Euclid launched in July 2023 with the primary science goals of better understanding the composition and evolution of the dark Universe. It carries two instruments: the VISible instrument (VIS) and the Near-Infrared Spectrometer and Photometer (NISP).
Quick Release 1 (Q1) was released in March 2025 and consists of approximately 35 TB of imaging, spectroscopy, and catalogs, covering four non-contiguous fields totaling 63 square degrees. Data products include MERged mosaics of calibrated and stacked frames; combined infrared spectra (SIR); and catalogs of MER objects, photometric redshifts and classifications (PHZ), and spectroscopic redshifts and line measurements (SPE).
Images¶
MER Mosaics — Retrieve both a full MER mosaic image and multi-wavelength cutouts, then subtract the background from the cutouts and extract sources.
Spectra¶
SIR 1D Spectra — Load a galaxy spectrum and plot it. Understand the wavelength, flux, and mask values.
Catalogs¶
MER Catalogs — Explore the columns in the MER final catalog, query for stars, and create a color-magnitude diagram.
PHZ Catalogs — Join the PHZ and MER catalogs and do a box search for galaxies with quality redshifts, load a MER mosaic cutout of the box, and plot the cutout with the catalog results overlaid. Then plot the SIR spectrum of the brightest galaxy and look at a MER mosaic cutout of the galaxy in Firefly.
SPE Catalogs — Join the SPE and MER catalogs and query for galaxies with H-alpha line detections, then plot the SIR spectrum of a galaxy with a high SNR H-alpha line measurement.
Merged Objects HATS Catalog — This product was created by IRSA and contains the Euclid MER, PHZ, and SPE catalogs in a single HATS catalog.
Introduction — Understand the content and format of the Euclid Q1 Merged Objects HATS Catalog, then perform a basic query.
Magnitudes — Review the types of flux measurements available, load template-fit and aperture magnitudes, and plot distributions and comparisons for different object types.
Special Topics¶
Cloud Access — Browse the on-cloud copy of Q1, then efficiently retrieve a MER mosaic cutout and a SIR spectrum.
Early Release Observations (ERO) - Star Clusters (deprecated; ERO is superseded by Q1) — Create multi-wavelength ERO image cutouts of a globular cluster, extract sources, and measure photometry. Then load Gaia sources at the location of the globular cluster, match with Euclid ERO catalogs, and visualize the results with Firefly.