Herschel Observers' Manual

List of Figures

1.1. Roll-out of the launcher for the Herschel-Planck mission on 13 May 2009 with the dark, threatening storm clouds visible behind.

1.2. Launch of the Herschel-Planck mission on an Ariane 5-ECA at 13:12UT on 14 May 2009. The Herschel-Planck mission logo is clearly visible at the top of the fairing. The fine weather and clear blue sky contrasts sharply with the conditions for roll-out (Figure 1.1), or those prevalent only a few hours before launch as the VIPs were taken to the launch viewing area in heavy rain during an intense storm.

1.3. Herschel flies free! The moment of separation of Herschel from the Sylda, which is still attached to the upper stage and covering Planck. This image was taken with the backward-facing camera on Herschel. The coastline and cloudscape below Herschel are clearly visible.

1.4. A sequence of images taken by British amateur astronomer Richard Miles using the 2-m Fawkes South Telescope in Australia of Herschel to the left of the image (identified), Planck and the Sylda to the right, 26 hours after launch, at approximately half the distance to the Moon. The movement of the three relative to the stars in the three minutes between the first and last image is quite obvious.

1.5. The telemetry received at MOC showing the oscillation in gyro response as the heavy cryocover swung open and oscillated, causing the entire satellite to wobble slightly until it had reached a stable open position. The large oscillation seen in this gyro signal (marked by the mauve coloured vertical lines on the monitor screen), showing the gyros activating to stabilise the satellite orientation, was the first evidence that the cryocover opening had been carried out successfully.

1.6. The Sneak Preview images of M51 in the three PACS bands, taken blind after cryocover opening on June 14/15th 2009.

1.7. A comparison of images of M51 at 160 microns for ISO, Spitzer and the Herschel sneak preview image, showing the improved resolution and sensitivity from Herschel's larger mirror. No comparable image exists from IRAS, which had a long wavelength cut-off of 100 microns, so the IRAS 100 micron image is shown for comparison.

1.8. The SPIRE First Light images of M74 (NGC 628) in 250, 350 and 500 microns, obtained on 2009 June 24. Messier 74 is a face-on Sa galaxy in Pisces, at approximately 32 million light years distance with a visual diameter of approximately 10 arcminutes.

1.9. The HIFI First Light spectra of DR21, obtained on 2009 June 22, superimposed on a Spitzer image of DR21 and its surrounding region. In the inset we see an enlargement of DR21, which is part of a large star-forming complex in Cygnus, with the positions where the three HIFI spectra represented were taken, superimposed on the image.

1.10. M31's once and future stars. A combined Herschel and XMM-Newton (x-ray) image of M31 showing dusty star-forming regions (Herschel) and the point-sources that represent highly evolved stars (XMM-Newton). The Herschel data were taken at 250 microns with SPIRE between 17 and 21 December 2010. In the XMM-Newton RGB image, red sources are sources that have soft spectra, dominated by low-energy x-ray emission, normally low-mass x-ray binaries, while the blue sources are sources with hard spectra dominated by high-energy emission, which are compact binaries with a neutron star or black hole secondary. This image contains what is effectively a snapshot of the star formation history of M31 and its two satellite galaxies, M32 (superimposed on the spiral arm below the nucleus of M31) and M110 (very faintly visible in the Herschel image to the top right).

1.11. Galaxies spread like grains of sand on a beach. Every source in this GOODS-N field, which is about the size of the Full Moon, is a distant galaxy. The insert to the left shows the indivdual frames in each of the SPIRE bands while the main image combines them as an RGB. The colour of the galaxy gives an indication of its red shift and, hence, distance: the reddest galaxies are the most distant and may be as much as 12 000 million light years away; blue objects are relatively nearby and may be as close as 6000 million light years. In the inset to the lower left we see, to the same scale, the very best sub-millimetre image of this field that had ever been obtained from the ground at this time. This inset image is the result of 20 nights of exposure from Mauna Kea with the James Clerk Maxwell Telescope + SCUBA, in exceptional observing conditions; this image is to the same scale as the Herschel image - the full SCUBA field is 2.5 arcminutes diameter - and shows exactly 5 sources compared to Herschel's 15000 sources in the full 4x4 degree field of this region detected in just 16 hours of exposure.

2.1. 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.

2.2. The Herschel telescope flight model seen in the clean room at ESTEC prior to transport to Kourou.

2.3. The Herschel cryostat.

2.4. The Herschel service module.

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

2.6. 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.

2.7. 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).

2.8. 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.

2.9. Diagram of the Herschel/Planck avionics.

3.1. The Herschel Focal Plane.

4.1. Temperatures of the primary mirror (M1), cryostat vacumm vessel (CVV) and sun-shield measured from OD40 to OD660. The monotonic increase of temperature from up to OD300 is well correlated to the seasonal temperature variation model.

4.2. 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.

4.3. SREM calibrated count rates in three counters (TC1, TC2 and TC3), rebinned in intervals of five minutes. from the 30th of October 2009 (OD 170) to 27th March of 2011 (OD 683). The slight decline of the count rates can be explained by an increased solar activity and the subsequent increase of shielding to Galactic cosmic rays. Several events are visble, the most conspicuous a small proton flare detected in OD 663 (7-8 March 2011).

4.4. SREM calibrated count rates from the archive of calibrated SREM data http://proteus.space.noa.gr/~srem/herschel/ for the year 2010.

4.5. SREM calibrated count rates for the 2012 January 23 and January 28 solar proton storms. The arrival of the shock wave from the Coronal Mass Ejection can be seen as a sharp peak in the proton flux approximately 36 hours after the initiation of the January 23 event.

4.6. SREM calibrated count rates from the archive of calibrated SREM data http://proteus.space.noa.gr/~srem/herschel/ for the year 2011.

4.7. SREM calibrated count rates from the archive of calibrated SREM data http://proteus.space.noa.gr/~srem/herschel/ for the year 2012.

4.8. SREM calibrated count rates from the archive of calibrated SREM data http://proteus.space.noa.gr/~srem/herschel/ for the year 2010-2012 on the same vertical scale. This representation shows the variation of the base level, that is, the cosmic ray element of the proton flux more clearly. In particular, there is a decrease in the cosmic ray flux in early 2010 and there may also be some low-level variations at other times.

4.9. 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.

4.10. Comparison of straylight optical models produced by M. Ferlet (priv. comm.) and observational results. In the top row, a Herschel observation has been planned with Jupiter in position 'I', while in the bottom row the Moon has been placed in position 'F'. In both cases, there is a very good agreement between the model prediction and the straylight results.

5.1. Herschel Space Observatory Ground Segment

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. These plots were made originally for a Herschel launch in 2007, but the range and timescale of variation remains unaltered for the actual launch date.

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. Although this example was calculated originally for a Herschel launch in 2007, the amplitude and timescale of variation remains the same for the actual launch date.

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. Although this example was calculated originally for a Herschel launch in 2007, the amplitude and timescale of variation remains the same for the actual launch date.

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.

7.1. The default Mission Planning Cycle that has been used in routine phase. Towards the end of the mission the Mission Planning cycle will be a strong function of the sky distribution of targets as remaining visibility and the need to complete scheduling will before the end of helium will drive the Mission Planning Schedule.