het salt type telescopes l.
Skip this Video
Loading SlideShow in 5 Seconds..
HET & SALT-Type Telescopes PowerPoint Presentation
Download Presentation
HET & SALT-Type Telescopes

Loading in 2 Seconds...

play fullscreen
1 / 11

HET & SALT-Type Telescopes - PowerPoint PPT Presentation

  • Uploaded on

HET & SALT-Type Telescopes. The Hobby-Eberly Telescope. The HET in Texas:. 27-m Mirror Alignment Tower. 26-m Diameter Dome. Tracker Beam. Telescope Structure. 11-m Primary Mirror array. Dome Opening. Control & Service Building. Telescope azimuth rotation bearing.

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
Download Presentation

PowerPoint Slideshow about 'HET & SALT-Type Telescopes' - Gideon

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.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
the hobby eberly telescope

The Hobby-Eberly Telescope

The HET in Texas:

27-m Mirror Alignment Tower

26-m Diameter Dome

Tracker Beam





Mirror array

Dome Opening

Control & Service Building

Telescope azimuth rotation bearing

Fibre-Coupled Instrument Room

10 metres

the hobby eberly telescope3

10 metres

The Hobby-Eberly Telescope

  • Primary mirror is 91 identical hexagonal spherical segments of about 1-m each.
  • Primary mirror is moved only in azimuth, not elevation.
  • Prime focus payload moves to track the stars.

Prime focuspayload



Mirror array

the arecibo concept
The Arecibo Concept:

Star moves E to W on sky

Centre of curvature at radius of primary mirror

Fixed elevation spherical mirror telescope with tracking on focal surface

(Arecibo is a radio telescope which first used the idea of tracking objects

by moving the prime focus payload

rather than the primary mirror).

Spherical focal surface: 1/2 of primary mirror radius

Tracker follows focus of star. It carries a payload consisting of optics and instruments.

Image moves W to E on the focal surface

Although pictured looking

straight up (i.e. at the zenith), HETis in

fact tilted 35º from the zenith.

Spherical Primary Mirror

how the telescope tracking works
How the telescope tracking works

Tracker centred

and pupil centred on primary mirror array. Full 9.2 metre collecting area.

Tracker off-centre

and pupil partially on primary mirror array. At worst extreme, still a 7 metre telescope!

Part of pupil off mirror is baffled at exit pupil position

salt payload
SALT Payload
  • Prime Focus Payload (~950 kg) mounts on the tracker hexapod:
  • Prime Focus Imaging Spectrograph (PFIS), now called RSS, the Robert Stobie Spectrograph
  • SALTICAM acquisition and science camera
  • Spherical aberration corrector
salt payload details
SALT Payload Details:
  • Prime Focus Payload (~950 kg) mounts via hexapod to tracker bridge and comprises:
  • Prime Focus Imaging Spectrograph (PFIS/RSS)
  • Acquisition camera
  • Guidance & focus
  • System
  • Optical fibre feed
  • Pupil baffle
  • Atmospheric dispersion corrector (ADC)
  • Spherical aberration corrector
  • Calibration system
  • 4 instrument foci fed by 45 deg “fold” mirrors

Guide & focus probes



Fibre feed



Exit pupil baffle

Atmospheric Dispersion


SAC structure


Payload structure (rotating & non-rotating components) made of carbon


Dummy PFIS/RSS mass

Instrument rotator ring

Hexapod legs


Tracker beam