Sanjay Bhatnagar's Home Page

About me

Who I appeared to be	Who I appear to be	Who I really am
			Sanjay Bhatnagar Scientist, National Radio Astronomy Observatory, Socorro, New Mexico, NM - 87801, USA	Phone: +1 (575) 835 7376 (W) E-mail: sbhatnag AT nrao DOT edu

Press releases:
High Throughput Computing at a National Scale
• Astronomers & Engineers Use a Grid of Computers at a National Scale to Study the Universe 300 Times Faster
EVLA Early Science:
• Expanded VLA Flexing New Scientific Muscle
• NRAO Image of the week (Jun 11, 2022)
EVLA Science Press release:
• NRAO Image of the week (Cannonball Pulsar, Nov 27,2021)

NRAO Newsletter articles:

• Deep Imaging at a National Scale (22 March, 2024)
• Commissioning Effort for Wide-field, Wide-band Imaging (11 Oct., 2016)
• CASA Image Processing (19 Oct., 2015)
• Imaging & Calibration Algorithm Research at the NRAO (Oct, 2008)
• I lead the Algorithms Research and Development Group (ARDG). The group is involved in research and development for new imaging and calibration algorithms for EVLA and ALMA.
  • The group runs the LibRA project. This software is now used for R&D with external groups and industry partners, and for scientific collaborations.
  • Earlier, I was also involved in the scientific software part of the CASA project.
• I am the author and maintainer of the GNU Fussy Project. It implements a programming language with automatic error propagation to compute the error in the result of arbitrary mathematical expressions. The GNU Fussy language syntax is similar to the C progamming language and can be used with minimal learning to write mathematical code with automatic error progration. E.g.

          >x=70d pm 50'
          >printn x
           ( 70d00'0.00" +/-   0d50'0.00")
          >cos(x)
  	   0.34202 +/-    0.01367
  	

  fussy is implemented as a virtual machine, and the algorithm for automatic error propagation and its proof of correctness is described here.
• The latest version of the document describing the Data Selection Syntax in CASA is here [PDF format].
• My involvement in Radio Astronomy started at the National Center for Radio Astrophysics, Pune, India.  I was involved, from the beginning, in the building of the Giant Meterwave Radio Telescope (GMRT),
• I now work at the Array Operation Center (AOC), Socorro, New Mexico, USA of the National Radio Astronomy Observatory (NRAO).


• I got my PhD degree from TIFR/University of Pune, India. My thesis (htlatex build) was the first thesis which used the GMRT for imaging at low frequencies. This involved debugging the instrument, developing offline and online software, debugging the correlater, etc. I ultimately used the GMRT in the imaging mode to study Galactic SNRs and ISM at low frequencies. Sensitive high resolution imaging at low frequencies is crucial for the study of SNRs which are brighter and less confused with thermal emission at low frequencies (SNR Paper-I, SNR Paper-II).
  
  We also developed the LeakyCal algorithm to measure antenna based polarization leakages using only the co-polar visibilities. I quite like the interpretation of the leakages on the Poincare Sphere and the connection to Pancharatnam Phase of optics that I learned from R.Nityananda.


• I am a member and the co-chair of the SKA Calibration and Imaging Task Force. There have been eight CALIM meetings so far:

  CALIM2005, hosted by ASTRON at Dwingeloo, The Netherlands, 2005

  CALIM2006, hosted by the SKA SA and South African Astronomical Observatory at Cape Town, South Africa, Dec. 4-8, 2006

  CALIM2008, hosted by CSIRO and UWA at Perth, Australia, Apr. 7-9, 2008

  CALIM2009, hosted by NRAO, at Socorro, New Mexico (USA), Mar. 30 - Apr. 2, 2009

  CALIM2010, hosted by ASTRON at Dwingeloo, The Netherlands, Aug. 22-27, 2010

  CALIM2011, at Manchester, UK, 25-29 July 2011

  CALIM2012, hosted by SKA-SA at Cape Town, South Africa, Dec. 3-7, 2012

  CALIM2014, hosted by CSIRO/ATNF, Kiama, Australia, March 3-6, 2014

  CALIM2016, hosted by NRAO at Socorro, New Mexico, Oct. 10-14, 2016



• The first of the Cells to Galaxies Workshop was held on September 21-23, 2022 at St. Paul, MN.
  This brought together researchers in the radio astronomy and medical imaging communities together for the first time at a national scale in the US.