Tests of photometry: the case of the NGC 3370 ACS field

Abstract

A critical analysis and comparison of different methods for obtaining point spread function (PSF) photometry are carried out. Deep ACS observations of NGC3370 were reduced using four distinct approaches. These reductions explore a number of methodological differences: software packages (DAOPHOT and DOLPHOT), input images (individual and stacked frames), PSF models (synthetic and empirical), and aperture correction methods (automatic and manual). A comparison of the photometry leads to the following results: 1) Photometric incompleteness between individual reductions shows only a minimal difference (<10%). 2) Statistical errors are 20% to 30% smaller for DAOPHOT runs on stacked frames than DOLPHOT runs on individual frames. 3) Statistical errors assigned directly by the photometry codes are 25% to 50% smaller than the errors measured from artificial star tests. 4) Systematic errors are magnitude dependent and become larger at the faint end, at the level of ${\sigma }_s\sim 0.1$ mag. 5) The automatic aperture correction routines in DOLPHOT result in a significant systematic error (${\sigma }_s\sim 0.05$ mag). 6) Individual reductions agree well at the 0.02 mag level when the systematic errors are properly corrected through artificial star tests. The reasonable agreement between the reductions leads to important implications that i) the reduction dependent errors can be reduced to a 1% level in the luminosity distance scale, and ii) the stacked frame photometry can be a good means to study non-variable stars in external galaxies.

18 pages, 11 figures, 5 tables, submitted

References in corpus (20)

• A Comprehensive Measurement of the Local Value of the Hubble Constant with 1 km/s/Mpc Uncertainty from the Hubble Space Telescope and the SH0ES Team
• A distance to the Large Magellanic Cloud that is precise to one per cent
• Measurements of the Hubble Constant: Tensions in Perspective
• The ACS Nearby Galaxy Survey Treasury
• Calibration of the Tip of the Red Giant Branch (TRGB)
• The Quenching of the Ultra-Faint Dwarf Galaxies in the Reionization Era
• A distance determination to the Small Magellanic Cloud with an accuracy of better than 2 percent based on late-type eclipsing binary stars
• Distances to PHANGS Galaxies: New Tip of the Red Giant Branch Measurements and Adopted Distances
• Tip of the Red Giant Branch Distances. I. Optimization of a Maximum Likelihood Algorithm
• I Zw 18 revisited with HST/ACS and Cepheids: New Distance and Age
• Forward Global Photometric Calibration of the Dark Energy Survey
• The Metallicity Distribution of Intracluster Stars in Virgo
• The Tip of the Red Giant Branch Distances to Type Ia Supernova Host Galaxies. IV. Color Dependence and Zero-Point Calibration
• The Carnegie-Chicago Hubble Program. IX. Calibration of the Tip of the Red Giant Branch Method in the Mega-Maser Host Galaxy, NGC4258 (M106)
• Color-Magnitude Diagrams of Resolved Stars in Virgo Cluster Dwarf Galaxies
• A new red giant-based distance modulus of 13.3 Mpc to the Antennae galaxies and its consequences
• Sizes, Half-Mass Densities, and Mass Functions of Star Clusters in the Merger Remnant NGC 1316: Clues to the Fate of Second-Generation Globular Clusters
• The outermost stellar halo of NGC 5128 (Centaurus A): Radial structure
• DrizzlePac 2.0 - Introducing New Features
• Faint Stars in a Faint Galaxy: I. Ultra Deep Photometry of the Boötes I Ultra Faint Dwarf Galaxy

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