Hello Astro Data Lab community,
I am relatively new to the field, so I appreciate your patience if these questions are somewhat basic. I am currently working with the NOIRLab Source Catalog DR2 (NSC DR2) and have a couple of questions regarding magnitude-to-flux conversion and photometry consistency.
1) AB Magnitude System & Flux Conversion
Are the magnitudes across all bands in the NSC DR2 strictly in the AB system? Specifically, can I reliably convert these magnitudes to flux density in Janskys using the standard formula:
$$S_{\nu} = 3631 \times 10^{-0.4 \times \text{mag}}$$
The NSC DR2 paper mentions that Pan-STARRS1 (PS1) was used for northern data calibration, while other catalogs and models were used elsewhere. This mixed calibration has left me a bit confused about whether a uniform AB zero-point applies everywhere.
2) Instrumental Consistency & Transmission Curves for SED Fitting
Because the NSC is a unified catalog built from multiple telescopes and instruments (e.g., DECam, Mosaic, 90Prime), the effective transmission curves inherently vary. Since transmission curves of different instruments are different, doesn't this mean that magnitude values are not consistent throughout the catalog?
3) Synthetic photometry
For the purpose of synthetic photometry and constructing Spectral Energy Distributions (SEDs), which specific transmission curves and effective/mean/pivot wavelengths are recommended for each band?
Thank you in advance for your time and guidance!
Best regards,
Abdurakhmon