Copyright © Michael Richmond.
This work is licensed under a Creative Commons License.

#
Why are there two "families" of H_{0}?

One of the cosmological parameters which drives
a great deal of astronomical research is
**H**_{0}, also known as Hubble's constant.
It is simply (hah!)
a local measure of the rate at which the universe
is expanding.

Data taken from
Tonry et al., ApJ 475, 399 (1997)

Q: Using the data above, what is the local value of H_{0}?

For the real meat of today's menu,
please visit one of the lectures in another
class of mine, one concerned with
the Cosmological Distance Ladder
.

####
Some important concepts from this class

What might appear on a test question?
Well, any of the following are fair game --
but this is not an exhaustive list.

- extinction by the Earth's atmosphere
- extinction and reddening in the ISM
- cross-sections and event rates for particle detectors
(e.g. neutrinos, gamma rays)
- the blackbody spectrum, peak wavelength at a given temperature
- brehmsstrahlung radiation
- the virial theorem
- diffraction and its effect on angular resolution
- line emission from atoms (especially hydrogen)
- optical depth and mean free path of photons
- typical properties of CCDs and CMOS detectors
- spectral resolving power
**R**
- basic optical properties of a generic telescope
- basic optical properties of a diffraction grating
- radio regime: spectral index
- radio regime: brightness temperature
- signal and noise for a Poisson-like source
- physics: gravity, Kepler's Laws
- physics: non-relativistic Doppler shift, relativistic Doppler shift and redshift
- astronomy: Hubble's Law
- conversions: degrees to radians, square degrees to steradians
- conversions: meters, AU, parsec
- conversions: energy, wavelength, frequency
- conversions: intensity and magnitude, distance modulus and distance
- conversions: magnitude to flux

Copyright © Michael Richmond.
This work is licensed under a Creative Commons License.