Public Universe · Student worksheet
From catalogue value to reproducible claim
Could another researcher reconstruct your claim after the catalogue changes?
Data and starting point
Choose one exoplanet with a reported period and another measurement of interest. Follow its NASA Exoplanet Archive link to the parameter references. The site uses the Planetary Systems Composite Parameters catalogue: values for a planet can come from different papers or calculations.
Investigation
- Write a narrow, testable claim using a quantity, unit and scope. Record the planet identifier and name, displayed value, asymmetric uncertainty or limit, mass provenance if relevant, page URL and catalogue retrieval timestamp.
- Follow the parameter’s archive reference to the original study. Record title, authors, publication year and DOI or stable URL. Identify whether the value was measured, fitted or calculated, and whether its uncertainty has a stated confidence convention.
- Compare a second quantity for the same planet. Check whether it comes from the same study and model assumptions. Explain why combining composite values can produce an inconsistent physical model.
- Save the selected source rows or a small permitted extract, keeping field names and units. Add a README with query/filter, access time, source reference, exclusions and every conversion. For code, record package versions and random seeds if used.
- Swap your evidence package with a partner. Ask them to reproduce the claim without further explanation. Record discrepancies and revise the package. Distinguish rerunning your calculation from independently validating the science.
Submit
Submit the claim, a two-measurement provenance table, the small evidence package and a short peer audit identifying at least one limitation or unresolved assumption.
Build the evidence trail
Quantity / value / units / uncertainty or limit / original reference:
Retrieval time versus publication date or observation epoch:
Peer audit: what could be reproduced, and what still needs evidence?
Public Universe · Teaching notes
From catalogue value to reproducible claim
Learning outcomes
- Trace a measurement through its catalogue and literature reference.
- Distinguish retrieval time, publication date and observation epoch.
- Preserve enough evidence to reproduce a narrowly stated scientific claim.
Discussion and interpretation
The composite catalogue fills parameter gaps using multiple references and may include calculated quantities. It is a starting point for investigation; a row is not guaranteed to be a single self-consistent physical solution.
An archive retrieval timestamp is not an observation date. Students should explicitly mark unavailable epoch, uncertainty or confidence metadata rather than manufacture precision.
Keep the package small and respect source-specific reuse and attribution requirements. Do not include personal account data or credentials. A checksum can help establish that saved bytes have not changed, but does not establish scientific correctness.
Assessment criteria
- Traceable references for each quantity, including units and uncertainty conventions.
- A preserved input and documented procedure that a partner can follow.
- An honest distinction between reproducibility, source agreement and validity.
Primary sources and further reading
- NASA Exoplanet Archive: about composite parametershttps://exoplanetarchive.ipac.caltech.edu/docs/pscp_about.html
- NASA Exoplanet Archive: how composite values are calculatedhttps://exoplanetarchive.ipac.caltech.edu/docs/pscp_calc.html