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Browsing by Author "Sreejith, A. G"

Browsing by Author "Sreejith, A. G"

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  • Balloon UV experiments for astronomical and atmospheric observations 
    Sreejith, A. G; Mathew, J; Mayuresh, Sarpotdar; Nirmal, K; Ambily, S; Prakash, A; Safonova, M; Murthy, J (SPIE-The International Society for Optical Engineering, 2016-08)
    The ultraviolet (UV) window has been largely unexplored through balloons for astronomy. We discuss here the development of a compact near-UV spectrograph with fiber optics input for balloon flights. It is a modified ...
  • Characterization of the HD 219134 multi-planet system I. Observations of stellar magnetism, wind, and high-energy flux 
    Folsom, C. P; Fossati, L; Wood, B. E; Sreejith, A. G; Cubillos, P. E; Vidotto, A. A; Alecian, E; Girish, V; Lichtenegger, H; Murthy, J; Petit, P; Valyavin, G (Oxford University Press on behalf of the Royal Astronomical Society, 2018-12)
    HD 219134 hosts several planets, with seven candidates reported, and the two shortest period planets are rocky (4–5 M⊕) and transit the star. Here, we present contemporaneous multiwavelength observations of the star ...
  • Characterization of the HD 219134 multi-planet system II. Stellar-wind sputtered exospheres in rocky planets b & c 
    Vidotto, A. A; Lichtenegger, H; Fossati, L; Folsom, C. P; Wood, B. E; Murthy, J; Petit, P; Sreejith, A. G; Valyavin, G (Oxford University Press on behalf of the Royal Astronomical Society, 2018-12)
    We present a 3D study of the formation of refractory-rich exospheres around the rocky planets HD219134b and c. These exospheres are formed by surface particles that have been sputtered by the wind of the host star. The ...
  • Characterization of the HD 219134 multi-planet system II. Stellar-wind sputtered exospheres in rocky planets b & c 
    Vidotto, A. A; Lichtenegger, H; Fossati, L; Folsom, C. P; Wood, B. E; Murthy, J; Petit, P; Sreejith, A. G; Valyavin, G (Oxford University Press on behalf of the Royal Astronomical Society, 2018-12)
    We present a 3D study of the formation of refractory-rich exospheres around the rocky planets HD219134b and c. These exospheres are formed by surface particles that have been sputtered by the wind of the host star. The ...
  • Design and modeling of a tunable spatial heterodyne spectrometer for emission line studies 
    Nirmal, K; Sridharan, R; Sriram, S; Murthy, J; Ambily, S; Safonova, M; Sreejith, A. G; Mathew, J; Mayuresh, Sarpotdar (SPIE--The International Society for Optical Engineering, 2018-04)
    Spatial heterodyne spectroscopy (SHS) is an interferometric technique similar to the Fourier transform spectroscopy with heritage from the Michelson interferometer. An imaging detector is used at the output of an SHS to ...
  • Development of Data Acquisition Methods for an FPGA-Based Photon Counting Detector 
    Ambily, S; Mayuresh, Sarpotdar; Mathew, J; Sreejith, A. G; Nirmal, K; Prakash, A; Safonova, M; Murthy, J (World Scientific Publishing Co., 2017-03)
    MCP-based detectors are widely used in the ultraviolet (UV) region due to their low noise levels, high sensitivity and good spatial and temporal resolution. We have developed a compact near-UV (NUV) detector for highaltitude ...
  • High altitude Balloon experiments 
    Sreejith, A. G (Indian Institute of Astrophysics, 2012-07)
    We are beginning a program of high altitude balloon flights at the Indian Institute of Astrophysics with the eventual goal of ultraviolet spectroscopy from high altitude balloons. The primary purpose of these flights is ...
  • High-altitude ballooning programme at the Indian Institute of Astrophysics 
    Akshata Nayak; Sreejith, A. G; Safonova, M; Murthy, J (Indian Academy of Sciences, 2013-03-25)
    Recent advances in balloons and in electronics have made possible scientific payloads at costs accessible to university departments. The primary purpose of high-altitude ballooning programme is to test low-cost ultraviolet ...
  • The near ultraviolet transient surveyor (NUTS): An ultraviolet telescope to observe variable sources 
    Ambily, S; Sarpotda, Mayuresh; Mathew, Joice; Binukumar, G; Sreejith, A. G; Nirmal, K; Murthy, J; Safonova, M; Mohan, Rekhesh; Aggarval, Vinod Kumar; Nagabhushanam, S; Jeeragal, Sachin (Springer, 2022-08)
    Observing the ultraviolet (UV) sky for time-varyiable phenomena is one of the many exciting science goals that can be achieved by a relatively small aperture telescope in space. The Near Ultraviolet Transient Surveyor ...
  • Near UV imager with an MCP-based photon counting detector 
    Ambily, S; Mathew, J; Mayuresh, Sarpotdar; Sreejith, A. G; Nirmal, K; Prakash, A; Safonova, M; Murthy, J (SPIE-The International Society for Optical Engineering, 2016-07)
