Honors ＆ Experience

• Vice President for Academic Affairs, National Tsing Hua University (2014/02 - 2015/11 )
• Associate Vice President for Academic Affairs, National Tsing Hua University (2011 - 2014/01 )
• President, Astronomical Society of the Republic of China (ASROC)  ( 2008 - 2011 )
• Professor, Institute of Astronomy and Department of Physics, National Tsing Hua University  (2006 - present )
• Chair, Department of Physics, National Tsing Hua University  (2008 - 2011 )
• Director, Institute of Astronomy, National Tsing Hua University  (2008 - 2011 )

Research Interests

(1) Nuclear Compton Telescope (NCT): 
The NCT project is a joint effort of several institutions in Taiwan and Space Sciences Lab, UC Berkeley. It is a balloon-borne telescope designed to study astrophysical sources of hard X-ray and gamma-ray emission with high spectral resolution, moderate angular resolution, and novel sensitivity to gamma-ray polarization. NCT is a pioneer work for developing the next generation Compton telescope. The heart of NCT is an array of novel cross-strip germanium detectors, each of 15-mm thickness and 5400 mm ^2 active area, with full 3D position resolution < 2 mm ^3. NCT performs Compton imaging in the 0.2-10 MeV gamma-ray band, and can simultaneously perform coded-mask imaging in the 20-100 keV hard X-ray band. Two balloon flights have been conducted in 2005 and 2009. We are currently planning another balloon flight of the NCT instrument from Australia in 2013/2014. Satellite missions carrying NCT-like instruments will be proposed to NASA.(2) The UltraPhot Project: This project is collaboration between NTHU and Paris Observatory, France. UltraPhot is a multi-fiber fast photometer planned to mount on UT2 (Kueyen) of ESO's Very Large Telescope (VLT) at Cerro Panaral, Chile. UltraPhot will be taking data at 100 Hz for 200 objects at the same time. With such a fast photometry in the optical band, coupled with an 8-m telescope, the search for stellar occultation by outer solar system bodies in the Kuiper Belt or the Oort Cloud is expected to have high return. A prototype (Miosotys) is being tested on the 193-cm telescope at the Observatory of Haute-Provence (OHP), in Southern France.(3) X-ray Occultation of Trans-Neptunian Objects (TNOs): In addition to the TNO occultation search in the UltraPhot project, we have also been searching for X-ray occultation events caused by TNOs. Some suspicious events were found in the RXTE/PCA X-ray light curve of Sco X-1 at millisecond time scales. It opens up a new window for TNO surveys, particularly for the smallest, most abundant TNOs. The implication to the distribution of TNOs is being studied.(4) White Dwarf Oscillations: We are building a fast camera to search for white dwarf p-mode oscillations to study the structure of white dwarfs and possible applications in other fields such as SNIa progenitors and its explosion mechanism.

Selected Publications

• H.-K. Chang, C.-Y. Liu, K.-T. Chen, Search for serendipitous trans-Neptunian object occultation in X-rays, Monthly Notices of the Royal Astronomical Society, 429, 1626 (2013)
• H.-K. Chang, C.-Y. Liu, K.-T. Chen, Millisecond dips in the 2007-09 RXTE/PCA lightcurve of Sco X-1 and one possible occultation event, Monthly Notices of the Royal Astronomical Society, 411, 427 (2011)
• H.-K. Chang, S. Boggs, Y.-H. Chang, The Nuclear Compton Telescope (NCT) project – Scientific Goals and Expected Sensitivity, Advances in Space Research, 40, 1281 (2007)
• H.-K. Chang, S.-K. King, J.-S. Liang, P.-S. Wu, L. C.-C. Lin, J.-L. Chiu, Occultation of X-rays from Scorpius X-1 by Small Trans-Neptunian Objects, Nature, 442, 660 (2006)
• more….