Welcome to MAOPhot 1.1.5, a PSF Photometry tool using Astropy 6.1.6 and Photutils 2.0.2
1.1.5 Changes
- Image can be dragged by Shift+Left-mouse-button;
- Image can be zoomed in, and zoomed out with mouse wheel
MAOPhot 1.1.4 Changes
- Support for APASS DR10 [along with AAVSO, GAIA DR2, and APASS DR9]
- Added Setting: Max qfit , [‘qfit’ is quality of PSF fit, lower number is better fit; MAOPhot discards any PSF fit with qfit > Max qfit”; anything below 0.1 is considered good]
- Added Setting Min Separation Factor [this x FWHM = the minimum distance (in pixels) such that any two sources separated by less than this distance will be placed in the same group]
- Added Setting: "From Fits" checkbox for CCD Filter; when unchecked user can manually override FILTER value in Fits header
- “Find Peaks” and “Iterative PSF Photometry” now uses DAOStarFinder
- In APASS DR10, remove any entries with Johnson (V) > maglimit until cgi-bin/apass_dr10_download.pl is fixed
- Use mouse wheel and shift-mouse wheel to scroll
Critical changes
- insure that all fitted PSF's have qfit (Quality of Merit) < "Max qfit" ; Only the lowest qfit match found within the "Matching Radius" is used. This match may not be found until a later iteration of "Iterative PSF Photometry".
- use of APASS DR10. The "Maximum Ensemble Magnitude", in Settings, is used to limit the inital comps received from the AAVSO. for a FOV > 60', a mag limit of 15 is recommended, FOV > 120', a mag limit of 12 is recommended
PSF photometry models the star's light distribution as a mathematical function called the Point Spread Function (PSF), which describes how the star's light spreads across the detector. The PSF is then fitted to the star to determine its total flux, accounting for overlaps with nearby stars.
This program was derived from “MetroPSF” by Maxym Usatov. It has been renamed and extended to produce AAVSO reports exclusively and to facilitate generating an effective PSF for PSF photometry.
MAOPhot calculates stellar magnitudes from FIT formatted digital photographs using PSF photometry. It produces an extended AAVSO (American Association of Variable Star Observers) report (https://www.aavso.org/aavso-extended-file-format) which can be submitted to AAVSO using their online tool WebObs (https://www.aavso.org/webobs).
MAOPhot uses the PSF (point spread function) Photometry exclusively.
MAOPhot is written in Python using Astropy (a common core package for astronomy). MAOPhot also uses Photutils. See "PSF Photometry" which describes many of the classes and methods used in MAOPhot. (https://photutils.readthedocs.io/en/stable/user_guide/psf.html)
MAOPhot has been redesigned for AAVSO reporting only and includes, but is not limited to the following enhancements:
o uses Astropy 6.1.6 and Photutils 2.0.2
o generation of an Effective PSF model (EPSF model), and the ability to create a ‘rejection list’ of stars that the user can select that will not be part of the EPSF model generated
o option to use a Gaussian PRF (Pixel Response Function) as model
o Uses Iterative PSF Photometry, an iterative version of PSF Photometry where new sources are detected in the residual image after the fit sources are subtracted
o PSF Photometry using an ensemble of comparison stars or a single comp star
o generation of Two-Color Photometry (B, V), (V, R) or (V, I), and Single Image Photometry reports in AAVSO extended format
o use of telescope Transformation Coefficients (needed for Two Color Photometry)
o user can specify check star and list of comp stars
o manually select a star for measurement
o intermediate results are saved as .csv files
o optionally enter an AAVSO Chart ID when retrieving comparison star data
See HelpFile.pdf for more information.