H.E.S.S. Project Chronology

Milestones and events in the history of the project

H.E.S.S. Phase I: 2004, 2003, 2002, 2001, 2000, 1999, 1998, 1997, 1996, 1994/95

With the inauguration of the four Phase I telescopes in September 2004 and first exciting physics results, the construction and commissioning of H.E.S.S. Phase I is complete (and therefore this part of the project chronology); the telescopes are in routine operation. For further scientific results, please see the H.E.S.S. publications and the H.E.S.S. Source of the Month.

2004

November 04

The H.E.S.S. Collaboration publishes the first image of a supernova where the shell is resolved as a source of TeV gamma rays (Nature 432, 75 (2004), Nature article , reprint , MPG press release (in German) , CNRS/IN2P3/CEA press release (in French), PPARC press release , APOD)

October 04

First H.E.S.S. physics results published in a refereed journal: Very high energy gamma rays from the direction of Sagittarius A* (Astronomy and Astrophysics, v.425, p.L13-L17 (2004)).

October 2nd: Open Day at the H.E.S.S. site attracts about 300 visitors. See here for pictures. The preceeding public lecture on Oct. 1 was also very well attended, and was followed by a lively discussion.

September 04

September 29 - October 1st: H.E.S.S. collaboration meeting at the Gemeindezentrum Foundation in Windhoek.

Inauguration of the four H.E.S.S. Phase I telescope, with an Open H.E.S.S. workshop at the Heja lodge on Sept. 27 and the official inauguration by Prime Minister Gurirab on the H.E.S.S. site on Sept. 38. The event included a presentation of the H.E.S.S. project by Heinz Völk, messages by Prof. Kiremire (UNAM), Dr. Mokhele (NRF/RSA), Dr. Spiro (IN2P3/France), Prof. Lüst (MPG/Germany), Dr . Giacobino (French Ministry), Dr. Berghöfer (BMBF/Germany), Mr. Faro (French Embassy), Dr. Massing (German Embassador) and the keynote speech by the Prime Minister. See here for pictures, and the inauguration web pages.
A brochure created for the inauguration provides information about the H.E.S.S. instrument, the science, and first results (Powerpoint version with full-resolution images - 15 MB).

July 04

An extensive range of H.E.S.S. physics results is presented at the International Symposium on High Energy Gamma-Ray Astronomy in Heidelberg, July 26-30. Among the highlights are the TeV gamma ray image of SNR 1713, for the first time resolving the supernova shell as the origin of the radiation, the unidentified TeV gamma-ray source in the PSR B1259 field of view - showing for the first time two sources in a single field of view - and the precise measurements of gamma rays from the direction of the Galactic center.

April 04

H.E.S.S. collaboration meeting in Durham, April 5-7.

March 04

DAQ upgrade adding 4 dual 2.8 GHz nodes and memory upgrade of farm nodes. Reorganization of control framework to speed to run startup times and data preanalysis.

Measurements to characterize performance of local and central trigger system with all telescopes.

Discovery of PSR 1259-63 in VHE Gamma-Rays with H.E.S.S.: detection of very-high-energy gamma-ray emission from the binary millisecond pulsar PSR 1259-63 at the 5.9-sigma level. The source was observed for a total of 4.6 hr live-time between Feb. 26 and Mar. 5 with the full four-telescope Cherenkov array. Preliminary estimates yield a flux at about 10 percent of the level of the Crab nebula (0.4 photons/min gamma-ray excess detected after selection cuts). Announced as IAU telegram / Astronomer's Telegram. PS 1259-63 is one of the few known pulsars forming a binary system. The pulsar is in a highly elliptical orbit around a star with about 10 times the mass of the sun. The massive "Be" star is very hot and is ejecting material from its surface, in form of a disk around the equator (see here for an illustration of a Be star). Every 3.5 years, near the point of closest approach, the pulsar passes through this disk and emerges 30 days later. During the this time, electrons accelerated by the pulsar find a dense target of photons from the Be star, which are upscattered to high energies and detected as gamma rays. For more information on this pulsar, see e.g. here or here.

January 04

Since January 04 regular operation of the 4-telescope H.E.S.S. system.

2003

December 03

The last of the four H.E.S.S. Phase I telescopes was completed by installing the camera. At the same time, the cameras of the other three telescopes were upgraded to the latest state, including an improved readout bus. First four-fold coincident events were observed in the night of Dec. 10, tracking Pictor A. See here for an image of the full telescope system.

