Ground-Based Observational Astronomy is the sub-field of astronomy focused on how to make measurements of the universe from the surface of the Earth.
Understanding how telescopes focus light onto a detector and making sense of this detected light is is second only to making sure the measurements and their analysis are repeatable.
Measurements made with the tools of observational astronomy (telescopes and detectors attached to them) are measured from science images and are given in either absolute or relative scales.
The digital detector attached at the focal plane of the telescope generates counts. These counts contain the desired source signal which has been attenuated along its optical path due to atmospheric extinction along with a number unwanted signals/effects. These are the additional photon flux due to the background sky brightness as well as the unwanted detector effects: the dark signals and the erroneous pixel-to-pixel variation in sensitivity due to inhomogeneities in the detector or an imperfect optical system.
The removal of the unwanted signal and calibration to account for detector, optical system, or atmospheric effects in the frame counts is called Data Reduction. The result of a properly reduced frame is a science frame. It is from a science frame that most physical quantities can be estimated.
The removal of the detector and optical system effects is covered in Data Reduction I: Reduction to Top-of-Telescope. The identification and further reduction of the counts associated with sky brightness (a.k.a., light pollution) is covered in Data Reduction II: Removal of Sky Brightness. The conversion of the counts to a magnitude scale and the final step of data reduction is handled in Data Reduction III: Reduction to Top-of-Atmosphere. The quantization of confidence in all of these measurements is discussed in Signal-to-Noise.
Before interacting with or even generating a science image, any astronomer should be familiar with exactly what the detector measures (photons). From this understanding of radiant energy in the form of integrated spectral radiance or of photons, astronomers can extract absolute physical quantities (e.g., radiative flux) or relative quantities (e.g., magnitudes).
A science image or science frame is a light frame that has been calibrated to account for optical system and detector contributions or non-uniformities as well as to the top-of-atmosphere. For us, a science frame is a frame whose counts have been calibrated such that all of the counts present in the frame are thought to be proportional to the amount of spectral energy received from the source over the integration time if there were no atmosphere. It is from these frames that you can estimate most physical quantities.
Though they are often necessary, the generation of a science image for our purposes does not include astrometric calibration.
Discuss diffraction and Airy Disks
Discuss Rayleigh Criterion & Dawes Limit
Discuss what seeing is.
Discuss how we measure seeing at UMBC Obs
Link to another wiki page about what a magnitude is. Discuss how scope can be magnitude limited.
Discuss how to we measure our limiting magnitude.
Discuss what tracking/guiding is (no mentions of software).
Discuss how poor tracking/guiding can cause limiting behavior in imaging.
Discuss how we arrive at best tracking/guiding rates.
Discuss what focus is.
Discuss how poor focus can cause limiting behavior in imaging.
Discuss how we arrive at best focus.
Discuss what is meant by the focal speed/ratio. What information does this convey?
(All without any mention of our specific cameras)
Discuss what is meant by Plate Scale.
Discuss pixel dimensions on detector and how to determine ideal angular resolution.
Discuss detector sizes and how to determine FOV.
Nyquist-Shannon Sampling Rate
Sources