SWS INSTRUMENT: Merging

SWS INSTRUMENT

9.) Merging

Merged observations:

SWS can observe simultaneously in the SW and LW section:
SW and LW grating scanner are independent
two lines/ranges can be scanned at the same time
but through the same aperture
band 5 FP observations can be merged with S06-like SW scans
but band 6 FP observations can't be merged (see comment)
-> lay-out of the SWS grating section

Serendipitous data:

each of the two grating sections contains two arrays:
serendipitous data appear, if both arrays of a grating section
receive signals with properly calibrated wavelengths assigned

this is ususally the case, if neighbouring orders of a spectrum
are mapped simultaneously onto the two detector arrays of
the SW or LW section
one array sees then the intended part of the spectrum (e.g.
a line), the other serendipitous data (usually continuum)
check, if wavelengths of serendipitous data are within the
AOT band limits for the used band/order/aperture
gain and reset time settings might not be optimal or the detector array might have been illuminated insufficiently

Warning:
Any flux data that have an unique wavelength (unequal zero) assigned appear in the AAR - also serendipitous data. Some of these data might be useless.

Comment on SWS07 (from SWS IDUM § 4.5):

Due to a slight internal misalignment of the Long Wave FP there are problems merging FP observations with grating observations when observing through aperture 3. The effective aperture of the FP is displaced from the center of the grating aperture by approximately 10 arcseconds, causing an approximately 40 % drop in throughput of the FP when pointing is determined by the grating. The solution decided on was to define a fourth effective aperture, centered on the FP aperture, and carry out all observations through this. This means the SW grating now loses approximately 40 % of its throughput. Therefore LW FP observations (26 - 44 µm) and SW grating observations (7.0 - 13.16 µm) through aperture 3 will not be merged. If any aperture 3 grating observations are requested they will be done after the FP observations. This change was considered acceptable as the main purpose of AOT 7 is FP observations. Merging is still carried out when observations are made using apertures 1 or 2\index.

However, some early AOT 7 observations were carried out before this change was implemented. Observers may therefore receive FP data merged with SW grating observations in the range 7 to 13.16 µm.

SWS TUTORIAL / SWS INSTRUMENT : ... bands < merging > AOTs ...

Last update: 30-Jul-1998 by D. Kunze ( mail to: isodata@mpe.mpg.de )