readHdus

function readHdus(bytes, options?): ReadHdusResult;

Defined in: hdu/read-hdus.ts:264

Walk every Header-Data Unit in a FITS source. Headers are parsed; data units are located and measured but not decoded, so the whole structure of a multi-gigabyte file is enumerable from a buffer cheaply.

The deprecated random-groups format is rejected with FitsUnsupportedError. A conforming extension of an unrecognized type is returned with type: "unknown" and its bytes skipped so later HDUs stay reachable. If a structural keyword needed to size a data unit is missing or out of domain, enumeration stops there (lenient, with the HDU’s dataSizeKnown set to false) or throws FitsStructureError (strict) rather than desync every later offset.

Parameters

Parameter	Type
bytes	Uint8Array
options	ParseHeaderOptions

Returns

ReadHdusResult

Example

import { readHdus, findHdu } from "@fits-js/core";

const { hdus } = readHdus(bytes);
const sci = findHdu(hdus, "SCI", 1);

See

FITS Standard v4.0 §3.3-3.4: primary HDU and extensions (random groups: §6)