4 Science Target Recipe Details

 4.1 POINT_SOURCE
 4.2 EXTENDED_SOURCE
 4.3 FAINT_POINT_SOURCE
 4.4 POINT_SOURCE_POL

There are three basic recipes available for reducing science target observations: EXTENDED_SOURCE, POINT_SOURCE, and FAINT_POINT_SOURCE. These three have many variants that dictate the use or lack of calibration data. For example, there exists a POINT_SOURCE_NOFLAT recipe that is meant to be used for point source reduction without flat-fielding. The use of these variants is typically avoided, as the basic recipes can often flag uncalibratable data.

In addition, dual-beam polarimetry can be reduced using the POINT_SOURCE_POL recipe. This recipe is a variant of the POINT_SOURCE recipe.

4.1 POINT_SOURCE

The POINT_SOURCE recipe is used to reduce observations of point sources. It reduces data using all of the steps outlined in Section 3

.

The following variants are available: POINT_SOURCE_NOARC (no arc spectrum extracted), POINT_SOURCE_NOFLAT (no division by a flat-field), POINT_SOURCE_NOFLAT_NOARC, POINT_SOURCE_NOFLAT_NOSTD, and POINT_SOURCE_NOSTD (no division by a standard star).

4.2 EXTENDED_SOURCE

The EXTENDED_SOURCE recipe is used to reduce observations of extended sources. It differs from the POINT_SOURCE recipe in that EXTENDED_SOURCE skips the spectrum extraction and proceeds directly with ?? and ?? .

The following variants are available: EXTENDED_SOURCE_NOARC (no arc spectrum extracted), EXTENDED_SOURCE_NOFLAT (no division by a flat-field), EXTENDED_SOURCE_NOFLAT_NOARC, EXTENDED_SOURCE_NOFLAT_NOSTD, and EXTENDED_SOURCE_NOSTD.

4.2.1 EXTENDED_SOURCE_WITH_SEPARATE_SKY

In addition to the variants to EXTENDED_SOURCE listed above, EXTENDED_SOURCE_WITH_SEPARATE_SKY exists for very extended sources where it is not possible to nod along the slit, thus a separate sky is used for sky-subtraction. The separate sky is reduced using the ?? calibration recipe.

The following variants are available: EXTENDED_SOURCE_WITH_SEPARATE_SKY_NOFLAT (no division by a flat-field), EXTENDED_SOURCE_WITH_SEPARATE_SKY_NOFLAT_NOSTD (no division by a flat-field or by a standard star), and EXTENDED_SOURCE_WITH_SEPARATE_SKY_NOSTD (no division by a standard star).

4.3 FAINT_POINT_SOURCE

The FAINT_POINT_SOURCE recipe is used to reduce observations of point sources that are faint enough that they may not be detected in the beam detection step described in Section 3.3.2. In this case, the locations of the beams as determined for the standard star are used to extract the object. Optimal extraction is still used.

The following variants are available: FAINT_POINT_SOURCE_NOFLAT (no division by a flat-field), FAINT_POINT_SOURCE_NOFLAT_NOSTD (no fivision by a flat-field and no extraction of an arc spectrum), and FAINT_POINT_SOURCE_NOSTD (no extraction of an arc spectrum).

4.4 POINT_SOURCE_POL

Dual-beam spectropolarimetry data can be reduced using the POINT_SOURCE_POL recipe. This recipe reduces data using the steps in Sections 3.1, 3.2, and 3.3. The data can be taken in any order between waveplate positions, but corresponding object-sky pairs for a given waveplate position must be observed together. Spectrum extraction is done such that separate E and O beam spectra are created for each waveplate position. After a cycle of eight observations has done, corresponding to one object-sky pair at each of the 0-, 45-, 22.5-, and 67.5-degree waveplate angles, the pipeline calculates the I, Q, and U Stokes parameters, from which the percentage polarization, polarization intensity, and polarization angle spectra are calculated.