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Drop a FITS file (.fits / .fit / .fts) here, or open one from disk. Parsing and rendering happen entirely in your browser — nothing is uploaded.

READING FILE…

CUTOFFS

HISTOGRAM

COLORMAP

Smooth pixels Show grid

X, Y—

VALUE—

RA, DEC—

VIEW

ZOOM—

CENTER—

POS —

VALUE —

ZOOM —

SCALE linear · pctl 99.5%

drag to pan · wheel to zoom · double-click to fit

About Reticle

A from-scratch FITS reader and renderer. No parsing or image libraries are used — the FITS binary format, WCS approximation and colormaps are all implemented directly in this page.

Known limitations, so nothing here overclaims:

Compressed FITS (.fits.gz, tile-compressed / RICE / HCOMPRESS) is not decoded.
WCS is a linear tangent-plane approximation from CRVAL/CRPIX/CDELT or CD — no SIP/TPV distortion terms.
BINTABLE / ASCII table extensions are listed but not rendered — image (array) HDUs only.
BLANK keyword handling is not applied; NaN/Inf floats render as transparent.