1 / 18

The Taiwanese-American Occultation Survey (TAOS I)

The Taiwanese-American Occultation Survey (TAOS I). Matthew Lehner ASIAA. Why attempt an occultation survey?. Direct searches well-suited to objects larger than R ~30 km Much of the mass may be in smaller objects Models predict a major change in size distribution for smaller objects

tejano
Télécharger la présentation

The Taiwanese-American Occultation Survey (TAOS I)

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. The Taiwanese-American Occultation Survey (TAOS I) Matthew Lehner ASIAA

  2. Why attempt an occultation survey? • Direct searches well-suited to objects larger than R ~30 km • Much of the mass may be in smaller objects • Models predict a major change in size distribution for smaller objects • Occultations of bright stars can reveal smaller and/or more distant objects! • No orbital information! • Can measure inclination distribution if enough events.

  3. Occultation Events Fresnel Scale: F = 2 km at 50 AU Minimum event width: Objects in relative motion, v ~ 25 km/sec Event timescale ~200ms! 10 km

  4. Spectral Instruments SI-800 thinned, backside illuminated, 2048×2052 CCD cameras: Readout time of 2.5 seconds, want 5 Hz sampling

  5. “Zipper Mode” • “rowblocks” of 76 rows • Sky background 27 times as bright • Streaks from bright stars • Readout every star in image at 5 Hz 512×76 rowblock

  6. Occultation by (286) Iclea2006 February 6

  7. TAOS: four small robotic telescopes • 50 cm aperture • F/2.0 • 3 square degree field • 2K square CCD • Robotic operation • Synchronized imaging

  8. The telescopes operate at the Lu-Lin Observatory in Central Taiwan

  9. TAOS Results from 2009

  10. Wang et al. (2009)

  11. Data Volume • 810.1 hours of three telescope data in 2009 analysis • 2590.4 hours now collected • 711.1 hours of four telescope data • Sensitivity goes as the power of number of telescopes • Improved selection criteria • Expect significant improvement in sensitivity for next analysis run 2009 analysis

  12. Frame Transfer Camera • Full frame readout • 2×2 binning • 10 Hz • No zipper mode • No streaks • No excess sky • Only ¼ FOV • 1k×1k imaging area • 2 to 3 times as many stars • Limiting magnitude R=14 rather than 11.5 400 600 220 α~0.3 α~0.4

  13. The Trans-neptunian Automated Occultation Survey (TAOS II) Matthew Lehner ASIAA

  14. A factor of 100 • 7 times more of observing time • 250 observable nights/yr • 1-5 times higher event rate (model dep.) • 20 Hz sampling, higher S/N • smaller objects • 10 times more stars monitored • Rlimit= 17.5 with 1/2 FOV • 40 times higher SNR needed • Larger aperture • Better seeing & sampling • No zipper mode!

  15. Telescope #1 Primary Telescope #3

  16. Camera • High speed readout with ultra low noise • High duty cycle Monolithic CMOS • new technology • Back-illuminated • 200 KHz readout • 2e- read noise • sub-aperture readout mode • large format now available 2.5k × 2.5k 16 µm pixels 80% coverage 154 mm

  17. San Pedro Màrtir

More Related