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fits-js

Changelog

The fits-core changelog lives alongside the source:

0.1.0

Section titled “0.1.0”

GitHub release · Latest

References: #4 · #6 · #7 · #8 · #11 · #12 · 26916cd · 74e8422 · a1ec3a0 · 853b19a · 1783b56 · 8f15e80

@fits-js/core

npm 0.1.0github 0.1.0

  • Header parsing:
  • parseHeader(bytes): fixed and free-format cards into a FitsHeader, reporting byteLength, endFound, and recovered violations on warnings
  • Typed values: logical, integer, float including the Fortran D exponent, complex, string with quote escaping
  • CONTINUE long strings and HIERARCH keywords including the ESO dialect
  • FitsHeader accessors get, getAll, getString, getNumber, getBoolean, comments, history; big integers come back exact as bigint
  • Lenient by default, matching astropy tolerance on real archive headers; { strict: true } rejects standard violations
  • HDU enumeration:
  • readHdus(bytes): walk every Header-Data Unit, locating and sizing each data unit from its keywords per the FITS size formula
  • findHdu(hdus, name, version?): lookup by EXTNAME/EXTVER; an absent EXTVER matches version 1
  • Primary, IMAGE, BINTABLE (including the A3DTABLE alias), and ASCII TABLE recognized; unknown conforming extensions are skipped so later HDUs stay reachable
  • Structural keywords are domain-validated; a missing or out-of-domain value stops enumeration with a warning and dataSizeKnown: false (lenient) or throws FitsStructureError (strict), rather than desyncing later offsets
  • Empty, shorter-than-one-block, or all-zero input reports no HDUs on warnings (lenient) or throws (strict); SIMPLE = F is surfaced as a warning in both modes
  • Random groups rejected with FitsUnsupportedError
  • readImage(hdu, reader, opts?): decode the pixels of a primary or IMAGE HDU through any reader:
  • Every BITPIX (8/16/32/64/-32/-64), decoded from FITS big-endian into the matching typed array
  • astropy-parity BZERO/BSCALE: a scaled image widens to the narrowest float that preserves it, with BLANK as NaN; the unsigned-integer convention yields Uint16/Uint32/BigUint64 (and Int8 for the signed-byte form)
  • Unscaled integer images stay integer with BLANK exposed as blank, a documented deviation from astropy
  • N-dimensional cubes; a { region } rectangular cutout fetches only the bytes the region spans
  • { raw: true } returns the on-disk array; an AbortSignal cancels the read
  • Tile-compressed images (ZIMAGE = T) reject with FitsUnsupportedError naming the algorithm, not a malformed-file error
  • Adds the FitsImage, ImageArray, ImageRegion, and ReadImageOptions types
  • The RandomAccessReader byte-source abstraction, one parser over any source:
  • BytesReader (in-memory) and BlobReader (browser Blob/File)
  • NodeFileReader (Node/Bun/Deno): async factory taking a path or URL, dynamic node:fs/promises import so importing the barrel stays browser-safe
  • HttpRangeReader (HTTP Range): LRU page cache, request coalescing, If-Range validators, short-206 follow-up, whole-body fallback when the server ignores Range, injectable fetch, AbortSignal
  • Failures are typed: request, HTTP-status, and mid-stream body errors all throw FitsIoError carrying url / status / offset and the underlying cause
  • openFits accepts signal?: AbortSignal, checked before every block read. A header without an END card reports dataSizeKnown: false, so readImage refuses the declared data unit of a malformed header.
  • openFits(reader): lazy HDU enumeration over any byte source:
  • Only header blocks are read; each data unit is sized from its keywords and seeked past, never fetched, so a remote file enumerates without materializing it and a later readImage cutout fetches only its region
  • Same sizing, classification, and strict/lenient code as readHdus, so well-formed files enumerate identically
  • maxHeaderBlocks (default 1000) bounds a malformed source that never emits END