Joint Multiband Photometry with crowdsource
- 1Space Telescope Science Institute
- 2NSF National Optical-Infrared Astronomy Research Laboratory
Abstract
We present a new multiband extension to the crowdsource photometric pipeline, enabling simultaneous fitting across multiple imaging bands in crowded fields. The core idea is that multiple images of the same part of the sky should have the same sources at the same locations; only the fluxes in the different images should be allowed to vary in fitting. The framework also allows us to use all images of a given region to detect faint sources, with configurable weighting among the different bandpasses as appropriate for different source spectra. Similar concepts are already present in other crowded field packages like DAOPHOT and DOLPHOT; we now include it in the crowdsource fitting approach. We describe the mathematical formulation of the multiband fit and demonstrate its performance using the Wide-field Infrared Survey Explorer (WISE) W1 and W2 imaging as a concrete application. The multiband algorithm improves flux consistency and reduces band-to-band positional scatter relative to independent-band fitting. We test the method on unWISE coadded tiles spanning both sparse and crowded regions and quantify improvements in photometric agreement and astrometric stability. This framework provides a general foundation for future multiband crowded-field catalogs.
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BibTeX
@article{behera2026joint,
title = {{Joint Multiband Photometry with crowdsource}},
author = {Jayashree Behera and Edward F. Schlafly and Aaron M. Meisner and Lucas Napolitano},
journal = {The Astrophysical Journal},
year = {2026},
month = oct,
doi = {10.3847/1538-4357/aead9c},
url = {https://iopscience.iop.org/article/10.3847/1538-4357/aead9c},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Joint Multiband Photometry with crowdsource
AU - Jayashree Behera
AU - Edward F. Schlafly
AU - Aaron M. Meisner
AU - Lucas Napolitano
PY - 2026
DA - 2026/10/30
JO - The Astrophysical Journal
DO - 10.3847/1538-4357/aead9c
UR - https://iopscience.iop.org/article/10.3847/1538-4357/aead9c
AB - We present a new multiband extension to the crowdsource photometric pipeline, enabling simultaneous fitting across multiple imaging bands in crowded fields. The core idea is that multiple images of the same part of the sky should have the same sources at the same locations; only the fluxes in the different images should be allowed to vary in fitting. The framework also allows us to use all images of a given region to detect faint sources, with configurable weighting among the different bandpasses as appropriate for different source spectra. Similar concepts are already present in other crowded field packages like DAOPHOT and DOLPHOT; we now include it in the crowdsource fitting approach. We describe the mathematical formulation of the multiband fit and demonstrate its performance using the Wide-field Infrared Survey Explorer (WISE) W1 and W2 imaging as a concrete application. The multiband algorithm improves flux consistency and reduces band-to-band positional scatter relative to independent-band fitting. We test the method on unWISE coadded tiles spanning both sparse and crowded regions and quantify improvements in photometric agreement and astrometric stability. This framework provides a general foundation for future multiband crowded-field catalogs.
SN - 1538-4357
SN - 0004-637X
ER -