Help with initial observatory considerations

[MultumInParvo]

Hi All,

I am new to astronomy but have been reading here and elsewhere for a few months and have got some great input that has led to some solid purchases so far (SW ED80, Atik mono CCD, ST80/Atik guider on an NEQ6), and hope I can get some good pointers to set me on the path planning and then building my observatory.

I need to have a permanent place to site this as my work often restricts my available time so want to do what I can to maximise time observing.

For now I am getting familiar with everything and observing visually (jaw agape and/or giggling as all newbies do, surely), but time will come when I would like to be able to image from the warm, or even further away as I am regularly based elsewhere, so want to start thinking about this well in advance.

I have quite a bit of land around me so have many options to site the observatory, but many trees surrounding many of these areas, and whilst I have scoured this DIY Observatory thread, but still have some basic questions that perhaps could become a Stickie for new folks like me, but I'd be just as happy if someone said "buy this book" or "call this person":

1. What are the basic considerations for the observatory beyond a watertight structure, a stable base for the pier, power and network/internet access?
2. Given I'd be killed if I put the observatory in the middle of our field (not to mention it might attract unwanted attention) if I had to choose bits of sky with unobstructed views, which would these be? i.e. unobstructed view of Polaris for alignment plus clear skies from 090 to 180 degrees from at least 20 degrees above the horizon and get what you can with the rest? I have tried to get perspective on what I can see by using Sky Safari, but being so new I don't know what I'll be missing by making the site choices as the year rolls by
3. It seems to me that imaging observatories can be small, but given I might want something like a 200mm (or larger!) Newt in there, is there a way of estimating the optimal size of "cold" room?
4. One for the Architects perhaps - I see pictures of observatories on platforms attached to buildings, large balconies if you like, how would I give my telescope the necessary stability? i.e. if the platform overhung the edge of the brick side wall, should I bolt the pier to the wall and have it rise through the platform?

I have quite a few pictures I have taken of my site that I can share to help me see i9f I am thinking on the right lines, but I do think I have found an optimal location that shouldn't ruffle too many feathers.

Ironically, it's adding a retractable roof dormer on the back of my Garage (just to the NE of the house), over the top of our chicken coop, which I made out of a shed that would have been great for an observatory!

Pictures from google maps so oriented North, first is the whole site, second is the area with easy access to power and network, note all the trees and tall bushes everywhere:

Thanks in advance for your input,

Ian

Edited June 26, 2018 by MultumInParvo

[laser_jock99]

A good, clear southern horizon is the main requirement.

[pmlogg]

Ian

It sounds as if you have put quite a lot thought into it already.  When I was planning mine I read David Arditti's book 'Setting up a Small Observatory: From Concept to Construction'.  It covers both dome and roll on roll off.  I found several good pointers.  One was to not make it too small - got to be able to get around the back of the telescope no matter what imagers etc. are fitted to it, without tripping over any features or items you might store in the observatory.  Another was to have more power sockets than you think you will need.  How to get power in has been discussed by a lot of threads but with your property being large it might be a limiting factor for you.

One mistake I made was to not make the pier quite high enough so that the imager was at risk of striking the little top surface I'd built around it.  That was made worse when I upgraded to a longer refractor.  I've now made an extension but it's not as solid as the original pier - my next DIY task to resolve that!

[tobblerone]

On the #2 question I agree that the south view is most important. A view of Polaris isnt nessesary at all but makes things easier. At the same time, you wont have to polar align that often with a permanent setup hopefully ☺️ Most of that is visible north will sooner or later be visible in the south as well but not the other way around. (Please correct my if my thinking is incorrect here). Of course it depends on how dark your skies are at summer, mine arent dark at all (57 degrees north, Sweden). I prioritized east and south views when deciding on where to put my future observatory. 

Will take a few years before I can evaluate if I made te right move ?

