Indian payloads (RT-2 Experiment) onboard CORONAS-PHOTON mission

RT-2 Experiment (RT - Roentgen Telescope) is a low energy gamma-ray instrument which is designed and developed as a part of Indo-Russian collaborative project of CORONAS-PHOTON Mission to study the Solar flares in wide energy band of electromagnetic spectrum ranging from UV to high-energy γ-rays (~ 2000 MeV). RT-2 instruments will cover the energy range of 15 keV to 150 keV extendable up to ~ 1 MeV. It consists of three detectors (two Phoswich detectors, namely, RT-2/S, RT-2/G and one solid-state imaging detector RT-2/CZT) and one processing electronic device (RT-2/E). Both Phoswich detectors will have time resolved spectrum, whereas the solid-state imaging detector will have high resolved image of the solar flares in hard X-rays. We have used Co-57 (122 keV) radio-active source for onboard calibration of all three detectors. In this paper, we briefly discuss the in-flight performance of RT-2 instruments and present initial flight data from the instruments. This mission was launched into polar LEO (Low Earth Orbit) (~ 550 km) on 30th January 2009 from Plesetsk Cosmodrome, Russia

Instruments of RT-2 Experiment onboard CORONAS-PHOTON and their test and evaluation II: RT-2/CZT payload

Cadmium Zinc Telluride (CZT) detectors are high sensitivity and high resolution devices for hard X-ray imaging and spectroscopic studies. The new series of CZT detector modules (OMS40G256) manufactured by Orbotech Medical Solutions (OMS), Israel, are used in the RT-2/CZT payload onboard the CORONAS-PHOTON satellite. The CZT detectors, sensitive in the energy range of 20 keV to 150 keV, are used to image solar flares in hard X-rays. Since these modules are essentially manufactured for commercial applications, we have carried out a series of comprehensive tests on these modules so that they can be confidently used in space-borne systems. These tests lead us to select the best three pieces of the 'Gold' modules for the RT-2/CZT payload. This paper presents the characterization of CZT modules and the criteria followed for selecting the ones for the RT-2/CZT payload. The RT-2/CZT payload carries, along with three CZT modules, a high spatial resolution CMOS detector for high resolution imaging of transient X-ray events. Therefore, we discuss the characterization of the CMOS detector as well.Comment: 26 pages, 19 figures, Accepted for publication in Experimental Astronomy (in press

Instruments of RT-2 Experiment onboard CORONAS-PHOTON and their test and evaluation V: Onboard software, Data Structure, Telemetry and Telecommand

The onboard software and data communication in the RT-2 Experiment onboard the Coronas-Photon satellite is organized in a hierarchical way to effectively handle and communicate asynchronous data generated by the X-ray detectors. A flexible data handling system is organized in the X-ray detector packages themselves and the processing electronic device, namely RT-2/E, has the necessary intelligence to communicate with the 3 scientific payloads by issuing commands and receiving data. It has direct interfacing with the Satellite systems and issues commands to the detectors and processes the detector data before sending to the satellite systems. The onboard software is configured with several novel features like a) device independent communication scheme, b) loss-less data compression and c) Digital Signal Processor. Functionality of the onboard software along with the data structure, command structure, complex processing scheme etc. are discussed in this paper.Comment: 24 pages, 2 figures, Accepted for publication in Experimental Astronomy (in press

RT-2 Detection of Quasi-Periodic Pulsations in the 2009 July 5 Solar Hard X-ray Flare

We present the results of an analysis of hard X-ray observations of the C2.7 solar flare detected by the RT-2 Experiment onboard the Coronas - Photon satellite. We detect hard X-ray pulsations at periods of ~12 s and ~15 s. We find a marginal evidence for a decrease in period with time. We have augmented these results using the publicly available data from the RHESSI satellite. We present a spectral analysis and measure the spectral parameters.Comment: 12 pages, 8 figures and 3 tables, accepted for publication in The Astrophysical Journa

Detection of GRB 090618 with RT-2 Experiment Onboard the Coronas-Photon Satellite

We present the results of an analysis of the prompt gamma-ray emission from GRB 090618 using the RT-2 Experiment onboard the Coronas-Photon satellite. GRB 090618 shows multiple peaks and a detailed study of the temporal structure as a function of energy is carried out. As the GRB was incident at an angle of 77 degree to the detector axis, we have generated appropriate response functions of the detectors to derive the spectrum of this GRB. We have augmented these results using the publicly available data from the Swift BAT detector and show that a combined spectral analysis can measure the spectral parameters quite accurately. We also attempt a spectral and timing analysis of individual peaks and find evidence for a systematic change in the pulse emission characteristics for the successive pulses. In particular, we find that the peak energy of the spectrum, E_p, is found to monotonically decrease with time, for the successive pulses of this GRB.Comment: 12 pages, 6 figures, 3 tables, Accepted for publication in The Astrophysical Journa

