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. You may try the 'Bulk Download' feature, instead.
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. You may try the 'Bulk Download' feature, instead.
When should I use the Jump‑To‑File control?
- You are running several large (bulk or ZIP) downloads one after another.
- After each successful download the system shows the name of the last file that was retrieved.
- Before starting the next download, make sure the same filters and sorting you used for the previous download are applied.
- Enter that filename in the Jump‑to‑File box and click Submit.
- The table will be refreshed so the list starts at that file, letting you pick the next batch of files for your bulk or ZIP download.
What exactly does Jump‑To‑File do?
Jump‑To‑File re‑positions the file list so that the first row displayed is the file you entered, based on the current filters and sort order. It simply updates the view to help you select the next batch of files for bulk or ZIP downloads.
Tip for speedy results: using the default sorting (usually ID‑descending) yields the most performant response.
The downloaded zip file does not contain all the files that I selected. Why?
There is a per‑ZIP limit. When your selection exceeds the limit, the system only includes files up to that threshold.
The UI shows the name of the last file that was added to the ZIP.
To get the remaining files:
- Copy that filename.
- Paste it into the Jump‑To‑File input (found at the bottom‑left of the download page).
- Click Submit – the list will start from that file, letting you pick the next batch.
Alternative: Use the Download in Bulk button, which bypasses the ZIP‑size limit by streaming files individually.
When downloading data, how do I select data to ensure zip volume limits imposed by the application?
You may use the Select feature to specify the size (in MB) that you want to download and also specify the serial number of the first row that you want to select the data from, then submit your request. This selects data continuosly starting from the specified row. Additionally, it shows you the last selected filename, to help you select data for the next zip download.
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.