25MAMAD1 - FUV-MAMA Pseudo-Aperture


The 25MAMAD1 filter is intended to be used for spectroscopic observations with the G140L and G140M gratings.  Although it is the same optical element as 25MAMA, it should be used when the target has been offset to the D1 position, away from the region of amplifier "glow" in the FUV-MAMA to minimize the contribution from the dark current when observing very faint targets.  This aperture moves the target 2 arcseconds above the bottom edge of the FUV-MAMA to avoid the detector glow region. It is yet to be determined if the throughput for a target at this position is significantly different from that obtained at the standard position.

Special Considerations

Refer to Section 25MAMA—FUV-MAMA Clear for information concerning the properties of the 25MAMD1 filter.  Note that it can only be used with the G140L and G140M gratings.