Sally R. Heap

An Infrared coronagraphic survey for substellar companions

We have used the F160W filter (1.4–1.8 μm) and the coronagraph on the Near-Infrared Camera and Multi-Object Spectrometer (NICMOS) on the Hubble Space Telescope to survey 45 single stars with a median age of 0.15 Gyr, an average distance of 30 pc, and an average H magnitude of 7 mag. For the median age we were capable of detecting a 30MJ companion at separations between 15 and 200 AU. A 5MJ object could have been detected at 30 AU around 36% of our primaries. For several of our targets that were less than 30 Myr old, the lower mass limit was as low as 1MJ, well into the high mass planet region. Results of the entire survey include the proper-motion verification of five low-mass stellar companions, two brown dwarfs (HR7329B and TWA5B), and one possible brown dwarf binary (Gl 577B/C).

Proton radiation testing of digital micromirror devices for space applications

Abstract. Scientists are interested in using digital micromirror devices (DMD) as slit-masks in multiobject spectrometers on future space missions. A favored orbit is at the second Lagrangian point (L2). A requirement for mission planning is to determine how long such microelectrical mechanical systems devices would remain operational given the L2 radiation environment, which is primarily composed of solar protons and cosmic rays. To this end, we initiated DMD proton testing. Three DMDs were irradiated with high-energy protons (35 to 50 MeV) at the Lawrence Berkeley National Laboratory 88 in. Cyclotron. Assuming a typical spacecraft shielding of 100 mils of aluminum, our tests imply that DMDs remain fully operable in a five-year mission at L2 with a margin of safety of 4.5.

Constraining Galaxy Evolution With Hubble’s Next Generation Spectral Library

We present Hubble’s Next Generation Spectral Library, a library of UV-optical spectra (0.2-1.0 μ) of 378 stars. We show that the mid-UV spectrum can be used to constrain the ages and metallicities of high-redshift galaxies presently being observed with large, ground-based telescopes.

First results from the Space Telescope Imaging Spectrograph

The STIS instrument was installed into HST in February 1997 during the Servicing Mission 2. It has almost completed checkout and is beginning its science program, and is working well. Several scientific demonstration observations were taken to illustrate some of the range of scientific uses and modes of observation of STIS.

Hubble Space Telescope Advanced Camera conceptual design

A design for an advanced camera (AC) third-generation Hubble Space Telescope scientific instrument is discussed. The AC is a three-channel spectrophotometric camera with wavelength sensitivity from 115-1000 nm. The AC, if selected, would be launched in 1999 for installation on HST. The axial bay design incorporates optical correction for the aberrated HST primary mirror and evolutionary advances in imaging capability.