Astra 4A (originally Sirius 4) is one of the Astra communications satellites owned and operated by SES at the Astra 5°E orbital slot providing digital television and radio broadcasts, data, and interactive services to Nordic countries, eastern Europe and sub-Saharan Africa in the 11.70 GHz-12.75 GHz range of the Ku band and 18.8 GHz-21.75 GHz range of the Ka band.

In June 2010, the affiliate company was renamed SES Astra (then a subsidiary company of SES) and the Sirius 4 satellite was renamed Astra 4A.

Launched in July 2012, this satellite provides a similar European and African coverage and was originally named Sirius 5, but renamed to Astra 4B in 2010 and then to SES-5 in 2011.

The Astra 4A designation was originally given in June 2005 to 33 transponders of the NSS-10 craft (itself formerly called AMC-12) owned by another then subsidiary of SES, SES New Skies, and positioned at 37.5° west for broadcast, data, and telecommunications into Africa.

The remainder of the spacecraft was called Sirius 4 at that time (from November 2007 to June 2010).