- India
The Chandrayaan-2 Large Area Soft X-ray Spectrometer (CLASS) onboard the Chandraayaan-2 spacecraft around the Moon, has been remotely measuring the lunar X-ray fluorescence spectra since September, 2019. The primary objective of the... more
The Chandrayaan-2 Large Area Soft X-ray Spectrometer (CLASS) onboard the Chandraayaan-2 spacecraft around the Moon, has been remotely measuring the lunar X-ray fluorescence spectra since September, 2019. The primary objective of the experiment is to provide global maps of O, Mg, Al, Si at a resolution of 12.5 km/pix and of Ca, Ti and Fe at localized regions during enhanced solar activity, using the lunar X-ray fluorescence measurements in the 0.5 to 10 KeV range. CLASS is an array of swept charge devices (SCDs), a variant of X ray Charge Coupled Devices (CCDs) that provide good spectral resolution and large area. The quality of X-ray measurements strongly depends on accuracy of its calibration techniques. In this work, the results from the pre-launch calibration of the instrument that combines experimental measurements and simulations are described. The spectral redistribution function of the swept charge device is simulated using an augmented version of a previously developed charg...
Research Interests:
Understanding the origin and evolution of the lunar volatile system is not only compelling lunar science, but also fundamental Solar System science. This white paper (submitted to the US National Academies' Decadal Survey in Planetary... more
Understanding the origin and evolution of the lunar volatile system is not only compelling lunar science, but also fundamental Solar System science. This white paper (submitted to the US National Academies' Decadal Survey in Planetary Science and Astrobiology 2023-2032) summarizes recent advances in our understanding of lunar volatiles, identifies outstanding questions for the next decade, and discusses key steps required to address these questions.
Research Interests:
Introduction The objective of Chandrayaan-1 Xray Spectrometer (C1XS) was to map the abundances of major rock-forming elements (viz., Mg, Al, Si, Ti, Ca and Fe) on the lunar surface using the X-ray Fluorescence (XRF) technique [1]. Low... more
Introduction The objective of Chandrayaan-1 Xray Spectrometer (C1XS) was to map the abundances of major rock-forming elements (viz., Mg, Al, Si, Ti, Ca and Fe) on the lunar surface using the X-ray Fluorescence (XRF) technique [1]. Low solar flare occurrences during C1XS observation period (Nov.’2008 – Aug.’2009) hampered the objective of global elemental mapping. However, C1XS with its high spectral resolution measured the x-ray signals of rockforming elements simultaneously under different solar flare conditions. Also, some of the observed C1XS spectra clearly show the direct evidence of x-ray signature of Sodium from the Moon. We derived the elemental abundances from C1XS data using an XRF inversion algorithm called x2abundance [2] that we developed. Here we report the observation of enhanced sodium near the young crater Tycho on the lunar surface. C1XS Observations: Majority of C1XS flare observations were made during July 2009, when the Sun was relatively active in x-rays. Simul...
Research Interests:
Research Interests:
Research Interests:
We present observations of particle bursts during passages through Earth's magnetotail in the Chandrayaan-1 X-ray Spectrometer (C1XS) nine-month data.
Research Interests:
Research Interests:
Research Interests: Engineering and Physics
Research Interests: Physics and Solar Physics
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
We report on RXTE-PCA observations of SLX 1746-311 during a ∼100 day outburst in April 2003. We present the 3–20keV PCA energy spectra of the source and study evolution of spectral parameters. The burst spectrum is soft with Tin ∼1.3keV... more
We report on RXTE-PCA observations of SLX 1746-311 during a ∼100 day outburst in April 2003. We present the 3–20keV PCA energy spectra of the source and study evolution of spectral parameters. The burst spectrum is soft with Tin ∼1.3keV at the beginning of the outburst. There is a clear evidence of a hard power law component throughout the outburst. There is also an indication of a broad iron line. The source exhibits three state transitions with considerable change in the hardness ratio at low count rates. We discuss the possible scenario under which this unusual behaviour can be explained.
Research Interests:
Research Interests:
We report on RXTE-PCA observations of SLX 1746-311 during a ∼100 day outburst in April 2003. We present the 3–20keV PCA energy spectra of the source and study evolution of spectral parameters. The burst spectrum is soft with Tin ∼1.3keV... more
We report on RXTE-PCA observations of SLX 1746-311 during a ∼100 day outburst in April 2003. We present the 3–20keV PCA energy spectra of the source and study evolution of spectral parameters. The burst spectrum is soft with Tin ∼1.3keV at the beginning of the outburst. There is a clear evidence of a hard power law component throughout the outburst. There is also an indication of a broad iron line. The source exhibits three state transitions with considerable change in the hardness ratio at low count rates. We discuss the possible scenario under which this unusual behaviour can be explained.