DRAFT Version of EMIR Commissioning Report
Carsten Kramer with contributions from Juan Penalver, Clemens Thum, Hans Ungerechts, Helmut Wiesemeyer, Albrecht Sievers, Gabriel Paubert, Walter Brunswig, Melanie Krips, Sascha Trippe, Dirk Muders, Albert Greve, Karl Schuster
Related documents: EMIR Installation report by Santiago Navarro et al.
Nasmyth Offsets
The Nasmyth offsets were determined to be -39.0"/+5.5" for the left beam and +51.0"/+5.5" for the right beam. The left beam is used for most EMIR setups, i.e. for single band E0 or E2 observations, and for dual band E0/E2 and E0/E1 observations. The right beam is used for E1, E3, E1/E3. At present, the observer has to set the Nasmyth offsets in PaKo. They are not yet set automatically when switching the EMIR setup.
Alignment
The above figure shows the alignment between the four EMIR bands and between the two polarisations of each band. The overall alignment is better than 1 arcsec.
Foci
The above figure shows the focus between different polarisations of the same band. There are no significant differences between these foci.
This figure shows the focus between different bands. The largest deviation is about 0.3 mm, similar to the situation with the ABCD receivers. For dual band observations, the telescope should be focussed to the high frequency band.
Telescope Efficiencies
Freq
HPBW
Feff
Beff
Aeff
S/TA*
Comments
GHz
arcsec
%
%
%
Jy/K
86
29
95
81
63
5.9
145
16
93
62
57
6.4
330
7
89
32
29
12.0
The main beam and aperture efficiencies, and the beam widths, were derived from Mars observations at about 43 deg Elevations, i.e. near the maximum of the gain elevation curve on March, 4th, 2009. The forward efficiencies were derived from Skydips. The ellipticity of the beams is better than 90% in all cases.
Continuum backends
At present, only the central 1GHz of each 4GHz chunk are being used for continuum detection. Broad band 4GHz wide continuum detectors are in preparation.
Spectrometers
During commissioning, we used the 4MHz filterbank and the two auto correlator backends WILMA and VESPA, partly in parallel. A variety of VESPA setups were checked, covering the range of resolutions between 3kHz and 1.25MHz and a wide range of bandwidths. VESPA parallel mode was also checked. However, it is not possible to check all possible setups. The 1MHz filterbank has not yet been commissioned.
Observing modes
The following switching modes were re-commissioned: position switching (onoff), wobbler switching, and frequency switching. Beam switching was checked using the continuum backends. The on-the-fly mapping mode was re-commissioned, in combination with position switching and with frequency switching.
EMIR setups
Band Edges
Commissioning observations
- The following figure shows a spectrum of Orion IRc2 covering 32GHz of the 3mm window. It was taken with WILMA in wobbler switched mode in two EMIR setups in 30minutes of on+off observing time. Each EMIR setup used 16GHz simultaneously, both sidebands, with one polarisation. One broken WILMA unit was later repaired. The 4MHz/8GHz Filterbank was used in parallel, but data are not shown here.
- A long 4 hour integration in the 3mm window the Cloverleaf, a quasar at high redshift, resulted in a flat baseline with 0.4mK at 150km/s resolution. For this, we used WILMA in wobbler switching mode.