Observational Techniques and Telescopes Flashcards
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Read the first 6 Observational Techniques and Telescopes flashcards as text
What is the magnitude scale in astronomy?
Answer: A logarithmic scale of stellar brightness where lower numbers indicate brighter objects
The magnitude scale is a logarithmic measure of brightness where each step of 1 magnitude corresponds to a brightness ratio of ~2.512, with lower (and negative) numbers indicating brighter objects.
What is the difference between apparent and absolute magnitude?
Answer: Apparent is how bright a star looks from Earth; absolute is its intrinsic brightness at 10 parsecs
Apparent magnitude is how bright an object appears from Earth, while absolute magnitude is its intrinsic brightness defined as the apparent magnitude it would have at a standard distance of 10 parsecs.
What is a charge-coupled device (CCD) in astronomy?
Answer: A highly sensitive electronic light detector that converts photons to electrical signals
A CCD (charge-coupled device) is a silicon-based electronic detector that converts incident photons into electrical charges with high quantum efficiency (~90%), revolutionizing astronomical imaging and replacing photographic plates.
What is photometric redshift?
Answer: Estimating galaxy redshift from broadband photometry using color information across multiple filters
Photometric redshift estimates a galaxy's distance by fitting its observed colors across multiple broadband filters to spectral energy distribution templates, yielding an approximate redshift without time-consuming spectroscopy.
What is the purpose of a coronagraph?
Answer: To block out the central bright source so faint nearby objects like exoplanets or the solar corona can be observed
A coronagraph is an optical device that blocks the direct light from a bright source (like a star) to allow observation of much fainter nearby objects such as the solar corona, circumstellar disks, or exoplanets.
What does 'seeing' refer to in ground-based optical astronomy?
Answer: The stability and clarity of Earth's atmosphere that affects image sharpness
Astronomical seeing refers to the blurring and twinkling of celestial objects caused by turbulence in Earth's atmosphere, typically measured in arcseconds; better seeing means less turbulence and sharper images.