1. SNR classification 15 points
A source has S = 650 e⁻ in a 16-pixel aperture, with sky = 200 e⁻/pix, dark = 6 e⁻/pix, and read noise = 7 e⁻. Compute the SNR and classify the detection.
Problems
2. Zero-point application 15 points
Using the zero point ZP = 19.457 derived in Lecture 5 from the standard-star table, compute the calibrated V magnitude of a target with 95000 counts in a 30 s exposure.
3. Aperture bias 15 points
An aperture captures only 80% of a star’s total flux due to its finite radius. Compute the resulting magnitude bias (in mag) introduced by this aperture choice, and state whether the measured magnitude is too bright or too faint relative to the true value.
4. Uncertainty budget 15 points
Combine a zero-point uncertainty of ±0.02 mag with an instrumental measurement uncertainty of ±0.018 mag in quadrature, and report the target magnitude from Problem 2 with its combined uncertainty.
Due and Scope
Submit a clear solution with equations, units, labeled quantities, and a short narrative interpretation for each problem. Show every reduction step and state your assumptions explicitly; a correct final number without visible work receives partial credit at most.
OpenStax Companion Reading
Verify against OpenStax Astronomy 2e Chapter 17.1 (brightness of stars) before instructional release.
References and Data Sources
- Corresponding lecture slides and notes for this unit.
- OpenStax Astronomy 2e (local reference copy: references/openstax-astronomy-2e.pdf).
- Course datasets under
materials/ASTR210/data/where referenced above.