Right Ascension & Declination Toolkit

Two independent tools: convert a single coordinate between decimal degrees and sexagesimal, or measure the offset between two positions.

Coordinate Converter One position → decimal degrees and sexagesimal

Input

Format

Decimal degrees Sexagesimal

RA (decimal degrees)

Dec (decimal degrees)

Seconds precision

Accepts spaces, colons or symbols — 12 30 00, 12:30:00, 12h30m00s, +22°30′00″. Decimal RA is in degrees; sexagesimal RA is in hours.

Results

Decimal degrees

—

Sexagesimal

—

Enter a coordinate above.

Separate tool

Position Difference Two positions → ΔRA, ΔDec and angular separation

Input

Format

Sexagesimal Decimal degrees

Position A

RA Dec

Position B

RA Dec

Seconds precision

FITS load reads only the header (a few kB), never the image data. Both positions are treated as being in the same equinox — no precession is applied.

Results — B minus A

Δ components (coordinate difference)

—

Angular separation (great circle)

—

On-sky offset (ΔRA × cos Dec, ΔDec)

—

Position angle of B from A (E of N)

—

Enter two positions above.

RA is normalised to [0°, 360°); Dec is constrained to [−90°, +90°].
Separation uses the Vincenty great-circle formula, which stays exact from milliarcseconds to 180°.
Runs entirely offline — no network access, no data leaves this page.