This page provides information on the status of the 30m telescope for the visiting astronomers. The IRAM staff tries to keep this page up to date as much as possible. It may however happen that some information is outdated. Please contact the Astronomer of Duty or the Operator in case of doubt. Note that the present instrumentation and software at the telescope is summarized here: [http://www.iram.es/IRAMES/telescope/telescopeSummary/telescope_summary.html Telescope Summary] (CK, 30.8.08)
System - General
- The New Control System (NCS) supports source coordinates in Equatorial J2000.0 system. More system, i.e. B1950, Galactic Coordinates, etc., will be soon available.
- Observations near and towards the Sun are not yet supported.
Observations with "rotated" wobbler and the bolometer are possible within the bolometer pool; contact the pool manager, Stephane Leon, on how to prepare such observations. After finishing with rotated Wobbler, make sure that the operator puts the rotation back to exactly 0 degrees.
- Automatic calibration and processing of heterodyne data using the MIRA software is in operation for all observing modes. MIRA can also be used manually and offline.
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Antenna and wobbling secondary
- Antenna tracking errors, i.e. deviations between the commanded and actual position of the telescope, of more than 1 arcsecond are known to occur at high elevations of more than 84 degrees and/or under strong wind conditions. Please contact the Operator or Astronomer of Duty (AoD) for instructions and consider changing to a different source at lower elevations or stopping the observations. (ck - 30.8.08)
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Frontends
SIS Receivers A, B, C, D
- Image/Signal gain-ratio calibration is supported by NCS, processing in MIRA. It is highly recommended to use this feature!
A standard table of T_cold calibration temperatures for A, B, C, D receivers is implemented in the NCS. This built-in table covers most frequencies.
![/!\](/moin_static1911/modernized/img/alert.png "/!\")
Outside this range, T_cold has to be set manually, ask the RX engineers or operators! Tables and plots: http://gra-lx1/mainWiki/ReceiverGroupColdLoadPlotsCurrent (2007-10-11 dj)
- Receiver C150 shows low continuum signal at the higher frequencies (>168 GHz). It has to be fully checked. Use D150 instead. (2005-11-16)
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HERA
HERA is a HEterodyne REceiver Array, a 3x3 dual polarisation array in the 1.2mm band
- SSB (Single side band) tuning tables for standard frequencies.
- Sideband rejections not determined (2004-12-01 AW). Use standard value of 0.1!
- For HERA calibration, measured values of the load temperatures are automatically used!
- Watch the computer control of the derotator closely (2002-12-22). Make sure the derotator tracking is stopped after observations, i.e., set to zero degrees in "frame".
- The automatic tuning of both HERA1 and 2 can be improved by manually changing the mixer current according to DJ; HERA Pool managers should be aware of this, and operators will receive training (2007-09-19 RM)
- HERA 2 is more noisy than HERA 1, limiting HERA2's useful frequency range to below about 242 GHz (2006-09-27 HU according to info from SN)
- The control software does not yet support connecting HERA2 to the 4MHz backend (2008-08-29 wb). Note that paKo does not issue any warning. (ck)
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Bolometers
- MAMBO1 is OFFLINE
- MAMBO2 was re-installed and commissioned the week 13.11.2007/20.11.2007 (AS)
- MAMBO2 is on standby (ck 30.8.08)
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Backends
- 4 MHz Filterbanks cannot be used with HERA2 (28-8-08 wb, ck)
- ABBA1 is active as ABBA2 is currently commissioned at the MPIfR. It shall be reinstalled in September 08. (ck)
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Computer/Software
- Midnight bug: Online data processing, in a few circumstances, still may have problems with scans extending over midnight. Please check data and report problems to Albrecht Sievers. It is safer to avoid long scans extending over midnight. (update by ck)
