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2 years ago in Astronomy , Stellar Kinematics By Aaqib
Do reduced proper motions of stars depend on observing conditions?
I'm working on a kinematic study of halo stars using data from a mix of all-sky surveys and targeted observations. I need to combine datasets with potentially different photometric systems and astrometric precision. Before I do, I have to understand if differences in seeing, exposure time, or catalog zero-points could systematically alter the derived reduced proper motions and bias my population analysis.
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By Jayalakshmi Answered 1 year ago
This is an excellent and essential question for anyone working with multi-epoch astrometry. The reduced proper motion itself is an intrinsic quantity, but every term in its calculation is observation-dependent. From my experience cross-matching Gaia with legacy surveys, I've seen two major pitfalls. First, proper motion errors, which can be significant for faint stars or short baselines, propagate directly. Second, and more subtly, the apparent magnitude can shift with different photometric filters or if the source is blended in poor seeing. I would recommend always comparing your values against a high-fidelity reference like Gaia for a control sample to quantify any systematic offsets in your specific dataset before drawing scientific conclusions.
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