Advanced Search

The Advanced Search link (Figure 3.2) is used to search in an existing, selected catalog for other criteria than source name (or alias). A common example is to search for a calibrator at a position nearby your source of interest. This Advanced Search link will bring up a dialog box in the main editing window. In that window, select the catalog(s) in which the search should be performed, and select the table(s) with the required parameters by ticking the upper left tick-box of the relevant tables. On top you can quickly select All or None catalogs and subsequently toggle individual catalogs. Only when you tick a table, its options and editing fields become active. More than one catalog and more than one parameter table may be selected; the search interprets additional parameters as an AND condition. Be patient as searching can take a while; please do not continue clicking with the mouse button until the search operation has finished.

Figure 3.2: Web browser screen shot of the "Advanced Search" options with a filled in example of a cone search in combination with a minimum flux density.

A Cone Search searches a radius, entered in degrees, around a position (J2000). The resulting table should be sorted in increasing distance from the position, though you would want to check that; the table can be resorted if desired (by clicking table headers that can turn orange). Positions are interpreted as decimal degrees if not supplied as, e.g., 1h 37m [41.3s] for R.A., and [+]33d 9' [35"] for Dec., not supplied as a group of three numbers separated by a space or a colon, or otherwise not recognized as a sexagesimal entry. to activate the interpretation in the fields entered, click with the mouse button somewhere outside the boxes (to validate the input). Always check the coordinates after entering each position or after pressing the "Search" button; it will replace your values with the interpretation of the validation procedure. You should check these values; the validation procedure will always be able to convert your entered values with these rules, but you are the only one to know whether the validation conversion is sensible! For example, if you type 01 37 in the R.A. field, i.e., without indication of hour or minutes, you will see that it ignores the space and interprets this R.A. as 137 degrees (9h 8m) - funny eh? We're working on it.

Activating the Calibrator Code search allows to search for sources with a closure phase structure code (P, S, W, X) equal or better than the code selected for a certain observing band and VLA array configuration. This Calibrator Code is not the code that used to end up as the AIPS calibrator code (A, B, C, T), which is an indication of positional accuracy. Consult the VLA calibrator manual for more information on the definition of these codes and positional accuracies (http://www.vla.nrao.edu/astro/calib/manual/).

A Flux Density search searches for flux densities above the given limit in the selected observing band. This is of course only useful when flux densities are included in the catalog(s) selected.

The Name search is the same search action with the same string rules as for the string entered in the top search tool in the left hand side column, with the difference that here more than one catalog can be searched, and that other constraints can be included.

The Right Ascension and Declination searches are performed on a coordinate range, with the equal or larger than (>=), or equal or smaller than (<=) operators on the given limits. It uses the same rules on entering positions as for the Cone Search. When both limits are given, the search returns the sources between the limits (i.e., you will see proper results for a search on sources with R.A. between 23 and 01 hours).

Figure 3.3: Web browser screen shot of results of the Advanced Search. Hovering with the mouse over structure (or flux or aliases) displays the calibrator list information (when available).