ASTR 340 Problem Set 07: Capstone Error Budget and Proposal Trade-Space

Problem set for lecture unit 7.

Problems

1. RSS error budget for a new scenario 20 points

A photometric measurement has a Poisson term of 8.0 mmag, a flat-field residual of 4.0 mmag, and an extinction-correction residual of 6.0 mmag. Compute the total RSS error budget and identify the dominant term.

2. Aperture trade-space 15 points

Using the collecting-area (D²) scaling, estimate how much longer an exposure with an 8.1 m telescope (Gemini-class) would need to reach the same SNR as a 300 s exposure with the 10 m Keck aperture, in the background-limited regime.

3. Resolution requirement check 15 points

A science case requires resolving a 30 milliarcsecond angular separation at K band. Using Keck's AO-corrected diffraction-limited FWHM (46.7 mas, Lecture 11), determine whether this requirement is achievable with Keck's AO system at the representative Strehl ratio used throughout this course, and justify your answer.

4. Full proposal synthesis 20 points

Write a short (4-6 sentence) technical justification paragraph, in the style of Lecture 14's capstone framework, that combines your Problem 1 error budget and Problem 3 resolution check into a single coherent argument for or against a specific proposed Keck AO observation.

Due and Scope

Submit a complete derivation with equations, units, labeled quantities, and a short narrative interpretation for each problem. Show every step; a correct final number without a visible derivation receives partial credit at most, and quoting a lecture number without adapting it to this problem's specific inputs receives no credit for that step.

OpenStax Companion Reading

OpenStax Astronomy 2e (local reference copy: references/openstax-astronomy-2e-extracted.txt), Chapter 6 (astronomical instruments), descriptive only; this course exceeds that introductory treatment throughout.

References and Data Sources