Archive for Wide Survey

The Euclid Survey(s)

Posted in Euclid, The Universe and Stuff with tags , , , , , , , , , on February 27, 2024 by telescoper

Since it’s been a couple of weeks since Euclid commenced its routine survey operations, I thought I would share this little video from the European Space Agency that shows how the surveying will proceed over the next six years with explanatory text adapted from here:

This animation shows the location of the fields on the sky that will be covered by Euclid’s wide (blue) and deep (yellow) surveys. The sky is shown in the Galactic coordinate system, with the bright horizontal band corresponding to the plane of our Milky Way.

The wide survey will cover more than one third of the sky as shown in blue. Other regions are avoided because they are dominated by Milky Way stars and interstellar matter, or by diffuse dust in the Solar System – the so-called zodiacal light. The wide survey is complemented by a deep survey, taking about 10% of the total observing time and repeatedly observing just three patches of the sky called the Euclid Deep Fields, highlighted in yellow.

The Euclid Deep Field North – towards the top left – has an area of 20 square degrees and is located very close to the Northern Ecliptic Pole. The proximity to the ecliptic pole ensures maximum coverage throughout the year; the exact position was chosen to obtain maximum overlap with one of the deep fields surveyed by NASA’s Spitzer Space Telescope.

The Euclid Deep Field Fornax – in the lower right of the image – spans 10 square degrees and is located in the southern constellation Fornax, the furnace. It encompasses the much smaller Chandra Deep Field South, a 0.11 square degree region of the sky that has been extensively surveyed in the past couple of decades with the Chandra and XMM-Newton X-ray observatories, as well as the Hubble Space Telescope and major ground-based telescopes.

The third and largest of the fields is the Euclid Deep Field South – between the Large Magellanic Cloud and the Euclid Deep Field Fornax. It covers 20 square degrees in the southern constellation of Horologium, the pendulum clock. This field has not been covered to date by any deep sky survey and so has a huge potential for new, exciting discoveries. It has been planned to be observed from the ground by the Vera C. Rubin Observatory.

P.S. According to my latest calculations, I shall have retired by the time the Wide survey is completed.

Leave a comment »

A Euclid Milestone!

Posted in Euclid, The Universe and Stuff with tags , , , , , , , , on February 9, 2024 by telescoper

I just heard some excellent news about Euclid so thought I would post a quick update here. I won’t say much because there will no doubt be official communications from the European Space Agency and the Euclid Consortium. You can find a variety of Euclid-related posts on this blog here.

Over the past few months, there has been a huge amount of activity relating to commissioning the instruments, verifying their performance, and measuring parameters of the optical system that will be needed for analysis of the huge amount of data due to come from Euclid. All this effort fed into the Mission Commissioning Results Review (MCRR) which concluded yesterday that all was well.

This is an important milestone for Euclid because, in ESA parlance, it marks the change from a project to a mission. Until commissioning, there is a project manager who works with ESA and the industrial contractors to ensure everything functions properly; when nominal operations start the project team is disbanded and the mission team takes over; and so it came to pass that the Project Manager (Giuseppe Racca) handed over the reins to the Mission Manager (Pierre Ferruit).

That’s when the role of the Euclid Consortium increases substantially. In particular the Science Ground Segment (SGS), which includes the pipelines that will process the data, has been declared to be ready for business. You can read more about the SGS here but here’s a graphic that shows how data comes from the telescope, external telescopes, or simulations, then run through their respective pipelines for VIS, NISP, or external data, then are merged into a coherent format. Pipelines then extract scientific information and compute science data products for further analysis

Each element of this diagram is rather complex. Here, for example, is the organization of the Science Data Centre (SDC) component of the Science Ground Segment at the bottom of the above picture, consisting of computing centers responsible for implementing and running the data processing pipelines:

Anyway, the immediate upshot of all this is that full surveying activities of Euclid can now proceed. The Euclid mission will conduct primarily two different surveys: a “Wide Survey”, covering about 15,000 square degrees on the sky, and a “Deep Survey” of about 50 square degrees, where the instruments will observe three fields much longer than the rest of the sky to capture much fainter galaxies and hence look further out into space. I understand that the Wide Survey will commence in earnest on 14th February.The timescale from now is that the first full set of survey data (DR1) will be available internally to the Euclid Consortium in May or June 2025 and will be made public a year later (i.e. by June 2026).

That doesn’t mean that Euclid will be silent until 2026. In fact, the first batch of post-launch papers will come out very soon, in May 2024. This will include science papers resulting from the Early Release Observations – the data from these will also be made public at the same time – as well as an overview paper for the whole mission and papers describing the details of NISP and VIS instruments using measurements made during commissioning. There will also be a release in May 2025 of data from the Deep Survey patch of about 50 square degrees.

So, the board is set. The pieces are moving.

1 Comment »