later when the dome was ready to deliver. Unfortunately they are built in Norwich and I live in Somerset, so there was a hefty delivery charge. They also offer to assemble everything for a small fee and given that I was into this for quite a sum already, I thought I may as well ensure it got set up properly. I bought an Astro Engineering pier from them too. On the appointed day the guys from Pulsar arrived and set about work, fortunately in good weather. They were finished by mid-afternoon and showed me how the observatory worked - as well as installing up the basic Shelyak Dome Tracker software on my PC. Unfortunately we hit a bit of a snag here, as it wouldn't work! I got a second laptop out, and fortunately it did work on that - but when I checked it again a few hours later after they had gone, it didn't work anymore. Time to pull my hair out! To cut a long story short, I had email communication with the guys from Shelyak and Pulsar over the next 24 hours - they identified a problem with a component not working properly at low temperatures (a December install) and they sent me a new unit. They also wrote a new driver, which meant that the faulty component wouldn't cause trouble anymore anyway. Good service.

When I finally got permanent electricity installed to my observatory, I set up my kit properly. The dome moves by two motorised wheels (blue) pressing on the side of the dome. These are powered by a 12v 10a transformer. There is another wheel (the grey one) which is attached to a rotary encoder so the dome knows how far it has travelled. The "home" position is set by a metallic sensor - mine is at 290 degrees. You can see it in between the IR sensors below - it's just a bit of tin foil.  When the dome is told to home itself, it rotates until it finds the home sensor and then sets its internal position to 290. From there on, it counts clockwise and anticlockwise motion via the rotary encoder. In addition to the computer control, the dome can be set to track at sidereal rate (or various fractions/multiples thereof - remember, the dome isn't equatorially mounted) if you didn't want to use a computer. The Shelyak unit is nicely hidden away behind the dome controller metalwork too. It connects to the computer via RS232, but they throw in a USB-RS232 cable in case you need one.

The shutter mechanism is attached to the dome part which makes getting power to it more difficult. The solution that Pulsar have come up with is a 12V battery and a solar panel. To send signals from the Shelyak Dome Tracker, they have utilised an IR connection. The open/close shutter will thus only work when the dome is at the home position, as this is when the IR sensors are aligned. It closes the shutter by means of a chain and sprocket. There is a manual open/close button in addition to the computer control.

wheels.jpg

irsensor.jpg

To get the dome automated you need to enter a few details, such as the size of the observatory, the number of steps for a full revolution, the position of the pier how high the centre of the scope is above the rotation axis of the mount.

domesetup.jpg

After that, it's plain sailing - rather than use the normal ASCOM driver for the mount, you use the ASCOM Dome Control driver instead (comes with ASCOM) - which itself connects to the dome and to the mount. You slave the dome to the mount and then when you issue slew commands, it moves both the dome and the mount to the right position and keeps them there throughout the night.

domecontrol.jpg

And this is it in action:

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Nice Dome and video, is there some kind of sensor for when it starts to rain and how quickly can it close if it does rain.

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Nice Dome and video, is there some kind of sensor for when it starts to rain and how quickly can it close if it does rain.

The video is real time - it closes at one speed only. I haven't counted, but it's about 10 seconds.

There is an "emergency" input on the Shelyak Dome Tracker. This can be linked to a weather station or rain sensor (or even a big red button). If activated, a signal would be sent to close the shutter. HOWEVER, the way that the shutter controller is wired up by Pulsar means that it will only close if it is in the home position (which is rather unlikely).

I may look into changing the standard pulsar IR wiring for some kind of wireless affair, so that the dome could be made to open/close at any point of rotation.

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The only modification I have made to the standard setup so far is the addition of non-slip tape.


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Hi, I am just about to start this process, dome bought, not bought automation yet, trying to justify, but interested in your thread. However, you state that there is a thread showing your base build but I can't find it. I would be very interested in viewing it as I haven't made up my mind circular or square. Could you possibly send me the thread? Thanks

Regards

mike

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Sorry - just found this but see you found the thread already. Good luck with your build.

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Hi David,

Just a bit of information for you David, indeed all out there thinking of automating a Pulsar Dome. I have just about completed mine, all working, just about, but I did have problems with the shutter closing which Gary at Pulsar put down to the positional IR sensors, it wouldn't close on the computer or switch only by waving your hand in front of the sensor even when correctly  aligned in the Home position. To cut a long Pulsar have now binned the IR Sensors and have a radio link to the dome which means that the shutter can open and close anywhere in the 360 arc, no need to motor to the home position. I had my upgrade (possibly the first) fitted last week and it works like a dream, absolutely perfect operation; a good improvement to the automation installation.

regards

Mike

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"Jealousy is the shadow of greed"

