This is Version 2.0 of the STARSFLUX catalog of absolute spectral-flux calibrators.

A manuscript describing the STARSFLUX catalog has been submitted to MNRAS as Gamez Rosas,V., et al., 2026; Catalog of stellar spectra for absolute flux calibration for infrared observations

The STARSFLUX spectra are based on NewEra PHOENIX models described in : Hauschildt, P.H., et al., 2025, A&A 698,47

Accessing the catalog

The home page of this site:starsflux provides five links:
Download starlist: download an ASCII table of the MDFC names (mostly the SIMBAD names) of all stars
Download star table: download a CSV table containing the star names, DR3 names, DR3 coordinates, and the DR3 Astrophysical Parameters for all stars. The parameters are listed here
Download FITS files: if you know the exact name of a star, enter it here to download the FITS file, fetch a plot of the spectrum,
or fetch a summary of the Fits File header (mostly the values of the DR3 Astrophysical Parameters for this star)
Search by substring: if you know a part of the star name, enter it here. A list of up to 50 matches will be shown for further selection
Search by alias: if you know the name of the star in another catalog (e.g. 2MASS) enter it here and we will search for it in SIMBAD

What is in the FITS files?

A STARSFLUX FITS file contains a PRIMARY Header/Data Unit (HDU) and three Binary Table Extension HDUs
The PRIMARY HDU contains a header section and a data/image section.
The Primary header contains a series of keyword/value pairs describing the DR3 Astrophysical Parameters for this star and the selection of PHOENIX models that were used to construct the spectrum.
The data section contains a single long array of double precision (64-bit) floating point numbers representing the STARSFLUX spectrum for the star, in Janskys (Jy).
Binary Table 1:'OBSMAGS' contains a list of the observed catalog magnitudes (GAIA, 2MASS, ALLWISE) that were used to scale the PHOENIX model spectra for this star.
Binary Table 2:'MODMAGS' contains a list of synthetic photometric magnitudes from the model spectrum that should approximate the observed magnitudes in the previous table
Binary Table 3:'WAVE' contains the wavelengths (microns) corresponding the the spectrum in the PRIMARY HDU

DR3 Parameters in STARSFLUX CSV table:

Column Name	Description
Name	SIMBAD Star Name
RAJ2000	Right Ascension
DECJ2000	Declination
DR3Name	DR3 catalog number
Gmag	Gband magnitude
BPmag	Bband magnitude
RPmag	Rband magnitude
Teff	Effective temperature from GSP-Phot Aeneas best library using BP/RP spectra
Teff-S	Effective temperature from GSP-Spec MatisseGauguin using RVS spectra and Monte Carlo realisations
logg	Log Surface gravity from GSP-Phot Aeneas best library using BP/RP spectra
logg-S	Log Surface gravity from GSP-Spec MatisseGauguin using RVS spectra and Monte Carlo realisations
[Fe/H]	Iron abundance from GSP-Phot Aeneas best library using BP/RP spectra
[Fe/H]-S	Iron abundance from GSP-Spec MatisseGauguin using RVS spectra and Monte Carlo realisations
[alpha/Fe]-S	Alpha element ratio from GSP-Spec MatisseGaugin using RVS spectra and Monte Carlo realisations
SpType	MK Spectral Type

Hints to select a good calibrator:

SearchCal is a tool developed by the JMMC to assist the astronomers in this calibrator selection process for long baseline interferometric observations. It can be accessed here: SearchCal "

A guide for selecting calibrators for MATISSE can be found in the SearchCal Wiki Page: Search Cal Hints

In the same webpage can be found a catalogue of known bad calibrators: Bad Calibrators

We strongly recommend using the infrared excess ("IRflag") and calibrator ("CalFlag") flags displayed in the catalog of Cruzalebes et. al 2019 to identify good calibrators. We remark that it is highly recommended that the calibrator's magnitudes match those of the science target.

For requesting other spectra, npy files, fits files, or any complementary data please contact v.gamezrosas@southampton.ac.uk

This page is in constant change, for any doubts please write us to the email provided above.

Last update: 13 July 2026