Gemini Planet Imager 2.0

Overview

The GPI 2.0 upgrade rewrites the instrument’s control software from proprietary IDL into Python, organized as one class per hardware assembly — calibration, cameras, coronagraph, pointing, shutters — over a shared RPC backend. I focused on the CAL (calibration) subsystem: porting its alignment-and-centering routine and CAL commands, linting, and fixing defects surfaced during migration.

Design decisions 04

• The CAL routine was ported line-by-line with explicit accounting: every executable IDL line maps to a documented Python translation, so a reviewer can confirm no behavior was silently dropped in the migration.
• Deferred operations fail loudly instead of silently: not-yet-ported routines raise NotImplementedError or emit runtime warnings at their original call sites, so missing functionality is visible during a run rather than quietly skipped and corrupting a calibration.
• The calibration math keeps its exact numerical behavior — same RPC command identifiers, 3-sigma outlier rejection, 30 mas sanity threshold, 10-sample/1 s tip-tilt cadence — rather than being “improved” during the port, to avoid silent scientific regressions.
• A legacy assumption the new pipeline never exercises is hard-coded and documented instead of ported as a dead conditional branch; legacy bookkeeping calls remain as warning-emitting stubs so call sites stay intact for future work.

Python · IDL · RPC · pytest

listed under research →