Composite Chandra/optical image of the "plerion" (see the previous page for another example) called the "Crab Nebula" in X-rays (blue) and optical (red), with the Crab pulsar the bright star in the center of the ring. This object is the result of a supernova explosion seen during 1054 AD by Astrologers in the Far East and possibly native Americans. The gamma-rays seen by H.E.S.S. come from the donut-shaped X-ray nebula
 

 

Constructed and Maintained by
Estie Nel
North West University

Public visit to the H.E.S.S. Telescopes on Farm Goellschau, 100 km south of Windhoek (10h00 - 16h00).

The H.E.S.S. Collaboration invites the public to make use of the transportation offered by the H.E.S.S. Collaboration to visit the telescope on Saturday, 2 October. Gamma-Ray Astronomers working on the telescope will give you a guided tour through the facilities. The road to the H.E.S.S. site on the farm Goellschau is accesible from the Travel section.

Arrangements:

Interested parties are welcome to travel to Göllschau Farm, via the C 26 (Kupferbergpass Road), which should take about 1 ½ hours. Scientists will be in attendance for the whole day to show visitors around.

Please bring hats, suncream, sunglasses, closed shoes, as most of the tour will be in the sun. 
  Bring your cameras along.
  Cold drinks and food will be provided in a tent.
  The tour of the telescopes is free of charge.
  Booking in advance not necessary.
  However, camping is not possible on Göllschau Farm, but the neighbouring farms, Weissenfels or Hakos, or Weener at the foot of the Gamsberg, or Melrose and Prospekt closer to Windhoek have camping places.
Travel arrangements:
  The Namibia Scientific Society will provide a bus for interested parties not wanting to drive out by themselves.
  Departure: 7:30 at the back entrance of the Namibia Scientific Society in Love Street.
  Return journey will be after lunch.
  Costs per person N$ 120.00.
  Booking essential.
 
Some special visitors on this day include:
(1)
The South African Nomathemba Kontyo, winner of the Mars Mission assignment competition. She will be accompanied by Byren Mitchel Archary, Deputy Director: Science Platforms of the South African Department of Science and Technology on this informal visit.
(2)
A few students from the National Astrophysics and Space Science Program (NASSP) of South Africa, which attracts students from the continent of Africa. This trip to Namibia is jointly sponsored by NASSP and the Unit for Space Physics of the North-West University the South African partner for H.E.S.S.)
THE HIGH ENERGY STEREOSCOPIC
SYSTEM DETECTION TECHNIQUE
 

Very high energy gamma-rays from any cosmic source trigger an electron-photon cascade at an altitude of 10 km above sea level. Since the electrons move faster than the speed of light in the atmosphere, a shock front in the atmosphere with associated Cerenkov light is formed. This flash of blue light covers a diameter of more than 200 meter at ground level, but with a duration of a few thousandth of a millionth of a second. Ultrafast imaging cameras at the focus of each of the four telescopes capture the image, which looks different in each of the cameras. From the orientation of the image in each camera, H.E.S.S. can determine the arrival direction of the gamma-ray within a few arcminutes, even though the original Cerenkov flash was spread over more than a degree. Read the official website of H.E.S.S. for more details.
DATA ANALYSIS PROCEDURES: EXTRACTING THE GAMMA-RAY EVENTS FROM THE DIRECTION OF THE CRAB NEBULA

 

Program: HESS Open Day
Saturday, 2 October, 2004
The same CHANDRA X-ray image of the Crab Nebula (blue) and central pulsar indicated by the yellow circle. The artwork represents the Crab pulsar, with superstrong magnetic field (shown as "earlobes") and two polar cones. The pulsar mass is comparable to that of our sun, but is tiny with a diameter of only 20 to 30 kilometers. It spins around at a rotation rate of 30 times a second, resulting in a dynamo-type powerhouse, which fills the pulsar wind or plerion with energetic particles and magnetic fields. These energetic particles radiate the X-rays and gamma-rays.
   
   
   
   
Detection of TeV gamma-rays from the Crab Nebula with the stereoscopic system of telescopes. The blue parts represent the unwanted cosmic ray background, whereas the red excess represent gamma-rays coming directly from the Crab Nebula. The graph at the bottom represents the number of events as a function of the angular distance from the Crab Nebula. The circular object represents an area of the sky around the Crab Nebula, which is seen as a red dot at the center of the image. The sky appears to be void of other sources of gamma-rays within a few degrees from the Crab. Adapted from images prepared by Wystan Benbow for the H.E.S.S. Collaboration.
  
Namibia, 27 September - 2 October 2004