    We are developing a compact UV Imager using light weight components, that can be own on a small CubeSat or a balloon platform. The system has a lens-based optics that can provide an aberration-free image over a wide field ...
  • Noise modeling and analysis of an IMU-based attitude sensor: improvement of performance by filtering and sensor fusion 
    Nirmal, K; Sreejith, A. G; Mathew, J; Mayuresh, Sarpotdar; Ambily, S; Prakash, A; Safonova, M (SPIE-The International Society for Optical Engineering, 2016-07)
    We describe the characterization and removal of noises present in the Inertial Measurement Unit (IMU) MPU- 6050, which was initially used in an attitude sensor, and later used in the development of a pointing system for ...
  • Opto-mechanical assembly and ground calibration of LUCI 
    Mathew, J; Nair, B. G; Sriram, S; Kamath, P. U; Prakash, A; Mayuresh, Sarpotdar; Ambily, S; Nirmal, K; Sreejith, A. G; Safonova, M; Murthy, J; Brosch, N (SPIE--The International Society for Optical Engineering, 2018-08-20)
    The Lunar Ultraviolet Cosmic Imager (LUCI) is an innovative all-spherical mirrors telescope, proposed to fly as a scientific UV imaging payload on a lunar mission in collaboration with Indian Aerospace Company-TeamIndus, ...
  • Pointing system for the balloon-borne astronomical payloads 
    Nirmal, K; Sreejith, A. G; Mathew, J; Mayuresh, Sarpotdar; Ambily, S||Prakash, A; Safonova, M; Murthy, J (SPIE-The International Society for Optical Engineering, 2016-12)
    We describe the development and implementation of a light-weight, fully autonomous 2-axis pointing and stabilization system designed for balloon-borne astronomical payloads. The system is developed using offthe-shelf ...
  • Predicting UV sky for future UV missions 
    Safonova, M; Mohan, Rekhesh; Sreejith, A. G; Murthy, J (Elsevier, 2013-02)
    Software simulators are now widely used in all areas of science, especially in application to astronomical missions: from instrument design to mission planning, and to data interpretation. We present a simulator to model ...
  • Prospect for UV observations from the Moon 
    Safonova, M; Mathew, J; Mohan, Rekhesh; Sreejith, A. G; Murthy, J; Brosch, N; Kappelmann, N; Sharma, A; Narayan, R (Springer, 2014-10)
    Space astronomy in the last 40 years has largely been done from spacecraft in low Earth orbit (LEO) for which the technology is proven and delivery mechanisms are readily available. However, new opportunities are arising ...
  • Prospect for UV observations from the Moon. II. Instrumental design of an ultraviolet imager LUCI 
    Mathew, J; Prakash, A; Mayuresh, Sarpotdar; Sreejith, A. G; Nirmal, K; Ambily, S; Safonova, M; Murthy, J; Brosch, N (Springer, 2017-02)
    We present a design for a near-ultraviolet (NUV) imaging instrument which may be flown on a range of available platforms, including high-altitude balloons, nanosatellites, or space missions. Although all current UV space ...
  • Prospect for UV observations from the moon. III. assembly and ground calibration of lunar ultraviolet cosmic imager (LUCI) 
    Mathew, J; Nair, B. G; Safonova, M; Sriram, S; Prakash, A; Mayuresh, Sarpotdar; Ambily, S; Nirmal, K; Sreejith, A. G; Murthy, J; Kamath, P. U; Kathiravan, S; Prasad, B. R; Brosch, Noah; Kappelmann, Norbert; Gadde, Nirmal Suraj; Narayan, Rahul (Springer, 2019-03)
    The Lunar Ultraviolet Cosmic Imager (LUCI) is a near-ultraviolet (NUV) telescope with all-spherical mirrors, designed and built to fly as a scientific payload on a lunar mission with Team Indus—the original Indian entry to ...
  • A Raspberry Pi-based attitude sensor 
    Sreejith, A. G; Mathew, J; Mayuresh, Sarpotdar; Mohan, Rekhesh; Akshata Nayak; Safonova, M; Murthy, J (World Scientific Publishing Co., 2014-11)
    We have developed a lightweight low-cost attitude sensor, based on a Raspberry Pi, built with readily available commercial components. It can be used in experiments where weight and power are constrained, such as in ...
  • A software package for evaluating the performance of a star sensor operation 
    Mayuresh, Sarpotdar; Mathew, J; Sreejith, A. G; Nirmal, K; Ambily, S; Prakash, A; Safonova, M; Murthy, J (Springer, 2017-02)
    We have developed a low-cost off-the-shelf component star sensor (StarSense) for use in minisatellites and CubeSats to determine the attitude of a satellite in orbit. StarSense is an imaging camera with a limiting magnitude ...
  • Studies of Earth's Atmosphere from Space and near Space 
    Sreejith, A. G (Indian Institute of Astrophysics, 2017-03)
    "We are conducting high-altitude balloon experiments at Indian Institute of Astrophysics using small scientific payloads for atmospheric and astronomical studies. The ultraviolet (UV) window has been largely unexplored ...

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