give resolution time in minutes for the given user story, only provide the number of minutes in the output without any other text

User story: Inspired by some anomalous behavior in simulated DESC DC2 imaging, I started an  investigation of the difference between {{psf}} magnitudes and  {{CircularAperture_12_0}} magnitudes (used for calibration) on {{calexp}} s.  This comparison is particularly important because the aperture correction maps  that are applied to all fluxes in both {{calexp}} source catalogs and coadd  catalogs are derived from this relationship.  It turns out that there is  significant curvature in the psf - aper relationship.  These plots use all the  stars used for the psf modeling across all 103 ccds in a visit, the same stars  that were used to compute the aperture correction map:   !visit_1258_delta_psf_vs_calib_mag.png|thumbnail!   All of these plots are for some sample i-band images, but the problem is seen  across a wide range of bands and images, see  https://lsstc.slack.com/archives/C2JPXB4HG/p1576703633032000 and following.    Also notable is that the scatter is reduced if you do not apply the aperture  corrections to the psf fluxes, though an overall offset appears (as is expected  if you don't compute any aperture correction):   !visit_1258_delta_psf_uncorr_vs_calib_mag.png|thumbnail!   The shape of the curvature is consistent with that expected from a sky offset.  This is further demonstrated by comparing the psf - aper bias for different  aperture sizes:     |!visit_35870_delta_psf_uncorr_vs_aper12_mag.png|thumbnail!|!visit_35870_delta_psf_uncorr_vs_aper17_mag.png|thumbnail!|    Further investigation has shown that the bias is indeed caused by offsets in  the sky, and in fact are tracked by the {{LocalBackground}} estimation:   !visit35870_localback_vs_delta.png|thumbnail!    That is, when delta-mag (psf - aper) is negative, the local background is  negative as well (for faint stars where the background matters).    The basic problem is that we have (known) issues with the background in the  calexp images which we correct in the coaddition stage.  However, these issues  create problems in both the photometric calibration and the aperture correction  computation which confuses the background problem (which is an additive  problem) with the zeropoints and aperture corrections (which are multiplicative  corrections).    A pragmatic solution proposed by [~<USER> is to do what was originally intended:  only use bright stars when computing the aperture correction map.    I ran {{processCcd}} on a single i-band exposure where the aperture correction  was computed only with stars that were used for the psf modeling and had psf  s/n > 250.  This of course does not fix the curvature, but leads to much  reduced scatter at the bright end between calibration and psf magnitudes:     !visit_35870_delta_psf_vs_aper12_mag_default.png|thumbnail!|!visit_35870_delta_psf_vs_aper12_mag_aperbright.png|thumbnail!|    Finally, I ran all of VVDS i-band from RC2 through {{singleFrameDriver}} with  the new configuration, and ran {{validate_drp}} (without jointcal) for both the  RC2 "vanilla" processing from {{w_2019_46}} and from the new {{aperbright}}  processing.  The PA1 metric reduced from 23.6 mmag to 19.5 mmag, or a  difference in quadrature of approximately 13 mmag, which is quite a difference.  |!validate-vanilla_hsc-i_pa1.png|thumbnail!|!validate-aperbright_hsc-i_pa1.png|thumbnail!|  
Answer: 4153.0