Comprehensive Multidimensional Liquid Chromatography-Mass Spectrometry for the Characterization of Charge Variants of a Bispecific Antibody

Identification and further characterization of antibody charge variants is a crucial step during biopharmaceutical drug development, particularly with regard to the increasing complexity of novel antibody formats. As a standard analytical approach, manual offline fractionation of charge variants by cation-exchange chromatography followed by comprehensive analytical testing is applied. These conventional workflows are time-consuming and labor-intensive and overall reach their limits in terms of chromatographic separation of enhanced structural heterogeneities raised from new antibody formats. For these reasons, we aimed to develop an alternative online characterization strategy for charge variant characterization of a therapeutic bispecific antibody by online mD-LC-MS at middle-up (2D-LC-MS) and bottom-up (4D-LC-MS) level. Using the implemented online mD-LC-MS approach, all medium-and even low-abundant product variants previously identified by offline fraction experiments and liquid chromatography mass spectrometry could be monitored. The herein reported automated online mD-LC-MS methodology therefore represents a complementary and in part alternative approach for analytical method validation including multiattribute monitoring (MAM) strategies by mass spectrometry, offering various benefits including increased throughput and reduced sample handling and combined protein information at intact protein and peptide level.Proteomic

Detailed analytical characterization of a bispecific IgG1 CrossMab antibody of the knob-into-hole format applying various stress conditions revealed pronounced stability

In recent years, a variety of new antibody formats have been developed. One of these formats allows the binding of one type of antibody to two different epitopes. This can for example be achieved by introduction of the "knob-into-hole" format and a combined CrossMab approach. Due to their complexity, these bispecific antibodies are expected to result in an enhanced variety of different degradation products. Reports on the stability of these molecules are still largely lacking. To address this, a panel of stress conditions, including elevated temperature, pH, oxidizing agents, and forced glycation via glucose incubation, to identify and functionally evaluate critical quality attributes in the complementary-determining and conserved regions of a bispecific antibody was applied in this study. The exertion of various stress conditions combined with an assessment by size exclusion chromatography, ion exchange chromatography, LC-MS/MS peptide mapping, and functional evaluation by cell-based assays was adequate to identify chemical modification sites and assess the stability and integrity, as well as the functionality of a bispecific antibody. Stress conditions induced size variants and post-translational modifications, such as isomerization, deamidation, and oxidation, albeit to a modest extent. Of note, all the observed stress conditions largely maintained functionality. In summary, this study revealed the pronounced stability of IgG1 "knob-into-hole" bispecific CrossMab antibodies compared to already marketed antibody products.</p

Detailed Analytical Characterization of a Bispecific IgG1 CrossMab Antibody of the Knob-into-Hole Format Applying Various Stress Conditions Revealed Pronounced Stability

In recent years, a variety of new antibody formats have been developed. One of these formats allows the binding of one type of antibody to two different epitopes. This can for example be achieved by introduction of the "knob-into-hole" format and a combined CrossMab approach. Due to their complexity, these bispecific antibodies are expected to result in an enhanced variety of different degradation products. Reports on the stability of these molecules are still largely lacking. To address this, a panel of stress conditions, including elevated temperature, pH, oxidizing agents, and forced glycation via glucose incubation, to identify and functionally evaluate critical quality attributes in the complementary-determining and conserved regions of a bispecific antibody was applied in this study. The exertion of various stress conditions combined with an assessment by size exclusion chromatography, ion exchange chromatography, LC-MS/MS peptide mapping, and functional evaluation by cell-based assays was adequate to identify chemical modification sites and assess the stability and integrity, as well as the functionality of a bispecific antibody. Stress conditions induced size variants and post-translational modifications, such as isomerization, deamidation, and oxidation, albeit to a modest extent. Of note, all the observed stress conditions largely maintained functionality. In summary, this study revealed the pronounced stability of IgG1 "knob-into-hole" bispecific CrossMab antibodies compared to already marketed antibody products.Proteomic

Onboard performance of the RT-2 detectors

The RT-2 Experiment onboard the CORONAS-PHOTON satellite is designed to study the spectral, temporal, and spatial details of solar hard X-ray flares in the 15–150 keV range. Above this energy (and upto 1000 keV), it also acts as an omni-directional gamma-ray detector with a capability to study gamma-ray bursts (GRB), bright solar flares, and X-ray pulsars. With an ensemble of hard X-ray detectors with different fields of view and coding devices, it also has the capability to investigate the spectrum of Cosmic Diffuse X-ray Background. The performance of the detectors from 2009 February to November is described in this paper. Results obtained on a few GRBs and solar flares are also briefly discussed