Lecture 5 Observations

measure objects' properties

Its relation with us: distances

how can we evaluate the measurements

kinematic properties

position

motion

mass

compare with reference stars

photometric redshifts

spectroscopic redshifts

Newton II law: gravity and rotation

viral theotem

dynamic properties

size

angular size and distance

flux and distance for unresolved stars/exoplanets

mass and period for orbit

luminosity:flux and distance

temperature

kinetic

effective

color

excitation

ionization

age:population

environment

composition

atomic and molecular: spectrum

sturcture

magnetic field

time evolution:difficult

dark matter and central blackhole

parallax

trigonometry

angular size to actural size

use sun-earth distance as a ruler

require velocity

luminosity and standard candles

period and brightness

other methods:Hubble constant

two principles

errors always occur

measurement is to improve SNR

two groups of concepts

accuracy vs precision

systematic vs random errors

two way to simulate errors

Poisson

Guassian

error propagation

do partial differential