WST ETC

IFS i

Type: Integral Field Spectrograph

Spaxel Size: 0.25"

IQ Telescope: 0.10" FWHM

IQ Instrument: 0.13" FWHM

Moffat Beta: 2.50

RON: 1.0 e⁻

Dark Current: 1.0 e⁻/pixel/h

Blue Channel:

Range: 3700-6400 Å

Å/pixel: 0.48

LSF: 2.5 pixels

Red Channel:

Range: 6200-9800 Å

Å/pixel: 0.64

LSF: 2.5 pixels

Blue

Red

MOS High Resolution i

Type: Multi-Object Spectrograph (High-Res)

Fiber Aperture: 1.00"

IQ Telescope: 0.1875" FWHM

IQ Instrument: 0.16" FWHM

Moffat Beta: 2.50

RON: 1.0 e⁻

Dark Current: 1.0 e⁻/pixel/h

Blue Channel: (dioptric)

Range: 4009-4431 Å

Å/pixel: 0.027, Pixel Size: 0.0925"

LSF: 3.6 pixels

Green Channel: (dioptric)

Range: 4522-4998 Å

Å/pixel: 0.032, Pixel Size: 0.0925"

LSF: 3.6 pixels

Yellow Channel: (dioptric)

Range: 5424.5-5995.5 Å

Å/pixel: 0.043, Pixel Size: 0.0925"

LSF: 3.6 pixels

Red Channel: (dioptric)

Range: 6080-6720 Å

Å/pixel: 0.048, Pixel Size: 0.0925"

LSF: 3.6 pixels

Blue

Green

Yellow

Red

MOS Low Resolution i

Type: Multi-Object Spectrograph (Low-Res)

Fiber Aperture: 1.03"

Pixel Size: 0.208"

IQ Telescope: 0.1875" FWHM

IQ Instrument: 0.20" FWHM

Moffat Beta: 2.50

RON: 1.0 e⁻

Dark Current: 1.0 e⁻/pixel/h

Blue Channel:

Range: 3700-4770 Å

Å/pixel: 0.206

LSF: 6.8 pixels

Green Channel:

Range: 4630-6080 Å

Å/pixel: 0.266

LSF: 6.8 pixels

Yellow Channel:

Range: 5920-7710 Å

Å/pixel: 0.344

LSF: 6.8 pixels

Red Channel:

Range: 7490-9800 Å

Å/pixel: 0.362

LSF: 6.8 pixels

Blue

Green

Yellow

Red

Spectral Coadding

Only positive numbers are allowed

Spatial Coadding

Object Displacement [arcsec]

Value must be between 0 and 0.6

SED

SED Type

Type

Redshift (z)

Redshift must be ≥ 0

Temperature [K]

Temperature must be > 0

Redshift (z)

Redshift must be ≥ 0

Index

Redshift (z)

Redshift must be ≥ 0

Central λ [Å]

Central wavelength must be > 0

FWHM [Å]

FWHM must be > 0

Spectrum File (.txt, .dat)

Two columns: wavelength, flux.
Optional header comments:
# nm or # aa (wavelength unit, default: Å)
# fl or # ph (flux unit, default: erg/cm²/s/Å)

Normalize to magnitude

Brightness

Magnitude System

Magnitude

Filter

Flux [erg/cm²/s]

Flux must be > 0

Morphology

Type

R_eff [arcsec]

R_eff must be > 0

n

n must be > 0

Airmass

Airmass must be between 1 and 3

PWV

FLI

FLI must be between 0 and 1

Moon-Target Separation (deg)

Moon-Target separation must be between 0 and 180°

Seeing at 5000 Å

Seeing must be positive

Computation Mode

DIT [s]

DIT must be positive

NDIT

NDIT must be a positive integer

SNR

SNR must be positive

Wavelength [Å]

Wavelength must be positive

RESULTS

Version 1.2 - 29 April 2026 Changelog

Changes in v1.2 vs v1.0

• Throughput curves (all channels) delivered by Olga Bellido (WST System Engineer) for v1.0 and remain valid in v1.2.

• Fixed sky background area computation: now correctly uses pi*r^2 (previously a typo was computing pi^2*r*2).

• Fixed IFS red-channel RON: now 1.0*sqrt(2) = 1.4 e- (consistent with blue channel; previously was 1.0*2^0.25 = 1.2 e-).

• Fixed MOS surface-brightness SNR computation that was raising an error.

• Fixed MOS total throughput: now includes the fiber injection fraction (fiber inj. frac.); a dedicated fiber inj. frac. curve is now shown in the web plots.

• Added moon-target separation as a user-settable parameter (MOON_SEP, default 45°); previously fixed at 45° internally.

• Fixed MOS object displacement validation range: now correctly 0–0.6 arcsec (previously the web interface rejected values above 0.3 arcsec).

• Fixed SkyCalc sky background retrieval: bypassed skycalc_ipy.get_sky_spectrum() to call SkyModel directly and read the returned FITS HDUList with format="fits" explicitly, resolving an IORegistryError from newer astropy versions. Moon altitude is now correctly derived as z_moon = rho + z_target, satisfying the SkyCalc constraint for all airmasses.

- Contact: ✉️ wst_etc_feedback@inaf.it

📥 API Script 📓 Notebook i

WST ETC API — wst_cli.py

1. Save config with 📥 Save Config button

2. Edit JSON, optionally add "compute_mode"

3. python wst_cli.py config.json -o out.json

Compute modes:

dit_ndit — DIT+NDIT→SNR (default)

dit_snr — DIT+SNR→NDIT

ndit_snr — NDIT+SNR→DIT

best — SNR→optimal DIT+NDIT

Options:

-o file save to file · -i 4 indent · -c collapse arrays

Notebook:

📓 API_results.ipynb — Jupyter notebook to load and plot API results

Configure parameters and click Compute to see results here...