The VELA HOTEL piggyback panels on 1961 CORONA flights

These flights provided detailed evidence for the radiation enhancement known as the South Atlantic Anomaly. The anomaly had previously been identified by Soviet scientists in data from the second Korabl'-Sputnik in Aug 1960 and hinted at by Yoshida, Ludwig and Allen (1960, JGR 65,807) in reanalysis of Explorer I data.
1961 Aug 30Discoverer 29 Agena B No. 1112 CORONA Mission 9023 (KH-3)
1961 Sep 17Discoverer 31 Agena B No. 1114 CORONA Mission 9024 (KH-3)
1961 Nov 5Discoverer 34 Agena B No. 1117 CORONA Mission 9027 (KH-2)
1961 Dec 12Discoverer 36 Agena B No. 1119 CORONA Mission 9029 (KH-3)
The X-ray detectors had two channels: a thin CsI detector which sees bursts of low energy particles above a threshold; the second channel is a large plastic scintillator which sees harder X-rays and is insensitive to the softer auroral emission.