F25SRF2D1 - FUV-MAMA, Longpass Pseudo-Aperture


The F25SRF2D1 filter is intended to be used with the G140L and G140M gratings for spectroscopic observations of very faint targets at the D1 position.  It provides an intermediate degree of rejection of geocoronal emission: better than F25MAMAD1, but worse than F25QTZD1.  This is the same physical aperture as the F25SRF2 aperture and is available for use with the FUV-MAMA detector 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 F25SRF2—FUV-MAMA for information concerning the properties of the F25SRF2D1 filter.  Note that it can only be used with the G140L and G140M gratings.