TB* procedures are used to interpret a FITS Binary table. Procedures in the /fits_table directory are used to interpret a FITS Additional procedures in the pro/fits_table directoryĪre then required to interpret binary and ASCII tables. Of the following procedures from the IDL Astronomy Library: FXADDPAR, FXPAR(), FXPARPOS(), FXMOVE(), FXPOSIT(), GETTOK(), MRD_HREAD, MRD_SKIP, MRD_STRUCT(), and VALID_NUM()Ĭan be used to read FITS headers and arrays of a specified extensions User must specify all scaling as either floating point or double The application of TSCAL/TZERO keywords is not Options are available to read/write IDL unsignedĭata types, and to map variable length binary tables into IDL pointers.Įxtension into an IDL structure can incur extraĬPU and virtual memory overhead if one is not interested MRDFITS can read Unix, bzip2 and FPACK compressedįiles. Use, and has been tested with many FITS files. Single IDL structure variable, which is then available for further IDL Use and remember- the MRDFITS() procedure can read The use of these procedures is described in theirĭocumentation header, with further information The procedure MWRFITS() will write an IDLįITS file, with many options available (binary or ASCII table, default Standard FITS data types into IDL arrays (for primary images and imageĮxtensions) or structures (for binary or ASCII tables). The four classes of IDL FITS I/O procedures are brieflyĭescribed below, along with the strengths and possible drawbacks ofĮach method. Procedures such as FITS_READ and FTAB_EXT. I/O at the procedure level, it may be desirable to use more efficient But mapping a table intoĪn IDL structure includes extra overhead, so that when performing FITS That one is comfortable with IDL structures).
Procedure for analyzing FITS files at the IDL prompt level (provided which can read a FITS table into an IDL structure -is the easiest However, each method also has its own strengths and weakness for any
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Historical, as different groups developed the software independently. Reason for having four different methods of FITS I/O with IDL is partly Of procedures for reading, writing, and modifying FITS files. The IDL Astronomy Library contains four different sets The HDUs following the first (or primary) HDU areĪlso known as extensions, and thus a FITS file containing tabular data Vector data can be present in any HDU, but tabular data cannot appear Header describes the content of the associated data unit, which mightīe a spectrum (IDL vector), an image (IDL array), or tabular data inĪSCII or binary format (often read as an IDL structure). Images that in IDL is usually read into a string array variable. Information on calling CFITSIO from other languages such as C++ and Python.Ĭontains documentation for working with FITS files in Python.īriefly, a FITS file consists of a sequence of one or Home Page at Goddard Space Flight Center. Information on processing FITS files with C, rather than Detailed information on the FITSįITS Support Office at Goddard Space Flight Center. Interchange format for digital images, FITS files are now often used asĪ working data format, and can be used to store ASCII or binary tabular Although originally conceived as simply a FITS (Flexible Image Transport System) is a standardized data format