RECOMMENDED INTEGRATION TIMES FOR MEASURING STANDARD SPECTRA ------------------------------------------------------------ Times are in minutes. A W indicates too weak to be useful as a standard. Source 12CO CS HCO+ HCN 13CO C18O CI CH3OH H2CO ------ 4-3 3-2 2-1 7-6 5-4 4-3 3-2 4-3 3-2 3-2 2-1 3-2 2-1 7-6 5-4 5-4 3-2 461 345 230 342 244 356 267 355 265 330 220 329 219 492 338 242 363 218 W3(OH) 2 2 2 5 5 5 5 5 5 5 2 5 2 10 5 5 5 4 L1551-IRS5 5 5 5 5 5 5 5 ? ? ? ? ? ? ? ? ? W ? CRL618 5 5 2 ? ? W W ? ? W W W W W ? ? ? ? OMC1 2 2 2 2 2 2 2 2 2 2 2 2 5 5 2 2 2 2 N2071IR 2 2 2 5 5 2 2 5 5 5 2 5 5 10 5 5 5 5 OH231.8 5 5 5 W ? W W W W 5 5 W W ? W W ? ? IRC10216 2 2 2 5 2 W W 2 2 5 2 W W W W W W W 16293-2422 5 2 2 5 5 5 5 2 2 5 2 2 2 10 ? ? ? ? NGC6334I 5 2 2 5 2 5 5 5 5 5 5 2 2 5 ? ? ? ? G34.3 2 2 2 2 2 2 2 2 2 2 2 5 2 5 ? ? ? ? W75N 5 2 2 5 2 2 2 5 5 2 2 5 5 10 ? ? ? ? CRL2688 5 2 2 ? ? W W 5 5 5 5 5 5 ? ? ? ? ? NGC7027 5 5 5 5 5 5 5 ? ? W ? ? ? ? ? ? ? ? N7538IRS1 2 2 2 5 2 5 5 5 5 5 2 5 5 10 ? ? ? ? ATMOSPHERE 5 5 5 W W W W W W W W W W W W W W W The sources below are no longer active standards GL961 5 2 2 RCW38 CIT6 5 5 5 M17SW 2 2 2 S140 2 2 2 2 2