The imgcat0_apmags code performs a lot of steps and hence produces a lot of intermediate output files. Where do they go? Like the image_catalogs output files the code deposits them in a subdirectory in the ./local_reds directory. Becasue there are a lot of files, I use a subdirectory there that takes the base name of the image being reduced. Hence, in the example where we process 20191018T024545.3_acm_sci.fits, the data files are deposited in:

 
% cat imgcat0_apmags.config   
ApRadPix   16.0
NumPixMin  8
rin   22.0 
rout 35.0 
NumPixMinOp  5  

% imgcat0_apmags /home/sco/AUTO_match_for_wcs/S/20191018T024545.3_acm_sci.fits -c  

% cd ./local_red/ApMags/20191018T024545.3_acm_sci/        # subdirectory where output files are deposited  
 

Next I list all of the important files in reverse order of creation. Hence, in the example below, the last (and most useful) table file created was the table file with basename ApMags. The first regions file created, that contains region markers for all of the sources in the original imgcat0 catalog, was 20191018T024545.3_acm_sci.cdfp_4profs.reg. I break up this listing with some terse cooment strings (in green) that describe the diffreent file sets. Note that most of these products are table file so that I can easily plot with them or operate on them with various table functions.

 

% ls -lt --time-style=full-iso 2019* 

-rw-r--r-- 1 sco sco     705 2020-07-04 15:42:00.291824354 -0500 20191018T024545.3_acm_sci_ApMags.parlab
-rw-r--r-- 1 sco sco    3589 2020-07-04 15:42:00.291824354 -0500 20191018T024545.3_acm_sci_ApMags.table
   # The final product: a table file of corrected instumental aperture magnitudes.  

-rw-r--r-- 1 sco sco     613 2020-07-04 15:42:00.263824116 -0500 20191018T024545.3_acm_sci_OpAps.parlab
-rw-r--r-- 1 sco sco    4108 2020-07-04 15:42:00.263824116 -0500 20191018T024545.3_acm_sci_OpAps.table
   # The aperture magnitudes computed in ptimal apertures  

-rw-r--r-- 1 sco sco     107 2020-07-04 15:42:00.191823500 -0500 20191018T024545.3_acm_sci_GCspline.parlab
-rw-r--r-- 1 sco sco    1663 2020-07-04 15:42:00.191823500 -0500 20191018T024545.3_acm_sci_GCspline.table
   # The spline-derived table of the mean flux growth curve points  

-rw-r--r-- 1 sco sco     208 2020-07-04 15:42:00.191823500 -0500 20191018T024545.3_acm_sci_meanGC.parlab
-rw-r--r-- 1 sco sco     715 2020-07-04 15:42:00.191823500 -0500 20191018T024545.3_acm_sci_meanGC.table
   # The mean flux growth curve points from all computed profiles   

-rw-r--r-- 1 sco sco     411 2020-07-04 15:42:00.191823500 -0500 20191018T024545.3_acm_sci_quartile.stats
   # derived statistics for quartile parameters   

-rw-r--r-- 1 sco sco    4382 2020-07-04 15:42:00.067822441 -0500 20191018T024545.3_acm_sci_bkgannuli.reg
   # region file showing the background annuli for the optimized apertures    

-rw-r--r-- 1 sco sco  140942 2020-07-04 15:42:00.067822441 -0500 20191018T024545.3_acm_sci.info
   # indo file  t stored the mido2.sh photometry   

-rw-r--r-- 1 sco sco    2448 2020-07-04 15:41:59.859820664 -0500 20191018T024545.3_acm_sci_OpAps.reg
   # region file showing the the optimized apertures    

-rw-r--r-- 1 sco sco   32767 2020-07-04 15:41:59.567818169 -0500 20191018T024545.3_acm_sci_profiles_full.table
-rw-r--r-- 1 sco sco     485 2020-07-04 15:41:59.551818032 -0500 20191018T024545.3_acm_sci_profiles_full.parlab
   # table file containing all profiles   

-rw-r--r-- 1 sco sco    4401 2020-07-04 15:41:59.567818169 -0500 20191018T024545.3_acm_sci_profiles.table
-rw-r--r-- 1 sco sco     801 2020-07-04 15:41:59.559818100 -0500 20191018T024545.3_acm_sci_profiles.parlab
   # table file containing profile parameters for each source   

-rw-r--r-- 1 sco sco    3096 2020-07-04 15:41:59.519817758 -0500 20191018T024545.3_acm_sci.profpars
   # input file for the profiles.sh code    

-rw-r--r-- 1 sco sco    4220 2020-07-04 15:41:59.423816938 -0500 20191018T024545.3_acm_sci_bkgannuli_4profs.reg
   # background annuli for sources with profile calculation    

-rw-r--r-- 1 sco sco    2381 2020-07-04 15:41:59.215815161 -0500 20191018T024545.3_acm_sci_apertures.cdfp_4profs.reg
   # apertures for stars bright enough for profile calculation    

-rw-r--r-- 1 sco sco   16428 2020-07-04 15:41:59.203815058 -0500 20191018T024545.3_acm_sci.cdfp_4profs.reg
   # all original imgcat0 sources     

-rw-r--r-- 1 sco sco 2401920 2020-07-04 15:41:59.043813690 -0500 20191018T024545.3_acm_sci.fits
   # original FITS image     


-rw-r--r-- 1 sco sco    1047 2020-07-04 15:41:59.635818750 -0500 20191018T024545.3_acm_sci_imgcat0_apmags.summary
   # A summary of the measurement parameters used      

% cat 20191018T024545.3_acm_sci_imgcat0_apmags.summary 
Summary of imgcat0_apmags parameters used for basename = 20191018T024545.3_acm_sci 

For profile calculation to derive quartile radii: 
Min number of allowed pixels for objecte selected from imgcat0 (NumPixMin) = 8 
Fixed aperture radius (in pixels) of objects selected (ApRadPix )          = 16.0 
Inner bkg radius (r1, in pixels)                                           =      21.000000 
Outer bkg radius (r2, in pixels)                                           =      42.000000 

For optimal aperture photometry: 
Median half-light radius in pixel units (R50)                              = 4.225000 
Median 75-percent radius in pixel units (R75)                              = 5.973000 
Smallest allowed optimal aperture (rsmallest)                              = 4.225000 
Radius in pixel units of inner background annulus (rin)                    =      11.946000 
Radius in pixel units of outer background annulus (rout)                   =      23.892000 
Minimum allowed NumPix (imgcat0) for final sources with apertures          = 5