FourStar User GUIs

2012-01-25

Location of this document: http://instrumentation.obs.carnegiescience.edu/Software/FourStar/stargui.html

The 'StarGUI' runs on a Mac/Xserve computer and is written in the programming language 'C' utilizing the 'Carbon' framework. All communication of the GUI with other components is done via the ethernet nework (TCP/IP sockets) and therefore does not require any special drivers. 'StarGUI' is the user interface for the observer; its main window shows all controls necessary to start an exposure or run a sequence of exposures and telescope moves (dither-macro).

Index

Camera: Macros; Macro Commands
Data Display
Telescope: SkyMap; Object Lists; Airmass

FourStar Software Main Page

Camera GUI

This window is the main user interface for the observer; it shows all controls necessary to start an exposure or run a sequence of exposures and telescope moves (macro).

ExpTime edit field: The exposure time can be set in multiples of 1.456 seconds (ie. the cycle time of the ASIC code).
ReadMode popup-menu: The 'ReadMode' may be set to take double correlated exposures or Fowler samples (multiple endpoints).
Gain popup-menu: We implemented two gain settings; the 'FullWell' setting utilizes a higer gain (2.5 e/DU) and is better suited for broad-band imaging, while the 'LowNoise' setting (1.5 e/DU) minimizes the effective read noise.
FilterCombo popup-menu: The software abstracts the two filter wheels, the field flattener and a variable pupil to a 'FilterCombo' that automatically selects the appropriate combination of optical elements.

Go button: Starts a loop-sequence.
Loops edit field: Defines how many exposures are taken per sequence. Loops of up to 64 exposures may be taken by pressing the 'Go' button of the GUI.
Object edit field and object type popup-menu
Comment edit field: are written to the FITS header; the object type is selectable from a list (eg. 'astro' or 'standard').

Execute button: Execute the macro file in the File edit field.
File edit field: Macro file name to be run. If the name does contain a full path the system looks for it in the $HOME/Library/Application Support/FourStar folder.
Select button: Opens a file selector dialog.
Line: Displays the current macro line that is beeing executed.
Pause button: Pauses the running macro. A dialog "prepare to pause" will open that switches to "macro paused" after the current command has finished.
Create Dither button
Create Stare button: Opens a dialog that lets the user customize prefefined macros types. These tools allow to easily create complex macros. See the Macros chapter for details.
Abort button: Aborts the running macro and exposure loop.

The data is simultanously written to upto three different disks. Usually the first disk is the internal disk of the Control-Mac, serving as an online backup for the raw data. The second disk is the RAID array that allows the data pipeline to reduce the data in near realtime. A third path may be set to write the data to an (oberserver supplied) USB disk. Writing to the USB disk in parallel creates a small delay (about 2 seconds per loop) and is not recommended for short exposure time sequences.

Macros

Macros are ASCII files (extension .macro) that contain a list of commands that will be executes sequentially, ie. there are no commands that allow to affect the program flow.
The CameraGUI provides two tools that allow to easliy create commonly used macros. Custom macros may be written using any text editor. A complete list of commands is given below.

Dither Macros

The example on the left creates a dice5 macro with a step size of 26 arcseconds, rotated by 30 degrees (dice5r30_26c.macro).
The example on the right creates an extended source macro (sos_p11_p22_26c.macro) that does a

poisson-11 pattern at the sky position (900 arcsec east), then a

poisson-22 pattern at the object position, then a

poisson-11 pattern at the sky position

The observer may choose from a number of standard patterns (eg. dice5 or square9) or may create a randomized dither pattern of a given size and number of positions. The 'random' (start at the center) and 'poisson' (start at random position) patterns are created using a 'Travelling Salesman' like optimization algorithm. The software first creates a random pattern of 'n' positions within a box with

 width  =  height  =  2 * step_size

that fulfill the following restriction for the distance between any two points

 min_dist  >  [ sqrt(2) * step_size ]  / sqrt(n)

In the second step the software optimizes the path through all points by minimizing a cost function

 cost = SUM(i,j=1..n, i!=j) { ABS[dist(i,j) - step_size]^3 }

This function avoids very short moves while still minimizing the overall path length and therefore the total runtime of the dither macro.
The Macro tool also allows for repeating a (different) pattern on and off the sky to faciliate the imaging of extended sources.

Stare Macros

Example stare macro

The Stare macro tool lets the observer create calibration macros (ie. no telescope offsets) or allow long exposure sequences that exceed the loops limit (64). The example above creates a macro that takes 100 darks at an exposure time of 10 seconds and then another 100 at 20 seconds exposure time.

Macro Command List

go [nloops]: Start exposure loop. The optional parameter sets the number of Loops in the GUI.
move dx dy: Offset the telescope by dx (arcsec in R.A.) and dy (arcsec in Dec.).
move_coord dx dy: Offset the telescope by dx and dy (same as move) and move the guiders in the opposite direction. This command turns the guiding off before the move and turns it back on after the move.
move_coord_async dx dy: experimental telescope offset that only waits for the telescope offset and continues the macro before the guider probes have reached their destination position.
guiding {0,1}: Turn guiding off or on. This command is implicitly executed before/after coordinated telescope/guider offsets.
filter name: Set the filter-combo name (from list in popup menu)
readmode name: Set the readmode name (from list in popup menu)
exptime value: Set the exposure time to value
gain name: Set the gain to name (from list in popup menu)
obstype: Set the observation type to name (from list in popup menu)
pause: Pauses the macro and opens a dialog box that allows to resume the macro.
sleep value: Delays the macro execution for value seconds.
exit: Stop the macro. This command is optional; if there is no exit command the macro stops after the last command.

Data Display

The 'Quick-Look' tool displays all four arrays (pixel averaged) in the 'Overview' window at the proper sky orientation. A simplified compass rose (green circle) points North and East. The data can be viewed at various color mappings and may be scaled manually or automatically. The scaling algorithm may be set to use the entire data range of all four arrays or scale each indiviual array separately to improve contrast.

The 'Quick-Look' tool may either show the raw data or use any previously data image to display a sky-subtracted image. All exposures of a loop are kept in memory and may be inspected by clicking the up/down arrow on the GUI.

A magnifier window allows the observer to zoom into any area and inspect the data. The tool shows the minimum and maximum pixel values and also calculates the average and standard deviation within a circular aperture of a given radius. Finally the tool calculates an estimate of the FWHM (in pixels) of an object at the cursor position.

Telescope

The 'Telescope-GUI' displays basic telescope related information like coordinates, current airmass and sidereal time. It allows the observer to initiate small offsets, either just moving the telescope or coordinated offsets where the guider is moved the same distance in the opposite direction.

2009-04-08, Christoph C. Birk, Carnegie Observatories