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SIMBAD Astronomical Database (CDS Strasbourg)

SIMBAD contains data on over 17 million astronomical objects beyond the Solar System, including identifications, coordinates, photometry, proper motions, parallaxes, radial velocities, spectral types, and bibliographic references.

Base URLs

TAP endpoint (recommended):

https://simbad.cds.unistra.fr/simbad/sim-tap/sync

Script interface:

https://simbad.cds.unistra.fr/simbad/sim-script

Simple query endpoints:

https://simbad.cds.unistra.fr/simbad/sim-id
https://simbad.cds.unistra.fr/simbad/sim-coo

Authentication

No API key required. All endpoints are public.

Key Endpoints

1. TAP Queries (ADQL — recommended for programmatic use)

POST /simbad/sim-tap/sync
Content-Type: application/x-www-form-urlencoded

Parameters:
  REQUEST=doQuery
  LANG=ADQL
  QUERY=<adql query>
  FORMAT=json|votable|csv|tsv
  MAXREC=<max rows>

Parameter	Type	Description
`REQUEST`	string	`doQuery`
`LANG`	string	`ADQL`
`FORMAT`	string	`json`, `votable`, `csv`, `tsv`.
`QUERY`	string	Required. ADQL query.
`MAXREC`	int	Max rows returned. Always set to avoid downloading millions of rows.

Example — look up object by name:

https://simbad.cds.unistra.fr/simbad/sim-tap/sync?request=doQuery&lang=adql&format=json&query=SELECT basic.OID, ra, dec, main_id, otype FROM basic JOIN ident ON oid = ident.oidref WHERE id = 'M31'

Example — cone search (objects within 5 arcmin of coordinates):

https://simbad.cds.unistra.fr/simbad/sim-tap/sync?request=doQuery&lang=adql&format=json&query=SELECT TOP 50 main_id, ra, dec, otype FROM basic WHERE CONTAINS(POINT('ICRS', ra, dec), CIRCLE('ICRS', 10.684, 41.269, 0.083)) = 1

Note: radius in CIRCLE is in degrees (5 arcmin = 0.083 deg).

Example — objects by type (e.g., all pulsars):

https://simbad.cds.unistra.fr/simbad/sim-tap/sync?request=doQuery&lang=adql&format=json&query=SELECT TOP 100 main_id, ra, dec, otype FROM basic WHERE otype = 'Pulsar'

2. Identifier Query (simple lookup)

GET /simbad/sim-id?Ident={name}&output.format=votable

Parameter	Type	Description
`Ident`	string	Required. Object name (e.g., `M31`, `Sirius`, `NGC 1275`).
`output.format`	string	`votable`, `html`.

3. Coordinate Query

GET /simbad/sim-coo?Coord={coords}&Radius={radius}&Radius.unit={unit}&output.format=votable

Parameter	Type	Description
`Coord`	string	Required. Coordinates, e.g., `10.684 +41.269` or `00 42 44 +41 16 09`.
`Radius`	float	Search radius. Default: 2.
`Radius.unit`	string	`arcmin`, `arcsec`, `deg`. Default: `arcmin`.
`output.format`	string	`votable`, `html`.

4. Script Interface (for multi-command queries)

POST /simbad/sim-script
Content-Type: application/x-www-form-urlencoded

Body: script=<script text>

A script consists of configuration lines followed by query commands:

output console=off script=off
format object "<format string>"
query id <object name>

Query commands: - query id <name> — lookup by name (e.g., query id M31) - query coo <ra> <dec> radius=<value><unit> — cone search (units: d=deg, m=arcmin, s=arcsec) - query id wildcard <pattern> — wildcard search (e.g., query id wildcard NGC 10*) - query sample <criteria> — criteria search (e.g., query sample otype='Star' & Vmag < 5.0)

Multi-object queries — include multiple query id lines in a single script:

output console=off script=off
format object "%IDLIST(1) | %COO(A D;ICRS) | %OTYPE"
query id M31
query id M42
query id M101

Script Format Codes

Format codes define which fields appear in script output. Use inside format object "...".

