USING THE TWENTY METER Installing the receiver on

USING THE TWENTY METER Installing the receiver on the 20 Meter Telescope

Facts: • • Fully Steerable L-band Receiver 1. 3 -1. 8 GHz Resolution = 0. 7 degrees Sky patterns: Daisy, Map, On-Off, Track • Two Spectral Modes: Low (wide band) /High (narrow band) resolution • Pulsar Mode NRAO/AUI/NSF 2

Low Resolution/High resolution? NRAO/AUI/NSF 3

Sky Pattern Spectral resolution Why? On-off Low and high • Good for measuring intensity of your object. • Can add multiples together in hi-res mode to look for extragalactic hydrogen Daisy Low Traces a flower-petal pattern. Good for measuring the strength of a source. Map Low/High Good for making an image of an area of sky. Must be several degrees on a side! EG: Nebulae, galactic plane Track High good for observing spectra in high -resolution mode Pulsar Low good for observing known pulsars Example https: //goo. gl/bry. Idj

Data Products Data are archived at the Green Bank Observatory: www. gb. nrao. edu/20 m � Radio Observing � Click on ID � Link to observatory url NRAO/AUI/NSF 5

Searching the Archive Getting Advice https: //www. gb. nrao. edu/20 m/ NRAO/AUI/NSF 6

Low Resolution EG 1: Mapping nebulae NRAO/AUI/NSF 7

Nebulae are clouds of hot ionized gas. Electron accelerates as it passes near a proton. radio waves are released 8

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0329+54 Vela Low resolution EG 2: Known pulsars 0531+21 10

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High Resolution Looking for atomic and molecular transitions (spectral lines) Atomic Hydrogen and Hydroxyl can be observed with the 20 Meter. 12

Gas Spectra Neon Sodium 434 nm 656 nm 486 nm Hydrogen 13

Hydrogen Atoms Electron accelerates to a lower energy state 0. 21 meters =1420. 41 MHz NRAO/AUI/NSF 14

http: //ned. ipac. caltech. edu/forms/calculator. html NRAO/AUI/NSF 15

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