ASTR 472 Lab 07: Survey Completeness and Galactic H I Mapping

Lectures 13-14 ยท selection correction and rotation inference

Learning objectives

Preparation, materials, and setup

Use Python 3 with the standard library (or a spreadsheet capable of regression and plotting), the supplied ../data/survey_injections.csv, and the relevant lecture notes. Record file name, row count, columns, units, and provenance level before editing. No facility observing time is assumed.

Dataset status: the supplied compact record is synthetic/instructor-provided (level 3), not an archived observation. Compare its analysis workflow with the real survey or observatory source cited in ../reference-log.md.

Computed check: corrected surface density = 71.43 deg^-2; Poisson-only uncertainty = 2.062 deg^-2.

Apparatus and procedure

  1. Partition injection/recovery rows by flux bin and sky tile; compute p_hat and binomial standard error for each stratum.
  2. Compute corrected surface density and Poisson uncertainty for the supplied detection count and usable area.
  3. Propagate completeness uncertainty using first-order derivatives and compare with Poisson-only uncertainty.
  4. Use the supplied l and v_LSR measurements with the stated flat-rotation parameters to compute Galactocentric radii.
  5. Load ../data/hi_kinematics_teaching.csv separately from the injection table and compute model-dependent Galactocentric radii from its longitude and v_LSR columns.
  6. Write a reproducible analysis note separating survey products, teaching records, model assumptions, and unresolved systematics.
  7. Use CDS catalog J/A+A/594/A116 and its ReadMe to select a listed 20-by-20-degree Galactic HI4PI FITS subcube nearest l=30 degrees, b=0 degrees. Record the actual file name, coordinates, FITS WCS, velocity convention, units, access date, and checksum; compare one real spectrum and a numerical N_HI integral with the supplied synthetic injection exercise.

Measurement record and uncertainty

RecordRequired entry
InputFile, release/source, units, masks or flags, and provenance level.
ModelEquation, parameter values, convention, and approximation.
StatisticsFit covariance or counting error plus one calibration/selection/systematic term.
ValidationIndependent recomputation, residual plot, and limiting-case check.

Submit completeness plot, corrected-density calculation, kinematic radius table, and a one-page method/provenance note.

Deliverables and criteria

Interpretive boundary

A completeness-corrected estimate remains conditional on injection realism, usable-area masks, and the adopted circular-rotation model. State explicitly which parts of your result are facts about this prepared teaching record and which are transferable inference methods.

References and provenance

Course teaching record: ../data/survey_injections.csv, level 3. Real facility/survey context: reference log. No external image is used.