Field Detail

• NDARRAY_PREFIX

  public static final java.lang.String NDARRAY_PREFIX

  Prefix for NDArray-related FITS header cards.

  See Also:

  Constant Field Values

• END_CARD

  public static final nom.tam.fits.HeaderCard END_CARD

  Image of end-of-header card.

• NDARRAY_ORIGIN

  public static final java.lang.String NDARRAY_ORIGIN

  FITS header card for indicating NDArray origin values. An integer (1, 2, ... ) is appended to this value for the different axes like for NAXIS.

  See Also:

  Constant Field Values

• NDX_PREFIX

  public static final java.lang.String NDX_PREFIX

  Prefix for NDX-related FITS header cards.

  See Also:

  Constant Field Values

• NDX_XML

  public static final java.lang.String NDX_XML

  FITS header card for location (relative URL) of XML representation.

  See Also:

  Constant Field Values

• WCS_ENCODING

  public static final java.lang.String WCS_ENCODING

  Default encoding used for writing WCS into FITS headers.

  See Also:

  Constant Field Values

• FITS_BLOCK

  public static final int FITS_BLOCK

  Standard size of a FITS block in bytes.

  See Also:

  Constant Field Values

• MAX_NCOLSTD

  public static final int MAX_NCOLSTD

  Maximum number of columns in standard FITS BINTABLE extension.

  See Also:

  Constant Field Values

• REQUIRE_HIERARCH

  public static boolean REQUIRE_HIERARCH

  Whether HIERARCH convention is used; true by default.

Constructor Detail

• FitsConstants

  public FitsConstants()

Method Detail

• defaultFitsExtensions

  public static java.util.List<java.lang.String> defaultFitsExtensions()

  Gets the default permitted list of extensions which identify a FITS resource in the path part of a URL.

  Returns:

  unmodifiable list of default FITS extensions - ".fits", ".fit" etc

• configureHierarch

  public static void configureHierarch()

  Ensures that use of the HIERARCH convention when dealing with FITS headers is set to the state expected for STIL operation. If this involves changing the current setting, a warning is issued through the logging system.

  The general idea is that this is only issued once per JVM. If other components are resetting the hierarch handling that might not be enough, but there's no mechanism to ensure that it stays set anyway.

  The main reason this is necessary is that WideFits handling requires HIERARCH, but there is no per-call configuration of whether the convention is in use, so it has to be set on a global basis.

• createUnsortedHeader

  public static nom.tam.fits.Header createUnsortedHeader()

  Creates a Header instance which does not perform any unsolicited reordering of the header cards. Some versions of nom.tam.fits force the EXTEND keyword to go directly after the NAXISn keywords. That screws up specification of the FITS-plus magic number, which is expected to have VOTMETA directly after NAXISn. Headers created using this method will leave header cards in the order they are added.

  Returns:

  new empty header

  See Also:

  nom.tam.fits github discussion

• createHeaderCard

  public static nom.tam.fits.HeaderCard createHeaderCard​(java.lang.String cardImage)

  Create a HeaderCard from a FITS card image.

  Parameters:

  cardImage - the 80 character card image

  Returns:

  card object

• headerIterable

  public static java.lang.Iterable<nom.tam.fits.HeaderCard> headerIterable​(nom.tam.fits.Header hdr)

  Returns an iterable over HeaderCards for a given Header.

  Parameters:

  hdr - header

  Returns:

  iterable over hdr's cards

• skipHDUs

  public static long skipHDUs​(nom.tam.util.ArrayDataInput stream,
                              int nskip)
                       throws java.io.IOException

  Skips forward over a given number of HDUs in the supplied stream. If it reaches the end of the stream, it throws an IOException with a Cause of a TruncatedFileException.

  Parameters:

  stream - the stream to skip through

  nskip - the number of HDUs to skip

  Returns:

  the number of bytes the stream was advanced

  Throws:

  java.io.IOException

• isMagic

  public static boolean isMagic​(byte[] buffer)

  Indicates whether the supplied buffer is the start of a FITS file. Its contents is checked against the FITS 'magic number', which is the ASCII string "SIMPLE  =".

