Personal Website
Office¡G886-3-5742952(PHYS R711)
Laboratory¡GHigh Energy Astrophysics Group
Lab Tel¡G886-3-5742953 (PHYS R710)


  1. 1991-1994 Ph.D. in AstroPhysics, Bonn University, German
  2. 1989-1991 M.S. in Physics, National Taiwan University, R.O.C.
  3. 1983-1987 B.S. in Physics, National Tsing Hua University, R.O.C.
Professional Experience
Current position¡G
  1. 2006.8-present, Professor of Physics, National Tsing Hua University
  1. 2000-2006, Associate Professor of Physics, National Tsing Hua University, R.O.C.
  2. 1997-2000, Assistant Professor of Physics Dept., National Tsing Hua University, R.O.C.
  3. 1996-1997, Postdoctoral research fellow of Physics Dept., National Tsing Hua University, R.O.C.
  4. 1994-1996, Postdoctoral research fellow of Nonproliferation and International Security Division, Los Alamos National Laboratory, U.S.A.
Research Fields
    1. AstroPhysics
Research Interests and achievement
Updated in December, 2009

(1) The Nuclear Compton Telescope (NCT) project :
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 April 2010. 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 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, new phenomena may be discovered, for example, in close binaries and young stellar objects (YSOs), and particularly in the search for stellar occultation by outer solar system bodies in the Kuiper Belt or the Oort Cloud. A test model (MEFOS) 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) Isolated Neutron Stars :
Isolated neutron stars exhibit themselves in many different ways, like most radio pulsars, gamma-ray pulsars, Anomalous X-ray Pulsars (AXPs), Soft Gamma Repeaters (SGRs), and some isolated X-ray sources. Some of them may have extremely strong magnetic fields of 10^ 15 G , dubbed ¡¥magnetars'. Some of them might be in fact ¡¥quark stars'. Most of them show various kinds of emission mechanisms in their magnetospheres. We study these sources in both theoretical and observational aspects.
Selected Publications
  1. [2009] J. Takata, H.-K. Chang (2009) Non-thermal emissions from outer magnetospheric accelerators of middle-aged pulsars, MNRAS 392, 400
  2. [2007] H.-K. Chang , S. Boggs, Y.-H. Chang (2007) The Nuclear Compton Telescope (NCT) project ¡V Scientific Goals and Expected Sensitivity, Advances in Space Research , 40, 1281
  3. [2007] H.-K. Chang, J.-S. Liang, C.-Y. Liu, S.-K. King (2007) Millisecond Dips in the RXTE/PCA Light Curve of Sco X-1 and TNO Occultations, MNRAS 378, 1287 (2007)
  4. [2006] H.-K. Chang, S.-K. King, J.-S. Liang, P.-S. Wu, L. C.-C. Lin, C.-J. Chiu Occultation of X-rays from Scorpius X-1 by Small Trans-Neptunian Objects, Nature 442, 660 (2006)
  5. [1999] H.-K. Chang, D.-Y. Chou, M.-T. Sun., In Search of Emerging Magnetic Flux underneath the Solar Surface with Acoustic Imaging, ApJ 526, L53 (1999)
  6. [1997] H.-K. Chang , D.-Y. Chou, B. LaBonte, the TON team, Ambient Acoustic Imaging in Helioseismology , Nature 389, 825 (1997)
  7. [1997] H.-K. Chang, C. Ho, RXTE Observation of PSR B1951+32 , ApJ 479, L125 (1997)
  8. [1995] H.-K. Chang, Magnetic Inverse Compton Scattering above Polar Caps , A&A 301, 456 (1995)
    • All Publications (Expansible)