fitsTableJS

Yes, a JavaScript library for reading FITS Binary Tables :)

Dependencies

This library is dependent upon jDataView

• https://github.com/vjeux/jDataView

Installation

Include the dependent library and fitsTableJS

<script src="path/to/jdataview.js" type="text/javascript" charset="utf-8"></script>
<script src="path/to/fitsTable.js" type="text/javascript" charset="utf-8"></script>

Usage

Using an XMLHttpRequest, retrieve an array buffer or binary string of the FITS file.

var xhr = new XMLHttpRequest();
xhr.open('GET', "url/to/shazaam.fits", true);
xhr.responseType = 'arraybuffer';
xhr.onload = function(e) {
    var ft = new FitsTable(xhr.response);
};
xhr.send();

// The header must be read first
ft.readHeader();

// Then we may read the columns
ft.readColumns();

// Access the data
console.log(ft.data);

// Column names are recorded as an array
console.log(ft.columnNames);

// Number of rows and columns
console.log(ft.rows);
console.log(ft.columns);

// You can read a single row at a time and access the data
ft.readColumn();
console.log(ft.data);

Notes for me

These are the fields that describe the columns and data format in the test data.

• TTYPE1 = 'flux '
• TFORM1 = 'D '
• TTYPE2 = 'best_fit'
• TFORM2 = 'D '
• TTYPE3 = 'wavelength'
• TFORM3 = 'D '
• TTYPE4 = 'and_mask'
• TFORM4 = 'J '
• TTYPE5 = 'or_mask '
• TFORM5 = 'J '
• TTYPE6 = 'inverse_variance'
• TFORM6 = 'D'

How we do it

• Parse for the FITS header
• Read the above key/values
• Unpack the binary data using jDataView

TODO:

Support the follow data types that appear in FITS binary tables:

FITS format code	Description	Number of 8-bit bytes
L	logical (Boolean)	1
X*	bit	*
B	Unsigned byte	1
I	16-bit integer	2
J	32-bit integer	4
K*	64-bit integer	4
A	character	1
E	single precision floating point	4
D	double precision floating point	8
C	single precision complex	8
M	double precision complex	16
P*	array descriptor	8

\* Not yet implemented or not yet tested

References

http://packages.python.org/pyfits/users_guide/users_table.html

BAM!