Frequently Asked Questions
Application Related
I am facing issue when trying to download the data by clicking on files. What can be done?
This is usually observed when you are using high latency network. You might try using chrome browser or integrate a download manager with your existing browser.
Also note that if you do not use the website for 30 minutes, it times out. In such a scenario, first login to PRADAN and then resume your download.
Also note that if you do not use the website for 30 minutes, it times out. In such a scenario, first login to PRADAN and then resume your download.
I am facing issue when trying to download the data by clicking on Download button. What can be done?
Please take a look at the message displayed above the table, it will guide you appropriately. You may also click on individual files to download the data.
The downloaded zip file does not contain all the files that I selected.
There is a limit defined on the number of file selection based on their sizes. This is also indicated in the warning message which is displayed when trying to download more than the defined limit. You may use the 'Select' feature provided below the data table to help you select the data.
When downloading data, how do I select data to ensure zip volume limits imposed by the application?
You may use the Select feature provided at the end of the payload pages to specify the serial number of the first row that you want to select, then specify the volume of data that is to be selected and then click select. This selects rows continuosly starting from the specified row, and shows you the last selected row in the table. This helps you to know the first row for your next selection.
If you want to select files manually, please use the file size column to know the individual file size and download button displays the limit imposed, to appropriately select the data.
If you want to select files manually, please use the file size column to know the individual file size and download button displays the limit imposed, to appropriately select the data.
After registration and email verification, it shows "Either the page does not exist or you do not have access to this page". How can I get access?
This means that the data access permission is to be assigned to you by the administrator. Please use the 'Contacts' page to reach the administrator.
Data related
What is the energy range of GRASP?
Electrons: 0.5 - 10 MeV, Protons: 4.5 - 85 MeV , Alphas: 18 - 85 MeV
How many detectors are there in GRASP?
Two detectors: a thin silicon PIN detector (acts as deltaE detector), a thicker CsI(Tl) scintillator (acts as E detector).
Are there different modes of operation for the payload?
Yes, there are primarily two different modes of operation: event mode and matrix mode.
Event mode processes each particle interaction and stores information of energy deposition in each detector with a time-stamp. Thus, it provides the actual E-delta E values from which particle identification can be done. This mode requires more memory and thus is used (switched to automatically) when the incident particle rate is low.
Matrix mode is a mode wherein on-board binning of E-delta E values occurs. The payload, in this mode, provides a coarsely binned 2D histogram per second. The histogram is made at a fixed, linear binning of 16X8 E-delta E bins such that it covers the entire energy deposition range for the particles.
Event mode processes each particle interaction and stores information of energy deposition in each detector with a time-stamp. Thus, it provides the actual E-delta E values from which particle identification can be done. This mode requires more memory and thus is used (switched to automatically) when the incident particle rate is low.
Matrix mode is a mode wherein on-board binning of E-delta E values occurs. The payload, in this mode, provides a coarsely binned 2D histogram per second. The histogram is made at a fixed, linear binning of 16X8 E-delta E bins such that it covers the entire energy deposition range for the particles.
What is the default mode of operation?
Default mode is matrix mode. As the particle flux at GEO orbit is higher than ~100 cps, the system automatically sets itself to matrix mode. The payload has been operating in this mode all along.
How is the particle identification done?
The instrument is designed to work in coincidence mode: a near-simultaneous signal generation from both the detectors implies that the incident radiation is charged particle. The ratio of the energy deposition in both the detectors is an indication of the charge and mass of the particle. The electronics gain is adjusted such that at any given time, only one of the species (either electrons or protons/alphas) is captured in the histogram of the matrix mode, while the other species are relegated to the saturation channels or the zero channel.
Is there proton contamination in electron flux and vice-versa?
The instrument is designed to minimize the cross-species flux contamination in the data. Nevertheless, due to the generation of secondary electrons by incident primary protons there can be some contamination (up to a maximum of 5%). The extent of the flux contamination depends on the individual flux of electrons and protons and also their spectra. Under nominal conditions (solar quiet conditions), the level of flux contamination is negligible due to absence of energetic protons at GEO orbit.