We describe the details into the design and development of a low-cost yet efficient telescope control system (TCS) and observatory control software (OCS) for the 50cm telescope at the Indian Astronomical Observatory. The TCS and OCS facilitate precise pointing and tracking of the main axes, handle peripheral sub systems such as the secondary focuser and the filter wheel, conduct observation, monitor weather and incorporate safety interlocks, aimed to run the telescope in a robotic manner. The TCS comprises a computer, control hardware components and an efficient programmable system on chip (PSoC) based motion controller. A distributed control architecture on the controller area network (CAN) bus allows for controlling many subsystems in a modular fashion. The control algorithm comprises the close loop proportional integral derivative (PID) controller and the motion profiler, which ensure very precise pointing and tracking performances. After optimum tuning of the PID gains, we could achieve performance that otherwise one can expect only in large telescopes. The control level pointing accuracy is 3 arc-seconds and unguided sidereal tracking accuracy of 2 arc-seconds over 10 minutes is achieved. The TCS related high-level calculations such as topo-centric and geocentric corrections and the pointing model etc. are carried out in a dedicated computer system, whereas the low-level control program runs in the PSoC. The pointing model software developed is automated and computes the coefficients by image processing using the plate solve method. The OCS which is the top most layer in the control architecture, handles the filter wheel, the detector, the enclosure, the weather station as well as many safety mechanisms. The OCS combined with the scheduler tool and client-server architecture facilitates the un-manned operation of the telescope.
Hanle echelle spectrograph (HESP) is a high resolution, bench mounted, fiber-fed spectrograph at visible wavelengths. The instrument was recently installed at the 2m Himalayan Chandra Telescope (HCT), located at Indian Astronomical Observatory (IAO), Hanle at an altitude of 4500m. The telescope and the spectrograph are operated remotely from Bangalore,(∼ 3200km from Hanle), through a dedicated satellite link. HESP was designed and built by Kiwi Star Optics, Callaghan Innovation, New Zealand. The spectrograph has two spectral resolution modes (R=30000 and 60000). The low resolution mode uses a 100 micron fiber as a input slit and the high resolution mode is achieved using an image slicer. An R2 echelle grating, along with two cross dispersing prisms provide a continuous wavelength coverage between 350-1000nm. The spectrograph is enclosed in a thermally controlled environment and provides a stability of 200m/s during a night. A simultaneous thorium-argon calibration provides a radial velocity precision of 20m/s. Here, we present a design overview, performance and commissioning of the spectrograph.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.