Minimum partial coding of snr images

[samueleronchini]

I was trying to run the imaging on this grb
https://gcn.nasa.gov/circulars/32023

I wanted to check at which partial coding fraction the GRB is at t0.

So I run event.create_skyview in this way:

energybins = [15, 350] * u.keV

t0=673969345.989204

time_bins = [0,0.2]*u.s

skyview = event.create_skyview(timebins=time_bins, 

energybins=energybins, is_relative=True, recalc = True, T0=t0, 

input_dict=dict(aperture="CALDB:DETECTION", pcodethresh=0.01))

Then I plot the snr image along with the pc map, and I find that the snr image does not have data below pc = 0.05, even if I specified pcodethresh=0.01.

I also checked the header of the file and I see pcodethresh=0.01

As a consequence, if I try to run a mosaic, no source is found, likely because the GRB was never at a pc > 0.05, but is for sure at pc > 0.01

The plot I attach shows the snr heat map with the pc line at 0.05. Te pc line at 0.01 is outside the plot, on the right. The GRB location is at the center of the plot.

[parsotat]

This issue is caused by the hardcoded filtering that is done here:

BatAnalysis/batanalysis/bat_skyview.py

Line 448 in 6f668fe

idx = np.where(self.pcode_img <= 0.05)

This is affecting the plotting of the image and not the source detection since the input_dict=dict(aperture="CALDB:DETECTION", pcodethresh=0.01), where pcodethresh is explicitly set to be 0.01. Thus, the source detection goes down to a partial coding of 1%.

to work around this for plotting purposes, you can simply load in the full image from the file and set it to the attribute of interest. Here is show an example for the SNR image :

skyview.snr_img = BatSkyImage.from_file(skyview.snr_img_file)