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← Revision 21 as of 2015-05-28 08:55:59 ⇥
Size: 2271
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| Deletions are marked like this. | Additions are marked like this. |
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| Comments: (1) HERA2 pixels 4 and 9 are not operational anymore. <CK 9-May-2014> | Comments: '''Gim''' is the image band rejection. (1) Note that the HERA2 frequency range is more restricted than for HERA1. In addition, HERA2 pixels 4 and 9 are instable and should be flagged in data processing. <CK 9-May-2014> |
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| * Observations with HERA in combination with EMIR or MAMBO, are not possible. | * It is not possible to simultaneously observe with HERA and any of the other frontends. |
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| HERA is working in single sideband mode (1 GHz Bandwidth). That means the receiver cannot detect for a given channel the two sidebands at once. However you can use different frequencies for the two sets of polarizations. In this mode and by using the FTSs you can use the 1st polarization (9 single polarization pixels, for example in LSB) for 12CO(2-1) and the 2nd polarization (another 9 single pol pixels, also in LSB) for simultaneous covering of 13CO(2-1) and C18O(2-1). This mode is interesting for Galactic observations as it gives you all three lines simultaneously and therefore with good observing efficiency and good cross calibration - although each line as said only in single polarization. | * The alignment of the two polarisations is described in the HERA manual. * Nasmyth offsets are described in the [[http://www.iram.es/IRAMES/mainWiki/EmirforAstronomers#Reports_and_publications|report]] on the commissioning of New Optics installed in April 2015. * HERA has two local oscillators, one for each polarization. Simultaneous observations of e.g. the 12CO and 13CO 2-1 lines are hence possible with both polarisations. Note that, in addition, the C18O 2-1 line lies within the 1GHz bandpass next to the 13CO line. |
HERA 1mm array receiver
Rx |
# |
Pol |
tuning range |
Trx |
IF |
IF Bw |
Gim |
Rem. |
|
|
|
|
[GHz] |
[K] |
[GHz] |
[GHz] |
[dB] |
|
|
HERA1 |
9 |
H |
215-272 |
110-380 |
4 |
1 |
~10 |
|
|
HERA2 |
9 |
V |
215-241 |
120-340 |
4 |
1 |
~10 |
|
(1) |
Comments: Gim is the image band rejection. (1) Note that the HERA2 frequency range is more restricted than for HERA1. In addition, HERA2 pixels 4 and 9 are instable and should be flagged in data processing. <CK 9-May-2014>
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". Over the range of tunable frequencies, the beamwidth varies between 12" and 9".
HERA manual, version 2.0 by Sievers et al. 2006
Schuster et al. 2004, A&A, 423, 1171 A 230 GHz Heterodyne Receiver Array for the IRAM 30m telescope (local copy)
- It is not possible to simultaneously observe with HERA and any of the other frontends.
- The alignment of the two polarisations is described in the HERA manual.
Nasmyth offsets are described in the report on the commissioning of New Optics installed in April 2015.
- HERA has two local oscillators, one for each polarization. Simultaneous observations of e.g. the 12CO and 13CO 2-1 lines are hence possible with both polarisations. Note that, in addition, the C18O 2-1 line lies within the 1GHz bandpass next to the 13CO line.