The overall active mission duration for Euclid is planned to be at least 6.5 years, with main survey operations lasting 6 years after an initial commissioning phase of 3 months following launch. If Euclid continues to be operational after this time, a mission extension could follow with additional surveys. Well characterized and validated data will be made public in three main data releases (DR1, DR2, DR3), phased with the survey progress, with the final DR3 a year after the end of the main survey.

Preceding each major DR are “quick releases” (Q1, Q2, Q3, Q4) of selected areas and data-products, to demonstrate the data to be expected, and to allow scientists to sharpen their data analysis tools.


The main component of the Q1 data shall contain Level 2 data of a single visit (at the depth of the Euclid Wide Survey) over the Euclid Deep Fields (EDFs): 20 deg2 of the EDF North, 10 deg2 of EDF Fornax, and 23 deg2 of the EDF South. The deep fields will be visited multiple times during the mission. Click here for the scope and content of Q1, and here for the product definition of Q1.

Euclid will carry out two types of surveys:

  • The Wide Survey covering ~15000 (deg)2 of the extragalactic sky, the main survey of the mission.
  • Deep Fields totaling~ 50 (deg)2 of deep fields and calibration observations regularly interleaved within the main survey schedule.

Key Information on the Euclid Wide Survey:

  • Core survey, required to meet mission objectives.
  • ~15000 (deg)2, nearly half of the extragalactic sky.
  • VIS imaging of galaxy shapes down to AB magnitude 24.5 (10 σ, extended source)
  • NISP photometry in the Y, J and H near-infrared bands (0.92 – 2.0 µm) reaching AB magnitude 24 (5σ, point source) corresponding to a photometric redshift accuracy of σ(z)/(1+z)<0.05
  • Parallel to the VIS exposures, NISP will measure redshifts with σ(z)/(1+z)<0.001 of at least 1700 galaxies/(deg)2 with a completeness higher than 45% at a detection limit of 2×10-16 erg/s/cm2 (3.5σ) for a typical source of 0.5 arcsec in the wavelength range 1.25-1.85 µm (the red grism).
  • The detailed description of the Euclid Wide Survey can be found in Scaramella et al. 2022

The Reference Observing Sequence of the Euclid Wide Survey:

  • 4 dithered pointings per 0.53 deg2 FoV common to VIS & NISP
  • Simultaneous VIS IE and NISP red grism exposures of 570s
  • VIS shutter closed (taking biases, flats, & other calibration frames), NISP imaging JE, HE, YE
  • VIS 108s exp. during the HE exposure in the 1st pointing, to extend PSF dynamic range on relatively bright stars
  • After each pointing, a dither step is applied & a new grism position is selected (RGS000 & RGS180 at 2 angles each, offset by 4 deg, to allow spectral decontamination).


ATLAS is an asteroid impact early warning system developed by the University of Hawaii and funded by NASA. It consists of four telescopes (Hawaii ×2, Chile, South Africa), which automatically scan the whole sky several times every night looking for moving objects.

ATLAS will provide a warning time depending on the size of the asteroid – larger asteroids can be detected further from Earth. ATLAS will see a small (~20 meter) asteroid several days out, and a 100 meter asteroid several weeks out. A 100 meter asteroid has approximately 10 times the destructive force of the 2021 Tonga volcanic eruption.

ATLAS also processes the survey data to search for stationary transients, which are reported to the IAU Transient Name Server. These include supernovae, CVs, stellar outbursts, and fast transients such as GRB afterglows. We also have an agreement with LIGO to search for electromagnetic counterparts to gravitational wave sources. Our colleagues in Queen’s University Belfast, Harvard, and the Space Telescope Science Institute help run these programmes. We are in the top 3 reporting groups worldwide, with more than 300 supernovae candidates found during 2016. A full list of ATLAS transient discoveries can be accessed here.

ATLAS Forced Photometry

This is the ATLAS forced photometry server, which provides full public access to photometric measurements over the full history of ATLAS survey. After registration, a user can request forced photometry at any position on the sky either for a single position, a list of positions, or moving objects (by MPC name).

ATLAS is a quadruple 0.5m telescope system with two units in Hawaii (Haleakala and Mauna Loa), and one each in Chile (El Sauce) and South Africa (Sutherland). With the installation of the two southern units, we are robotically surveying the whole sky with a cadence of 1 day between -50 and +50 and 2 days in the polar regions, weather permitting. Two filters are used, cyan and orange (denoted c and o; all mags quoted are in the AB system).

As described in Tonry et al. (2018), ATLAS surveys the whole visible sky. On each night, a sequence of 4 x 30 second exposures are taken, spaced over a period of about one hour to provide identification and orbit constraints for near-earth objects (NEOs). Discovery of NEOs and potentially hazardous objects is the main purpose of ATLAS. However the all-sky, frequent coverage, to o ~ 19.5 makes it treasure trove for time domain science. A full description is on the ATLAS homepage at

The potential for transient object science and variable star science has been described in Smith et al. (2020) and Heinze et al. (2018), respectively. We release all our transient discoveries to the IAU’s Transient Name Server.

A forced photometry means that a point-spread-function is calculated for each image based on high signal to noise stars, and a profile fit is forced at the user’s input coordinates. The forced measurement can be made on either a target image (e.g. for the measurement of flux of a variable star), or on a difference image (e.g. for a lightcurve point for a transient). Data processing and photometry are described in more detail in Tonry et al. (2018) and Smith et al. (2020).