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WASS


The Wisconsin All-Sky Survey (WASS) sounding rocket program was a project to map the diffuse X-ray background at multiple bands between 0.1 and 6 keV by instruments flown on a series of rocket flights between late 1972 and early 1980.

The two November 1973 flights were launched from Australia’s Woomera Rocket Range. All other rocket launches were from the White Sands Missile Range in New Mexico. The same payload was used in eight of the flights, and a smaller version in two of the earlier flights (Dec 1972 and Nov 1973).

Scan paths for the rocket flights used in the survey, shown in galactic coordinates. The path for flight 25.045 is shown as a dashed line: This flight had a malfunctioning attitude control system.

Mission Characteristics

Lifetime
1972–1979
Special Features
Series of rocket flights to collectively map the diffuse soft X-ray background

Payload

Wisconsin All-Sky Survey rocket flights
Date Target (l,b) Flight No Date Target (l,b) Flight No
8 Dec 1972168.2, -9.5 13.083 1 Nov 1973227.9,-56.4 13.103
12 Nov 1973226.8,-66.6 13.102 20 Jul 1974 64.2,+12.8 13.084
8 Nov 1975131.8,-29.2 13.049 15 Jan 1977183.5,+15.3 13.122
25 May 1977 54.0,+41.6 26.061 6 May 1978 52.2,+63.7 13.137
15 Mar 1979193.7,+50.7 25.045 21 Jan 1980192.1,+41.4 25.051

Proportional Counter

Energy Range
0.1–6 keV
Field of View
6.5° circular
Gas proportional counter with three-sided anti-coincidence, filled with a 90% argon 10% methane mix at ∼1 atm pressure. Honeycomb Collimators gave a 6.5° circular field of view. Data collection was performed by scanning over a fan-shaped field. Each individual flight scanned roughly one eighth of the sky.

Science Highlights

First complete all X-ray survey of the diffuse background in seven different X-ray band.

Archive

The HEASARC hosts the WASS maps