We determined the relative spatial density of the Coma cluster galaxies selected by luminosity, and the contribution of the galaxies of each central brightness to the luminosity function (i.e. the luminosity function bi–variate in central brightness). The Coma cluster and control fields were imaged using the CFH12K (42 × 28 arcmin) and UH8K (28 × 28 arcmin) wide–field cameras at the Canada–Fran...

Since 1999, several BL Lac objects, such as PKS 2155–304 (z=0.116) and PKS 2005–489 (z=0.072) have been observed with the CANGAROO-II imaging atmospheric Cherenkov telescope. We obtained flux upper limits for these objects. Here we present the results of our observations of these objects, particularly those observed since 2000, and discuss the implications for the emission models and the absorp...

The Visible Integral-field Replicable Unit Spectrograph Prototype (VIRUS-P) has been in operation on the Harlan J Smith 2.7m Telescope at McDonald Observatory since October of 2006. The prototype was created to test the design and science capabilities of the full VIRUS instrument, wherein 150 copies of the spectrograph will be installed on the Hobby Eberly Telescope (HET). We here discuss the s...

The status of the HEGRA imaging air Cherenkov telescopes is summarized. We present results from a survey of the Galactic plane for point sources with a limiting flux of approximately a third of the flux seen from the Crab Nebula. For Mkn 421 (z = 0.031) we present the detection of spectral variability correlated with the flux. Finally, we summarize results of observations carried out on the mos...

It has been recently proposed [1] to use polarization of Compton scattered γrays to improve the imaging performance of Compton telescopes. Building upon that work, we detected the aforementioned polarization in a sample of 1.836 MeV γ-rays from the LXeGRIT Compton telescope. Here we present the measurement, together with detector oriented considerations on the application of the principle to a ...

Bioptic telescope is a visual aid used by some people with impaired vision for driving and to qualify for licensing. Data on how and when bioptic drivers use the telescope and what they look at with it are important in bioptic driving studies. A video-based technique to track bioptic drivers’ spectacle frames, which represent telescope aiming point, is presented in this paper. With three retro-...