Acta Apostolicae Sedis often cited as AAS, is the official gazette

Gazette

A gazette is a public journal, a newspaper of record, or simply a newspaper.In English- and French-speaking countries, newspaper publishers have applied the name Gazette since the 17th century; today, numerous weekly and daily newspapers bear the name The Gazette.Gazette is a loanword from the...

 of the Holy See

Holy See

The Holy See is the episcopal jurisdiction of the Catholic Church in Rome, in which its Bishop is commonly known as the Pope. It is the preeminent episcopal see of the Catholic Church, forming the central government of the Church. As such, diplomatically, and in other spheres the Holy See acts and...

, appearing about twelve times a year. It was established by Pope Pius X

Pope Pius X

Pope Saint Pius X , born Giuseppe Melchiorre Sarto, was the 257th Pope of the Catholic Church, serving from 1903 to 1914. He was the first pope since Pope Pius V to be canonized. Pius X rejected modernist interpretations of Catholic doctrine, promoting traditional devotional practices and orthodox...

 with the decree Promulgandi Pontificias Constitutiones (29 September 1908), and publication began in January 1909. It contains all the principal decrees, encyclical letters, decisions of Roman congregations, and notices of ecclesiastical appointments. The laws contained in it are to be considered promulgated when published, and effective three months from date of issue, unless a shorter or longer time is specified in the law.

It replaced a similar publication that had existed since 1865, under the title of Acta Sanctae Sedis

Acta Sanctae Sedis

Acta Sanctae Sedis was a Roman monthly publication containing the principal public documents issued by the Pope, directly or through the Roman Congregations....

. Though not designated as the official means of promulgating laws of the Holy See, this was on 23 May 1904 declared an organ of the Holy See to the extent that all documents printed in it were considered "authentic and official". As indicated above, the Acta Sanctae Sedis ceased publication four years later.

Acta Apostolicae Sedis is published in Latin.

Since 1929, Acta Apostolicae Sedis carries a supplement in Italian

Italian language

Italian is a Romance language spoken mainly in Europe: Italy, Switzerland, San Marino, Vatican City, by minorities in Malta, Monaco, Croatia, Slovenia, France, Libya, Eritrea, and Somalia, and by immigrant communities in the Americas and Australia...

, called Supplemento per le leggi e disposizioni dello Stato della Città del Vaticano, containing laws and regulations of Vatican City

Vatican City

Vatican City , or Vatican City State, in Italian officially Stato della Città del Vaticano , which translates literally as State of the City of the Vatican, is a landlocked sovereign city-state whose territory consists of a walled enclave within the city of Rome, Italy. It has an area of...

, the city-state founded in that year. In accordance with paragraph 2 of the Legge sulle fonti del diritto of 7 June 1929, the laws of the state are promulgated by being included in this supplement.

The Acta Apostolicae Sedis and the Acta Sanctae Sedis

Acta Sanctae Sedis

Acta Sanctae Sedis was a Roman monthly publication containing the principal public documents issued by the Pope, directly or through the Roman Congregations....

are available online at the Vatican's website:
http://www.vatican.va/archive/atti-ufficiali-santa-sede/index_en.htm