An outdoor observation deck, named At the Top, opened on 5 January 2010 on the 124th floor. At 452 m (1,483 ft), it was the highest observation deck in the world and the highest outdoor observation deck in the world when it opened.[70] Although it was surpassed in December 2011 by Cloud Top 488 on the Canton Tower at 488 m (1,601 ft),[71] Burj Khalifa opened the 148th floor SKY level at 555 m (1,821 ft), once again giving it the highest observation deck in the world on 15 October 2014.[25][26] The 124th floor observation deck also features the Tellscope electronic telescope, an augmented reality device developed by gsmprjct° of Montréal, which allows visitors to view the surrounding landscape in real-time, and to view previously saved images such as those taken at different times of day or under different weather conditions.[72][73][74] To manage the daily rush of sightseers, visitors are able to purchase tickets in advance for a specific date and time and at a 75% discount over tickets purchased on the spot.[75]