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Pointing and Focus - Check Surface

A simple method to measure the efficiency of the primary surface is to perform pointing observations toward flux density calibration sources. Here we are concerned with checking that the primary surface has not degraded (e.g., snow or ice sticking to the primary). The scheduling block checkSurface.sb, located at /home/astro-util/pointing/astrid, will perform Peak and Focus observations for this purpose. We recommend observations at L, X, and Q-band depending on the circumstances. Table 1 lists the expected properties for these three observing bands. Table 2 lists some properties of three flux density calibration sources. At least one of these objects should be visible at any time. The CLEO scheduler can be used with the flux density catalog to check source locations. N. B., the flux densites listed below are approximate values taken from Peng et al. (2000).

The antenna temperatures calculated by GFM must be corrected for the atmosphere. The antenna temperature corrected for the atmosphere is given by

,

where is the zenith opacity, and E is the elevation. The zenith opacity can be estimated from the High Frequency Weather Page.

Table 1: Receiver Band Properties

Table 2: Calibrator Properties

-- DanaBalser - 20 Dec 2005