The first public HDTV broadcast in the United States occurred on July 23, 1996 when the Raleigh, North Carolina television station WRAL-HD began broadcasting from the existing tower of WRAL-TV south-east of Raleigh, winning a race to be first with the HD Model Station in Washington, D.C., which began broadcasting July 31, 1996. The American Advanced Television Systems Committee (ATSC) HDTV system had its public launch on October 29, 1998, during the live coverage of astronaut John Glenn's return mission to space on board the Space Shuttle Discovery. The signal was transmitted coast-to-coast, and was seen by the public in science centers, and other public theaters specially equipped to receive and display the broadcast. The broadcast was made possible by the Harris Corporation, which sponsored the equipment necessary for transmitting and receiving the broadcast.High-definition television (HDTV) yields a better-quality image than standard television does, because it has a greater number of lines of resolution. The visual information is some 2-5 times sharper because the gaps between the scan lines are narrower or invisible to the naked eye. The larger the size of the television the HD picture is viewed on, the greater the improvement in picture quality. On smaller televisions there may be no noticeable improvement in picture quality.The lower-case "i" appended to the numbers denotes interlaced; the lower-case "p" denotes progressive. With the interlaced scanning method, the 1,080 lines of resolution are divided into pairs. The first 540 alternate lines are painted on a frame and then the second 540 lines are painted on a second frame. The progressive scanning method simultaneously displays all 1,080 lines on every frame, requiring a greater bandwidth.