Nod & Shuffle Masks

Preparations

The Nod & Shuffle mode and the definition of micro-shuffling and band-shuffling are described on the Nod & Shuffle page. The terms from that page will be used in the description below.

Setting the Nod & Shuffle specific parameters

When you have loaded the Object Table, you will notice that the catalog window has an option for setting "N & S parameters". Click this button and you will get a window that looks like this:

The following parameters need to be set:

1. Select "Microshuffle Mode" or "Band Shuffling Mode"
2. For "Microshuffle Mode",
   • Set "Slitlen (arcsec)" to the slit length in arcseconds you require;
   • The nod amount is defined only in the Observing Tool, not in the mask making software. The mask making software will design the masks with the objects centered in the slits.
   • Set "Shuffle amt (arcsec)" to the same value as the slit length, press return in that field to get the "shuffle amt (unbinned pix)" recalculated. Alternatively, you can set the "Shuffle amt (unbinned pix)", press return to the "Shuffle amt (arcsec)". Note down what the shuffle amount is in unbinned pixels - you need this for your phaseII preparations using the Observing Tool.
3. For "Band Shuffling Mode",
   • Set "Band Size (unbinned pix)". Default gives one band of slits at the center of the array in the y-direction.
   • Set "Shuffle amt (unbinned pix)" to the same amount as the "Band Size (unbinned pix)" Note down what the shuffle amount is in unbinned pixels - you need this for your phaseII preparations using the Observing Tool.
   • Click "Recalculate Bands" to see where the bands fall. The storage areas where you cannot place slits are shown as red-hatched areas, while the areas where slits can be placed have yellow rectangles around them.
   • Adjust the offset of the bands in the Y-direction, using the "Bands y Offset" as needed. To see the effect, click "Recalculate Bands"
4. When the Nod & Shuffle specific parameters have been set, click "Design N & S Mask files". This brings up the usual mask design window that allows you to select the grating, filter and wavelength. It also allows you to select the slit width if this was not already included in your Object Table. From here, proceed as for other masks.

• In "Microshuffle Mode":
  • The shuffle amount should be the same value as the slit length.
  • The nod in slit amount is defined only in the Observing Tool, not in the mask making software.
  • When the slit length, nod, and shuffle amount (arcsec) have been entered, the shuffle amount in unbinned pixels is automatically calculated.
• In "Band Shuffling Mode":
  • The shuffle amount (unbinned pixels) should be the same value as the band size.
  • When the shuffle amount (arcsec) is altered, the shuffle amount (unbinned pixels) is automatically changed to correspond with the band size.
  • The nod amount is defined only in the Observing Tool, not in the mask making software. You can either nod in the slits or nod off to sky.

Back to GMOS Mask Making Software Instructions

Last update April 30, 2004; Inger Jørgensen