Flamingos maskdesign
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First Run

Starting maskdesign

To run maskdesign you'll need 2 files. A 4096x4096 image geotran'd to match the plate scale at the MOS wheel, and a catalogue of the objects in that image. Both of these are standard output from the FLAMINGOS pipeline. You also need to be running ds9, or another iraf image display programme.

To start maskdesign just enter the command "maskdesign <image.fits> <catalogue.tran>"
Where <image.fits> is the name of your image file and <catalogue.tran> is the name of your catalogue file.

The programme will take a few seconds to load the image (or longer, depending on the speed of your computer), and will then ask you the following series of questions:

  • Input image rotation (0):
    The rotation of the image compared to the catalogue, see advanced.
  • Enter magnitude range for objects
    Minimum (10):
    Maximum (15):
    The minimum and maximum magnitudes, as given in the catalogue, of the objects you wish to observe.
  • Enter magnitude range for finder stars
    Minimum (10):
    Maximum (12):
    The minimum and maximum magnitudes, as given in the catalogue, of the objects you wish to use as finders.
  • Enter center position for mask in pixels
    x (2048):
    y (2048):
    The mask is 1160 pixels wide and 4096 high, so the x center determines which part of the image is used for the mask.
  • Enter slit width in pixels (12):
    The slit width is dependent on the telescope being used, recommended values are???
  • Enter minimum slit length in pixels (75):
    The slit length is also dependent on the telescope being used, recommended values are???
Once these values have been entered the programme will draw the available objects on the image, which will look something like this:
The green lines show the objects that are currently selected in the mask, the blue lines show all the available objects for this mask in your magnitude range. Objects marked with a magenta dot are those which match your finder star magnitude range.

Selecting objects for the mask.

The initial guess made by maskdesign for the selected objects is only based on their y position, so it is unlikely that it will pick a good mask for your study. To select different objects for the current mask press "u" when the cursor is near the object you wish to use. maskdesign will automatically select the nearest object and deselect any objects that would overlap in the y direction. Have a look at the design ethos page for advice on how to decide which objects should go in a mask.

Selecting finder stars.

To select a finder star press "f" when the cursor is near the potential finder object (marked with a magenta dot) that you would like to use. Finder stars are different to normal objects in that they can overlap in the y direction, in fact it is preferable to select stars that overlap as you minimize the space lost for normal objects. You should try to pick at least three finder stars, if you only use two the increase in position errors will lead to a longer alignment time at the telescope. You should also try to select objects at the opposite ends of the mask, to make the alignment process as accurate as possible.

Saving the designed mask.

When you have finished designing a mask press "U" to save the design. maskdesign will prompt you for a filename and then save three files. A .pos file for the laser, a .reg file to display the design in ds9 and a .bgs file that can be used as a template for an input file for the bogusIR reduction script.

Designing more masks

After you have saved a mask maskdesign will draw a new initial mask. As well as blue and green boxes you will now also have yellow ones, these are the objects that were chosen for the previous mask. If you have gaps between new useable objects (green & blue) where there are previously chosen objects, pressing the "i" key will automatically select objects to fill the gaps, these will be marked with magenta boxes.
Alternatively pressing the "a" key will start over, allowing you to input new parameters for the mask center and magnitude ranges.