Diff for "TelescopeSystemSummary"

This page summarizes the present instrumentation installed at the 30m observatory.
The current system status is described on a second page.

Frontends

Heterodyne Receivers

• EmirforAstronomers : new EMIR (Eight MIxer Receiver)

• HeraforAstronomers : HERA 3x3 dual-polarisation 1mm receiver

• AbcdforAstronomers : old ABCD receivers

• Web pages of the IRAM/Granada receiver group

Bolometers

Two large field bolometer cameras are installed: MAMBO1 with 37 pixels, and MAMBO2 with 117 pixels (MAx-Planck Millimeter BOlometer Array). Usually MAMBO2 is in use. Both cameras work at 1.2mm wavelength, the HPBW is 11", pixel spacing is 20", and the sensitivity is 1.5mJy. This is the rms after 10 minutes integration (normal bolometric conditions) with skynoise removal. See the MAMBO page for details.

Back to top

Telescope efficiencies and beam widths

Iram30mEfficiencies

Backends

• Backends for the new EMIR receiver, HERA, and MAMBO: BackendsForEmirHeraMambo

• Backends for the old ABCD receivers (till mid March 2009): BackendsForAbcdReceivers

Back to top

Control System

The 30-m telescope runs under the New Control System (NCS), see:

• NCS documentation Wiki with up-to-date Notes on NCS

Observing modes and source offsets in:

• Projection "Radio" (same offsets as in old CS) in Equatorial J2000.0
• "true angle" horizontal
• Nasmyth (receiver offsets)

Back to top

Observing Modes and Switching Modes

• for more details on observing and switching modes, see the section "NCS explained" in the pako cookbook

• swTotal stands for total power observations without switching, while still using the internal synchronization signals.

• swBeam beam switched observations using the chopper wheel on mirror M4.

• swWobbler switching the wobbling secondary (M2). The maximum allowed throw is +/-2'.

• swFrequency switching the local oscillator frequency

• Pointing: Using nearby (within 10 degree) pointing sources, <1" accuracy can be obtained; with absolute ("blind") pointing, the accuracy is about 2" rms, the receivers are aligned within 1.7" (see the Telescope Status page for current values). Checking the pointing and alignment (using e.g. a planet) is the responsibility of the observer.

• Focus: residual errors of <1mm may need correction. There are systematic differences of upto 0.6mm in the focus of the different receivers (cf. Telescope Status page). The focus is subject to change especially during sunrise and sunset.

• Position switching (psw): the combination of ONOFF with swTotal is called "Position Switching". Only relative off-source reference positions are possible.

• Wobbler switching (wsw): often called double beam switching mode: max. 240" throw at 0.25 Hz, standard phase duration 0.5 Hz.

• Frequency switching (fsw): max. 45 km/s throw up to about 10 Hz.

• On the fly mapping (Heterodyne): Works with all receivers and backends, typical dump rate 0.5 to 10 Hz. OTF can be observed without reference position, e.g. for galaxies, and MIRA is able to use emission-free OTF data as reference!

• Raster mapping is at present not offered. The observer may want to use either psw or otf instead.

• Polarimetry: using VESPA as an IF polarimeter

Back to top

Weather station and Taumeter

• Weather station

  • Wind velocity and direction measured on hill behind the telescope
  • Outside temperature and relative humidity measured at base of telescope. In case the sensors are frozen, the operator will use a mobile weather station and enter values by hand into the drive program.
  • Pressure measured at entrance to control building

• Taumeter does regular skydips to inform the observer about the sky transmission near 225 GHz. The local oscillator works at 225GHz. The IF is 1.5GHz and the bandwidth is 0.5GHz. It is a double-sideband Schottky receiver.

Back to top

Old Telescope System Summary page of September 07

This is page http://www.iram.es/IRAMES/mainWiki/TelescopeSystemSummary moderated by Carsten Kramer