Herschel Observers' Manual

List of Figures

1.1. The Herschel spacecraft has a modular design. On the left, facing the "warm" side and on the right, facing the "cold" side of the spacecraft, the middle image names the major components.

1.2. The Herschel telescope flight model.

1.3. The Herschel cryostat.

1.4. The Herschel service module.

1.5. Herschel s/c axes (from [RD1])

1.6. Left: Position of the Lagrange points for the Sun-Earth/Moon system. L2 lies 1.5 million kilometres from Earth. Right: An example of a Lissajous orbit around L2. The orbit x and y-axis are as shown in the plot on the left, the z-axis is normal to paper.

1.7. A 3D representation of a large halo orbit around L2. The Earth is located at (0,0,0). Red tracks are the projection on the three orthogonal planes of the 3D orbit (blue track).

1.8. Top: The sky visibility across the sky as a fraction of the total hours through the Herschel mission, represented as a colour scale (shown at right) where black represents 30% visibility and white represents permanent sky visibility. Bottom: sky visibility for two sample dates. Shadowed areas represent inaccessible sky areas.

1.9. Diagram of the Herschel/Planck avionics.

2.1. Brightness of the night sky, excluding contribution of the extragalactic background (from [RD5], adapted from Leinert et al. 1998, A&A, 127, 1). The spectral range covered by the PACS and SPIRE instruments of the Herschel Space Observatory are indicated. Atmospheric contributors, affecting ground-based observation in the optical and NIR, have been also displayed.

2.2. Cumulative (left) and differential (right) 24 μm number counts from [RD10]. The differential counts have been normalised to an Euclidean slope, dN/dSν ∼ Sν^-2.5. The curves show predictions from different recent models, including that from Lagache et al. 2003.

3.1. Herschel Space Observatory Ground Segment

5.1. The Herschel Focal Plane.

6.1. Position angle variation for sources on the ecliptic and at the ecliptic pole, in the zone of permanent sky visibility. For sources at intermediate ecliptic latitude the annual range of variation of PA will be between these two extremes.

6.2. An illustrative example. The position angle variation for PACS for an object at an ecliptic latitude of 59.5 degrees, close to the point of permanent visibility. The horizontal position is PA=000 degrees. The plotted positions of the PACS imaging detectors are for a hypothetical case with 2008 March 31st (start of visibility window) PA=127.4 degrees, 2008 June 15th (mid-window) PA=054.6 degrees, 2008 September 10th (end of visibility window) PA=333.7 degrees. The situation is effectively identical for other dates.

6.3. PA variation for a typical solar system object: Neptune's satellite Triton. Note how the PA variations over the course of a full observing window amount to less than 2 degrees. This makes it effectively impossible to accomodate map orientation or chopper angle avoidance constraints.

6.4. The background variation for Triton at 80 microns. The background is dominated at this wavelength by the Zodiacal Light contribution. As the elongation changes over the course of the observing window the background effectively doubles with time. At longer wavelength the ISM component will also change as the target moves across areas of different background. For objects relatively close to the Sun the ISM component may vary enormously in a comparatively short space of time.

6.5. The variation of the elongation of Io from the centre of Jupiter with time. The area in grey is the region when Io is either superimposed on the disk of Jupiter (in transit) or behind the disk of Jupiter (occulted). HSpot does not warn the user if visibility of a planetary satellite is limited in this way.

6.6. The variation in the offset of Io from the centre of Jupiter through an entire visibility window. The grey ellipse represents the approximate mean size of the disk of Jupiter. Note that the entire area of this plot is smaller than the field of view of either PACS or SPIRE. If requesting observations of a planetary satellite the observer should check the visibility of the satellite using the JPL Horizons program at the url: http://ssd.jpl.nasa.gov/horizons.cgi.