October 03

A TOO program for 215 ksec of joint multiwavelength observations of PKS2155 with RXTE was triggered on Oct. 17, based on the TeV activity of the source.

October 15-17: H.E.S.S. general meeting in Berlin, concentrating on a review of the data analysis and the discussion of the observation program for 2004.

September 03

Alignment of mirrors on the fourth and final Phase I telescope was completed on Sept. 28.

The ROTSE 3c robotic telescope for GRB observations is operating (see here for general information about the ROTSE project). About 1/3 of its observation time is available to H.E.S.S. and is currently used for optical AGN monitoring; first light curves have been generated (e.g. for PKS 2155-304).

The third camera has been installed on telescope CT4 and was successfully commissioned. The telescope is now included in the central trigger system, which is operated in a '2 out of 3 telescope' requirement. Trigger rates are in the range of 220 Hz. About 1/3 of all triggered events are 3-fold coincidences, the remaining 2/3 involve only two telescopes. Here one of the early 3-fold coincident events (from September 22).

For the first time, online event building is active, combining the images from all telescopes in a single file, synchronized by the central trigger system. The data streams from all telescopes are directed to a single processor, where data are buffered and sorted. Every few seconds, the data stream is redirected to a different CPU to balance the load.

Quasi-online calibration and data analysis is now running on the processor farm in Namibia, and provides detailed monitoring information and results of a full image analysis shortly after a data run has ended.

Installation of mirrors on the fourth telescope ("CT1") was completed in early September and the alignment of mirrors is in progress. (For technical and historical reasons, the telescope labels ("CT1" through "CT4") differ from the order of commissioning; the first telescope ready for data taking was CT3, followed by CT2, CT4, and finally CT1).

August 03

Results on the detection of the Crab Nebula and of the AGN PKS 2155 were presented at the International Cosmic Ray Conference in Kashiwa, Japan, together with numerous more technical contributions. Also reported were data on Supernova 1006, where no signal could be detected. A compilation of the 14 conference contributions can be found here; slides of (some of) the talks and the posters are reproduced here.

Telescope coincidence trigger now in routine operation; telescope trigger thresholds were lowered from 4 pixels above 4 p.e. to 3 pixels above 4 p.e., increasing the telescope trigger rate from about 250 Hz to 2 kHz, and resulting in a two-telescope coincidence rate of about 100-120 Hz.

Shift operation is becoming routine, with close to 80% of the dark time used for data recording.

Installation of mirrors on the fourth telescope has started and is progressing well.

July 03

Alignment of the mirrors of the third telescope was completed in early July. At the same time, the optical characteristics of the first two telescopes were checked once more. No variation in the point spread function is seen over a period of a year, demonstrating the excellent stability of the dish.

June 03

The ROTSE 3C telescopes is being installed and commissioned on the H.E.S.S. site ( unloading of the telescope, installation, telescope in its shelter, opened for observations). ROTSE III is a third generation robotic telescope aiming to locate GRBs; part of its observation time is available to H.E.S.S. for other purposes. First light was reported on June 18, with images of Cen A (full field of view, enlarged section)

The central hardware trigger system for the telescopes was installed and commissioned. Is is based on VME units (top crate in the rack) and allows to trigger on arbitrary combinations of telescopes, with appropriate computer-controlled delays to compensate differences in shower arrival times at the telescopes.

May 03

Installation of mirrors on the third telescope is progressing.

April/May 03

Routine data taking with two telescopes pointing at the same source, but triggered independently. First results concerning the detection of the Crab Nebula and of the AGN PKS2155 presented at the "Second VERITAS Symposium on TeV Astrophysics of Extragalactic Sources" and submitted to the ICRC.

March 03

March 5: first two-telescope events were recorded, at this point still synchronized in software on the basis of event times in the two telescope. The distribution of event time differences between telescopes CT2 and CT3 shows a pronounced peak around t=0 due to coincident stereo events.

February 03

Mirrors of the second telescope were realigned to account for a small shift in focal plance location compared to the dummy camera used in the initial alignment.

The camera of the second telescope was installed successfully: arrival of the truck on site, unloading of the camera body, the front section of the camera body is taken off for installation, transport to the telescope, rails are used to move the camera body in, installation of the front section, and finally the camera complete with PMT drawers (Feb. 4).

