48

SECTION 7. STANDARD EXTENSIONS

Table 7.2.

Mandatory keywords in ASCII table extensions.

#

Keyword

1

XTENSION= 'TABLEuuu'

2

BITPIX = 8

3

NAXIS = 2

4

NAXIS1

5

NAXIS2

6

PCOUNT = 0

7

GCOUNT = 1

8

TFIELDS

.

.

.

(other keywords, including (if TFIELDS is not zero) . . . )

TTYPEn, n=1, 2, . . . , k where k is the value of TFIELDS (Recommended)

TBCOLn, n=1, 2, . . . , k where k is the value of TFIELDS (Required)

TFORMn, n=1, 2, . . . , k where k is the value of TFIELDS (Required)

.

.

.

last

END

7.2

The ASCII Table Extension

The ASCII table extension provides a means of storing catalogs and tables of astronom-

ical data in FITS format. Each row of the table consists of a fixed-length sequence of

ASCII characters divided into fields that correspond to the columns in the table. The

first keyword in an ASCII table extension shall be XTENSION= 'TABLEuuu'.

7.2.1

Mandatory Keywords

The header of an ASCII table extension must use the keywords defined in Table 7.2.

The first keyword must be XTENSION; the seven keywords following XTENSION (BITPIX

. . . TFIELDS) must be in the order specified with no intervening keywords.

XTENSION Keyword

The value field shall contain the character string value text

'TABLEuuu'.

BITPIX Keyword  The value field shall contain the integer 8, denoting that the array

contains ASCII characters.

FITS Standard