Identification

Code	Description	Example Output
`%IDLIST(1)`	Primary identifier	`M 31`
`%IDLIST`	All identifiers	`M 31, NGC 224, UGC 454, ...`
`%MAIN_ID`	Main identifier	`M 31`

Coordinates

Code	Description	Example Output
`%COO(A D;ICRS)`	RA Dec ICRS (sexagesimal)	`00 42 44.330 +41 16 07.50`
`%COO(d d;ICRS)`	RA Dec decimal degrees	`10.6847083 +41.2687500`
`%COO(A D;GAL)`	Galactic coordinates	`121.1743 -21.5733`

Object Properties

Code	Description	Example Output
`%OTYPE`	Object type (condensed)	`Galaxy`
`%SP`	Spectral type	`A1V`
`%MT`	Morphological type	`SA(s)b`

Photometry

Code	Description
`%FLUXLIST(V)`	V-band magnitude
`%FLUXLIST(B)`	B-band magnitude
`%FLUXLIST(U;B;V;R;I)`	Multiple bands
`%FLUXLIST(J;H;K)`	Near-infrared bands

Kinematics

Code	Description
`%PM`	Proper motion (mas/yr)
`%PLX`	Parallax (mas)
`%RV`	Radial velocity (km/s)

Predefined Format Levels

Basic:    "%IDLIST(1) | %COO(A D;ICRS) | %OTYPE"
Detailed: "%IDLIST(1) | %COO(A D;ICRS) | %OTYPE | %SP | %FLUXLIST(V)"
Full:     "%IDLIST(1) | %COO(A D;ICRS;J2000) | %OTYPE | %SP | %FLUXLIST(U;B;V;R;I;J;H;K) | %PM | %PLX | %RV | %MT"

Key TAP Tables

`basic` — Main Object Table

Column	Type	Description
`oid`	BIGINT	Internal object identifier (primary key)
`main_id`	VARCHAR	Primary object identifier
`ra`	DOUBLE	Right Ascension in degrees (ICRS)
`dec`	DOUBLE	Declination in degrees (ICRS)
`otype`	VARCHAR	Condensed object type code
`sp_type`	VARCHAR	Spectral type
`plx_value`	DOUBLE	Parallax in milliarcseconds
`plx_err`	DOUBLE	Parallax error
`pmra`	DOUBLE	Proper motion in RA (mas/yr)
`pmdec`	DOUBLE	Proper motion in Dec (mas/yr)
`rvz_radvel`	DOUBLE	Radial velocity (km/s)
`rvz_err`	DOUBLE	Radial velocity error
`galdim_majaxis`	DOUBLE	Galaxy major axis (arcmin)
`galdim_minaxis`	DOUBLE	Galaxy minor axis (arcmin)
`galdim_angle`	DOUBLE	Galaxy position angle (degrees)

`ident` — Identifier Table

Column	Type	Description
`oidref`	BIGINT	Reference to `basic.oid`
`id`	VARCHAR	Identifier string

`flux` — Photometric Measurements

Column	Type	Description
`oidref`	BIGINT	Reference to `basic.oid`
`filter`	VARCHAR	Filter name (U, B, V, R, I, J, H, K, u, g, r, i, z, G, etc.)
`flux`	DOUBLE	Magnitude value
`flux_err`	DOUBLE	Magnitude error
`bibcode`	VARCHAR	Source reference bibcode

`mesDistance` — Distance Measurements

Column	Type	Description
`oidref`	BIGINT	Reference to `basic.oid`
`dist`	DOUBLE	Distance value
`unit`	VARCHAR	Distance unit (pc, kpc, Mpc)
`minus_err`	DOUBLE	Lower error
`plus_err`	DOUBLE	Upper error
`method`	VARCHAR	Measurement method
`bibcode`	VARCHAR	Source reference

`has_ref` / `ref` — Bibliographic References

has_ref links objects to references (oidref → basic.oid, oidbibref → ref.oidbib).

`ref` Column	Type	Description
`oidbib`	BIGINT	Bibliography object ID
`bibcode`	VARCHAR	ADS bibcode
`title`	VARCHAR	Paper title
`journal`	VARCHAR	Journal name
`year`	INTEGER	Publication year

`otypedef` — Object Type Definitions

Column	Type	Description
`otype`	VARCHAR	Object type code
`description`	VARCHAR	Human-readable description

Common Object Types (otype)

Code	Description
`Star`	Star
`HII`	HII region
`PN`	Planetary nebula
`SNR`	Supernova remnant
`Galaxy`	Galaxy
`AGN`	Active galactic nucleus
`QSO`	Quasar
`GClstr`	Galaxy cluster
`GlobCl`	Globular cluster
`OpCl`	Open cluster
`Pulsar`	Pulsar
`WD*`	White dwarf
`Planet`	Extra-solar planet
`**`	Double/multiple star
`V*`	Variable star
`X`	X-ray source

Query SELECT * FROM otypedef ORDER BY otype for the full list.

