stella.util
Class MasterDark

java.lang.Object
  stella.util.MasterDark

public class MasterDark
extends Object

A class that reads dark frames and constructs a master dark and a sigma map out of it. For shutterless operation, like on the stella guider, a short exposure time should be used to create a master bias and a master dark, record the exposure times, and use for guiding the bias as recorded with the short exposure time and as the dark fits the difference in the long dark and the short dark.

Nested Class Summary

static class	MasterDark.Xtend Packs all extensions into a single file.
static class	MasterDark.Xtendfind Packs all extensions into a single file, operates with a file filter on the current directory.

Field Summary

private int	bitpix The number of bits per pixel.
private nom.tam.fits.ImageHDU[]	darks All dark data.
private nom.tam.fits.ImageHDU	masterdark The master dark, per extension
private nom.tam.fits.ImageHDU	sigmadark The master dark sigma map.
private int	xsize The size of the image, x-direction.
private int	ysize The size of the image, y-direction.

Constructor Summary

MasterDark(List<File> ff)

MasterDark(List<File> ff, int xtension)

MasterDark(String fitsbase, int start, int count, int xtension)
Constructs a new master dark with a base fits name, a starting index and the number of images to read.

Method Summary

private static nom.tam.fits.Header	addCardsToHeader(nom.tam.fits.Header head, List<nom.tam.fits.HeaderCard> cards) Adds a list of header cards to the fits header.
private boolean	createMasterDark(nom.tam.fits.Header head) Creates a master dark image HDU and ists sigma map in the following way: Depending on the number of bits, the image data is cast to an appropriate double-indexed array.
private static String	getFilename(String base, int nr)
private static List<File>	getNumbered(String fitsbase, int start, int count)
static void	main(String[] arg) Reads the fitsbase as the first command line argument, the starting number as second and the number of images as third.
private static void	printCounts(Number[] counts) Prints a number array to system.out
private static boolean	writeHDU(File file, nom.tam.fits.ImageHDU hdu) Writes an image hdu to the given fits file.
boolean	writeMasterDark(File darkfile) Writes the master dark to the provided fits file.
boolean	writeMasterDark(File darkfile, List<nom.tam.fits.HeaderCard> cards) Writes the master dark to the provided fits file.
boolean	writeMasterSigma(File darkfile) Writes the master dark sigma to the provided fits file.
boolean	writeMasterSigma(File darkfile, List<nom.tam.fits.HeaderCard> cards) Writes the master dark sigma to the provided fits file.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

darks

private nom.tam.fits.ImageHDU[] darks

All dark data. First index of fits file, second xtension

bitpix

private int bitpix

The number of bits per pixel.

xsize

private int xsize

The size of the image, x-direction.

ysize

private int ysize

The size of the image, y-direction.

masterdark

private nom.tam.fits.ImageHDU masterdark

The master dark, per extension

sigmadark

private nom.tam.fits.ImageHDU sigmadark

The master dark sigma map.

Constructor Detail

MasterDark

public MasterDark(String fitsbase,
                  int start,
                  int count,
                  int xtension)

Constructs a new master dark with a base fits name, a starting index and the number of images to read. The images sizes are checked for equality and stored. The number of bits per pixel is also checked and stored.

MasterDark

public MasterDark(List<File> ff)

MasterDark

public MasterDark(List<File> ff,
                  int xtension)

Method Detail

getNumbered

private static final List<File> getNumbered(String fitsbase,
                                            int start,
                                            int count)

getFilename

private static String getFilename(String base,
                                  int nr)

writeMasterDark

public boolean writeMasterDark(File darkfile)
                        throws nom.tam.fits.FitsException

Writes the master dark to the provided fits file.

Throws:

nom.tam.fits.FitsException

writeMasterDark

public boolean writeMasterDark(File darkfile,
                               List<nom.tam.fits.HeaderCard> cards)
                        throws nom.tam.fits.FitsException

Writes the master dark to the provided fits file.

Throws:

nom.tam.fits.FitsException

writeMasterSigma

public boolean writeMasterSigma(File darkfile)
                         throws nom.tam.fits.FitsException

Writes the master dark sigma to the provided fits file.

Throws:

nom.tam.fits.FitsException

writeMasterSigma

public boolean writeMasterSigma(File darkfile,
                                List<nom.tam.fits.HeaderCard> cards)
                         throws nom.tam.fits.FitsException

Writes the master dark sigma to the provided fits file.

Throws:

nom.tam.fits.FitsException

addCardsToHeader

private static nom.tam.fits.Header addCardsToHeader(nom.tam.fits.Header head,
                                                    List<nom.tam.fits.HeaderCard> cards)

Adds a list of header cards to the fits header.

writeHDU

private static boolean writeHDU(File file,
                                nom.tam.fits.ImageHDU hdu)
                         throws nom.tam.fits.FitsException

Writes an image hdu to the given fits file.

Throws:

nom.tam.fits.FitsException

createMasterDark

private boolean createMasterDark(nom.tam.fits.Header head)
                          throws nom.tam.fits.FitsException

Creates a master dark image HDU and ists sigma map in the following way:

• Depending on the number of bits, the image data is cast to an appropriate double-indexed array.
• The darks are traversed pixel by pixel. On each pixel, from the array of darks we extract a one-dimensional array holding the pixels values.
• The array is sorted, the median is used as the master value and the FWHM (defined as pixel[5/6]-pixel[1/6]) is the sigma value.
• This value are placed in the ImageHDU of the masterdark and the master sigma.
• The now ready image hdu can be writtn to files.

Returns:

False on failure.

Throws:

nom.tam.fits.FitsException

printCounts

private static void printCounts(Number[] counts)

Prints a number array to system.out

main

public static void main(String[] arg)
                 throws nom.tam.fits.FitsException

Reads the fitsbase as the first command line argument, the starting number as second and the number of images as third.

Throws:

nom.tam.fits.FitsException