How to convert flux from counts to erg.

[RHK]

Hello everyone.
I am trying to translate the flux of a source observed by a telescope, in different units.
In my case, I have the flux equal to counts/cm^2/sec in a given energy band (15-50 keV) and I want to translate this information in erg/cm^2/sec, in the same energy band
Here you can find an example: http://heasarc.gsfc.nasa.gov/docs/swift/results/transients/weak/GX304-1.png

Does anyone know how can I do that?

Every suggestion is really appreciated.
Ciao

 

[SHISHKABOB]

each count is just a photon with that specific energy level, so you just have to multiply the number of photons by the energy of the photons. Then of course convert from keV to erg, which just means multiplying by some conversion constants.

er wait, I think I misread the graph, sorry >.> what's on the bottom axis?

 

[RHK]

The time, in MJD (modified julian date, it is like "days").

 

[SHISHKABOB]

oh, I see, I'm sorry but I thought I could help but I don't know either

 

[pmacias]

To convert flux from counts to erg, you will need to use the conversion factor for the specific instrument you are using. This conversion factor can usually be found in the instrument's calibration files or in the instrument's documentation.

Once you have the conversion factor, you can use the following formula:

Flux (erg/cm^2/sec) = Counts (counts/cm^2/sec) * Conversion Factor

For example, if your instrument's conversion factor is 1.5 x 10^-9 erg/count, you would use the formula:

Flux (erg/cm^2/sec) = Counts (counts/cm^2/sec) * 1.5 x 10^-9 erg/count

In the case of the example you provided, you can see that the counts in the 15-50 keV energy band is 1.5 x 10^-9 counts/cm^2/sec. If we use the conversion factor of 1.5 x 10^-9 erg/count, we can calculate the flux in erg/cm^2/sec as:

Flux (erg/cm^2/sec) = 1.5 x 10^-9 counts/cm^2/sec * 1.5 x 10^-9 erg/count = 2.25 x 10^-18 erg/cm^2/sec

Therefore, the flux in the 15-50 keV energy band is 2.25 x 10^-18 erg/cm^2/sec.

Remember to always check your units and conversion factors to ensure an accurate and precise conversion.