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 * Eight single pixel receivers A,B,C,D, and the 3x3 dual-polarisation HERA receiver are installed in the [http://www.iram.es/IRAMES/telescope/telescopeSummary/receiver6.html receiver cabin]. ==== ABCD dual polarisation receivers (till mid March 2009) ====

 * Eight single pixel receivers A,B,C,D are installed in the [[http://www.iram.es/IRAMES/telescope/telescopeSummary/receiver6.html|receiver cabin]]. It is planned to replace them by EMIR in mid March 2009.
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 * [http://www.iram.es/IRAMES/groups/receiver/receiver.html More information on the heterodyne receivers.]
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 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. [http://www.iram.fr/IRAMFR/PV/lowfreqs/report.ps.gz Test report of 2004], [http://www.iram.fr/IRAMFR/PV/lowfreqs/spectra.html Test spectra]  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. [[http://www.iram.fr/IRAMFR/PV/lowfreqs/report.ps.gz|Test report of 2004]], [[http://www.iram.fr/IRAMFR/PV/lowfreqs/spectra.html|Test spectra]]
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 1. HERA is a heterodyne receiver array consisting of two arrays of 3x3 pixels with 24" spacing. The two arrays have orthogonal polarization (V, H) the two polarizations pointing at identical locations on the sky. HERA is equipped with a derotator allowing to follow a source in the sky maintaining the same "footprint". The tunable range is between 215 and 272 GHz. In this range the beamwidth varies between 12" and 9".  * Last status before dismantling the ABCD receivers in March 2009:
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  * [http://www.iram.es/IRAMES/otherDocuments/manuals/HERA_manual_v20.pdf HERA manual, version 2.0] by Schuster et al. 2006   * Image/Signal gain-ratio calibration using the continuum backends(!) is supported by NCS, processing in MIRA. It is highly recommended to use this feature!
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  * [http://esoads.eso.org/abs/2004A%26A...423.1171S Schuster et al. 2004, A&A, 423, 1171] A 230 GHz Heterodyne Receiver Array for the IRAM 30m telescope ([http://www.iram.es/IRAMES/otherDocuments/manuals/0179hera.pdf local copy])   * Cold load temperature:
   * A standard table of Tcold calibration temperatures for A, B, C, D receivers is implemented in the NCS. This built-in table covers most frequencies. (Use: pako>receiver /temp L)
   * /!\ Outside this range, Tcold has to be set manually (use pako>receiver /temp "Tcold"), ask the RX engineers or operators! [[http://gra-lx1/mainWiki/ReceiverGroupColdLoadPlotsCurrent|Tables and plots (internal link)]] (2007-10-11 dj)

  * /!\ CHECK Receiver C150 shows low continuum signal at the higher frequencies (>168 GHz). It has to be fully checked. Use D150 instead. (2005-11-16)

  * In the receiver cabin, Martin-Puplett interferometers MPI are used to seperate frequencies to be send to two different receivers. An overview of the receiver cabin optics is given [[http://www.iram.es/IRAMES/telescope/telescopeSummary/receiver6.html|here]]. The MPIs have high losses at certain frequency ratios, especially at a ratio of 3. Simultaneous observations of e.g. HCN(1-0) and HCN(3-2) or HCO+ are therefore difficult and may lead to increased receiver noise temperatures, depending on how the MPI is optimized.

ABCD dual polarisation receivers (till mid March 2009)

  • Eight single pixel receivers A,B,C,D are installed in the receiver cabin. It is planned to replace them by EMIR in mid March 2009.

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

Rx

#

Pol

Rx combinations

tuning range

Trx

IF

IF Bw

Gim

Rem.

AB

CD

AD

BC

[GHz]

[K]

[GHz]

[GHz]

[dB]

A100

1

V

X

X

(72-)80.0-115.5

60-80

1.5

0.5

>20

1.

B100

1

H

X

X

(72-)81.0-115.5

60-85

1.5

0.5

>20

1.

C150

1

V

X

X

130-183

70-125

4

1

15-25

D150

1

H

X

X

130-183

80-125

4

1

08-17

A230

1

V

X

X

197-266

85-150

4

1

12-17

B230

1

H

X

X

197-266

95-160

4

1

12-17

C270

1

V

X

X

241-281

125-250

4

1

10-20

2.

D270

1

H

X

X

241-281

150-250

4

1

9-13

2.

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. Test report of 2004, Test spectra

  2. Noise increasing with frequency
  3. Last status before dismantling the ABCD receivers in March 2009:
    • Image/Signal gain-ratio calibration using the continuum backends(!) is supported by NCS, processing in MIRA. It is highly recommended to use this feature!
    • Cold load temperature:

      • A standard table of Tcold calibration temperatures for A, B, C, D receivers is implemented in the NCS. This built-in table covers most frequencies. (Use: pako>receiver /temp L)

      • /!\ Outside this range, Tcold has to be set manually (use pako>receiver /temp "Tcold"), ask the RX engineers or operators! Tables and plots (internal link) (2007-10-11 dj)

    • /!\ CHECK Receiver C150 shows low continuum signal at the higher frequencies (>168 GHz). It has to be fully checked. Use D150 instead. (2005-11-16)

    • In the receiver cabin, Martin-Puplett interferometers MPI are used to seperate frequencies to be send to two different receivers. An overview of the receiver cabin optics is given here. The MPIs have high losses at certain frequency ratios, especially at a ratio of 3. Simultaneous observations of e.g. HCN(1-0) and HCN(3-2) or HCO+ are therefore difficult and may lead to increased receiver noise temperatures, depending on how the MPI is optimized.

AbcdforAstronomers (last edited 2009-05-28 13:49:17 by visitor13)