SPACETRC / JWST SPECTRAL LABORATORY
Measurable traces
inside the light.
Open real James Webb measurements with wavelength, flux, uncertainty and quality masks. Overlay spectra, measure a line window and export the method alongside the data.
No MAST connection starts on page load. These three spectra are dated extracts from real public JWST x1d products; observations are from 2022 and calibration versions from 2022/2025. No recalibration has been performed.
01 / CHOOSE MEASURED DATA
Three products. Explicit provenance.
The NGC 7319 target field, a separate background pointing and different instruments/apertures are compared. Matching units do not mean matching physical areas or calibration. Overlay is visual; no automatic normalization or background subtraction is applied.
No spectrum loaded. Source retrieval: 2026-10-24T19:14:30Z
02 / WAVELENGTH · FLUX · QUALITY
One chart, explicit units.
Horizontal axis: µm; vertical axis: Fν / Jy. DQ is a bitmask; a nonzero value does not mean zero flux. DNU: bit0; NON_SCIENCE: bit9. Overlay refuses mismatched units. Jy is not converted to surface brightness in MJy/sr without aperture information.
Visible measurement table · first 120 rows
| Product | λ / µm | Fν / Jy | σFν / Jy | DQ |
|---|
Exports preserve every row in the view; this table shows only the first 120.
03 / EDUCATIONAL MEASUREMENT
Line centroid and conditional redshift.
Select a line window and two separate continuum windows in the primary product. The tool subtracts a locally constant continuum and computes the first wavelength moment of Fν samples. It does not identify a line or molecule; this is not a physical line-profile fit.
No measurement yet.
Method, uncertainty propagation and limitations
The continuum is an inverse-variance weighted constant from two side windows, assuming independent errors. Centroid μ = Σ λᵢ Δλᵢ (Fνᵢ−C) / Σ Δλᵢ (Fνᵢ−C); absorption reverses the sign. Bin widths come from adjacent wavelength midpoints. Propagation includes the line-sample errors and shared continuum uncertainty.
Redshift z = μ/λ₀−1; uncertainty propagates the centroid and supplied rest-wavelength error. Fν→Fλ conversion, pixel covariance, continuum slope, blends, instrumental line spread and wavelength systematic errors are not included. Results should not be treated as definitive publication-ready measurements.
04 / MAST · CURRENT PRODUCT DISCOVERY
Which other spectra cover this target?
Search the official MAST spectral service for x1d product filenames by exact target name and a window up to 0.5 µm wide. This is product discovery: it does not load new files into the chart, download large cubes or request telescope observations.
No current search has run. Dated spectra work in the static preview; current reads require the native WordPress connection.
Official MAST search guide ↗Sources, rights and research note
Selected standard public JWST mission data are credited to NASA/ESA/CSA James Webb Space Telescope, STScI MAST and program 2732. Other MAST holdings may have different licensing or access conditions; this page packages no DSS, GSC or community HLSP data. No institutional partnership or endorsement is claimed.
Dates, instrument, aperture, source filename, actual calibration version and SHA-256 checksums travel with the data. Export does not imply a new scientific observation; it records source measurements and the educational method applied in this browser.