Next: Quantitative comparison of line
Up: mrtcal-check
Previous: Observations dedicated to the
Contents
Figure 5:
Two examples of unprocessed VESPA spectra calibrated with
MIRA and MRTCAL (black and red in the lower panels). The upper
panels show the difference spectrum. Both polarizations and all
consistent scans (same setup and observing mode) have been averaged.
The three central channels of each spectrum have been masked as
spikes are expected in the center of the three adjacent 40MHz units
for VESPA due to technical reasons (Paubert 2002).
|
Figure 6:
Comparison of unprocessed (except for blanking of spikes and a
spurious feature in E3) FTS200 spectra calibrated with MIRA and
MRTCAL. The spectra are overplotted in black and red in the lower
panels. The difference spectrum is displayed in the upper panels.
Both polarizations and all scans (4 scans for setup E1 POINT2MM and
E3 L338890, 6 for E1 L170250 and 10 for E230 L224250) have been
averaged for each setup and observing mode, indicated in the upper
right of each plot. All visible narrow features are spectral lines.
|
Figure 5 compares two MIRA and
MRTCAL-calibrated lines covered at high resolution with VESPA.
Figure 6 compares MIRA and MRTCAL-calibrated
FTS spectra for all four frequency setups. In all cases, default
calibration settings were used. Both polarizations and all consistent scans
were averaged. Spikes and a spurious signal at intermediate frequencies
5.62 and 11.24
0.01GHz in the E330 setup, which stems from
interference with a network switch in the backend room, have been
blanked. No futher processing was applied. In particular, no baselines were
subtracted.
The line shape observed at high spectral resolution show variations of the
order of at most a few percents (cf. Fig. 5). Systematic differences are discernable
on spectral lines in Fig. 6, with either MIRA-
or MRTCAL-calibrated spectra showing higher intensities depending on the
frequency. For instance, the differences are exacerbated for setup
E150/L170250 that is situated close to the upper edge of the atmospheric
window of the 2mm band (it shows a notable increased in the baseline noise
at the high frequency end). These differences will be quantified and
explained in the next sections
Next: Quantitative comparison of line
Up: mrtcal-check
Previous: Observations dedicated to the
Contents
Gildas manager
2023-06-01