Master Jedi Yoda

So I would just like to say I'm chuffed for you and may your rain sensor be redundant

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Hi David,

Just a bit of information for you David, indeed all out there thinking of automating a Pulsar Dome. I have just about completed mine, all working, just about, but I did have problems with the shutter closing which Gary at Pulsar put down to the positional IR sensors, it wouldn't close on the computer or switch only by waving your hand in front of the sensor even when correctly  aligned in the Home position. To cut a long Pulsar have now binned the IR Sensors and have a radio link to the dome which means that the shutter can open and close anywhere in the 360 arc, no need to motor to the home position. I had my upgrade (possibly the first) fitted last week and it works like a dream, absolutely perfect operation; a good improvement to the automation installation.

regards

Mike

Yes, I heard. I had a few problems with the IR sensors too, though I could usually get them to work on the second attempt if not the first. What helped was reducing the size of the metal "home" position foil. The other thing I noticed was that the shutter opened itself on occasion - especially when taking photographs with flash for these threads.

Anyway, Gary called me a month or two ago and told me about their plans - and offered me a free wireless upgrade, I think for helping talk someone else through their installation. I've been away so only got round to sending the units back to him this morning (I live a few hundred miles away, so mine is coming in the post rather than a personal installation). Glad to hear that it's much better. The other suggestion I had for him was some kind of spring mechanism on the little grey "counting" wheel to ensure it keeps good contact.

Hi .What would be the cost of

something like this.

Steve.

See http://www.pulsarobservatories.com/

(but about £6,000)

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This is a great thread. Very interesting. Thanks for the detailed account.

Olly

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Hi Dave, 

I guess I am lucky only living 20 miles down the road, Dave came to fit it, it cost me £100 including fitting which was OK, prhaps a bit miffed because the initial design did not work properly but anyway all sorted now. Dave, I have just statred a thread re setting up the synchronisation of the scope to dome, I do not know whether you have had any experience of my problem, perhaps you could have a look at it and comment if you have any ideas, as I said it is all working but not quite as advertised still nearly there. If ever we get a clear night here it will be sorted  :angel8:

Regards

Mike

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Well, I got the impression it was free anyway - although I'd be happy to pay a small amount (and will certainly offer to pay the postage, which is not inconsiderable).

You can see my settings above. Similar settings (different units) are also in the scopedome program itself (click setup on the same program that you click slave to scope).

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Sorry to bump this.  I have a 2.7m Pulsar dome which is motorised.  Bought it 5 years ago so the motor doesn't come with any encoder.  I presume I would need to change to motor if I wanted to link to the mount but I can usually get the dome rotation about right.  The biggest problem I have is that I can't do an automated meridian flip because the change in position of the scope after the flip means I'm imaging the inside of the dome.  Does this set up allow automated flips?  If it does then I might be looking at an upgrade!

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Yes, it does.

The dome design has changed though - the dome I have allows the motor to be fixed to the wall and AC driven wheels drive on the dome. The old design I believe has a battery powered motor fixed to the dome and the wheels drive on the wall.

You'd have to speak to Pulsar to see if it works with the old drive system. Don't see why not, but you'd have to have some kind of flying lead to the computer or wireless RS232 adapter.

I also now have the wireless shutter control.

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Martin

I have a 2.2m Pulsar dome which I've managed to motorise with an DIY Arduino, M542 Stepper Motor Controller and a Stepper motor  - it slaves to the mount and allows for auto flips. I'm just in the process of motorising the shutter.

If you want any details, PM me and I'll let you know the details.

Steve

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I have now also bought a second hand Polaris. I believe it is the older older model since there are wall flanges that prevent use of a driving wheel on the internal rim. To address this I am just replacing two of the support wheels with pulley wheels driven by a motor attached to the frame. It needs at least two pulleys wheels since not all support wheels are in contact. I may yet drive directly this way if I can't get even enough conta t and have to go sprung.

Positional control is via the magnetometer over rf to the dome, which requires a solar panel, a battery and a charge controller. No great shakes there. Motor control from robotelectronics.co.UK and pointing via POTH from ASCOM to address rates and flip. The primary issues I have found using this is that the battery must get enough charge during the day. Not always easy.

Mike

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that ascom driver had me puzzled, there are a few connection options, this hopefuly solves a few problems

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Hi,

I know this is a bit late for this posting but I have just purchased the Shelyak dome tracker system and  trying to install it into my Pulsar 2.2m dome.

At the moment I can't even get my Win10 computer to talk to the controller. I am using a USB - to - serial connector and have downloaded the software. However, I keep getting a message "drive error".

If anyone can help it would be very much appreciated.

Dave

 

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The Shelyak system is two generations ago of the Pulsar dome control system. It was followed by the excellent Lesvedome system before the current proprietary system was introduced.

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