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

Differences between revisions 4 and 57 (spanning 53 versions)

THIS PAGE IS STILL UNDER CONSTRUCTION For the moment, please use the old [http://www.iram.es/IRAMES/telescope/telescopeSummary/telescope_summary.html Telescope System Summary page] BR

This page summarizes the present instrumentation at the 30m observatory. BR The current status is described on another [http://www.iram.es/IRAMES/mainWiki/TelescopeSystemStatus page].

TableOfContents(4)

Frontends

Heterodyne Receivers

Eight single pixel, dual-sideband receivers A,B,C,D, and the 3x3 dual-polarisation HERA receiver are installed.
Four of the 8 A,B,C,D receivers can be used simultaneously. HERA cannot be combined with other receivers.

Rx	Pol						tuning range	Trx	IF	IF Bw	Gim	Remarks
							[GHz]	[K]	[GHz]	[GHz]	[dB]
A100	V	X		X			(72-)80.0-115.5	60-80	1.5	0.5	>20	1.
B100	H	X			X		(72-)81.0-115.5	60-85	1.5	0.5	>20	1.
C150	V		X		X		130-183	70-125	4	1	15-25
D150	H		X	X			130-183	80-125	4	1	08-17
A230	V	X		X			197-266	85-150	4	1	12-17
B230	H	X			X		197-266	95-160	4	1	12-17
C270	V		X		X		241-281	125-250	4	1	10-20	2.
D270	H		X	X			241-281	150-250	4	1	9-13	2.
HERA1	H					X	215-272	110-380	4	1	~10	2.,3.
HERA2	V					X	215-241	120-340	4	1	~10	2.,3.

Remarks:

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
Noise increasing with frequency
[http://www.iram.es/IRAMES/mainWiki/HeraWebPage More information on HERA ]

Bolometers

|| Bolometer || Beam || Lambda|| Pixels || Spacing || rms (1.) ||

MAMBO I	11"	1.2 mm	37	20"	1.5 mJy
MAMBO II	11"	1.2 mm	117	20"	1.5 mJy

rms after 10 minutes (normal bolometric conditions) with skynoise removal.

Efficiencies and Half-power beam width

Below you find the most recent values for the forward and beam efficiencies. We have also compiled the [http://www.iram.es/IRAMES/telescope/telescopeSummary/effi_history.html value of the efficiencies in the past].
Here you can find the [http://www.iram.es/IRAMES/telescope/telescopeSummary/beam_effis.html 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).

Backends

Spectrometers

Table

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
Polarimetry: using VESPA as an IF polarimeter
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.

-  ⇤ ← Revision 4 as of 2008-08-30 19:57:30 → 
  Size: 3609
  Editor: 24
  Comment:
+   ← Revision 57 as of 2008-08-31 19:16:30 → ⇥
  Size: 5687
  Editor: 24
  Comment:
-Deletions are marked like this.
+Additions are marked like this.
 Line 3:
-Line 8:
+Line 7:
-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]. 
 
[[TableOfContents(3)]]
+'''THIS PAGE IS STILL UNDER CONSTRUCTION''' For the moment, please use the old [http://www.iram.es/IRAMES/telescope/telescopeSummary/telescope_summary.html Telescope System Summary page] [[BR]]



This page summarizes the present instrumentation at the 30m observatory. [[BR]] The current status is described on another  [http://www.iram.es/IRAMES/mainWiki/TelescopeSystemStatus page].

[[TableOfContents(4)]]
-Line 14:
+Line 16:
-=== Heterdyne Receivers ===
+=== Heterodyne Receivers ===
-Line 16:
+Line 18:
-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
+ * Eight single pixel, dual-sideband receivers A,B,C,D, and the 3x3 dual-polarisation HERA receiver are installed.

 * Four of the 8 A,B,C,D receivers can be used simultaneously. HERA cannot be combined with other receivers. 

||'''Rx''' ||'''Pol'''||   ||   ||   ||   || ||'''tuning range''' || '''Trx'''   || '''IF'''    || '''IF Bw''' || '''Gim'''  || '''Remarks''' ||
||         ||         ||   ||   ||   ||   || ||'''[GHz]'''        || '''[K]'''   || '''[GHz]''' || '''[GHz]''' || '''[dB]''' || ||
||A100     || V       || X ||   || X ||   || ||(72-)80.0-115.5         || 60-80       ||  1.5        || 0.5         || >20        || '''1. '''||
||B100     || H       || X ||   ||   || X || ||(72-)81.0-115.5         || 60-85       ||  1.5        || 0.5         || >20        || '''1.'''||
||C150     || V       ||   || X ||   || X || ||130-183            || 70-125      ||  4          || 1           || 15-25      || ||
||D150     || H       ||   || X || X ||   || ||130-183            || 80-125      ||  4          || 1           || 08-17      || ||
||A230     || V       || X ||   || X ||   || ||197-266            || 85-150      ||  4          || 1           || 12-17      || ||
||B230     || H       || X ||   ||   || X || ||197-266            || 95-160      ||  4          || 1           || 12-17      || ||
||C270     || V       ||   || X ||   || X || ||241-281            || 125-250     ||  4          || 1           || 10-20      || '''2.'''||
||D270     || H       ||   || X || X ||   || ||241-281            || 150-250     ||  4          || 1           ||  9-13      || '''2.'''||
||HERA1     || H       ||   ||   ||   ||   || X || 215-272            || 110-380     ||  4          || 1           || ~10        || '''2.,3.'''||
||HERA2     || V       ||   ||   ||   ||   || X || 215-241            || 120-340     ||  4          || 1           || ~10        || '''2.,3.'''||
 
'''Remarks:''' 

 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

 1. Noise increasing with frequency

 1. [http://www.iram.es/IRAMES/mainWiki/HeraWebPage More information on HERA ] 

=== Bolometers ===

|| Bolometer ||	Beam ||	Lambda|| Pixels || Spacing || rms (1.) || 
|| MAMBO I || 	11"|| 	1.2 mm ||	37 ||	20" ||	1.5 mJy||
||MAMBO II ||	11" ||	1.2 mm ||	117 ||	20" ||	1.5 mJy||

 1. rms after 10 minutes (normal bolometric conditions) with skynoise removal.

== Efficiencies and Half-power beam width ==

 * Below you find the most recent values for the forward and beam efficiencies. We have also compiled the [http://www.iram.es/IRAMES/telescope/telescopeSummary/effi_history.html value of the efficiencies in the past].

 * Here you can find the [http://www.iram.es/IRAMES/telescope/telescopeSummary/beam_effis.html plot] with the most recently measured beam efficiencies.
-Line 20:
+Line 59:
- * 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
+) The HPBW can be well fit by: HPBW('') = 2460/freq(GHz). ''
-Line 23:
+Line 61:
- * Noise increasing with frequency
+''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 ''
-Line 25:
+Line 63:
- * 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".
+''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 ''
-Line 27:
+Line 65:
-=== Bolometers ===
+''Table ''
-Line 29:
+Line 67:
+''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). ''

== Backends ==
=== Spectrometers ===
-Line 31:
+Line 73:
-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.

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).

== Spectral Line Backends ==

Table
+=== Bolometer backends ===
-Line 57:
+Line 75:
- * 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
 * Polarimetry: using VESPA as an IF polarimeter
 * 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.
+ * '''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
 * '''Polarimetry''': using VESPA as an IF polarimeter
 * '''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.