M31/M33 Photometry; Paper IV

Note: Official photometry data repository can be found at http://go.uis.edu/m31m33photcat.

Broadband BVRI CCD photometry with ASTRODON Johnson-Cousins filters was obtained with the 20-inch telescope at the Barber Observatory with an Apogee U42 CCD camera using a back-illuminated E2V CCD42-40 chip. All images were flat-fielded and bias and dark subtracted.

PSF fitted photometry was measured using DAOphot. Star PSFs on the images were modeled by a elliptical Gaussian. Parameters for the PSF (along with their first order derivatives with respect to position on the image) were determined using no fewer than 20 bright stars in each image.

The photometry was calibrated using an ensemble of no fewer than seven comparison stars selected from the APASS catalog data release 9 (Henden et al., 2015; https://www.aavso.org/apass). Quoted errors in the photometry are calculated using the standard deviation of the photometry zero point from the comparison stars. The photometry has not been transformed. Transform coefficients for the system are available on request. The telescope/camera/filter combination used has in the past only required small corrections (less than 0.05) for the most extreme red objects.

The columns of the text files are: JD, Mag, Mag_error, (average color of comparison stars), Filter, (number of stars potentially blended with this PSF), (distance in pixels from star center to RA,Dec of the target), (name of the target)

NOTE: The photometry is preliminary and subject to change. The final results will be published in a separate paper in the coming months.

Click below to download all the photometry files. Individual datasets may be downloaded in the table that follows.

 Download Photometry

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