ermask for large areas

[micmic]

Hello,

Reading the documentation of the ermark routine, it's not clear
1. what is the default values for threshold1 and threashold2 parameters
2. why "Valid pixels need to have at leas 10% of the maximum exposure"

In the figure below, I show the exposure map of a big (~3deg radius) region of the sky in which the exposure is highly uneven, which results in the exclusion of the majority of the region using detmask.
I tried to lower threashod1 to anything <10% but it gives an error:

Code: Select all

 ermask: 1.7.1 eSASS4DR1 feb 01 15:54:43 2024
 ermask/fput_i1image: **ERROR3** Error creating FITS file
 ermask: FAILED

I need this to run erbox afterwards as detmask seems to be a required entry (I tried setting detmask_flag="N" but it complains with "No detection mask for exposure").

Thanks

[micmic]

Forgot the image:

Screenshot 2024-05-19 at 1.03.26 PM.png (101.42 KiB) Viewed 320 times

[GeorgLamer]

Dear eSASS user,

in sky tiles with large exposure variations the parameter threshold1 should be set to very small values or 0.0 in order to generate a detection mask where all pixels are valid. The 10% mentioned in the documention just refer to the example call of ermask.
If the task fails to write the FITS file, most likely a file with the same name already exists. Please delete the old file or set task parameter clobber=yes.

Best regards,
Georg Lamer