4 Comparison of the ALMA and Herschel - ESO

Figure 6: A three-dimensional plot of frequency, angular resolution and resolution for the instruments
compared in Fig. 5.
From Fig. 6, we see that Herschel HIFI approaches the velocity resolution capable with
ALMA, while for all other instruments, the velocity resolutions are much lower.
4.2 Comparisons of Observational Techniques
4.2.1 Broadband Measurements
ALMA will have a much larger collecting area than Herschel. However, at specific
frequencies, usually near water vapour lines, the Earth’s atmosphere attenuates signals,
perhaps completely blocking these. For the SPIRE bolometer array, there is a significant
overlap with ALMA receiver bands 8 to 10. The PACS bolometer array provides shorter
wavelength data needed to determine SEDs. In Fig. 7 we show the coverage on a spectrum
of the starburst galaxy M82 for different redshifts.
14