Here is an update on things at SPM.

Domes: We are negotiating with a new crane company after the one we were dealing with couldn't commit to a date to bring a sufficiently large crane to SPM for the dome installation. The new company is a bit more expensive, but they are a larger company and they so far seem quite a bit more professional. They will visit the site Saturday to see what needs to be done, and the UNAM crew is pushing to get them to commit to do the installation next week.

We finished the installation of the "slit hoists" in the domes today. These are bars that hang from each of the dome shutter supports, and are used to remove and install the secondary housings to provide access to the secondary mirrors. Here are a couple photos, probably not of much interest, but it wasn't the easiest job so I'm showing the results!

This is the slit hoist bar. It pivots at the top, and is stored by bolting the bottom of the bar to the shutter support. When in use, the bar is released at the bottom so it hangs vertically, and a chain hoist is attached to the big hole at the bottom. A cable will be attached to the bar and fed through the pulley. Pulling on the cable (with a come-along to be attached to the bottom of the dome) will pull the secondary structure away from the telescope.

Close up of the bottom of the slit hoist bar and pulley.

Pivot at the top of the slit hoist bar.

Enclosures: The painting is slowly coming along. The outside of the skins at Site #2 was painted yesterday. Here is a photo.

They still need to paint the stair stringers and hand rails, as well as the sunshade support structure.

The crew went to work on the interior of the Site #3 enclosure today. They are pretty far behind schedule, so the company is going to send up a second crew to help speed things up. As it is, they expect to finish sometime around the middle of August.

Telescope installation: We were planning to start this next week, but we want to wait until the painting is done (and the domes are installed, of course, but at the moment the painting is the critical path item). We have therefore delayed the start of the telescope installation until the end of August at the earliest.

We have made some progress on the first step, however, which is locating celestial north on each of the enclosure floors. We went through this process a few years back when we were aligning the embedded fixtures for the foundations. The method we use is to look at the shadow of a plumb bob line, at local noon this shadow will lie perfectly to the north. I meant to have this done by now at all three sites, but unfortunately we have been having thunderstorms or clouds every day starting a little before noon (local noon here is approximately 12:48pm, so there was no sunlight at this time). Finally, yesterday and today were very clear and sunny all day, so we were able to locate celestial north at Sites #2 and #3. I am happy to report that in both cases, the north-south line was directly along a straight line between the north and south columns of the enclosures. This means that 1) the embeds were aligned correctly and didn't move during the concrete pours, and b) the columns are vertical so the enclosure is pretty plumb. The telescopes should fit well inside the enclosures and on the piers after polar alignment. We hope the good weather continues so we can finish this step tomorrow.

To do list:

For those keeping track, here is what needs to be finished before we can start installing the telescopes:

1) Find celestial north at Site #1. Hopefully tomorrow.

2) Hang doors in enclosures and install exhaust fan housings. This should be done on the next visit from the construction crew, not sure when that will be though, hopefully next week.

3) Install hatch hoist (to lift hatch door on each observing floor for mirror and instrument handling). I believe Ruben has the parts already and he plans to install them during his next visit, which will probably coincide with the visit of the construction crew.

4) Dome installation. Hopefully next week.

5) Install panel on wall in each observing chamber to hang dome control boxes. I have the two of the panels cut (waiting on delivery of another piece of plywood), and the brackets have been made to mount the panels onto the enclosure columns. I will finish making the panels once I get the parts, and install them after the domes are installed.

6) Install dome azimuth encoder and home switch. I will do this after the domes are installed. This seems like it should be a fairly easy job.

7) Center and bolt down scissors lift tables, and install hydraulics. They tables will most likely be bolted down during next visit of construction crew, while we will hold off on the hydraulics until after the domes are installed. We still need to get the electrical guys back to install a power connection to the hydraulics.

8) Install lights. I agreed to do this myself in order to save a few $1000's. I didn't realize that we had around 50 light fixtures to install. I will start this after the domes are installed.

9) Install GPS box outside each enclosure. I will do this after the painting is finished. No rush on this, we can do the heavy lifting on the telescope installation without these, they won't be needed until we get the mounts operational.