At Chilgapsan Observatory in Cheongyang County, a group means 20 or more visitors. Individual/group prices are KRW 1,000/700 for primary pupils, 2,000/1,500 for middle and high school students, and 3,000/2,500 for adults aged 19+. Groups must reserve by phone at 041-940-2790. Weekend group visits are not permitted. Some local residents and eligible visitors may receive additional discounts; confirm required documents and applicability. Address: 178-46 Hantigogae-gil, Jeongsan-myeon, Cheongyang-gun.