S. Bhatnagar: Research interests

Astronomical Techniques

Low frequency astronomy

Scientific computing/software


Research interests

My general areas of interest are observational astronomy, astronomical data analysis techniques, and scientific & mathematical software.

  1. Astronomical Techniques
  2. I am interested in developing data analysis techniques suited for the future telescopes like ALMA and eVLA. I am also interested in investigating techniques specially suited for low radio frequency instruments like the 4P-Band VLA, GMRT and possibly for LOFAR. My current work is toward:

    Emission, particularly in the Galactic plane at low frequencies is complex requiring scale sensitive deconvolution for high fidelity imaging. The interferometric phase is also corrupted more severely at these frequencies by the ionosphere, where the turbulence is stronger and at comparatively smaller scales, making the antenna based complex gain direction dependent. Low frequency observations are also more severely affected by interference and with the increase in data volume, manual data editing is fast becoming infeasible.

    On-going or planned upgrades are aimed at improving the sensitivity, angular, temporal and frequency resolutions of existing aperture synthesis radio telescopes. The achievable sensitivity and imaging dynamic range of such instruments is limited by the errors due to existing calibration (including full beam polarization and leakage calibration) and imaging (deconvolution/grid ding) algorithms. New calibration techniques are therefore needed to fully exploit the capabilities of these new instruments. Similarly, new imaging techniques for improved gridding algorithms to account for quantization errors due to data gridding as well for building better imaging plane models for image deconvolution are required.

  3. Low frequency astronomy
  4. I am interested in, and am currently pursuing, low frequency Galactic Plane observations of selected Ultra Compact HII regions and continuum and line observations towards several Supernova Remnants.

    All such scientific observations at low frequencies in the Galactic Plane pose the data analysis challenges mentioned above and provide the focus for my research for developing new data analysis techniques.

    Deep, high resolution observations at low radio frequencies provide some unique observational data. In particular, current or planned low frequency instruments offer the required resolution and sensitivity for better understanding of Supernova Remnants, their number density and distribution in the Galaxy, interaction with the local Interstellar medium, probing the extended low density warm ionized gas in the Galaxy via Radio Recombination Line observations at low frequencies, probing current models for Ultra Compact HII regions, etc.

  5. Scientific Software
  6. Data rates and volume from the future instruments will be at least a few orders of magnitude higher than from existing instruments. Most of the new algorithms are aimed at better modeling of sky brightness as well as instrumental effects which inevitably requires more computing. Apart from data analysis algorithmic challenges mentioned above, this also poses a challenge from the point of view of runtime performance of the software.

    I am therefore interested in using modern high performance computing and software development techniques in developing scientific software. Significant advances have been made in these areas in other scientific fields dealing with large and complex data sets as well as in image restoration techniques. I am also interested in studying these new techniques with the goal of adapting them for radio astronomical data analysis.

Sanjay Bhatnagar 2005-06-29