January 03

To verify the absolute timing, one of the H.E.S.S. telescopes was pointed at the Crab Nebula and the optical radiation from the pulsar was monitored using a single PMT at the center of the Cherenkov camera. With only 5 min. of recording time, the pulsed signal is clearly visible. The pulsar phase shifts slightly with time, since pulsar parameters from late December are used in the analysis.

After final tests, the second camera is shipped from Paris to Namibia: the camera is first taken from LPHNE to LLR, where it is packed for transport. The camera drawers are packed separately. After the second camera has left, the mechanics of the third camera is brought from LLR to LPHNE, to be cabled and equipped,see here and here.

2002

December 02

Mirrors on the second telescope were aligned in late November/early December; the point spread function of the second telescope is identical to that of the first telescope. The telescope is now ready for the installation of the camera. Here and here images of the two telescopes with mirrors.

See also the Xmas version of a telescope and a peculiar Cherenkov image.

October 02

Mirrors were installed on the second for the four telescopes. The installation of the 380 mirror facets took less than two weeks; here pictures of the telescope on Oct. 26 and on Oct. 31.

Drives and control system were installed in the remaining two telescopes, and were tested successfully. All telescopes can now be steered from the control room.

September 02

2-4 September: Inauguration of the H.E.S.S. Experiment - the First Telescope.

Events to celebrate the official start of operation of the first telescope included an open H.E.S.S. Workshop on Sept. 2 at the Goethe Zentrum in Windhoek and the inauguration ceremony on Sept. 3 on the H.E.S.S. site, followed by a reception at the H.E.S.S. residence building. Speakers at the ceremony were Prof. W. Hofmann (MPIK), Prof. P. Katjavivi (UNAM), Prof. D. Vignaud, representing IN2P3, Dr. R. Adam, Dept. of Art, Culture, Science and Technology of RSA, Prof. H. Völk, representing Prof. P. Gruss (MPG), B. Faro, French Embassy, German Embassador H. Nestroy, and the Namibian Minister N. Angula. Pictures from the inauguration and the workshop are available here.

The sequence of events was concluded by a closed H.E.S.S. First Light Workshop on Sept. 4, also at the Goethe Zentrum in Windhoek.

Scanned articles covering the events in the press are reproduced here.

August 02

Due to extensive maintenance work on the camera, little additional test data are taken.

July 02

Test data are being recorded tracking objects such as PSR 1706-44 or PKS 2155-304. Typical data recording rates are around 150 Hz.

June 02

The 2nd telescope is fully cabled and ready for mirror installation.

June 11: the first camera is installed and operational! Images from the final steps of the installation: installation of Winston cone plate, test of the mechanism to open the camera lid. telescope with camera, the camera. First images of cosmic ray showers have been recorded, see e.g. here, here, and here.

Installation of the camera is progressing well; as of early June, the camera is in place, see also here - in the camera shelter - and tests are underway. Here a view from above, along the camera masts.

May 02

The camera transport arrived on site on May 23; here truck with the camera and the associated equipment, and the unloading.

On May 16, the first camera was shipped from Paris vis Frankfurt to Namibia: disassembly, leaving the lab, on the truck, destination Namibia. At the same time, the body of the 2nd camera was brought to Jussieu, where it will be equipped.

During commissioning studies, the first two telescopes ("CT2","CT3") were for the first time jointly tracking an object, with control and readout using the central DAQ system. Deviations between nominal and actual shaft encoder values are at the arc-second level.

April 02

Analysis of data taken earlier this year shows that the pointing of the telescopes can be controlled to a few arc seconds, using a guide telescope observing the sky and a second CCD camera monitoring the image.

April 12: Mechanical structures of all four telescopes are installed on site! In the background of the image the first telescope complete with mirrors, to the right the second, which is currently being commissioned, and on the left the two final telescopes. In the distance the Gamsberg. More images here.

Unfortunately, parts of the local fauna are very fond of the telescopes, and have found a new home there.

Early April: drives of the second telescope are installed. These drives are upgraded versions with improved guide wheels and better traction.

Upgrade of online software in progress.

March 02

While lab test of the first camera continue, perparations for the installation of the camera are in progress in Namibia: a camera shelter with a moveable roof will serve to protect the camera from sun and rain.

Feb. 02

Tests of the first camera continue in Paris, see e.g. image of a muon crossing the PMTs.

Construction on site is progressing: in the background the first two telescopes, in the foreground the baseframe of the third telescope under assembly. The fourth dish is already on site (background right).

