Section 1: Introduction Flashcards
interpretation of astronomical measurement
measure signal from detector
deduce properties of photons
infer properties of source
information arrives in the form of
photons, particles and gravitational waves from remote sources
(can also get in-situ detection of particles, EM fields i.e solar probe for sun)
this course will focus on photon detection and analysis, will deal with:
imaging
spectra
time series
some observations straddle the classifications of imaging, spectra and time series such as
imaging spectroscopy
radial velocity curves
photon detector technologies are defined as
a device wherein some measurable property changes in response to the effects on EM radiation
examples of photon detector technologies
1.semiconductor devices like CCDs
2. scintillators, geiger counters
3. antennas
4. bolometers
5. photo-multupliers
position-sensitive detectors
directly register an intensity distribution in the plane of the sky - need optics as well to focus the image onto detectors and filters to restrict the wavelength angle
examples of position-sensitive detectors
CCD detector
photographic plate for wide-field imaging
directionally-sensitive detectors
do not directly encode position on an x-y plane, instead give info about the direction from which radiation originates
examples of directionally-sensitive detectors
single radio antenna
gamma ray compton telescopes
energy-sensitive detectors
used for x-ray/gamma ray. A high energy photon interacts with matter to produce electron-ion or electron-hole pairs
amplitude of resulting electrical pule is proportional to photon energy
examples of energy-sensitive detectors
gas proportional counter
solid state detectors
physical variables we can work out
temperature
chemical abundance
magnetic field
velocity
distance and size
density
only physical variable that does not require spectroscopy
distance and size
