Observing Schedule

The image below shows the Herschel observations over the next month, plotted on a view of the Milky Way. The background image is based on the popular Chromoscope tool. You can drag the view around the sky, zoom in and out, and fade between wavelengths. For keyboard shortcuts, press the "h" key, and for more information about Chromoscope, see the Chromoscope blog. If the keyboard shortcuts are not working, try clicking on the Chromoscope image first. You can also see the same view in full screen. If you would like to see where Herschel has already observed, then please look at the Herschel Observing Log.

What are all the markers?

They show the Herschel observations planned for the next few weeks. See below for a key for the different symbols. The markers may take a few seconds to load, depending on your connection speed. You can find more information about the markers below.


The colour denotes the instrument(s) used for the observations:

HiFi Pacs Imaging Pacs Spectrometry Spire Imaging Spire Spectrometry Spire and Pacs (Parallel)

Other symbols:

The locations of the Sun, Earth and Moon, as seen from Herschel today, are also marked (sizes not to scale!):

Sun Earth Moon

Also shown are the locations of the major planets which Herschel can observe:

Mars Jupiter Saturn Uranus Neptune

Data source: Herschel Observing Schedule at Herschel Science Centre; JPL Horizons

What is all the information?

Clicking on a marker gives detailed information about the observation. For each observation, the information given is as follows:

Target Name: The astronomical name of the object being observed. Most stars and galaxies do not have a name, but rather just an ID number. To find a specific object in the image, use the Chromoscope search function by pressing the "s" key.

Proposal: Name of the key science project the observation is part of. Click the link for a description of the key project.

AOT: Type of observation, detailing the instrument and whether the observation involves imaging (e.g. PacsPhoto, SpirePhoto) or spectroscopy (e.g. PacsLineSpec, SpireSpectrometer). The observation type "SpirePacsParallel" uses both SPIRE and PACS instruments simultaneously.

Duration: The duration of the observation, in seconds.

Start Time: The date and time at which the observation will start. The "Z" at the end means that the time is in GMT (also known as "Zulu time").

Obs. ID: A unique identification number of the observation, used within the Herschel data analysis system.

AOR label: A label to identify the observation within the Herschel data analysis system.

RA and Dec: The location of the object in the sky, in coordinates relative to Earth. Right Ascension (RA) and Declination (Dec) are a fixed coordinate system relative to the sky, with RA running around the sky parallel to the equator, and declination running North to South. This means that over the course of the year, nearby objects such as the Sun, Herschel and the planets, move around the sky. While the coordinates are centred on Earth, Herschel is very close on astronomical terms, so stars and galaxies appear in almost exactly the same place. However, closer objects within the solar system will appear in slightly different places.

Why are the markers arranged like that?

Herschel can't look anywhere in the sky, as it has to be careful to avoid the Sun. It can only point between roughly 60o and 120o from the direction of the Sun. This ensures that the solar panels can generate enough power to run the satellite, while keeping the telescope itself out of direct sunlight which would disrupt the observations.

The markers are therefore in a ring around the sky, which creates a the pattern in the image above. The exact order of observations is carefully calculated to reduce the amount by which the telescope has to swing around the sky between objects, while still allowing it to be oriented correctly to communicate with Earth every day. Over the course of a year, Herschel orbits the Sun and so looks at a different region of sky. This means that the ring of markers will slowly move around the sky. The movement is aligned to the direction of Herschel's orbit, which is close to the plane of the Solar System, called the "Ecliptic Plane". Since the image above is rotated to put the Galaxy across the middle, rather than the Solar System, this movement will appear "diagonal" in the image above.

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