All mirrors (380) are installed on the first telescope (see a nice view of the dish with its mirrors, views of the telescope here and here, and an image of the telescope at night), and all (except for one with a drive problem) are fully aligned. The resulting point spread function at 70^o elevation has an rms width of 0.34 mrad; 80% of the light is contained within a radius of 0.42 mrad (for reference: the pixel diameter is about 3 mrad). A profile of the point spread function on axis is shown here.

Jan. 02

Since mid-January, the 128 kb data link to the site is activated.

The missing last 20 mirrors were installed on the first telescope, mirror alignment is being finalized and tests of tracking and pointing accuracy continue.

More images from the site, showing the first two telescopes, here another view.

2001

Dec. 01

At Paris, the assembly of the camera of the first telescope has been completed and first tests are in progress. Images show a section of the camera with Winston cones and PMTs - an appropriate picture for the season - and the whole camera, here in another view, here together with its lid and with partially installed Winston cones.

More pictures from the site: here the crew of NEC, the builder of the telescope structures, and the first two telescopes with the Gamsberg in the background.

Nov. 01

On Nov. 27/28, the steel structure of the second telescope was installed in site: here lifting the dish onto the baseframe and installation of the camera bock. Here a picture of both telescopes at sunset. At the same time, the fourth dish is nearing completion at the NEC workshop in Okahandija.

Nov. 4-10: H.E.S.S. collaboration meeting and astrophysics workshop at Ringberg, to define the initial observation program. A special highlight of the meeting was covered by the local newspaper.

First results concerning image quality and image stability look very good: the width of the spot size, in the relevant range of elevations, is very small compared to a size of the camera pixels, and the 6 mm deformation of the camera masts between horizon and zenith is well within specs. (The deformation is the camera masts is monitored and corrected using LEDs on the camera, viewed by a CCD camera on the dish.)

Oct. 01

A nice article in the Namibian Allgemeine Zeitung covers the progress of H.E.S.S.

First tests of the mirror alignment procedure were quite successful: Here the image of a star in the focal plane before alignment, with the mirror drive systems at their center position. Each spot corresponds to one mirror. Compare to the image after alignment, using about 2/3 of all mirrors. Alignment is automatized, using the CCD images to steer mirrors.

Commissioning of the telescope steering is progressing: here the Crab Nebula observed with the guide telescope attached to the dish of the first H.E.S.S. telescope. The guide telescope serves to monitor the precision of the pointing. Images of the guide CCD show that absolute pointing after a first alignment is good to about 1 arcmin, as expected, and that the rms jitter during tracking is at the level of 1-2 arcsec.

Picture of the day: Namibian desktop .

The residence building is nearing completion. Here a view from the other side and of the living area. Final touches are added to the control building with its workshop and the control room. A security guard is on duty.

Nicer pictures of the telescope with mirrors, also with two of the lightning protection masts. Here a large version. See also here.

Oct 4: first tests of telescope tracking under remote control from the control room, using the DASH DAQ and control system. Nominal and actual values of the azimuth and altitude encoders agree within the encoder resolution of a few arc-sec (rms). Plot of encoder deviations vs. time, in arc-sec.

Sept. 01

Funding was approved for the installation of a 2nd tape library and a farm of 31 dual Pentium processors at MPIK, targeted (among other applications) at simulations and data handling for H.E.S.S.

Mirrors of the first telescope are installed, apart from the last 20 mirrors where parts are missing. With the trained crew, about 40 to 50 mirrors were installed each day.

Installation of the mirrors on the first telescope is progressing well, see also here; as of Sept. 6, 139 out of about 380 mirrors were installed.

Aug. 01

Installation of cable channels was finalized, and the cables between the electronics hut and dish/camera were installed.

The processor farm consisting of 16 dual 800 MHz Pentium processors with 1.3 TB disks, DLT8000 tape drives and networking equipment was installed in the control building and commissioned. Additional PCs in the control room serve to control the experiment.

Installation of mirrors has started in the last days of August, see here and here.

Final assembly of camera mechanics is in progress.

July 01

The first telescope was properly balanced. Upgrades to its drives were implemented, and the drive systems were tested extensively. Performance of the tracking feedback loop is satisfactory, with rms deviations between nominal and actual encoder values of about 1-2 arcsec.

The 60 ``drawers'' for the first camera are complete and tested.

By late July, all 4200 photomultipliers for the first four cameras (incl. some spares) were delivered to Heidelberg.

June 01

Installation proceeds with the azimuth cable chain, the altitude cable chains and the drives. Initial tests showed that the drive systems work and allow to point the telescopes, but that certain modifications are required.

