We present a new radio map of HB9 at 232 MHz made at the Beijing Astronomical Observatory. We also present previously unpublished maps at 151 MHz, from the new Cambridge Low-Frequency Synthesis Telescope Survey, and at 4750 MHz, from the Effelsberg Telescope. These radio maps are compared with previously published maps at 408, 1420, and 2695 MHz, thus providing the most complete frequency cover...

In this paper we describe the operational strategy and performance of the Keck Observatory laser guidestar adaptive optics system, and showcase some early science verification images and results. Being the first laser guidestar system on an 8–10 m class telescope, the Keck laser guidestar adaptive optics system serves as a testbed for observing techniques and control algorithms. We highlight th...

Numerical simulation can provide a valuable tool in evaluating the characteristics of possible sites for new telescopes. This technique can provide accurate information about topographically induced atmospheric disturbances and turbulent boundary layers occurring in the high Reynolds number airflows over such sites. Results are given here for simulations of airflow at the two Gemini 8-m telesco...

In the North-Western part of Europe, ASTRON is building the world-largest largest low-frequency radio telescope. The telescope is based on phased array principles and is known as the LOw Frequency ARray (LOFAR). LOFAR is optimized for detecting astronomical signals in the 30-80 MHz and 120-240 MHz frequency windows. Since this part of the spectrum is in extensive use by others, special care mus...

ADONIS is an adaptive optics user friendly instrument for the ESO 3.6-m telescope. The modal control technique is presented as a tool for optimizing the control of ADONIS. The perturbed wavefront is spread over a base of modes treated by the system in terms of their behavior with respect to the observing conditions (turbulence characteristics, anisoplanatic angle and star magnitude). This optim...

In radio telescope arrays, the complex receiver gains and sensor noise powers are initially unknown and have to be calibrated. Gain calibration can enhance the quality of astronomical sky images and, moreover, improve the effectiveness of array signal processing techniques for interference mitigation and spatial filtering. A challenging aspect is that the signal-to-noise ratio (SNR) is usually ...

An important technique for discovering and characterizing planets beyond our solar system relies upon measurement of weak Doppler shifts in the spectra of host stars induced by the influence of orbiting planets. A recent advance has been the introduction of optical frequency combs as frequency references. Frequency combs produce a series of equally spaced reference frequencies and they offer ex...

We demonstrate that artificial bipolar structure can be detected using spectroastrometry when the point spread function (PSF) of a point source suffers distortion in a relatively wide slit. Spectro-Astrometry is a technique which allows us to probe the spatial structure of astronomical sources on milliarcseond (mas) scales making it possible to detect close binaries and to study the geometry an...

The Receiver Lab Telescope (RLT) is a groundbased terahertz telescope; it is currently the only instrument producing astronomical data between 1 and 2 THz. The capabilities of the RLT have been expanding since observations began in late 2002. Initial observations were limited to the 850 GHz and 1.03 THz windows due to the availability of solid state local oscillators. In the last year we have b...

Earth-like civilizations generate heat from the energy that they utilize. The thermal radiation from this heat can be a thermodynamic marker for civilizations. Here we model such planetary radiation on Earth-like planets and propose a strategy for detecting such an alien unintentional thermodynamic electromagnetic biomarker. We show that astronomical infrared (IR) civilization biomarkers may be...