Weather and Safety
The telescope operator is responsible for the safety of both the telescope and the personnel. This is not just yelling at someone you happen to see swinging from the JLG basket without a safety line. If, for instance, it starts snowing during the night and you decide that the roads are just not going to be safe much longer, you send everyone home right then. o If need be, call on-site Physical Plant personnel, any time of the day or night. They have 4-wheel drive vehicles and will drive anyone to and from work as needed. (Currently this would be Rex or Stuart, or either of the Safety Personnel Steve Bramlett).
Interpreting Weather at H.E.T.
Knowing the weather is one of the many fundamentals responsibilities of a TO. The RA will also be checking the weather periodically, and they can be a source of extra support with weather forecasting, however it is the TO’s call on whether or not the telescope closes down or not. Therefore, understanding the weather will help you make important decisions.
The master weather site for H.E.T is http://hetsky.as.utexas.edu/. This website was created by Chevo Terrazas and is a valuable tool. One thing to note about the location of H.E.T. is that our site is quite far away from the main radar dishes used by NOAA. The dishes NOAA uses are called NEXRAD (next generation radar), they work by sending out a burst of energy in the green wavelength. When this energy comes into contact with something, say dust grains or clouds, they bounce back to the radar dish providing the radar maps we use. The farther the green energy goes however, the higher up it will measure the weather event. See Figure 2 for a visual.
Figure 2 Since H.E.T. is quite far away from the radar dishes run by NOAA (See figure 3), our radar information is only measuring the tops of the storms and clouds, which is only providing a rough picture of the surrounding weather at H.E.T. It is recommended that when looking at the radar, you use both feeds from the closest radar dishes, which are located near El Paso and Odessa. Using both will reveal different events from one another. What Odessa will pick up on its radar is different then what El Paso will pick up on it radar. Figure 4 & 5 show an example of the different views the dishes will reveal to you.
Figure 3: Rough layout of the distance of the radar dishes to H.E.T. Since we are quite fara away, our radar data is a picture that needs to be put together from multiple views.
Figure 4: The difference in radar from El Paso and Odessa
Figure5 Example two of different radar readings
Along with the radar, we also use an All sky cam from some of the surrounding telescopes. Monet north, which is located at the end of the road by the summit building and LCGOT over on Mt. Locke have all sky cams which we use throughout the course of the evening. These visual cameras are helpful in showing the current over head conditions as well as any incoming clouds. We also have CCAM to help see the clouds in the immediate area (see section C under the stacking guide on page 16 for how to set up). There is a cloud sensor on the HETSky webpage, which links to a measuring system mounted on top of the summit building. This measures the temprature on the ground and above, and using the temperature changes can determine how cloudy it is in the immediate area. There are also sensors placed around the dome which measure temperature, humidity, wind speed, dust count and percipitation which one can find on the H.E.T. weather GUI. This GUI puts up alerts when the surrrounding area is is meeting the right requirements. This alert system is another powerful tool to use when determining whether to close or open the telescope. Be aware and cautious though, there have been times when the sensors report no rain, but when going outside and checking, there can noticible rain.
