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%)

The site of APEX at 5105m:

Pazifik

APEX

Quelle: Wikipedia

Quelle: ESO

APEX is in regular science operation since July 2005

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

APECS Class Diagram

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

@ www.apex-telescope.org cu…at the telescope