ADQL Query Patterns

Spatial Queries

Cone search — objects within a radius of a point:

SELECT main_id, ra, dec, otype
FROM basic
WHERE CONTAINS(POINT('ICRS', ra, dec), CIRCLE('ICRS', 83.633, 22.014, 0.5)) = 1

Parameters: CIRCLE('ICRS', center_ra_deg, center_dec_deg, radius_deg)

Box search:

SELECT main_id, ra, dec, otype
FROM basic
WHERE CONTAINS(POINT('ICRS', ra, dec), BOX('ICRS', 180.0, 0.0, 10.0, 5.0)) = 1

Parameters: BOX('ICRS', center_ra, center_dec, width_deg, height_deg)

Polygon search:

SELECT main_id, ra, dec
FROM basic
WHERE CONTAINS(POINT('ICRS', ra, dec), POLYGON('ICRS', 10.0, 40.0, 12.0, 40.0, 12.0, 42.0, 10.0, 42.0)) = 1

Angular distance:

SELECT main_id, ra, dec,
       DISTANCE(POINT('ICRS', ra, dec), POINT('ICRS', 10.68458, 41.26917)) AS dist_deg
FROM basic
WHERE CONTAINS(POINT('ICRS', ra, dec), CIRCLE('ICRS', 10.68458, 41.26917, 0.1)) = 1
ORDER BY dist_deg ASC

JOINs

-- V-band magnitudes
SELECT b.main_id, b.ra, b.dec, f.flux AS Vmag
FROM basic AS b
JOIN flux AS f ON b.oid = f.oidref
WHERE f.filter = 'V' AND f.flux < 6.0
ORDER BY f.flux ASC

-- All identifiers for an object
SELECT b.main_id, i.id
FROM basic AS b
JOIN ident AS i ON b.oid = i.oidref
WHERE b.main_id = 'M  31'

-- Distance measurements
SELECT b.main_id, d.dist, d.unit, d.method
FROM basic AS b
JOIN mesDistance AS d ON b.oid = d.oidref
WHERE b.main_id = 'M  31'

Cross-Matching Identifiers Between Catalogs

SELECT b.main_id, i1.id AS hipparcos_id, i2.id AS gaia_id
FROM basic AS b
JOIN ident AS i1 ON b.oid = i1.oidref AND i1.id LIKE 'HIP %'
JOIN ident AS i2 ON b.oid = i2.oidref AND i2.id LIKE 'Gaia DR3%'
WHERE b.otype = 'Star' AND b.plx_value > 50

Bibliography for Objects in a Region

SELECT b.main_id, r.bibcode, r.title, r.year
FROM basic AS b
JOIN has_ref AS hr ON b.oid = hr.oidref
JOIN ref AS r ON hr.oidbibref = r.oidbib
WHERE CONTAINS(POINT('ICRS', b.ra, b.dec), CIRCLE('ICRS', 83.633, -5.375, 0.5)) = 1
  AND r.year >= 2020
ORDER BY r.year DESC

Aggregation

-- Count objects by type in a region
SELECT otype, COUNT(*) AS count
FROM basic
WHERE CONTAINS(POINT('ICRS', ra, dec), CIRCLE('ICRS', 266.417, -29.008, 1.0)) = 1
GROUP BY otype
HAVING COUNT(*) > 5
ORDER BY count DESC

-- Average parallax by spectral class
SELECT SUBSTRING(sp_type, 1, 1) AS sp_class, AVG(plx_value) AS mean_plx, COUNT(*) AS n
FROM basic
WHERE sp_type IS NOT NULL AND plx_value IS NOT NULL
GROUP BY sp_class
ORDER BY sp_class

Response Formats

TAP JSON

{
  "metadata": [
    {"name": "main_id", "datatype": "char"},
    {"name": "ra", "datatype": "double"},
    {"name": "dec", "datatype": "double"}
  ],
  "data": [
    ["M 31", 10.6847, 41.2687]
  ]
}

Script Response

Plain text with pipe-delimited fields. Lines starting with :: are metadata — filter them out. Check for error or not found in data lines to detect failures.

Rate Limits

No formal rate limits documented. Best practices: - Add time.sleep(0.5) between sequential script queries - Use TAP/ADQL for batch queries instead of looping over the script interface - Always set MAXREC or use TOP N in TAP queries to avoid accidentally downloading millions of rows - Very large TAP queries may time out; tighten WHERE clauses or switch to async TAP at /simbad/sim-tap/async - Use VOTable format for large TAP results (preserves data types and units better than JSON)

Input Sanitization

When building ADQL or script queries from user-supplied object names, sanitize inputs to prevent injection: - Block newlines, carriage returns, tabs, quotes, semicolons, backslashes, and angle brackets in object names - Escape single quotes in ADQL string literals by doubling them (' → '') - Limit input length (128 chars is reasonable) - Collapse and trim whitespace