The ASTRO-1 space observatory will incorporate unique, state-of-the-art instrumentation for carrying out its world-class science programs.
The ASTRO-1 main imaging camera is a panchromatic, dual-channel imager with sensitivity from the near-UV to near-IR. The imager has a minimum field of view 10x larger than Hubble’s cameras, so that large surveys with diffraction-limited spatial resolution can be undertaken. The imaging scale is matched to JWST’s main camera; the 1.8-meter ASTRO-1 space telescope will have the same spatial resolution in the green-yellow part of the visible spectrum (570 nm) as JWST has at 2000 nm in the infrared, where its performance is optimized.
The characteristics of the Wide Field Imager shown in the illustrations are:
- Panchromatic sensitivity from 200-1070 nm
- Dual channel imager with dichroic split at 552 nm for simultaneous imaging in UV/blue-green and yellow-red/near-IR channels
- Field of view of 0.26 x 0.11 degrees for each of the channels with imaging scale of 33 milli-arcseconds per pixel
Each imaging channel has 10 filter bandpasses: 5 broadband filters for photometric observations of planets, stars and galaxies, and 5 narrowband filters for emission-line observations of nebulae. The baseline broadband filters are similar to those on Hubble’s cameras and overlap with the intended LSST broadband filter set. The narrowband filter set isolates the most important diagnostic spectral lines emitted by ionized gas in star forming regions, planetary nebulae, supernova remnants and other gaseous environments. The baseline filter sets are:
Broadband filter set (tentative):
- F220W – UV1 200nm - 240nm
- F280W – UV2 240nm - 320nm
- F360W – u-band 320nm - 403nm
- F475W – g-band 403nm - 552nm
- F525M – Visible continuum 503nm - 552nm
- F625W – r-band 552nm - 691nm
- F775W – i-band 691nm - 818nm
- F845M – Red continuum - 805nm - 885nm
- F870W – z-band 818nm - 922nm
- F1010W – y-band 950nm - 1070nm
Narrowband filter set (tentative):
- F280N – Mg II 280nm
- F373N – [O II] 372.7nm
- F469N – He II 468.6nm
- F486N – H-beta 486.1nm
- F501N – [O III] 500.7nm
- F630N – [O I] 630nm (or FQ924N CH4 Quad filter)
- F656N – H-alpha 656.3nm
- F658N – [N II] 658.3nm
- F672N – [S II] 672.4nm
- F953N – [S III] 953.2nm
The baseline architecture for ASTRO-1 includes UV-visible (UVIS) spectroscopy for making diagnostic measurements of celestial targets. The UVIS spectrograph will reveal physical conditions in a variety of space environments, as researchers infer motions, densities, temperatures, composition, and magnetic fields from high-quality spectra. Because ASTRO-1 will reside in a high orbit away from the Earth, the spectra will avoid contamination by atmospheric and geocoronal emission lines that plague spectra obtained from ground-based and low-Earth orbit observatories.
- R ~ 30,000-50,000 aperture far-UV spectroscopy covering ~102-200nm
- Multi-mode long-slit spectroscopy covering 200-1070nm
- ~1 arcmin cross-dispersion field; 0.1-0.5 arcsec slit widths
- Low, medium and high spectral resolutions
- Advanced large-format, low-noise detectors
High Contrast Imaging
ASTRO-1’s high orbit will provide excellent stability (thermal, vibrational) for making high contrast observations of objects in close proximity to bright central sources such as planets orbiting nearby stars or galactic structures surrounding quasars and supermassive black holes. An internal coronagraphic instrument can take advantage of ASTRO-1’s stability and diffraction-limited imaging performance. The high orbit also allows ASTRO-1 to be paired with a separate occulter/starshade spacecraft that can be flown in formation to block the light from bright sources in order to see faint objects (such as planets) in the immediate vicinity.
- Low-noise UVIS detector/camera used in tandem with coronagraph and/or starshade
- Achieve 1.e-9 or better contrast ratio for bright stars in the ~0.1-0.6 arcsecond radial range
- PIAACMC, OMC, or other internal coronagraph architecture with adaptive/deformable optics for exquisite wavefront control
- Flower-petal or similar starshade design for occulting bright sources and controlling diffracted/scattered light
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