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Source properties

In the Field Setup page, the user is asked for source parameters, such as a name, coordinates (which must be specified in the J2000 system), velocity and proper motion. The source names should only contain the following characters: a-z, A-Z, 0-9, -,+, _ or a . (full stop). Characters other than these will be removed or replaced when the project is validated. Regarding proper motions, the components in the Dec. and R.A. (cross declination) directions are both true angles on the sky and are used to convert the given source position to an observable one assuming that it refers to epoch 2000.

The ALMA telescope control system recognises a limited number of solar system objects that can be selected from a drop-down list. This same list also allows the use of an ephemeris for any object for which the coordinates as a function of time can be provided. This is loaded as a text file from the local disk and must be in the JPL HORIZONS format. For details on how to generate HORIZONS ephemeris files, please check Appendix A. When using an ephemeris, it is recommended to use time intervals not smaller than 10 minutes so as to keep the file to a manageable size. Files with up to 90000 rows have been successfully tested.

The velocity can be specified using the optical, radio, or relativistic convention (default radio). When changing the source velocity reference system between the available options of heliocentric, barycentric, topocentric, lsr and lsrk, the OT is not able to convert the velocity and you will be reminded of this via a pop-up dialogue. The velocities must be sufficiently similar such that all the sources can be observed in a single band. In addition, a maximum of five tunings per Science Goal are allowed and thus the sources must be grouped in velocity space in such a way that this limit is not exceeded. The OT will issue an error if this is the case.

Finally, the middle panel contains three fields that can be used during the technical review of the Phase-1 proposal. Although it is sometimes hard to be sure of the values before the source has actually been observed, in these cases please try and enter reasonable estimates (which would probably have been used in the technical justification anyway).

The above-described information (except Solar System objects) can be added to a Science Goal from an ASCII file using ``Load from File...''. This can be used to either load a set of additional pointings or to completely replace the list of currently-defined pointings. The, format of the ASCII source list is shown below; it should be possible to cut and paste this into a text editor:

Source Name, RA(sexagesimal) , Dec(sexagesimal), PMRA (mas/yr), PMDec(mas/yr),
Velocity (km/s), velocity reference frame, peak continuum (mJy), peak line flux (mJy),
expected polarization (%), expected linewidth (kHz)
--   This signals end of the header
ngc 253, 00:47:33.129, -25:17:17.808, 0.0, 0.0, 244.0, lsrk, 200, 1000, 2, 1500
ngc1068, 23:59:59.266, -00:02:02.774, 0.0, 0.0, 1133.0, topo, 1100.0, 30, 0, 20


next up previous contents
Next: Resolving source information Up: Field Setup Previous: Field Setup   Contents
The ALMA OT Team, 2013 Feb 27