Magnitudes with astrometry.net

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Karina Sepúlveda

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Jul 24, 2022, 1:27:24 PMJul 24
to astrometry
Hello, I am using Astrometry.net for the first time, I have an image of an open cluster and I see that with this program some flow tables were obtained. I wonder if this flux can be converted directly to an instrumental quantity to perform aperture photometry, through the equation that relates them both, or if it is necessary to work with these flux data from IRAF or SEXTRACTOR. Thank you very much

Jerry Zhang

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Jul 25, 2022, 1:13:52 PMJul 25
to astrometry
Hi, I think the fluxes need a 'standard', or 'zero point' to convert into magnitudes. I would suggest to cross-match with some catalog in the same filter of your image and use the magnitudes and fluxes of the stars that crossmatched as the zero points. The rest magnitudes can be obtained by simply using the logarithm law.

Dustin Lang

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Jul 25, 2022, 2:01:54 PMJul 25
to Karina Sepúlveda, astrometry
Hi,

The source detection and flux measurements done by Astrometry.net are very rudimentary, and not good enough to do photometric calibration with.  Sorry!

cheers,
dustin

On Sun, Jul 24, 2022 at 1:27 PM Karina Sepúlveda <k.sepul...@gmail.com> wrote:
Hello, I am using Astrometry.net for the first time, I have an image of an open cluster and I see that with this program some flow tables were obtained. I wonder if this flux can be converted directly to an instrumental quantity to perform aperture photometry, through the equation that relates them both, or if it is necessary to work with these flux data from IRAF or SEXTRACTOR. Thank you very much

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