IVOA Simple Cone Search Extractor

Point at any IVOA Simple Cone Search (SCS) service and pull every catalogue source within a circle of sky — give a centre (RA, Dec) and a radius, get back one structured row per astronomical object. One actor speaks to the entire Virtual Observatory: VizieR / CDS, HEASARC / NASA-GSFC, GAVO, IRSA / IPAC, NOIRLab, ESA, CADC and thousands of national and observatory data centres all expose the identical positional query, so there is no per-catalogue scraper and no list of hosts to maintain.

What it does

Simple Cone Search is the simplest and most widely deployed IVOA data-access standard. The request is a single HTTP GET:

GET <endpoint>?RA=<deg>&DEC=<deg>&SR=<radius_deg>

and the reply is a VOTable listing every catalogue row whose position falls inside the cone. This actor issues that request, parses the VOTable, and pushes one dataset row per source. The output columns are the catalogue's own columns (position, magnitudes, identifiers, proper motions, whatever the catalogue publishes) — they are dynamic per service, plus a few _-prefixed provenance fields (_endpoint, _ra, _dec, _sr, _rowIndex).

The VOTable parser accepts the TABLEDATA, BINARY and BINARY2 serializations, so it works on every compliant service regardless of the wire format it defaults to (GAVO / DaCHS services default to BINARY). The SCS in-band error channel (QUERY_STATUS=ERROR returned with HTTP 200) is surfaced as a real error — the actor never fabricates rows.

Input

Field	Description
endpoint	Base URL of a cone-search service (keep any ?table=... / catalogue selector).
endpoints	Optional list — run the same cone across several services at once.
ra	Cone centre right ascension, J2000: decimal degrees (0–360) or sexagesimal hours copied from SIMBAD/NED (00 42 44.3, 00:42:44.3, 0h42m44.3s).
dec	Cone centre declination, J2000: decimal degrees (−90…+90) or sexagesimal degrees (+41 16 09, +41:16:09, 41d16m09s).
sr	Search radius, decimal degrees (0.1 deg = 6 arcmin).
verb	Optional verbosity 1/2/3 (column detail).
maxRecords	Global cap on rows emitted (also sent as MAXREC).
timeoutSecs	Read timeout, default 120.
bearer / extraHeaders	Optional auth for gated deployments (never logged).

Example

{
  "endpoint": "https://irsa.ipac.caltech.edu/SCS?table=fp_psc",
  "ra": "10.6847",
  "dec": "41.269",
  "sr": "0.05"
}

returns the 2MASS point sources around the Andromeda Galaxy (M31).

Some more endpoints to try (each takes the identical RA / DEC / SR):

• https://heasarc.gsfc.nasa.gov/cgi-bin/vo/cone/coneGet.pl?table=zcat
• https://vizier.cds.unistra.fr/viz-bin/conesearch/I/239/hip_main
• https://dc.zah.uni-heidelberg.de/arihip/q/cone/scs.xml

Output

Each row is one catalogue source. Example (2MASS around M31, abridged):

{
  "ra": 10.688429,
  "dec": 41.263153,
  "designation": "00424522+4115473",
  "j_m": 15.314,
  "h_m": 14.728,
  "k_m": 14.522,
  "_endpoint": "https://irsa.ipac.caltech.edu/SCS?table=fp_psc",
  "_ra": 10.6847, "_dec": 41.269, "_sr": 0.05, "_rowIndex": 0
}

Pricing

Pay per result: you are charged per catalogue source row returned. A cone that contains no sources returns nothing and costs nothing.

Budget control: each row is billed as it is written (US$0.0005 per record on the FREE tier, lower on paid tiers). Set Max total charge on the run to cap spend: the Actor asks each service for no more rows than the budget (and maxRecords) allows, stops once the next row is no longer paid for, and sends no request at all if the budget cannot pay for one row. With several endpoints, if one fails after others succeeded, the rows already delivered are kept and the run ends with a non-zero exit so you can see it.

Notes

• Radius matters: on a dense catalogue a large SR returns a very large table. Start small.
• RA/Dec are J2000. Paste decimal degrees or sexagesimal (RA in hours HH MM SS, Dec in degrees ±DD MM SS); the log shows the converted degrees. The search radius sr is always decimal degrees.
• Services enforce their own maximum radius and row limits; a truncated result is logged as an overflow.