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.

Predicted view of the Euclid Deep Field Fornax. Credit: Euclid Consortium (image); NASA/ESA, Hubble, CANDELS, Koekemoer et al. 2011, Grogin et al. 2011 (data)

Key Information on the Euclid Deep Fields:

• ~ 50 (deg)² of deep fields and calibration observations regularly interleaved within the main survey schedule.
• Observed with both "red" and "blue" grisms.
• Required to assess the redshift purity and completeness of the spectroscopic Wide Survey.
• For the detailed description, see https://www.cosmos.esa.int/web/euclid/euclid-survey.

Location of the Euclid Deep Fields (EDFs) in Equatorial (celestial) coordinates (RA/Dec):

• EDFN (North) - 17:58:55.9 +66:01:03.7: 20 deg²​ ​ x 40 visits
• EDFS (South) - 04:04:57.84 -48:25:22.8: 23 deg²​ ​ x 45 visits
• EDFF (Fornax) - 03:31:43.6 -28:05:18.6: 10 deg²​ ​ x 52 visits, 7 visits within a few hours-days every ~9 months

*Each Deep Field visit is Wide-Survey-like.