IPAC Table Format

 

 

File Names:

The file name for an IPAC format table can up to 80 characters long which is case sensitive. File name can contain special characters, but no spaces, carets ("^"), or ampersands ("&") are allowed. Any tables which may be loaded into database have to follow DBMS constraints. It is highly recommended that all table names follow DBMS constraints.

Examples of valid IPAC table names:

  • Seyferts.tbl
  • MyListJ2k
  • LBD4_16A.dat

Examples of invalid IPAC table names:

  • 2mass&1999.tbl (contains a spatial character "&")
  • my file name (contains spaces)nitDynamicOptionLists
  •  

Table Organization:

The body of the table is organized as follows (red and green lettering are not part of the table, but are used to assist in explaining each line of the table):


\name=value                                                       Keyword lines
\ Comment                                                         Comment lines
|  column1 |  column2 | column3 | column4  |    column5       |   Column Names
|  double  |  double  |   int   |   double |     char         |   Data Types
|   unit   |   unit   |   unit  |    unit  |     unit         |   Units (optional)
|   null   |   null   |   null  |    null  |     null         |   Null Values (optional)
 2.0978     29.09056   73765     2.06000    B8IVpMnHg             Data Records


 1111111111 2222222222 333333333 4444444444 555555555555555555    

This sample row shows no data is allowed under the vertical bar
in the header.

Keyword and Comment Lines:

The user may define their own keywords at the top of each table file. These keywords follow the FITS keyword=value model, and are case sensitive. They must begin with the backslash ("\") character, with no spaces between the backslash and the keyword itself. The keyword is followed by an equals sign ("="), followed by the value. The IPAC table format allows spaces around ("=") signs. Header keyword string values should be quoted using single or double quotes.

 

A "\" followed by a space is treated as a comment line. Comment lines should have no more than 80 characters.

Examples of valid keywords and comments:

\catalog = sao
\date = "Wed Sp 20 09:48:36 1995"
\mykeyword = 'Another way for defining keyvalue string'
\ This is an example of a valid comment
\
|     ra   |    dec   |   sai   |      v   |    sptype        |
|    real  |   real   |   int   |    real  |     char         |
 

Examples of invalid keywords and comments:

     Catalog=sao                    No starting backslash 
     \This is not a valid comment   No space between backslash and comment
 

Column Headers:

There are up to four possible header lines for each column in the table, in the following order:

  • Column name (required)
  • Data Type (required)
  • Units (optional)
  • Null Value (optional)

Each header line must use the vertical bar ("|") character to mark the column boundaries. For example:


  |     ra   |    dec   |   sao   |      v   |    sptype        |
  |  double  | double   |   int   |    double|     char         |
  |    unit  |   unit   |   unit  |    unit  |     unit         |
  |    null  |   null   |   null  |    null  |     null         |
    2.09708   29.09056     73765    2.06000   B8IVpMnHg

Dashes can be used in place of the spaces in the header:

|-----ra---|----dec---|---sao---|------v---|----sptype--------|
    2.09708   29.09056     73765    2.06000   B8IVpMnHg
Bars ("|") at the start and end of each line are required. The use of tabs to fill spaces in the header lines is strictly forbidden.

Column Names:

The column names of an IPAC table may be up to 40 characters, which are case sensitive. The column names can be the combination of characters, numbers, or underscores ("_"). Blank/white spaces, tabs, dashes ("-") and other spatial characters are not allowed in column names. For example, use "U_mag" instead of "U mag."

In addition, when a data provider supplies the archive with a table that needs to be loaded into a database (DBMS), there may be more constraints on the column names, which are explained in the DBMS column constraints document. The archive strongly suggests that all column names follow these constraints.

Possible Data Types:

IPAC table format accepts the following data types:

  • int
  • double
  • float
  • real
  • char
  • date

In rare cases where the table is compact and there is not enough space for a complete data type name, a single character name equivalent can also be used as the data type:

  • i --- int
  • d --- double
  • f --- float
  • r --- real
  • c --- char Note: "date" cannot be replaced by "d".

Null Values:

The null value in the header defines actual null values for each column. The archive's table library can interpret the data records and store the data, together with null information, in the database if needed.

For example:

  |     ra   |    dec   |   sao   |      v   |    sptype        |
  |  double  | double   |   int   |    double|     char         |
  |    unit  |   unit   |   unit  |    unit  |     unit         |
  |    null  |   null   |   -999  |  -999.99 |     null         |
    2.09708   29.09056     73765    2.06000   B8IVpMnHg
    1.09708   19.09056      -999    -999.99   null
The table library interprets:
  • "-999" as null value for column "sao";
  • "-999.99" as null value for column "v";
  • and
  • "null" as null value for column "sptype".

Data Units:

IPAC format table allows a table provider to specify a unit for a column. A unit can be a character string, but using tabs in front, between, or behind a unit string is strictly forbidden. 
  |     ra   |    dec   |   ratio |
  |  double  | double   |   int   |
  |  degree  |  degree  |         |
  |    null  |   null   |   -999  |
    2.09708   29.09056     73765   
    1.09708   19.09056      -999
If there is no unit string the table is treated as unitless.

 

Examples of properly formed tables:

Boundaries of Column Data:

IPAC table format allows the following: 
|  column1 |  column2 | column3 | column4  |    column5       |   
|  double  |  double  |   int   |   double |     char         | 
 1111111111 2222222222 333333333 4444444444 555555555555555555
This example displays the data boundaries for every column. The value with character "1" defines the data boundary for column1, "2" for column2, and so on.

Examples: