Observatory Operations
Xplore Calibrator Finder
GUI Layout
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Xplore, a CARMA calibrator data viewer, is a Tcl/Tk application.
The graphical user interface is organized into 4 main areas. At the top is a menubar (1) with "File", "View", "Tools" and "Help" items. These items (in particular "View" and "Tools") offer various options, and current settings are summarized in the menubar status line.
Remaining areas are LST chart (2), map viewport (3), and observer's panel (4).
Menubar
The "File / Update" option remotely checks whether the calibrator database has been updated and the "File / Exit" option terminates the application.
The "View / GUI Size" option offers several choices for scaling the graphical user interface: small, default, large. An arbitrary scale factor may be submitted on the command line, for example: "xplore scale_factor=0.80".
The "View / Field of View" option offers several choices for the angular extent of the map viewport: 10, 20, 40, 60, 120, 180 degrees.
The "View / Wavelength Band" option offers several choices for spectral window: 1mm, 3mm, 1cm.
The "Tools / Solar System Objects" option activates plotting of sun and planets at a user specified epoch. Positions are generated using MIRIAD (CARMA data reduction package). If MIRIAD is not available locally, then xplore will attempt to download the data remotely.
The "Tools / CARMA Catalog Objects" option activates plotting of arbitrary objects from a user specified catalog.
An example of such a catalog is "carma_goto_newadd_ddmmmyy.cat" (ddmmmyy is a date tag), which is available in the xplore support directory ~/.xplore_support/ . This special catalog is downloaded whenever the calibrator database is updated using "File / Update". Importing the data highlights the part of the calibrator database that has changed as a function of wavelength band.
LST Chart
Sitting on top of the map viewport is the LST chart. Current LST is shown graphically by black triangle icons. This is continually updated. The horizontal red bar denotes the LST visibility range for the science source (reticle position). A 2nd color-coded bar appears when clicking on a calibrator in the map viewport. The total time above the elevation limit is also displayed numerically at the far right end of the LST chart. Lastly, bearing information (horizon coordinates) appears for either the science source or calibrator when dragging the mouse pointer over the respective bars. The adopted azimuth convention is 0->+360 from S->W->N->E->S.
Map Viewport
Calibrators are plotted here and various symbols are described in the map legend. Objects that have not been measured (small white box) or are extended in nature (small black box) should be avoided as calibrators. The red reticle at center of the map viewport corresponds to the science source position. Its coordinates are displayed in the observer's panel (4). A calibrator blinks when clicking on it with the left mouse button. The associated popup window then lists the name, most recent flux, measurement's date, frequency, and angular separation. Separation is relative to the science source (reticle position).
If Tcl/Tk's optional BLT extension is available, then a second popup window plots the calibrator's flux history (flux vs. Julian date). Several mouse functions are available in this window:
a) Without clicking, dragging the pointer across the plot tracks the Gregorian date and flux.
b) After a left click, dragging the pointer traces out a "marching ants" boundary. Another left click magnifies that area.
c) A right click zooms out.
These popup windows vanish when choosing the same calibrator again or when the scrollbars are used to shift the map viewport.
Observer Panel
In addition to using the viewport scrollbars, pointing direction may also be shifted by directly entering the reticle coordinates. Click the left mouse button in the entry boxes (3 for RA and 3 for DEC) to activate the text insertion cursor. The keyboard Tab key may also be used to cycle among the text entry boxes. An empty text entry box implies a null value. To submit coordinates, tap the keyboard Return/Enter key.
Observer panel includes access to the GOTO catalog. To add a pointing direction to the GOTO catalog, left click on the "+" button. The reticle coordinates will be stored in the catalog and a popup window will ask for a descriptive name tag. Once registered, left clicking on that tag in the GOTO catalog will shift the map viewport accordingly. To remove an entry from the catalog, select it first and then left click on the "-" button.
Options "Tools / Solar System Objects" and "Tools / CARMA Catalog Objects" automatically import into the GOTO catalog.
The observer's terrestrial (telescope) location as well as elevation limit may also be selected from the observer's panel. Hour angle range as shown in the LST chart is coupled to both terrestial location (via latitude) and elevation limit. The current LST is also coupled to terrestial location (via longitude).
Adjusting the flux threshold and angular separation contour in the observer's panel further constrains calibrator selection.
Flux Database
The calibrator database is automatically updated whenever the flux analysis group submits new data into CVS.
