Abstract: High resolution spectra of stars show a Doppler shift according to the earth's motion around the sun. This effect can be used to determine the Astronomical Unit.

Full Text of Proposal

Comments by OPC

General Comments: With two spectra, separated by half a year (which is stated in the proposal) it is possible to measure the orbital velocity of the earth: amplitude is 28 km/s, which corresponds to 0.5A at 5500A (i.e. R=10000). If only one spectrum can be obtained, the absolute velocity of the target (in this case Regulus) has to be known. A radial velocity standard could be used for this.

Visibility: this is getting late for Nov 18; perhaps at the very end of the night.

Special Comments: It is not clear if a (high resolution) spectrograph will be available.

Expected time consumption (including overhead): About 10 minutes including calibrations.

Proposed facility: Will depend on the availability of an adequate spectrograph