In situ reflectance to satellite reflectance

Hello all,
I want to convert the in situ reflectance to satellite reflectance using SRF.I have downloaded the SRF file but I found that the band wavelengths are different than that in the sentinel 2 handbook, for example; in S2 the handbook wavelength of B1 is 443 while in SRF B1 start from 411nm for S2B. My question is if I want to convert my in-situ data to satellite data, i need to start from 443 nm or from 411nm as in SRF file.
I am confused about this issue.
I have attached the SRF file and my calculations to convert B1 in situ data to satellite data for at two locations.
I will be appreciated if anyone help me and check the excel file and also clear this issue to me.
Thank you so much
Mona

S2-SRF_COPE-GSEG-EOPG-TN-15-0007_3.1.xlsx (856.8 KB)

point1,2.xlsx (41.8 KB)

443 is just the central wavelength of B1. It has a bandwidth of 20.
Sentinel-2 - Missions - Resolution and Swath - Sentinel Handbook - Sentinel Online (esa.int)
So, you should consider at least the values from 433 to 453. Probably, it is good to sue also the other wavelengths provided.
The latest SFR table differs from the on you are using:
Sentinel-2 Spectral Response Functions (S2-SRF) - Sentinel Online (esa.int)

The equation for the convolution is given here:
filters - Convolution of spectra to sensor response function? - Signal Processing Stack Exchange

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