Catching Rays: Gathering Information

Landsat image of HAWC Observatory
A Landsat “natural color” (actually false color) image from the USGS EarthExplorer website shows the HAWC Observatory and surrounding area. The large volcano near the center is Pico de Orizaba, while the smaller, darker cone located near 7 o’clock is Sierra Negra. The tiny, light-brown oval on the northeast slope of Sierra Negra is the observatory.

The HAWC Observatory is a collaboration between several universities and the governments of the United States and Mexico. All of these major players, along with individual researchers, have websites devoted to the project. The main HAWC Observatory website itself is a trove of information about the observatory and the science behind it.

Initially at least, I’m interested in locations and dimensions: The latitude and longitude of the site, the size of the water tank array, the width and height of the water tanks, and the size and shape of the photomultiplier tubes inside the tanks. Diagrams found online of the water tanks and of the site under construction provide most of what we need. With a little digging we can find out the make and model number of the photomultiplier tubes and download the manufacturer’s spec sheet.

For location, we learn from the HAWC Observatory website that the observatory is at roughly 19 degrees north, 97.3 degrees west. For a more precise location we can turn to SunEarthTools.com, which will also come in handy later when we set up the lighting for the scene.

EarthExplorer Search
The EarthExplorer search page, with the area around the HAWC Observatory selected.

For topography, we can turn to the United States Geological Survey. The USGS EarthExplorer provides digital elevation data as well as aerial and satellite images for (almost) the entire surface of the Earth. Some of the data sets are better than others. Our best option is a large-scale digital elevation file that covers most of central and southern Mexico (GMTED2010 7.5 arc-second, which has a resolution of about 250 meters).

Finally, scouring the Web turns up dozens of images that can be used as modeling references.

After a few hours of research, we have what we need to set up the scene, create an initial rendering, and rough in a comprehensive layout.

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