|
Size: 4648
Comment:
|
← Revision 212 as of 2009-07-07 13:46:21 ⇥
Size: 6292
Comment:
|
| Deletions are marked like this. | Additions are marked like this. |
| Line 3: | Line 3: |
| [[Anchor(beginOfPage)]] | <<Anchor(beginOfPage)>> '''Note that this page is no longer maintained. It has been replaced by a new page [[http://iram-institute.org/EN/content-page.php?ContentID=58&rub=7&srub=55&ssrub=58&sssrub=0&ssssrub=0|here]].(ck, 7.7.09).''' |
| Line 6: | Line 9: |
| 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]. | |
| Line 8: | Line 10: |
| [[TableOfContents(4)]] | ------ ------ ------ 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)>> |
| Line 12: | Line 22: |
| ==== A,B,C,D single pixel receivers ==== 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. |
|
| Line 15: | Line 23: |
| ==== HERA 3x3 dual-polarisation 1.2mm array ==== 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 |
* EmirforAstronomers : '''new''' EMIR (Eight MIxer Receiver) * HeraforAstronomers : HERA 3x3 dual-polarisation 1mm receiver * AbcdforAstronomers : '''old''' ABCD receivers |
| Line 18: | Line 27: |
| ||'''Rx''' ||'''Pol'''|| || || || || '''tuning range''' || '''Trx''' || '''IF''' || '''IF Bw''' || '''Gim''' || '''Remarks''' || || || || || || || || '''[GHz]''' || '''[K]''' || '''[GHz]''' || '''[GHz]''' || '''[dB]''' || || ||A100 || V || X || || X || || 80.0-115.5 || 60-80 || 1.5 || 0.5 || >20 || 1. || |
* [[http://www.iram.es/IRAMES/groups/receiver/receiver.html|Web pages of the IRAM/Granada receiver group]] |
| Line 22: | Line 29: |
| ||B100 || || || || || || || || || || || || || || ||C150 || || || || || || || || || || || || || || ||D150 || || || || || || || || || || || || || || ||A230 || || || || || || || || || || || || || || ||B230 || || || || || || || || || || || || || || ||C270 || || || || || || || || || || || || || || ||D270 || || || || || || || || || || || || || || ||HERA || || || || || || || || || || || || || || ||HERA || || || || || || || || || || || || || || |
=== Bolometers === |
| Line 32: | Line 31: |
| 1. 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 | 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.]] |
| Line 34: | Line 33: |
| 1. Noise increasing with frequency | [[#beginOfPage|Back to top]] |
| Line 36: | Line 35: |
| 1. 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". === Bolometers === Table |
== Telescope efficiencies and beam widths == |
| Line 40: | Line 37: |
| local contact for bolometers: Stephane Leon | Iram30mEfficiencies |
| Line 42: | Line 39: |
| == 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. Table 1) The HPBW can be well fit by: HPBW('') = 2460/freq(GHz). '' ''2) The data can be well fit by a Ruze function B_eff = 1.2 epsilon exp[-(4pi R sigma/ lambda)^2] with sigma being the rms value of the telescope optics deformations, R the reduction factor for a steep main reflector, epsilon the aperture efficieny of the perfect telescope and lambda the wavelength in mm. The data can be fit by R*sigma = 0.07 and epsilon = 0.69. The aperture efficiency of the 30-m telescope can be obtained using eta_a=B_eff*0.79 '' ''3) For a Gaussian source and beam size, and a source which is much smaller than the beam, S(Jy)/T_mb(K)=8.18E-7*theta(")^2*nu(GHz)^2 (Rohlfs & Wilson, Tools of Radioastronomy (2. ed., Eq. 8.20). Using the approximation in 1) yields for the 30-m telescope S/T_mb=4.95 Jy/K. S/T_A* is obtained by multiplying 4.95 J/K with F_eff/B_eff '' ''Table '' ''4) The values for F_eff are valid after the 12th of December 2000 when a new reflecting ring was put around the secondary mirror. The moon efficiencies are equal to forward efficiencies (Kramer et al. 1997). '' |
|
| Line 60: | Line 41: |
| === Spectrometers === Table |
|
| Line 63: | Line 42: |
| === Bolometer backends === == Spectral Line Observing Modes == * '''Position switching''': only relative OFF positions possible (radio projection offsets). * '''Wobbling secondary''': max. 240" throw at 0.25 Hz, standard phase duration 0.5 Hz. * '''Frequency switching''': max. 45 km/s throw at max. 0.5 Hz., with 100 kHz filters and autocorrelator only * '''On the fly mapping''': Works with all receiver and backends, typical dump rate 0.5-1 Hz |
* 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. |
| Line 70: | Line 91: |
| * '''Pointing''': Using nearby (within 10 degree) pointing sources, <1" accuracy can be obtained; with absolute ("blind") pointing, the accuracy is <4", the receivers are usually aligned within 2". 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 may be systematic differences (<0.4") in the focus of the different receivers. Check focus at least at after sunrise and sunset. |
[[#beginOfPage|Back to top]] == Weather station and Taumeter == * [[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 * [[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. [[#beginOfPage|Back to top]] Old [[http://www.iram.es/IRAMES/telescope/telescopeSummary/telescope_summary.html|Telescope System Summary page of September 07]] This is page http://www.iram.es/IRAMES/mainWiki/TelescopeSystemSummary moderated by Carsten Kramer |
Note that this page is no longer maintained. It has been replaced by a new page here.(ck, 7.7.09).
This page summarizes the present instrumentation installed at the 30m observatory.
The current system status is described on a second page
Contents
Frontends
Heterodyne Receivers
EmirforAstronomers : new EMIR (Eight MIxer Receiver)
HeraforAstronomers : HERA 3x3 dual-polarisation 1mm receiver
AbcdforAstronomers : old ABCD receivers
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
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:
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
- 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