Each Wednesday in January and February we open sales of group tickets for May and June. Spring is the peak of school group visits to the CSC, so whenever the tickets for this period are on sales, tourism industry representatives rush to buy them. This means as many as 27,000 people try to log in to our sales system (normally the number is approx. 2,000 people logged in at the same time). Despite our efforts and increased number of servers at that time, this situation leads to system operation slowdown and crashes. Bear in mind that it is much easier to buy tickets for individual visitors – to the CSC and Planetarium – on any other day than Wednesday.