Currently, the supported coronagraphic capabilities of STIS include
a selection of positions within the 50CORON aperture along one of two
wedges, and a single position along a bar at the top of the detector.
The smallest of these supported positions is at WEDGEA0.6,
corresponding to an inner working angle of ~0.3". An outsourced Cycle
20 STIS calibration program, 12923 (PI: Gaspar), recently investigated
new aperture locations located near the corners of the coronagraphic
bar (BAR10) as well as at the "bent finger" wedge (BAR5) located on the edge of
the aperture. These new positions allow high contrast imaging at a
minimum inner working angle of 0.15", with demonstrated performance
to ~0.2"--roughly 3 lambda/D, and close to a factor of two better than WEDGEA0.6.
A summary of the initial results of this program as well as detailed suggestions
on how to implement observations using these new aperture positions are
These new aperture positions are currently unsupported in APT. While the use of these new coronagraphic positions may become fully supported in a future cycle, for Cycle 22 they will remain "available-but-unsupported", and users must accept some additional risk for observations using them. See section 2.3 of the STIS Instrument Handbook, for a full discussion of these policies.