  Parameters:

  buffer - a byte buffer containing the start of a file to test

  Returns:

  true iff the bytes in buffer look like the start of a FITS file

• getInputStreamStart

  public static nom.tam.util.ArrayDataInput getInputStreamStart​(uk.ac.starlink.util.DataSource datsrc)
                                                         throws java.io.IOException

  Returns an input stream which can be used with the various FITS classes based on a given DataSource object, positioned at the start of the stream.

  Parameters:

  datsrc - the DataSource pointing to the file/HDU required

  Returns:

  an ArrayDataInput acquired from datsrc,

  Throws:

  java.io.IOException

• readHeader

  public static int readHeader​(nom.tam.fits.Header hdr,
                               nom.tam.util.ArrayDataInput strm)
                        throws nom.tam.fits.TruncatedFileException,
                               java.io.IOException

  Populates a header from an input stream, reporting its length in bytes. This does the same as Header.read(nom.tam.util.ArrayDataInput), but it returns the number of bytes read from the input stream in order to populate the header (including any padding bytes). There is no way to retrieve this information from the Header class in general; though Header.getSize() will sometimes give you the right answer, in the case of duplicated header keywords it can give an underestimate. This could be seen as a bug in nom.tam.fits classes, but there may be code somewhere which relies on that behaviour.

  You can make a Header from scratch by doing

       Header hdr = new Header();
       int headsize = read( hdr, strm );
   

  This method also differs from the Header implementation in that it does not print warnings to standard output about duplicate keywords.

  Parameters:

  hdr - the header to populate

  strm - the input stream supplying the data

  Returns:

  the number of bytes in the FITS blocks which comprise the header content

  Throws:

  nom.tam.fits.TruncatedFileException

  java.io.IOException

  See Also:

  Header.read(nom.tam.util.ArrayDataInput)

• writeHeader

  public static void writeHeader​(java.io.DataOutput strm,
                                 nom.tam.fits.Header hdr)
                          throws java.io.IOException

  Writes a header object to a DataOutput.

  Parameters:

  strm - destination stream

  hdr - the header to write

  Throws:

  java.io.IOException

• writeEmptyPrimary

  public static void writeEmptyPrimary​(java.io.DataOutput strm)
                                throws java.io.IOException

  Writes a null header representing an empty primary HDU to a stream.

  Parameters:

  strm - stream to write to

  Throws:

  java.io.IOException

• getDataSize

  public static long getDataSize​(nom.tam.fits.Header hdr)

  Utility function to find the number of bytes in the data segment of an HDU. As far as I can see, Header.getDataSize() ought to do this, but it doesn't seem to.

  Parameters:

  hdr - the Header

  Returns:

  the number of bytes in the data segment associated with hdr

• addTrimmedValue

  public static void addTrimmedValue​(nom.tam.fits.Header hdr,
                                     java.lang.String key,
                                     java.lang.String value,
                                     java.lang.String comment)
                              throws nom.tam.fits.HeaderCardException

  Adds a string-valued card to the header. If the value is too long, it is truncated appropriately, and a warning is emitted through the logging system.

  Parameters:

  hdr - header

  key - card key

  value - card value

  comment - card comment

  Throws:

  nom.tam.fits.HeaderCardException

• addStringValue

  public static void addStringValue​(nom.tam.fits.Header hdr,
                                    java.lang.String key,
                                    java.lang.String value,
                                    java.lang.String comment)

  Attempts to add a string-valued card to the header. If the value is too long, no header is added, and a message is emitted through the logging system.

  Parameters:

  hdr - header

  key - card key

  value - card value

  comment - card comment

• checkColumnCount

  public static void checkColumnCount​(WideFits wide,
                                      int ncol)
                               throws java.io.IOException

  Checks that a table with the given number of columns can be written. If the column count is not exceeded, nothing happens, but if there are too many columns an informative IOException is thrown.

  Parameters:

  wide - extended column convention - may be null for FITS standard behaviour only

  ncol - number of columns to write

  Throws:

  java.io.IOException - if there are too many columns