Orion's Belt Remote Observatory

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Mayhill, NM .
 

Welcome to Orion's Belt Remote Observatory!

You are standing at the top of "Mintaka Hill" overlooking the valley to the South. East is left and West to the right. North is behind you.

We are in the Sacramento Mountains of Southern New Mexico on the edge of the Lincoln National Forest. 
 

Construction of Orion's Belt





Ground breaking at Mintaka Hill for Orion's Belt Observatory began in May of 2016.

I decided to go with a sliding roof design. Several reasons. First is that having a dome requires control of aperture rotation. Not easy to have that work consistently. Second is the advantage of being able to install more than 1 pier in a larger structure with a sliding roof. Finally is the appreciation of the night sky we are fortunate to have here and the fact that I will be physically present in the observatory more often than I will be operating it off site. The 2 disadvantages for those thinking about this is that you may be more exposed to wind and if you are operating the observatory remotely, your scope will have to park properly before the roof can close. This may be problematic if the observatory is trying to shut down because of weather and your scope can't park! 

Site Work , Piers and Foundation

View from the Hill to the Southeast
After researching several possible contractor sources we decided on Backyard Observatories. They have built several observatories here and everyone I spoke to has been very happy with their choice. It's a little different process though from other building projects you may have been involved with. They don't do everything from top to bottom. You are responsible for preparing the site and creating the foundation depending on which type of infrastructure you decide on. Either a deck type which requires a square cement footing with cinderblock or a cement slab. Several folks expressed some concern regarding their cement slabs creating a large heat sink which possibly can degrade seeing due to convection created in the observatory. Therefore we decided on a deck design. We went with the size of 15' 6" square of which 5' 6" x 15' 6" consists of warm room. This was felt to be more than sufficient. This will allow 2 piers to be placed roughly 5' apart.
The bedrock in the construction zone was down about 2 feet. These images show initial site work and creation of the forms for the footings. You can see the holes dug for the piers. The decking sits about 9 1/2" above the top of the cinderblock and the tops of the piers will need to be approximately level with that so the pier forms will seem to sit pretty high up.
The next step in the project was to figure out the location of true North. This was for the purpose of correctly postioning the pier bolts for the telescope pier. Much of this will depend on what mount and pier you decide to use. To clarify then, there are cement piers in the ground anchored to the bedrock and telescope piers that sit on top of the cement, usually bolted to it. For myself, I am a long time Software Bisque user and have set up permanent mounts before so that's what I use. The Bisque piers are steel piers of varying heights with a half inch base that has 4 slots in them for the bolts. These slots are 1 inch and do allow for +/- 5 degrees of azimuth correction to the pole if you are slightly off but the key is to align the bolt orientation as closely as possible to true north. The risk is that being significantly greater than 5 degrees off will make it impossible to polar align your mount! For true north alignment therefore I rely on Polaris. I would not recommend a compass as there are magnetic sources everywhere which will throw things off. 
For aligning the pier to the true north-south line I used a device called a theodolite. This is the yellow object in the image. It is commonly used by surveyors.  There is a 20x sight tube mounted on a calibrated altazimuth base. I align the base to the pier such that the site tube is parallel to the edges of the pier which are square and then tape the base down. Then I raise the sight tube in altitude to, in this case ,34 degrees which is the elevation of Polaris above the horizon for our lattitude. If Polaris is not visible I move the pier, not the theodolite in azimuth until Polaris is centered. Now the square edge of the pier marks the north-south line!
We can then stake out the north-south line the following day and run a line between the stakes parallel to the square edge of the pier (which has since been removed) to show more clearly the line (large arrow). Another method to mark the line can be done during the day when the Sun crosses the meridian. At the very moment of crossing the Sun will cast a shadow along the north-south line (small arrow). However, for this method to work, the stake has to be perfectly vertical. Even a slight deviation will give you an erroneous reading. I found this to be very difficult to reproduce consistently and for that reason abandoned that methodology.
Next we create the templates for the pier bolts. This is a 30" high steel Bisque pier. We set it on a plywood square that will be slightly larger than the dimensions of the actual wooden pier form so we can adjust the alignment to the north south line. You can see the curved slots in the pier base. We ream 4 holes centered in the slots and place the 4 J-bolts measuring 1/2 inch by 12 inches
Template completed! The blue tape marks the north south line. The circles indicate where conduits are to be embedded in the cement for electric and for data.
The pier forms are wooden squares. One is a 3 foot and the other a 2 foot. The forms go down close to 2 feet to the bedrock. The cement is anchored to the bedrock with rebar (left) that is drilled down into it. This is definitely more than adequate for amateur imaging! After all, we're not trying to discover gravitational waves (I don't think)! If there is an earthquake there might be some pier movement but otherwise I believe we will be OK. You can see that the templates are placed on top of the forms and oriented so they are parallel to the north -south line indicated by the blue tape and in the far right image you can see the white cord on the right indicating the north south line. The builders oriented the forms to that line. I fine tuned it again with yet another Polaris alignment just before they poured the cement. I had to rotate the template just a few degrees! The conduit circle cut-outs are also seen in the templates.
On the left you can see the 2 forms prior to cement pouring with the templates in position. The north south thread is also faintly visible in the foreground. Center and right images are after pouring and placement of the cinderblock. The conduits are now seen exiting the piers to the north toward the warmroom
Cinderblock completed including J bolts for the frame. On the right you can see the round 12 inch sonotubes placed for the posts which will support the roof
We tested the fit of the Bisque pier on the cement and 4 bolts. Everything looks good. The pier base is level.
A trench has to be brought up from the house to carry 2 conduits, 1 data and 1 electrical. The trench is around a foot+ deep and 18 inches wide. There is no set depth and width as long as the conduits can be separated so there is no electrical interference
Not to be overlooked is the site work that must be done around the observatory to manage ground water and rain. We don't get much rain up here but when it comes it arrives in sudden bursts of large quantities of water, occasionally causing local flooding. 2 large berms were created around the perimeter of the north end of the property and additional gravel placed in the immediate vicinity of the structure. This is the view from the east end of the clearing looking west. You can see the foundation in the foreground

Framing and completion of the observatory structure

July 30, 2016

The BYO (Backyard Observatories) crew finally arrives!

Day 1 consisted of completion of the subflooring, completing the conduit from the piers to the warm room and to the electrical panel and 2 walls built. No disasters so far. The foundation walls were a tad off level to the north and west so they had to put shims but no other issues. 
The BYO crew arrives. Framing , subflooring and conduit connection are shown.
Finally the floor is done and 2 walls built, ready for assembly!

July 31, 2016

The day started out sunny and seasonable but rapidly declined to stormy and rainy. Walls went up today as well as the inside framing for the warm room. 
West wall with entry door
South wall with 2 foot fold down panel to improve access to southern sky

Inside the structure

Detail of warm room wall

Detail of observing room floor showing 2 piers

Aug 4, 2016

Structure completed! Inside the observatory showing south wall with the drop down panel. Actually there are 2 separate panels due to the weight. The wall height is 85". The height with the drop down open is 62". Note the insulation under the roof which keeps the heat from building up in the summer. The building has been wired with multiple outlets and a few wall lights
Roof opening! This can be done on site or remotely
The warm room! There is a window on each side for monitoring each pier. Center image shows the roof motor. Right image is inside the warm room looking out
Initial preliminary set up for mount calibration. I decided to go with 48 inch piers. This is on the larger of the 2 cement footings. Shown is a Paramount MEII, Tak TOA 130 NFB and Canon 60D