# Assessment Instructions: Problem Set 04 — Weighing the Sirius AB System with Kepler’s Third Law

## Inputs to Inspect
Student submission, this problem set, the solution key, the corresponding lecture slides/notes, and the referenced dataset(s) under `materials/ASTR310/data/`.

## Grading Standard
Award credit for correct method and units first, then for the specific numeric result. A student who shows correct reasoning with a small arithmetic slip should receive most of the available credit; a student with a correct-looking number but no visible derivation steps should not. Because this is a 300-level quantitative course, full marks require a genuine derivation (not just formula substitution) wherever the problem set asks for one.

## Problem-Level Criteria
- Problem 1: 15 points — correct unit conversions.
- Problem 2: 20 points — correct Kepler’s-third-law setup and arithmetic.
- Problem 3: 15 points — correct percent-agreement calculation.
- Problem 4: 15 points — correct escape-velocity arithmetic and correct physical explanation.

## Resubmission Policy
Students may resubmit within one week of receiving feedback. A resubmission must show a corrected derivation, not only a corrected final number, and should reference the specific feedback comment it addresses. Regrade to a maximum of 90% of the original point value unless the error was a grading mistake.

## Common Errors to Flag
- Using years and AU directly in the SI-unit form of Kepler’s third law without converting to seconds and meters.
- Confusing Sirius A and Sirius B’s masses/radii when computing escape velocity.
- Attributing the escape-velocity contrast to mass alone rather than the dominant radius (1/√R) effect.