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APEX(ATACAMA PATHFINDER EXPERIMENT)
Heiko Hafok, Dirk MudersMax-Planck-Institute for Radioastronomy, Bonn, Germany
APEX collaborators:
• Max-Planck-Institute for Radioastronomy, Bonn, Germany (50%)
• European Southern Observatory (ESO) (27%)
• Onsala Space Observatory, Chalmers, Sweden (23%)
APEX Key FactsTelescope
Location Llano de Chajnantor,
50km east San Pedro de Atacama, Northern Chile
Coordinates
Latitude
Longitude
Elevation
23º00′20.8″ South
67º45′33.0″ West
5107m
Telescope diameter 12 m
Total mass 125 t
Main reflector 264 aluminium panels, average panel surface r.m.s. 5 µm
Overall surface accuracy 17 µm
Pointing accuracy 2“ r.m.s. over sky
Manufacturer Vertex Antennentechnik GmbH, Germany
Optics:
f/D
Beam width (FWHM)
Receiver cabins
8
7.8 ″ (800 / f [GHz])
2 Nasmyth, 1 Cassegrain
Instrumentation:
Spectral coverage
Frontends
200-1500 µm
Heterodyn single-pixel + array receivers
Large bolometer cameras
Backends Facility Autocorrelator
New technology Fast Fourier Transform Spectrometer
ACS @ APEX
• APEX uses the same vendor-supplied control computers (ACU & PTC) and the same CAN bus interface (ICD 9) like ALMA
• It was thus decided to re-use the ALMA prototype telescope control software (TICS & ACS) and most of the corresponding control hardware setup
ACS / TICS Versions
• APEX is using TICS and thus ACS under VxWorks
• The ACS version in use has been determined by TICS (currently ACS 2.0.1)
• Preliminary work to port to ACS 6.x started, but currently on hold because of other commitments.
• This requires porting of both:– TICS under VxWorks (replaced in ALMA by a new
Control System based on Real Time Linux)– The APECS layer (see next slide)
APECS (APEX Control System)
• Developed a number of generic instrument interfaces and C++ components using the U Bochum code generator, UDP socket DevIO and embedded system SCPI parsers
• Added Python Observing Engine, Raw Data (MBFITS) Writer, Calibrator, Monitoring Engine, Observations Logger, Observer CLI based on IPython and many more (see ADASS XV)
• APECS v0.8 is now used regularly for science observations
Deployment
• APECS is deployed at three locations:– Telescope (co-rotating)– Control room Chajnantor– Control room Sequitor
• 8 PCs with ACS/TICS/APECS, 1 VME computer, 5 embedded systems
ACS Experience
• General setup works as expected• Distributed deployment without major
problems• Monitoring properties very valuable• Notification channel (in ACS 2) is affected
heavily by client behavior and can bring system to a halt
• Alarm system in ACS 2 not yet adequate• No access control for critical components