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Hubble Space Telescope
Phase I: 12082

Phase I: 12082
Extending COS/G130M Coverage Down to 905 Å

Purpose These observations will provide detailed sensitivity, wavelength range, and resolution measurements for two new lower wavelength COS FUV G130M central wavelength settings (covering 905-1171Å).
Description

These new settings will extend COS/G130M coverage down to 905Å in two new bandpasses; 1021-1171Å (BLUE) and 905-1055Å (Ultra-BLUE). The modes are chosen to provide continuous coverage from 905Å to the existing coverage in the G130M/1291Å setting with approximately 30Å of overlap in each mode for cross-calibration purposes. No focus adjustments will be made for these settings, as this is deemed an unnecessary risk to COS. The existing focus position for the G130M/1291Å setting will be used.

These new modes have the potential to provide greater than FUSE sensitivity at moderate (3,000-5,000) resolution.

Two targets will be observed for two orbits each:

  1. WD0320-539 (GSC-08493-00891, one of the flux standards used in determining the G140L sensitivity). Segment A may need to be turned off for these observations.
  2. REJ0503-289 (GSC-04717-00588, a hot EUVE bright WD). Segment A to be kept on for these observations.

Both targets have been observed with COS/G130M, IUE, GALEX, HST+STIS and FUSE. The second target has been observed with EUVE, with flux measured down to 250 Å. WD0320-539 will be our primary flux standard for Segment B, REJ0503-289 will be our flux standard for segment A. Both targets will be used for wavelength calibration. The numerous narrow and broad lines in REJ0503-289 will be used for resolution measurements.

These observations will rely upon the exploratory observations of GD50 in another project for health and safety checking and exposure time calculations.

Fraction GO/GTO Programs Supported Unknown
Resources Required: Observation 4 External Orbit
Resources Required: Analysis The COS IDT will perform all required analysis.
Products STScI will assist in mode implementation and any required adjustments to CALCOS and the COS reference files.
Accuracy Goals Resolution and sensitivity to 10%, wavelength scale to 100 km/s.
Scheduling and Special Requirements Special commanding and lamp flashing will be required. New OSM1 mechanism positions will need to be patched during commanding, similar to what is currently performed for some grating-specific target acquisition parameters.