MASKEXT-Extracts echelle orders using a mask created by ECHMASK

Description:

Extracts spectra from an image using a mask image. The mask pixel values should be the numbers of the spectra that fall in that pixel of the image. This routine is intended for use with echelle data, and the numbers in the image are expected to be based on echelle order numbers. The spectra are extracted into an image whose Y-axis is the order number of the spectra, and whose X-axis is that of the original data. The actual numbers in the image are expected to have the form (echelle order number)*10 + (sub order number), sub orders referring to separate spectra from the same order, as produced, for example, by the UCL echelle at AAO. MASKEXT will extract one specified sub-order from each order, or will add all the sub-orders together for each order.

Parameters:

IMAGE

Name of image containing spectra.

MASK

Name of mask image.

MLOW

Lowest order number to extract.

MHIGH

Highest order number to extract.

SUBORD

Sub-order to extract (0 => all).

REVERSE

Create output with order numbers reversed?

OUTPUT

Name of resulting set of spectra

Source comments:

 M A S K E X T

 Extracts spectra from an image using a mask image.  The mask
 pixel values should be the numbers of the spectra that fall
 in that pixel of the image.  This routine is intended for use
 with echelle data, and the numbers in the image are expected
 to be based on echelle order numbers.  The spectra are extracted
 into an image whose Y-axis is the order number of the spectra,
 and whose X-axis is that of the original data.  The actual
 numbers in the image are expected to have the form
 (echelle order number)*10 + (sub order number), sub orders
 referring to separate spectra from the same order, as
 produced, for example, by the UCL echelle at AAO.
 MASKEXT will extract one specified sub-order from each
 order, or will add all the sub-orders together for each order.

 Command parameters -

 IMAGE      (Character) The name of the image containing the
            spectra to be extracted
 MASK       (Character) The name of the mask image.
 MLOW       (Integer) The lowest order number to be extracted.
 MHIGH      (Integer) The higest order number to be extracted.
 SUBORD     (Integer) The sub-order number to be extracted.
            If zero, all sub-orders are added for each order.
 OUTPUT     (Character) The name of the resulting image.

 Command keywords -

 REVERSE    If set, the image created will have the
            spectral orders in reverse order - higher order
            numbers being at the start of the image.

 29th May 1988  KS/AAO.  Original version.

 Note -

 This version is an interim one - it really needs re-writing
 using DSA_RESHAPE_DATA and DSA_RESHAPE_AXIS.