Tech help please

Sorry to bother but 2 questions quickly:

  1. When I open up imaging catalog like this what does the type mean (i.e. what does EXP or DUP mean in the type)?

  2. If I want to open individual exposures I just get a message like this - how do I go on to access the actual exposure?

Sorry to bother - just still learning how to use the website.

For the imaging catalog – that’s showing you rows from the “tractor” catalog files (from the DR10 data release, in this case). These are documented here,

and the TYPE is saying what shape we think the object is. Most of them are PSF (point-source), REX (round exponential galaxy), EXP (elliptically-shaped exponential galaxy), DEV (elliptical deVaucouleurs
-profile galaxy), or SER (elliptical Sersic-profile galaxy). DUP is an unusual one that results when we have a galaxy whose coordinate matches to a Gaia source. We keep the Gaia source because we want to have all the Gaia sources available in the catalogs, but we mark it DUP because it’s superseded by the galaxy measurement.

For the exposures – if you click on the map and follow the “Single exposures” button, you can then follow the links such as “CCD decam g 317045 S2” to get details on that exposure. Or, if you click on the map and follow the “Data” link, you’ll get a table of exposures (like Legacy Surveys DR10 data for RA,Dec (51.6179, -51.3235)) with links to download individual chips.

Hope that helps!

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very much - thank you!