Diff for "TelescopeSystemSummary" - www.iram.es Main Wiki

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

Contents

Frontends
1. Heterodyne Receivers
2. Bolometers
Telescope efficiencies and beam widths
Backends
Control System
Observing Modes and Switching Modes
Weather station and Taumeter

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.

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

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)

Observing Modes and Switching Modes

Observing mode	swTotal	swBeam	swWobbler	swFrequency
Calibrate (Heterodyne)	X
Pointing	X	X	X
Focus	X	X	X
Tip (Skydip)	X
Track				fsw
ONOFF	psw		wsw
OTFMAP (Heterodyne)	otf/psw			otf/fsw
Raster
OTFMAP (MAMBO Bolometer)			X
VLBI	X

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

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.

Old Telescope System Summary page of September 07

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

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-This page summarizes the present instrumentation at the 30m observatory. The current status is described on another 
[http://www.iram.es/IRAMES/mainWiki/TelescopeSystemStatus page].
+This page summarizes the '''present instrumentation''' installed at the 30m observatory. <<BR>> The current system '''status''' is described [[http://www.iram.es/IRAMES/mainWiki/TelescopeSystemStatus|on a second page]].

<<TableOfContents(4)>>

== Frontends ==
=== Heterodyne Receivers ===

 * EmirforAstronomers : '''new''' EMIR (Eight MIxer Receiver)
 * HeraforAstronomers : HERA 3x3 dual-polarisation 1mm receiver
 * AbcdforAstronomers : '''old''' ABCD receivers

 * [[http://www.iram.es/IRAMES/groups/receiver/receiver.html|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 ([[http://www.mpifr-bonn.mpg.de/div/bolometer/#mamgo|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 [[http://www.iram.es/IRAMES/mainWiki/MamboWebPage|the MAMBO page for details.]]

[[#beginOfPage|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


[[#beginOfPage|Back to top]]

== Control System ==

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

 . [[http://www.iram.es/IRAMES/ncs30m/|NCS documentation]] [[http://mrt-lx1/mainWiki/|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)

[[#beginOfPage|Back to top]]

== Observing Modes and Switching Modes ==

|| Observing mode                  || swTotal || swBeam || swWobbler || swFrequency ||
|| '''Calibrate''' (Heterodyne)    || X       ||        ||           ||             ||
|| '''Pointing'''                  || X       || X      || X         ||             ||
|| '''Focus'''                     || X       || X      || X         ||             ||
|| '''Tip''' (Skydip)              || X       ||        ||           ||             ||
|| '''Track'''                     ||         ||        ||           || fsw         ||
|| '''ONOFF'''                     || psw     ||        || wsw       ||             ||
|| '''OTFMAP''' (Heterodyne)       || otf/psw ||        ||           || otf/fsw     ||
|| '''Raster'''                    || || || || ||
|| '''OTFMAP''' (MAMBO Bolometer)  ||         ||        || X         ||             ||
|| '''VLBI'''                      || X       ||        ||           ||             ||

 * for more details on observing and switching modes, see the section "NCS explained" in the [[http://www.iram.es/IRAMES/documents/ncs30mPako/Current/PDF/pako.pdf|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  [[http://www.iram.es/IRAMES/mainWiki/TelescopeSystemStatus|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. [[http://www.iram.es/IRAMES/mainWiki/TelescopeSystemStatus|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
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-== Receiver Parameters ==
+== Weather station and Taumeter ==
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-A maximum of four receivers, from the total of eight, can be used simultaneously. The following table summarizes the allowed combinations and some of the most important receiver characteristics. Plots of the receiver characteristics. HERA cannot be combined with other receivers; up to now not all frequencies have been pretuned. Hera has 18 pixels separated by 24". Local contact for HERA: Albrecht Sievers
+ * [[http://mrt-lx3.iram.es/tau/meteo-main.php|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
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-Table
+ * [[http://mrt-lx3.iram.es/tau/taumeter-main-db.php|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.
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-. Using a special external LO, frequencies down to 77 GHz can be measured with good sideband rejection. For frequencies below 77 GHz,
the sideband recection becomes weaker, and the sideband ratio reaches unity at 72 GHz
+[[#beginOfPage|Back to top]]
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-. Noise increasing with frequency
+Old [[http://www.iram.es/IRAMES/telescope/telescopeSummary/telescope_summary.html|Telescope System Summary page of September 07]]
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-. 2x(3x3) pixel receiver with a 24" separation of the pixels. Equipped with a derotator allowing to follow a source in the sky maintaining the same "footprint".

== Bolometer Parameters ==

Table

local contact for bolometers: Stephane Leon

 
== Efficiencies and Half-power beam width ==

Below you find the most recent values for the forward and beam efficiencies. We have also compiled the value of the efficiencies in the past .

Here you can find the plot with the most recently measured beam efficiencies.
+This is page http://www.iram.es/IRAMES/mainWiki/TelescopeSystemSummary moderated by Carsten Kramer