The control building is ready. In the background the generator building; power is available on the site since mid-June. One of the two generators, the switchboard.

The dish of the second telescope was transported to the site and assembled there.

The light pulser system integrated into the camera lid has been completed in Heidelberg and was shipped to Paris. There, the assembly of the first camera is progressing, see e.g. the fitting of the Winston cone plates.

May 01

385 of the motorized mirror support units - sufficient for the first telescope - have been completed and await shipment to Namibia.

On May 16, the camera masts of the first telescope were installed, see here and here. There lower bracing visible in the first image is removed after installation.

On May 14, the dish of the first telescope was lifted onto the baseframe. First, the dish was lifted face down into the baseframe, see here, here and here and here. The crane is then used to turn the dish, see also here, until it is in the stable position looking at the zenith. The end of a successful day.

H.E.S.S. collaboration meeting and MC meeting in Paris, May 9-11.

The body of the first camera has been brought to Jussieu and is being cabled. Production and testing of drawers is making good progress; see here some drawers inserted into the camera body.

The baseframe of the first telescope is erected on site, see also here. The platforms of the baseframe also provide new views of the dish and of the buildings.

April 01

Construction of the buildings is progressing: the control building and the residence. Unusually late rain and strange weather cause slight delays.

The rails for the remaining rails were installed as well as the central bearing for the first telescope.

The trial assembly of the telescope base frame is progressing at NEC. Detail of the elevation bearing and of one of the nodes.

The contract with Namibia Telecom concerning the microwave link to Windhoek has been signed.

March 01

The first camera body was delivered to Paris: overall view, front view, with a drawer, rear side, which will house the trigger system, the readout and the power supplies, connectors for the drawers.

At NEC, the mount for the first telescope is growing; the image shows one of the support towers for the elevation bearings, see also here. Also, work on the 2nd concentrator has started.

Cables for the mirror drive systems were installed on the first concentrator by the crew from Hamburg.

On March 2, the second half of the first concentrator arrived on site: en route, (the tanks of the Namibian Brewery in the back are NOT going to our site!), on Goellschau, arrival on site, aligning the two halfes, preparing for assembly.

Feb. 01

Thanks to an enormous effort at NEC, the first concentrator was finished on schedule, and on Feb. 28, the first half was transported to the site: leaving NEC, bypassing freeway bridges at at Brakwasser and Lafrenz, on the gravel road, entering Goellschau, on the telescope site, unloading.

After a three-week struggle with missing infrastructure and rain, the rails for the first telescope are installed. The rails are level to 0.2 mm, significantly better than the minimum requirement of +-1 mm.

Mid-February: the space frame and the mirror supports are added to the dish. First measurements of dimensions and angles show that the structure is within tolerences, with very few corrections required.

The contract for the control building, the generator building and the residence has been awarded. Here a first view of the control building...

Jan. 01

The dish of the first telescope is being assembled at NEC.

Mounting and surveying of the azimuthal rails has started on Goellschau. Progress is slower than planned, due to bad weather and customs problems.

The H.E.S.S. processor farm and networking components are under test at Berlin, before being shipped to Namibia. One rack contains 8 dual pentiums PCs (another 8 will be added), the other the Gbit-switch, disks and tape drives and their servers.

2000

Dec. 00

Just in time for Christmas, the 1:20 model of a H.E.S.S. telescope arrived at Heidelberg (full telescope, camera section). It shows the telescope in the final color, optimized to minimize heating in the sun during daytime, and halo in the PMT wavelength region during night time.

The "cherry picker" arrives at Heidelberg. It will soon be shipped to Namibia and will be used to access telecope mirrors.

The first switchboard for the telescope control and interlocking system was delivered and is under test in Heidelberg, see here and here.

Nov. 00

Three of the four foundations for the first telescopes are completed: overview (in the background the Hohenheim communications tower, which will link the site to Windhoek by a Microwave link), one foundation, the pad where the camera will be parked and locked.

Progress at NEC: the radial beams of the telescope dish ("box sections"). (For experts: can you find U. Dillmann, the SBP engineer, on the foto?)

The precision-machined azimuth rails are packed into a container to be shipped to Namibia; in the background more mirrors.

Oct. 00

Federal support for german H.E.S.S. groups approved

Steel structures of telescopes in production at NEC: welding of dish radial beams, detail of beam, finished beams, central hub of dish.

