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APEX Control System
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Home > Observing with APEX > APEX Control System > Basic APECS commands

Basic APECS commands

This page explains in detail the setup of observing projects at APEX through some basic APECS commands. Note that the information on this page is not needed to submit your project details - it is provided only for those who want to know more about APECS.

Frontends and Backends

The available frontends for APEX are listed on the system summary page. Possible receiver options currently include APEX-1 (known to the system as "het230"), APEX-2, LABOCA, FLASH (which is a PI instrument), and a few more.

With the arrival of the XFFTS backend, the setup for heterodyne projects is much simpler than before.

Example 1: LABOCA

frontends(['laboca'])
laboca.backends(['abba'])

Example 2: APEX-1

exec_apecs_script('shfi_commands')
setup_shfi(fename='het230',linename='co(2-1)',sideband='',mode='spec', cats='sys')

Source and line catalogs and selection

Source information and (in case of heterodyne observations) line information can be given as APECS commands or can be stored in catalogs which will be loaded after startup by the APECS system (which is the preferred way). There are system-wide catalogs, with e.g. pointing sources and widely accepted molecular line frequencies, and user catalogs, which include your target sources and special molecular line frequencies.

For projects with just one (or a few) sources it is probably easier to specify all source information using the source command of APECS instead of preparing a source catalog. An example would be:

source(name='R-And',x=('00:24:01.939','hms'),y=('38:34:37.12','dms'),system='eq',epoch=2000.0,velocity=-15.0,frame='LSR')

This command line contains all the information that you could have put into a source catalog.

Observing procedures, patterns, reference positions, offsets, ...

The basic switch mode for heterodyne observations currently is position switching. Other switch modes (wobbler switching and frequency switching) will be implemented in the future. For mapping of extended sources this switch mode can be combined with an on-source raster pattern. In addition, on-the-fly mapping is available, moving the telescope continuously and observing a reference position after each subscan.

Example setup and observing macros

We have collected a number of example macros which give you an idea how the projects are set up and observed in practice.

Further information

Full documentation of the APECS CLI can be found in the following document (pdf format):