Telescopes

11 flashcards · Physics · by inquisitive learner

1. parsec

   the astronomical distance at which the angle subtended by the Earth-Sun system (i.e 1 AU) is one arcsecond

2. collecting power is proportional to diameter2

3. magnification formula (angles)

   M=anglesubtendedbyimageateye/anglesubtendedbyobjectatunaidedeyeM = angle subtended by image at eye / angle subtended by object at unaided eyeM=anglesubtendedbyimageateye/anglesubtendedbyobjectatunaidedeye

4. Rayleigh criterion

   θ≈λD\theta \approx {\lambda \over D}θ≈Dλ​

5. collecting power

   a measure of an imaging system's ability to collect incident electromagnetic radiation

6. magnification formula (focal lengths)

   M=fo/feM= f_o / f_eM=fo​/fe​

7. absolute magnitude and apparent magnitude

   m−M=5log⁡d10m - M = 5 \log\frac{d}{10}m−M=5log10d​

8. charge-coupled device

   a semiconductor device where light is converted directly into digital information

9. Advantages of a CCD greater quantum efficiency; around 80% compared that of the human eye (4%)

10. quantum efficiency

    numberofphotonsdetectednumberofphotonsincident×100\frac{number of photons detected}{number of photons incident} \times 100%numberofphotonsincidentnumberofphotonsdetected​×100

11. How a CCD works When light strikes the CCD, the incident photons cause electrons to be released via the photoelectric effect; this causes the pixels to accumulate charge the amount of charge is proportional to the brightness, thus having a linear response