Response Formats¶

The API supports six response formats. Set the format using the Accept header or the format query parameter.

Supported formats¶

Format	Accept Header	`format` Param	Description
JSON (OMM)	`application/json`	`json`	Default. Structured OMM data with derived fields.
TLE 3-line	`text/plain`	`tle`	Traditional three-line element set (name + two data lines).
TLE 2-line	`text/x-tle-2line`	`2le`	Two data lines only (no name line).
OMM XML	`application/xml`	`xml`	CCSDS OMM standard in XML.
OMM KVN	`text/x-omm-kvn`	`kvn`	CCSDS OMM Keyword-Value Notation.
CSV	`text/csv`	`csv`	Comma-separated values with header row.

Format negotiation¶

You can request a format in two ways:

Accept headerQuery parameter

curl -H "X-Api-Key: YOUR_KEY" \
     -H "Accept: text/plain" \
     https://orbital-data-api.davidhsu.cc/api/v1/gp/25544

curl -H "X-Api-Key: YOUR_KEY" \
     "https://orbital-data-api.davidhsu.cc/api/v1/gp/25544?format=tle"

If both are specified, the format query parameter takes precedence.

Format examples¶

JSON (default)¶

{
  "OBJECT_NAME": "ISS (ZARYA)",
  "NORAD_CAT_ID": 25544,
  "EPOCH": "2026-03-12T14:22:37.000Z",
  "MEAN_MOTION": 15.50238117,
  "ECCENTRICITY": 0.000573,
  "INCLINATION": 51.6416,
  "APOGEE_KM": 422.1,
  "PERIGEE_KM": 418.3
}

TLE 3-line¶

ISS (ZARYA)
1 25544U 98067A   26071.59902778  .00012769  00000-0  22936-3 0  9990
2 25544  51.6416 290.4299 0005730  30.7454 132.9751 15.50238117414250

TLE 2-line¶

1 25544U 98067A   26071.59902778  .00012769  00000-0  22936-3 0  9990
2 25544  51.6416 290.4299 0005730  30.7454 132.9751 15.50238117414250

CSV¶

OBJECT_NAME,NORAD_CAT_ID,EPOCH,MEAN_MOTION,ECCENTRICITY,INCLINATION,APOGEE_KM,PERIGEE_KM
ISS (ZARYA),25544,2026-03-12T14:22:37.000Z,15.50238117,0.000573,51.6416,422.1,418.3

TLE format limitations¶

NORAD ID > 99,999

The TLE fixed-width format allocates only 5 characters for the NORAD catalog number. Objects with IDs above 99,999 (increasingly common as the catalog grows) cannot be represented in TLE or 2LE format.

For these objects, use JSON, XML, KVN, or CSV. Requesting TLE format for an object with a high catalog number will return a 400 error.

List endpoints¶

For endpoints that return multiple records (e.g., GET /gp), the format applies to each record in the collection:

JSON: returns { "data": [...], "pagination": {...} }
TLE/2LE: returns concatenated element sets separated by blank lines
CSV: returns a single CSV with header row and one row per record
XML/KVN: returns a single document containing all records