Change request #2194
Exposure keyword
| Status: | In Progress | Start date: | 09/15/2017 | ||
|---|---|---|---|---|---|
| Priority: | Normal | Due date: | |||
| Assigned To: |  Knödlseder Jürgen | % Done: | 10% | ||
| Category: | - | ||||
| Target version: | - | ||||
| Duration: |
Description
It will be great to have a total exposure at the position of observed source in header of lightcurve/spectrum/sky map files (e.g. in m^2*s units).
It seems that now there is no possibility to get this information.
Recurrence
No recurrence.
History
#1
Updated by Knödlseder Jürgen about 7 years ago
- Target version set to 1.5.0
Agree, this information (and probably also some other information) should be added. Don’t hesitate to put down a list of things that are useful for you.
#2
Updated by Knödlseder Jürgen about 7 years ago
- Assigned To set to Knödlseder Jürgen
#3
Updated by Knödlseder Jürgen about 7 years ago
- Status changed from New to In Progress
- % Done changed from 0 to 10
FITS header keywords were added to the sky map produced by ctskymap to inform about the dates and times covered by the input observations, as well as the event energies that were used.
The issue however requests in effect the exposure in units of cm^2 s which is a quantity that varies spatially. We have decided that we will optionally add the exposure map to the FITS file. The option can be controlled over a task parameter.
#4
Updated by Knödlseder Jürgen about 7 years ago
I looked a bit more into the issue of computing an exposure map within ctskymap. The issue is that the exposure is energy dependent. ctskymap combines in general events with vastly different energies into a map, hence you have to make an assumption about the spectral energy distribution of the events to create an exposure map. We definitely do not want to do this at the ctskymap level which should be a tool to generate model-independent sky maps from the events.
One way to achieve what you want is to go over cubes (ctbin, ctexpcube) which take the energy dependence into account.
We may also think about adding a ctexpmap tool that is similar to ctskymap and that computes an effective exposure map for a given spectral model.
For a light curve and spectrum produced by cslightcrv and csspec the situation is different since these methods directly returns fluxes and not counts. I’m not sure why you would need exposures in units of cm^2 s for these cases.
#5
Updated by Knödlseder Jürgen almost 7 years ago
- Target version deleted (
1.5.0)