"Representative" Spectra for the 345-GHz band

Rationale		Given infinite time and access to the JCMT, we would like to provide "standard spectra" for each receiver, against which the performance and calibration of the receivers can be judged on any given day. To this end a limited number of commonly-used spectral lines in a number of well-observed astronomical targets covering most parts of the sky were selected. "Standard" spectra meet an exacting condition: there must be enough observations of the same line/source combination to be able to define such a standard with confidence. In many cases, however, rather few such spectra have been obtained even though B3 has been around for some time. To fill this gap "representative" spectra for B3 are offered in the table below. These meet a much less exacting standard - only one such observation is needed, carried out with care under good conditions. Even this is not always possible; some of these spectra have been taken with earlier instrumentation, many results are simply suspect, and in a few cases, no data can be found in the archive. In some cases the data cannot be read due to subsequent advances in software facilities.
Seeing the data		Where such spectra exist the fact is indicated by . Clicking on this symbol shows the corresponding spectrum. Lines that are rather weak for use as eventual standards are indicated as "weak", or "v. weak" or "no line" if not useful as such under any circumstances (some sources do have lines of other species, however, as indicated by "no line*"). Spectra are color-coded: those plotted in green are obtained using channel A, while those plotted in red are obtained with channel B. Only one channel may be represented. All spectra are obtained in single-sideband mode, except for those taken before B3 arrived. In addition B3 spectra may be compared with those for B3i (the previous B-band receiver, and with those for B3 (the official standards, where they exist). The latter tables are no longer maintained due to lack of effort.

Back to top of page or to spectra for A3, W/C-band, or W/D-band

Receiver B3 -- "Representative" Spectra Reminder: B3 is a dual-channel receiver; i.e. it is capable of observing line radiation in orthogonal polarizations. Spectra are plotted with channel A shown in green, and channel B in red. All spectra shown have been obtained in single-sideband mode, except for those for which no B3 spectrum could be found and an earlier result is used.
Species		C18O	13CO	CH3OH	CS	CO	HCN	HCO+	H2CO
Transition		3-2	3-2	70-60A	7-6	3-2	4-3	4-3	505-404
Frequency		329.331	330.587	338.410	342.883	345.796	354.506	356.734	362.736
W3(OH)
L1551-IRS			no data	weak		weak		weak
CRL618	v. weak		no line*	weak				no line*
OMC1
N2071IR
OH231.8	v. weak		no line	weak				no line*
IRC10216	weak		no line*				no line*	no line1
16293-2422
NGC6334I
G34.3
W75N
CRL2688	no data		no line				no line	no line*
NGC7027	no line		no line					no data
N7538IRS1								no line?

^* Target line not present, but other lines appear in the signal band.

Additional Notes
(1) Bright line near middle is HCN 4-3 in LSB (suppressed image sideband); double-peaked line is HNC 4-3 in signal band (USB).

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Updated: 30 Nov 2004