めも1

using System.Threading;
using System.Globalization;

protected void Calendar1_PreRender(object sender, EventArgs e)
{
Calendar1.DayNameFormat = DayNameFormat.Full;

Thread threadCurrent = Thread.CurrentThread;
CultureInfo ci = (CultureInfo)threadCurrent.CurrentCulture.Clone();
ci.DateTimeFormat.DayNames = new string[] { "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" };
threadCurrent.CurrentCulture = ci;
}