Telescopes & Instrumentation

The Liverpool and Faulkes telescopes are identical 2.0 metre aperture alt-az telescopes designed and built in the UK by Telescope Technologies Ltd. The telescope optics are Ritchey-Chretien, with an f/3 primary and an f/10 final focal ratio. At the Cassegrain focus is an Acquisition and Guiding (A & G) unit with an off axis CCD autoguider, and a science fold mirror which can direct the science beam to any of 4 side ports or which can be retracted to allow the science beam to pass to the straight-through port. This allows different instruments to be placed at the focus of the telescopes in under 20 seconds.  The on-axis image quality at optical and infrared wavelengths is better than 0.4 arcseconds (80% encircled energy).

The RMS pointing accuracy of the telescopes is specified to be better than 2.0 arcseconds, allowing blind acquisition onto the 10 arcsec diameter integral field bundle of the spectrograph. Other specifications of the Liverpool Telescope, which are similar for the Faulkes Telescopes, can be found here.

The mechanical structure of the telescopes is lightweight yet stiff, with a natural frequency of order 20Hz and telescopes are thus very resistant to windshake, allowing a fully open enclosure, eliminating thermal image degradation and enabling rapid slewing (2 degrees/second) of the telescope to any part of the sky.

The telescopes have local weather stations which feed information on humidity, precipitation, wind speed, temperature, ice and dust to the control systems. The enclosures close automatically if these parameters go outside a preset range, or if any of the sensors fail.

The high level Telescope Control System (TCS) is based on the successful systems at the WHT and other UK telescopes and upon software developed for the Gemini telescopes. Low level control uses industry standard hardware, distributed control, a proven industry standard real-time operating system (QNX), optical tape encoders on the main axes and the instrument rotators, and servo motors.

The Robotic Control System (RCS) sits on top of the TCS and effectively replaces the human observer. This has three modes of operation:

• Normal Mode.  In normal mode, approved targets are selected from a database by a simple ``dispatch'' scheduler which makes the choice of the next observation to execute via parameters such as position on the sky, prevailing conditions and scientific or other priority.
• Override Mode.  The scheduler can be overridden automatically by external alerts, generated for example by the GCN for GRB's. The combination a rapidly-moving telescope with accurate setting, fast selection of instruments, an open enclosure and a hard-wired interrupt mean that the telescopes can acquire a GRB within one minute of an alert being generated by the GCN.
• GRID Enabled Mode.  In this mode the RCS makes time available in real time to obsevers or their agents worldwide using the standard e-STAR prototcols developed by JMU and Exeter.  This is the mode that is employed when the telescopes are operated as part of the proto-Robonet.

Instrumentation

The telescopes are equipped with a number of instruments.  The Liverpool Telescope instrumentation comprises:

CCD Imaging camera (RATCAM) a 2048 x 2048 array with 4.6 arcmin field of view; V=20 (SNR=10) in 20 sec.

Infra-red (JH) imaging camera (SupIRCam) - in collaboration with ICSTM - a 256 x 256 HgCdTl array, fov 1.7 arcmin, J~15 in 1 minute.

Prototype fibre-fed spectrograph - in collaboration with the University of Manchester - 3500-7000A, R~1000.

Double-beam fibre-fed spectrograph (FRODOSpec) - in collaboration with the University of Southampton - 3750-9000A, R=4000 and 8000.
This instrument is under construction in the UK and will be commissioned on the LT in Autumn 2005.

The Faulkes Telescopes each have:

Identical copies of the RATCAM camera with eight different filters. The FTN bad pixel masks are here. The FTN hawkcam zero points are here.

A low-resolution spectrograph developed from the LT/Manchester design via a PPARC grant to the University of Leicester in collaboration with JMU. These two identical spectrographs cover the 4400-8500A range at a resolution of 4A. The throughput is such that SNR=10 per resolution element for V=15 is obtained in 100 seconds.

The primary instruments that will be used in RoboNet-1.0 are thus the imaging CCD cameras and the low resolution spectrographs which therefore, together with the telescopes themselves, form a homogeneous set.