Seeing Monitor Implementation & Tiddler

[Robert Capon]

Hi Everyone:

I’ve implemented an SBIG Seeing Monitor, so am posting information on how to get it working with ACP in a Tiddler, along with some implementation tips. Using the application that comes with the Seeing Monitor, you can take the feed from the monitor and create an image of the seeing graph that the program outputs as a jpeg image and is refreshed each time a data point is added. Once the jpeg is created, you can access it through the ACP user interface.

Here’s the basic steps:

1) In ACP Doc Root, create a new folder entitled “Seeing Monitor”.
2) Set up the “Seeing Monitor” folder to be shared over your network.
3) Open the software program “Seeing Monitor” that comes with the monitor. In the menu “File” select “Set Default.” Fill in the image file name with the location on your shared network and the name of the file. I gave my filename “seeing.jpg”, so the whole thing looks like this:
“\\ComputerName\Seeing Monitor\seeing.jpg”
4) Go to the ACP Doc Root/Seeing Monitor folder, and verify that the jpeg image is there. (The file will only be updated when the Seeing Monitor is running).
5) OK, if you’ve gotten this far, you now have a jpeg file that will update every time a data point is added to the seeing monitor graph. Now you want to create the code to put this on an ACP web tiddler:

<script>
return "[img[/Seeing Monitor/seeing.jpg?" +
new Date().getTime() + "]]";
</script>

<<RefreshTiddler Refresh "Refresh Display" 900>>

6) Give your Tiddler a name. I named mine “Seeing Monitor”. If you want to include the Tiddler in your startup items, add this to your “StartupItems” tiddler:

[[Seeing Monitor]]

7) Below, you can see a screen shot of what the Tiddler looks like.

Here are a few implementation tips:


1) The consensus is that the seeing monitor should be on its own computer. This was the advice of the person who sold me the monitor as well as the author of the software, so I never tried it on the observatory CPU. The Seeing Monitor is pretty resource intensive, since it’s taking images rapidly, and averaging 9 images for every data point. It’s doing over 600 points per night, so it’s taking over 5000 images that are downloaded to make that happen. (When I checked, the seeing monitor was consuming 45% of the CPU resources on a dual-core machine.)
2) Accordingly, I set up a spare computer with the Seeing Monitor, and plugged it into the Ethernet Switch in the observatory. That makes the server available over the LAN to save files to the server running ACP, and also makes the server available over a VNC connection.
3) Try to keep the Seeing Monitor USB cable length as short as possible. The Seeing Monitor comes with a USB extender. But I located the computer just inside of the observatory wall from the Monitor, and am able to use a 6-foot USB cable without using the extender.
4) I used a DirectTV satellite dish bracket to mount the seeing monitor. They’re very common on EBay, and I bought one for $7.50—the shipping cost more than the mount. (EBay Search: DirectTV Satellite Bracket). I purchased a mailbox mounting board at Lowe’s for $3, and painted it with Rustoleum primer and outdoor paint. Then I attached the board to the satellite dish bracket using three screws with a counter-sink into the board so that the Seeing Monitor would mount flush. The pole is a standard 1.25-inch steel plumbing pipe (that’s about 1.5-inch outer diameter), 7-feet in length with 2-feet in a concrete footing using a 50-pound bag of Sac-Crete concrete. I built a sleeve using a 5-inch length of 1.5-inch PVC pipe (2-inch outer diameter), and then cut a ¼-inch slot in the sleeve so that it would compress around the plumbing pipe to make a perfect 2-inch fit for the satellite bracket. (When you look down the PVC pipe lengthwise it's shaped like then letter "C").
5) I took my first image with the satellite bracket, and found where the Seeing Monitor was pointing by doing an all-sky link at nova.astrometry.net. (See photo). From there, it’s very easy to adjust the Satellite bracket with the Altitude and Azimuth adjusting bolts.
6) When I got close to the North Celestial Pole, I used the SkyX Image link feature to align the center of the image with the NCP. (See Photo). The Image Link is superimposed over the celestial grid, so it’s very easy to adjust to the pole in a few minutes. For reference, when you do the Image Link, the pixel scale is 12.3 arcseconds per pixel.

Attachments: Photo of mount, screen shot of tiddler, all-sky astrometry image, SkyX image link

All best,

Rob