Final version of camera drawers under test in Paris: complete drawer with 16 PMTs and electronics, front view of PMTs

Sept. 00

First set of fabrication drawings of dish released for production

Progress in the construction of the telescope foundations is illustrated here, here, here and here. See also the title page of the "Windhoek Observer".

The first container leaves MPIK for Nambia, with 200 mirrors, two azimuth bearings, tools and workshop machines. More mirrors are ready for shipping.

Aug. 00

Steel for telescope structures (~200 t) delivered to NEC from Germany and South Africa.

Construction of telescope foundations started on Goellschau site ( Construction office on Goellschau; Water pipes leading to the H.E.S.S. site are installed; Excavation of the foundations for the first telescope; Foundation for the first telescope is being filled with concrete; Work on the foundation of the second telescope)

ARS custom integrated readout chips delivered to Paris; testing of chips commences

Special production run of comparator ICs for the trigger ordered from Le Croy

July 00

Namibian stamp showing the H.E.S.S. telescopes released

Preparation of mirrors starts: metal mounting plates are being glued to the mirrors

June 00

Campaign to measure night sky brightness in the Gamsberg area

International Symposium on High Energy Gamma-Ray Astronomy in Heidelberg, organized by MPIK

May 00

HV/divider circuits for 1st telescope delivered to MPIK

Apr. 00

Exchange of Notes between Germany and Namibia concerning H.E.S.S. project signed

Contract for mount and dish steel structures awarded to NEC, Namibia

Lease for H.E.S.S. Goellschau site signed

Start series tests of PMTs at MPIK

Jan. 00

First batches of PMTs delivered to MPIK

1999

Dec. 99

H.E.S.S. Ringberg Workshop

Nov. 99

Mirrors for first telescope delivered and measured

Sept. 99

Contract for PMTs awarded to Photonis

Aug. 99

Initiate bidding process for mount and dish steel structures

1st generation ``Smart Pixel'' 19-PMT prototype operational

Decision to use ARS-based readout with sector trigger

July 99

Cooperation agreement between UNAM and MPIK signed

Mirrors mounted on Namibia site for long-term exposure tests

Initiate bidding process for PMTs

BMBF support for Berlin H.E.S.S. group approved

May 99

Visit to Nambia to clarify administrative details, including representatives of the MPG general administration

Decision to locate H.E.S.S. on the farm Goellschau in the Khomas Highland of Namibia

Contract for design of site infrastructure awarded to SCE, Namibia

March. 99

Proposal by the french groups to use the ARS analogue memory ASIC for the PMT readout, combined with a CAT-like sector trigger scheme

Jan. 99

First batches of mirrors arrive at MPIK

Start series measurements of mirror characteristics at MPIK

1998

Dec. 98

Letter of support from the President of the Republic of Namibia

Nov. 98

Visit to Namibia by a french/german H.E.S.S. delegation; begin of negociations with the owners of the Farms Goellschau and Gamsberg

Offers of the Farms Goellschau and Gamsberg in the Khomas Highland of Namibia to host the H.E.S.S. telescopes

Contract for design of mount and dish awarded to SBP

Sept. 98

Contract for mirrors awarded to COMPAS and GALACTIKA

July 98

Campaign to measure atmospheric dust in Namibia

Initiate bidding process for mirrors

Feb. 98

Proposal of the ``Smart Pixel'' concept for the modular construction of the cameras and the trigger system

Jan. 98

H.E.S.S. collaboration established at Heidelberg meeting, including MPIK Heidelberg, Humboldt Univ. Berlin, Univ. Bochum, Univ. Hamburg, LSW Heidelberg, Univ. Kiel, Ecole Polytechnique, College de France, Univ. Paris VI-VII, Saclay, Univ. della Basilicata and INFN Rome, IAS-CNR Rome.

Decision to give sites in the Gamsberg area of Namibia highest priority

1997

Dec. 97

First visit to Namibia and South Africa to evaluate potential sites

Sept. 97

Decision for SBP design of mount and dish

Ringberg Workshop

Aug. 97

Coast Steel design study delivered

July 97

SBP design study delivered

Mar. 97

H.E.S.S. Letter of Intent

Feb. 97

Visit to, and evaluation of Calar Alto site, Spain

Jan. 97

SBP design study initiated

1996

Dez. 96

Vertex design study delivered

Oct. 96

Vertex design study for mount and dish initiated
Coast Steel design study initiated

Feb. 96

First design concepts for a new telescope system

1994/95

ESO/MPI-A survey of Gamsberg site in Namibia