- It is recommended to run the observations, i.e. to run Pako, on mrt-lx1. Pako does not run under the default gildas version on mrt-lx3, mrt-lx2. Use gag_aug06 before starting pako (2008-01-15 AS). BR Note: the instructions to start pako explicitly say to run it on mrt-lx1. The trick suggested by AS for mrt-lx2, mrt-lx3 may work, but it is not guaranteed. (update by ck)
- Data processing using MIRA or CLASS on mrt-lx3 occasionally slows down the observing system on mrt-lx1 as both system currently access the same disk, /vis, which is at present connected to mrt-lx3. This may mean that the work on mrt-lx3 has to be stopped as observations have priority. Please contact the AoD in case of such problems; for work with CLASS/GREG is helps to copy the 30m file over onto the local disk of mrt-lx2 and to continue working there. For MIRA processing of raw data, this would not help. We are working on a better solution. (2008-08-29 wb, ck)
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Heterodyne and Bolometer Pointing Model and Focus
The Pointing Model is maintained with respect to the 3mm receiver B100. The misalignment and focus error (D-focus) of the other receivers with respect to B100 is the following:
Rx misal.(") date D_focus(mm) date
A100 0.16 ±0.06 27-Feb-07, +0.09 ±0.03 13-Mar-07
A230 1.34 ±0.18 27-Feb-07, +0.43 ±0.02 13-Mar-07
B100 0.00 0.00
B230 1.74 ±0.16 27-Feb-07, +0.40 ±0.10 17-Apr-07
C150 1.26 ±0.24 5-Feb-07, +0.64 ±0.13 17-Apr-07
C270 0.78 ±0.18 5-Feb-07, +0.36 ±0.15 17-Apr-07
D150 1.03 ±0.13 12-Mar-07, +0.26 ±0.02 12-Mar-07
D270 1.40 ±0.19 12-Mar-07, +0.18 ±0.05 12-Mar-07- Pointing on spectral line sources like SiO masers is not yet supported by the data processing.
- heterodyne pointing model: last update: 2008-06-25, 29 points, previous rms = 2.58", new rms = 1.97"
- bolometer pointing model: last update: 2007-12-19, 46 points, previous rms = 2.33", new rms = 1.75"
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Pointing with SIS receivers A, B, C, D and HERA
Continuum instability ("ripple") can occur with all receivers, making pointing and focusing difficult.
In general some receivers are better than others in this respect as summarized here:
A100 generally OK for pointing. (2003-11-12) BR B100 OK, is best for pointing. B100 is the standard reference for the heterodyne pointing modelBR
C150 often bad for pointing, ripple. (2002-07-16) BR D150 generally good performance for pointing.(2002-07-16) BR A230 often unstable, bad for pointing and flux monitoring. (2003-11-12) BR B230 OK BR C270 can be unstable and difficult for pointing. (2007-04-30) BR D270 can be unstable and difficult for pointing. (2002-07-16) BR With HERA pointing may be difficult using beam switch mode - total power mode may give better results but requires excellent weather BR
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Other Items
Remote observing via VNC is available from Granada, Grenoble, Madrid, and Bonn. See https://mrt-lx1.iram.es/mainWiki/RemoteObserving
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Updates/History
To see the changes between the actual and the last version, please see Show Changes in the Wiki Interface. If you want to see the Revision History of this page, please see Get Info in the Wiki Interface.
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Legend
: OK
: ErrorThe wiki markup of these icons is:
(./) : OK
/!\ : Warning
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Obsolete
The following list of features better belongs the telescope summary page.
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)
All 4 Switching Modes are supported:
- total power
- beam switching
- wobbler switching
- frequency switching
Observing modes:
- Calibrate (for heterodyne)
- Pointing
- Focus
- Tip
- Track
- Frequency Switching
- ON-OFF
- Position Switching
- Wobbler Switching
- On-The-Fly Map
- Heterodyne
- Total Power (like Position Switching)
- Frequency Switching
- Bolometer
- Wobbler Switching
- Heterodyne
- VLBI