Driftscan of Sun at 1420 MHz. Also to calculate the beamsize of the dish.

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Another measurement method is from drift scan. We fix the dish at 1 point and let the rotation of the earth do its work (also useful if you don't have a rotor). Instead of frequency against SnR, we now plot the Power against time. The sun generates many types of radiation and we can also detect the sun at 1420 Mhz (thermal radiation). In this graph a drift scan of the sun. From the Gauss curve we can calculate the effective dish beam. At 50% of slope 1 we measure the time and at 50% of slope 2 we measure the time again. In this case we arrive at 2070 seconds. The earth rotates at a speed of 15 degrees per hour. This gives a dish beam (effective beam size) of 8 degrees, which corresponds to a dish diameter of 1.9 meters. For example, a dish diameter of 25 meters has a beam of 0.6 degrees. So a much higher resolved.

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In the green waterfall you see the sun driftscan horizontal but also a vague vertical line. Thats the HI from the Milky Way in the driftscan.