Data.Fits

Definitions for the data types needed to parse an HDU in a FITS block.

Data payload functions

parsePix :: Int -> BitPixFormat -> ByteString -> IO [Pix]

This is the main low-level function which parses the data portion of an HDU. You need and element count, a format and a bytestring. The resulting list is produced in column-row major order as specified in the standard.

pixsUnwrapI :: BitPixFormat -> [Pix] -> [Int]

Remove the Pix wrapper for integer Pix lists.

pixsUnwrapD :: BitPixFormat -> [Pix] -> [Double]

Remove the Pix wrapper for floating point Pix lists.

Main data types

data HeaderDataUnit

The HeaderDataUnit is the full HDU. Both the header information is encoded alongside the Axis payload.

Constructors

HeaderDataUnit

Fields

• headerData :: HeaderData

  Just the header part of the HDU

• payloadData :: ByteString

  The actual data payload

data HeaderData

The header part of the HDU is vital carrying not only authorship metadata, but also specifying how to make sense of the binary payload that starts 2,880 bytes after the start of the HeaderData.

Constructors

HeaderData

Fields

• simpleFormat :: SimpleFormat

  SIMPLE

• bitPixFormat :: BitPixFormat

  BITPIX

• axes :: [Axis]

  Axes metadata

• objectIdentifier :: StringValue

  OBJECT

• observationDate :: StringValue

  DATE

• originIdentifier :: StringValue

  OBJECT

• telescopeIdentifier :: StringValue

  TELESCOP

• instrumentIdentifier :: StringValue

  INSTRUME

• observerIdentifier :: StringValue

  OBSERVER

• authorIdentifier :: StringValue

  CREATOR

• referenceString :: StringValue

  REFERENC

Instances

Default HeaderData

Defined in Data.Fits

Methods

def :: HeaderData

data BitPixFormat

The BitPixFormat is the nitty gritty of how the Axis data is layed out in the file. The standard recognizes six formats: unsigned 8 bit integer, two's complement binary integers at 16, 32, and 64 bits along with 32 and 64 bit IEEE floating point formats.

Constructors

EightBitInt

BITPIX = 8; unsigned binary integer of 8 bits

SixteenBitInt

BITPIX = 16; two's complement binary integer of 16 bits

ThirtyTwoBitInt

BITPIX = 32; two's complement binary integer of 32 bits

SixtyFourBitInt

BITPIX = 64; two's complement binary integer of 64 bits

ThirtyTwoBitFloat

BITPIX = -32; IEEE single precision floating point of 32 bits

SixtyFourBitFloat

BITPIX = -64; IEEE double precision floating point of 64 bits

Instances

Show BitPixFormat

Defined in Data.Fits

Methods

showsPrec :: Int -> BitPixFormat -> ShowS

show :: BitPixFormat -> String

showList :: [BitPixFormat] -> ShowS

data Pix

Following BitPixFormat we have a tag for integer and floating point values. We box them up to ease parsing.

Constructors

PB Int

PI16 Int

PI32 Int

PI64 Int

PF Double

PD Double

Header Data Types

data SimpleFormat

The standard defines two possible values for the SIMPLE keyword, T and F. The T refers to a Conformant format while F refers to a NonConformant format. At this time only the Conformant, T, format is supported.

Constructors

Conformant

Value of SIMPLE=T in the header. supported

NonConformant

Value of SIMPLE=F in the header. unsupported

data Axis

Axis represents a single NAXIS record.

Constructors

Axis

Fields

• axisNumber :: Int

  The axis number under consideration

• axisElementCount :: Int

  The number of elements in this axis

Instances

Default Axis

The default instance for Axis is NAXIS=0 with zero elements.

Defined in Data.Fits

Methods

def :: Axis

data StringType

There are many types of strings defined in the FITS documentation. Refered to as "character string(s)" in the documentation, they can be null, empty, undefined, or contain characters (printable ASCII only).

Constructors

NullString

The NULL character string (e.g. AUTHOR=)

EmptyString

An empty string (e.g. AUTHOR="")

DataString

Plain ASCII data

Instances

Show StringType

Defined in Data.Fits

Methods

showsPrec :: Int -> StringType -> ShowS

show :: StringType -> String

showList :: [StringType] -> ShowS

data StringValue

A StringValue is a type paired with a possible value.

Constructors

StringValue

Fields

• stringType :: StringType

  Which StringType is this value?

• stringValue :: Maybe Text

  The payload of a character string

Instances

Show StringValue

Defined in Data.Fits

Methods

showsPrec :: Int -> StringValue -> ShowS

show :: StringValue -> String

showList :: [StringValue] -> ShowS

Default StringValue

The default instance of StringValue is an undefined string with no text.

Defined in Data.Fits

Methods

def :: StringValue

data NumberType

The FITS standard allows for the encoding of unsigned integers, signed integers, real numbers, and complex numbers. They are always ASCII encoded. See 5.2 of the standard for more details.

Constructors

IntegerType

HDU ASCII encoded integer number

RealType

HDU ASCII encoded real number

ComplexType

HDU ASCII encoded complex number

data NumberModifier

Utility data type to help with the ASCII representation of numbers

Constructors

Positive

HDU positive number value

Negative

HDU negative number value

Zero

HDU numeric value is zero, could be positive or negative

data NumberValue

NumberValue contains an encoded numeric record from a data field. This data type still needs to be converted into more useful Haskell data types.

Constructors

NumberValue

Fields

• numberType :: NumberType

  Key to decoding the structure

• realModifier :: NumberModifier

  Encoding the sign of the real part

• realPart :: Text

  All NumberType have a real part (sign stripped)

• imaginaryModifier :: Maybe NumberModifier

  Encoding the sign of the imaginary part

• imaginaryPart :: Maybe Text

  Only ComplexType have an imaginary part (sign stripped)

• exponentModifier :: Maybe NumberModifier

  Positive, Negative, or Zero

• exponent :: Maybe Int

  All NumberType may have an exponent

Instances

Default NumberValue

The default instance for NumberValue is a 32-bit integer of zero with no imaginary or exponent parts.

Defined in Data.Fits

Methods

def :: NumberValue

Utility

isBitPixInt :: BitPixFormat -> Bool

This utility functions quickly lets you know if you are dealing with integer data.

isBitPixFloat :: BitPixFormat -> Bool

This utility functions quickly lets you know if you are dealing with floating point data.

bitPixToWordSize :: BitPixFormat -> Natural

This utility function can be used to get the word count for data in an HDU.

Constants

hduRecordLength :: Int

A single record in the HDU is an eighty byte word.

hduMaxRecords :: Int

The maximum amount of eighty byte records is thirty-six per the standard.

hduBlockSize :: Int

The size of an HDU block is fixed at thirty-six eighty byte words. In other words 2,880 bytes. These blocks are padded with zeros to this boundary.