[MultumInParvo]

@laser_jock99 - My chosen vantage point should give me this, although some will be obscured.  Will make some  observations on field of view and angles above the horizon and report back to see if anyone has any thoughts

@pmlogg - I do try to think things through in advance, but ignorance and over-enthusiasm sometimes get the better of me... The book is ordered.  The second image is of the area that has easy (ish) access to power and network connectivity, with power and hardline network connections at my garage and workshop, the two most sensible places for siting things, I'm hoping I'll be ok.   I have noted the point about forward thinking and the pier height, now I just need to imagine how bad my aperture fever will get once astronomy has well and truly got under my skin.

@tobblerone - It's pretty dark here, not an official Dark Skies dark, but I can clearly see the Milky Way with the naked eye, so I'm hopeful.  Swedish summer has other good things though, the crayfish and vodka don't just consume themselves!

[Owmuchonomy]

Tips from my point of view,

1. You don’t need a view of Polaris so choose a good southern aspect

2. Don’t seal it up or put it directly on a concrete base otherwise you will be plagued by damp.

3. Measure carefully and thoroughly your set up view for wall clearance. I did this twice and still fell short on pier height which is now remedied.

4. Make it big enough for visitors. My cold room is 8ft square which is good for 4 people

[MultumInParvo]

@Owmuchonomy - good points, noted.  On point 2, I think I have seen people putting a polystyrene isolation band between the mount concrete and the rest of the slab, is this what you mean, or should I be looking at proper DPC type measures?  I did this when laying the base for my workshop and have not had any damp issues.

I think my difficulty is in knowing what a "good southern aspect" is, as my daft analyst brain shouts "its 091 to 269, horizon to zenith", which I know is tosh but inexperience is stopping me from knowing what level of limitations I accept versus changing the site to somewhere less convenient or less secure.

This is a proper First World problem this one, I have too much bloody choice to make a decision!

I seem to think I read that the first 20 degrees from the horizon are not much cop, so perhaps that can be one parameter to rule out locations, and I am guessing that another one could be "you need an arc of sky of at least X degrees to have enough exposure/capture time to image most DSOs".

Any input on this would be good and then I'll walk about and try to divine what I can see.

Would pictures from selected points help in advising me?

[Owmuchonomy]

In my experience the only sure way to keep things dry is raise the floor off the concrete base. Mine is 150mm which is highly recommended. In this way I get good circulation of air.

[pete_l]

As regards obstructed views, one thing to take into account is light pollution. If you have the option, losing sight of the most "orange" segment of sky will lose you the least.
I wouldn't be too concerned with losing sky beneath Polaris: everything that is under it will rotate around to be above (i.e. higher in the sky) at other times of the year.

One other thing you may care to consider is bats! They are a protected species and you are not allowed to disturb their breeding sites and habitats. It would be unfortunate if you were unable to use your observatory because some made their home there. It would also be worth looking at ways to discourage other wildlife (incl. wasps, ants and other insects) from taking up residence in your observatory - or even inside your kit. In the winter it would offer a nice, sheltered, cosy, environment, And some plastic insulation can be quite tasty (so I'm told) - especially for mice. Birds, too, might find it an attractive place to nest!

[pmlogg]

On flooring I used normal decking on a base of 2x4s.  The flooring has gaps of around 5mm for ventilation which has only once resulted in me loosing anything but I have put a thin matt covering part, I can move it if doing anything where something might fall and be lost.  The wood flooring always feels relatively warm, never cold like standing on concrete and I suspect better than rubber - but not as quiet.  I have one decking board hinged so that I can easily get at the cabling underneath (another reason for raised flooring).

My dehumidifier is controlled by an 'Inkbird' humidistat/thermostat (an recent upgrade from a simple timer). The dehumidifier has a pipe to drain outside. That normally works fine but sometimes the tank has filled, stopping the dehumidifier until it's cleared.  I did once have a dim-witted slug think the pipe was a good place to hide - had to flush it out with water, so now I try to make sure the pipe end doesn't touch the ground.  As the observatory is a dome there is natural ventilation between the fixed and rotating parts.  In 7 years never had a serious damp problem.

On wildlife I've not had anything trying to set up home other than a few spiders an occasional, lost slug. The door is a neat seal but not slug proof. The fiberglass walls are a bit slick for mice etc. to climb but slugs can manage that too!  We do have bats in the area which I like to watch but I think they would favour a roost a lot higher than my dome.  We get a lot of birds in our garden, with feeders right beside the dome. The wood pigeons like to perch on top and sometimes do what birds do; none have attempted to enter.

[nightvision]

Outdoor and obsy cabling considerations: Pipes can really attract slugs, had a motor control unit burnt out by a slug that thought a buried electrical conduit a good route to somewhere nice and warm.  It started a fire on the pcb where the mains transformer was mounted.  Now all conduit/cabling pipes are sealed with silicone. 

Edited July 5, 2018 by nightvision

[astronomer2002]

I have built quite a few observatories but never been lucky enough to have a large choice of where to put them.

The best place for an observatory is where it will cost you less grief from the family or intruders. Observatories that are a long trek from your house will get less use than those you can get to easily. Power is pretty much essential to run equipment and heaters to keep the observatory dry and unfrozen in winter. I have lost many a clear night when the domes have been frozen up. Having heating over winter also means your eyepieces won't mist up when you touch them. Of course, heating is intended to be on when you are not using the observatory!

I have built both run-off sheds and domes and it is my opinion domes offer the best protection for observing in this country. They shield the telescope and user from both wind and external lights which plague most of us in suburbia.

As mentioned here - size matters! Build the biggest you can as equipment grows in size at an alarming rate.

I once built a tiny flip-top shed (4.5ft square) to cover what I intended to use as a remotely controlled telescope. The trouble was that to try and check alignment of the optical train and to sort out why the goto wasn't going to required uncomfortable contortions and often working from outside the structure.  The result was I rarely used it and eventually replaced it with a small 2.2m dome. 

If there is any light pollution in your area it is better to make sure your observatory has good access to the darkest part of the sky. Clear southern sky is the best option, of course, but access to the darkest part of the sky if that is in the east or west will mean you can get the most out of your scopes even if you have to wait for objects to rotate into that part of the sky.  Also bear in mind any trees that are not under your control. Trees have a habit of growing very, very large! I have multiple observatories to try and get round obstacles I cannot remove (that's my excuse anyway).

Ian B

[MultumInParvo]

After quite a lay-off due to work and health conspiring against me, I'm back on with the build...

Taking into account your responses, I have selected a spot right in front of my workshop, even though this has one tree that is due south from me that is not in my control.

I'm aware I might be overthinking this, but have taken three panoramas and added some info on tree heights and compass points to get your input before I break ground for the pier:

Position A - easiest location 

I assume the trees at 20-ish degrees above the horizon aren't critical, but as I change position, just by a few metres the tree at 180 blocked much more sky.

Position B - right in front of one set of doors, but I can use others:

Wider field of view

Position C - right at the end of the workshop:

Widest field of view, but if I make the enclosure the 2m square i'd like, I'll encroach on the area at the side, which might be unpopular.

I do think this is the right place, but my compromise might be that I have a width of between 1.2m and 1.6m to play with without seeking marital planning permission, which we all know is hard to get and costs a lot...

Thinking ahead, if I wanted to put a larger scope in a 1.6m area, does anyone have experience of what the largest could be?  Could I assume if I won the lottery and bought an Esprit 150 I could fit it in?  My thought for now is i will only be using a refractor as I am away so often that this must be by nature a remote obsy, so regular attendance other than at weekends is pretty much out for any tweaking or adjusting.

As to height, I'm thinking of the walls being 2.4m high as with the workshop, which with a 1.6m/1.8m-ish pier should help shield me from some light pollution from the southeast, i.e. I will calculate the height to exclude the 1st 20-ish degrees from my horizon.

Perhaps I am missing a point here, as most pictures I see have the OTA in home position just below the top of the walls, but this shielding of the first 20 degrees above the horizon seems sensible to me.

All final thoughts appreciated here, and then I'll start a build thread..

Cheers,

Ian

 

Edited June 9, 2019 by MultumInParvo

[JeremyS]

11 minutes ago, MultumInParvo said:

I'm aware I might be overthinking this, but have taken three panoramas and added some info on tree heights and compass points to get your input before I break ground for the pier:

I'd always try and go for the widest field of view, which looks to be position C.