crds

library13.2.5pypypi✓ verified 85d ago

CRDS (Calibration Reference Data System) manages calibration reference files for HST, JWST, and Roman telescopes. It provides tools for selecting, downloading, and validating reference files. Version 13.1.16 supports Python >=3.7 and is actively maintained with regular releases aligned with telescope operations.

data observability

pip install crds

github ↗package ↗

INSTALL

IMPORT

SIG · CRDS

crds

datapythonv13.2.5

Install

8.4s avg

Import

2890ms

Disk

182MB

Pass rate

10/ 10

Env Coverage10 / 10

glibc

3.9–3.13

musl

3.9–3.13

Install & Compatibility

Where this runs

tested against v13.2.5 · pip install

no network on importno background threads

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

py 3.10–3.95 runs

installs and imports cleanly · install 0.0s · import 2.970s · 173.4MB

glibc

py 3.10–3.95 runs

installs and imports cleanly · install 8.4s · import 2.810s · 174MB

182MB installed

● package 182MB

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

crds

✓ import crds

Main module. Submodules like crds.client, crds.core are imported as needed.

BestReferences

✓ from crds import BestReferences

✗ from crds.client import BestReferences

BestReferences is imported from the top-level crds module, not from crds.client.

Basic usage: set server, create BestReferences with a context and observation parameters, then retrieve reference file mappings.

import crds from crds import BestReferences # Set server URL (optional, defaults to CRDS server) crds.set_server_url(os.environ.get('CRDS_SERVER_URL', 'https://crdsserver.stsci.edu')) # Get best references for an observation context = 'jwst_ops.pmap' # or use a specific context id obs = {'INSTRUMENT': 'NIRCam', 'DETECTOR': 'NRCA1', 'FILTER': 'F090W', 'DATE-OBS': '2023-01-01'} refs = BestReferences(context, obs) print(refs.get_references())

crds --version

Debug

Known issues

breakingCRDS 11.x dropped Python 2 support. Current versions require Python >=3.7.

fix

Upgrade to latest crds and use Python 3.7+. If you need Python 2 compatibility, stay on legacy versions (not recommended).

affects: <11.0

deprecatedThe function `crds.getreferences()` is deprecated. Use `BestReferences` class instead.

fix

Replace calls to crds.getreferences() with BestReferences context manager or direct instantiation.

affects: >=10.0

gotchaCRDS requires internet access to fetch reference files unless you set up a local cache. Without cache, it downloads files on demand.

fix

Set the environment variable CRDS_PATH to a local directory to cache downloaded files. Use CRDS_SERVER_URL to specify a mirror.

affects: all

gotchaWhen using BestReferences, the observation dictionary must include exact header keywords (case-sensitive). Missing keys cause KeyError.

fix

Always provide required keys: INSTRUMENT, DETECTOR, DATE-OBS, and any filter/grating/band specific to the instrument. Check instrument documentation.

affects: all

Errors

Common errors & fixes

ImportError: cannot import name 'BestReferences' from 'crds'

Outdated crds version (before 10.0) that doesn't have BestReferences class.

fix

Upgrade crds to latest: pip install --upgrade crds

crds.core.exceptions.CrdsNetworkError: Unable to connect to CRDS server

No internet access or incorrect CRDS_SERVER_URL. CRDS defaults to public STScI server; if blocked, set a mirror.

fix

Check network, set CRDS_SERVER_URL to a reachable server (e.g., https://crdsserver.stsci.edu), or use a local mirror.

KeyError: 'INSTRUMENT'

Observation dictionary missing required key 'INSTRUMENT'.

fix

Include all required keys: INSTRUMENT, DETECTOR, DATE-OBS. Example: obs = {'INSTRUMENT': 'NIRCam', 'DETECTOR': 'NRCA1', 'DATE-OBS': '2023-01-01'}

crds.core.exceptions.CrdsLookupError: No matching reference file found

No reference file for the given context and observation parameters. Could be obsolete context or incorrect parameters.

fix

Use a more recent context (pmap) or check that observation parameters match available reference files. Try context = 'jwst_ops.pmap' for latest.

Upgrade

Version history

13.2.5latest on PyPI · released Jun 18, 2026

Audit

Dependencies

requestsrequiredHTTP requests to CRDS server

astropyoptionalFITS file handling and table operations

Agent activity

29 hits · last 30 days

node

OpenAI (training)

Resources

githubhttps://github.com/spacetelescope/crds ↗

packagehttps://pypi.org/project/crds/ ↗