Skip to main content

COS/FUV Wavelength Tool

To assist users in preparing their Phase II proposals for Cycle 25 and later COS observations, we have developed a COS/FUV Wavelength Tool that allows users to visualize how the wavelength ranges covered by the allowed COS FUV settings (i.e. settings in supported mode) overlap with those of settings that have been withdrawn (i.e. not in supported mode) to preserve the lifetime of the COS FUV detectors. The withdrawn settings (i.e. not in supported mode) are plotted with dotted lines, while those in supported mode are plotted with solid lines. For each setting displayed, the four FP-POS are shown, from 1 to 4, lowest to highest on the figure. Lower FP-POS corresponds to higher wavelengths covered. For wavelength range information in tabular form, please see Section 5.10 of the COS Instrument Handbook and Tables 3a and 3b of the COS2025 webpage.

For more information on the Phase II policies, please see the COS2025 webpage.

How to use this tool

The tabs on the right side of the figure panel enable or disable the functionalities available in the plot. Hovering the mouse cursor over each of the tabs will display the function. Some of these are active when the figure is loaded; active functions have a teal left edge. The functions used in this plot are:

  • Pan: This allows users to click and drag to pan over the figure
  • Box Zoom: Allows the user to click and drag the cursor to create a rectangle which is zoomed
  • Wheel Zoom: Allows the user to change the zoom factor around the cursor location using the mouse wheel
  • Reset: Resets the figure back to its original state
  • Save: Save the figure as a png
  • Crosshair: Allows a user to display a cross hair on the figure with the mouse cursor as the center
  • Hover: Allows users to hover over lines in the figure to display the wavelength at the cursor location
Last Updated: 06/02/2023


HST Help Desk 

Please contact the HST Help Desk with any questions.