DCT-Photometry

Perform photometry on images from the Large Monolithic Imager at the Discovery Channel Telescope.

LMI_Photometry.py

This module contains three functions that produce useful photometry from raw .FITS images from LMI at DCT. To use, simply follow this example.

Requirements:

numpy, scipy, matplotlib, astropy, ccdproc, astroquery, photutils

Data_Reduction

func LMI_Photometry. Data_Reduction (directory, filters, targets, save_to=None, dark_exp=1.0, subtract_dark=False)

Creates and applies a master bias, flat, and dark (optional) frame to science images, saves in directory, and updates the .FITS header to make targets Simbad-compatible.

• Parameters:

  directory : str

  A directory containing raw .FITS images and calibration frames

  filters : dict

  Filters used and corresponding flat exposures

  {'filter' : flat exposure}
  

  targets : dict

  "SCITARG" name in .FITS header and corresponding name in Simbad

  {'FITS target name' : 'Simbad target name'}
  

  save_to : str, optional (default=None)

  Optional second directory to save calibrated frames to

  dark_exp : float, optional (default=1.0)

  Exposure time for dark frames

  subtract_dark : bool, optional (default=False)

  Set to True in order to subtract dark frame

  Note: LMI has negligible dark current

• Returns:

  None

Aperture_Photometry

func LMI_Photometry. Aperture_Photometry (directory, ap_radius, standards, show_figures=False)

Measures raw electron counts for a target star and utilizes the .FITS header to calculate and save fluxes and instrumental magnitudes. Flags specified stars as standards to be used for standard magnitude transformations.

• Parameters:

  directory : str

  A directory containing reduced .FITS images

  ap_radius : int

  Radius of aperture used for photometry

  standards : dict

  Simbad-compatible name with list of standard star names in the field

  {'Query Name' : ['Standard Query Name', 'Standard Query Name']}
  

  show_figures : bool, optional (default=False)

  Display optional figures that are relevant

• Returns:

  None

Convert_Magnitudes

func LMI_Photometry. Convert_Magnitudes (directory, filters, bin_size=10, show_figures=False)

Reads magnitudes and airmass values saved in the .FITS headers of standard stars, calculates a magnitude transformation for each filter used, then applies the transformation to science images to convert their instrumental magnitudes to standard magnitudes. Saves measurements and uncertainties in a .txt table in ascii format.

• Parameters:

  directory : str

  A directory containing reduced .FITS images instrumental magnitudes appended to the .FITS header

  filters : list

  A list of filters used

  ['filter 1', 'filter 2']
  

  bin_size : int, optional (default=10)

  Number of epochs target is observed

  show_figures : bool, optional (default=False)

  Display optional figures that are relevant

• Returns:

  None

ViewImage.py

Displays a given .FITS image. Useful for visual inspection for hot pixels, cosmic rays, saturation, etc.

LMI_Photometry_EXAMPLE.py

An example of how to use LMI_Photometry.py