Subsections

• 7.8.1 Obtaining the average signal per raster point
  • Ancillary data required:
• 7.8.2 Determination of the spectrum per raster point
  • Ancillary data required:

7.8 Signal Processing: PHT-S Raster Maps

The calibration which has been developed for single pointing PHT-S observations cannot be applied to PHT-S raster maps. This is because single pointing staring PHT-S measurements are always preceded by a 32 s dark measurement which stabilises the initial jump behaviour of the following sky measurement. For PHT-S raster maps, however, there is only one dark measurement at the very beginning and the initial illumination conditions from raster point to raster point change depending on the brightness distribution of the sky w.r.t. the raster pointings.

For OLP it has been decided to perform a direct calibration from signal per raster point to flux density using the average spectral response function for staring observations.

7.8.1 Obtaining the average signal per raster point

Detailed description: none

The average signal per raster point is obtained by applying processing steps 7.3.4 (deglitching), 7.3.5 (drift recognition), and 7.3.6 (mean signal per plateau). The PHT-S orbit dependent dark signal (step 7.4.1) is subsequently subtracted from the average signal.

Ancillary data required:

see respective processing steps.

7.8.2 Determination of the spectrum per raster point

Detailed description: Section 5.2.6 for calibration overview

The flux density $F_{\nu}^j(i)$ for raster point $j$ and PHT-S pixel $i$ is obtained by simply dividing the signal of that raster point by the average point source spectral response function for staring observations $C^{s,p}_{ave}(i)$:

$$F_{\nu}^j(i) = s^j(i)/C^{s,p}_{ave}(i)~~~~{\rm [Jy],~and}$$ (7.70)

$${\Delta}F_{\nu}^j(i) = \frac{{\Delta}s^j(i)}{s^j(i)}F_{\nu}^j(i)~~~~{\rm [Jy]}.$$ (7.71)

Ancillary data required:

The average spectral response function $C^{s,p}_{ave}(i)$ is listed in Cal-G file PSPECAL, see Section 14.19.1.