Call for spectroscopic data

To the P.I. of any past or ongoing spectroscopic programs (large or small) conducted within commonly observed extragalactic field surveys

< SIGNED LETTER available here >

Besides their direct scientific value for studying galaxies, large spectroscopic redshift samples are essential for properly training, calibrating, and validating photometric redshifts. This becomes particularly important and challenging for the next generation of cosmological surveys, which require high precision photometric redshifts. The photometric redshift teams for upcoming wide-field surveys such as ​ Euclid ​ , LSST, and ​ WFIRST ​ have highlighted the need to build a reference database of spectroscopic redshifts to train and later validate the various photometric redshift methods being developed for these surveys. Such a database will also be very useful for current programs.

We have started to collect spectroscopic redshifts in the following commonly adopted calibration and/or deep fields split between the Euclid primary and secondary calibration fields (but with the strong expectation that these fields include the key calibration fields for other surveys):

Euclid ​ Deep Fields:

  • North Ecliptic Pole: 1.8 deg radius circle centered at R.A.=17:58:56, Dec.=+66:01:04;
  • CDFS (including ​ GOODS-S​ ): 1.8 deg radius circle centered at R.A.=3:32:49, Dec.=-26:16:41;

Primary ​ Euclid ​ Calibration Fields:

  • COSMOS: 2.5x2.5 deg2 region centered on R.A.=10:00:30, Dec.=+02:30:00;
  • VVDS: 1x1 deg2 region centered at R.A.=02:25:59, Dec.=+04:29:40;
  • GOODS-N: 1x1 deg2 region centered at R.A.=12:36:44, Dec.=+62:14:24;
  • SXDS (including UDS): 2.5x2.5 deg2 region centered at R.A.=02:18:00, Dec.=-05:00:00;
  • EGS: 1x1 deg2 region centered at R.A.=14:19:27, Dec.=+52:40:56;
  • XMM-LSS/CFHT-LS W1: 9x8 deg2 region centered at R.A.=02:18:00, Dec.=-07:00:00.

Secondary ​ Euclid ​ Calibration Fields:

  • CFHT-LS D4: 1x1 deg2 region centered at R.A.=22:15:31, Dec.=-17:43:56;
  • CFHT-LS W2: 5x5 deg2 region centered at R.A.=08:57:49, Dec.=-03:19:00;
  • CFHT-LS W3: 7x7 deg2 region centered at R.A.=14:17:54, Dec.=+54:30:31;
  • CFHT-LS W2/SSA22: 5x5 deg2 region centered at R.A.=22:13:18 Dec.=+01:19:00.

We note that the field characteristics may slightly change due to operational constraints. The goal is not only to collect spectroscopic redshifts in these fields but also to merge redundant observations, investigate potential redshift assignment discrepancies as well as homogenize the quality flag scheme. Requirements on photometric redshift accuracy imposed by the cosmological objectives of these Stage IV experiments demand that the spectroscopy used for the photometric redshift training be as pure as possible.If you are P.I. of past or on-going spectroscopic programs in these fields, we would be much obliged if you were willing to allow us to incorporate your data into a master spectroscopic database.

We note that we are creating this spectroscopic database for one purpose: to improve the training/calibration of photometric redshifts for wide-field extragalactic surveys. Ultimately, our goal is to provide a unique, quality-homogenized master database of spectroscopic redshifts to the scientific community. If you wish your data to remain private, however, and be used only to help the survey photometric redshift calibration efforts, we will not incorporate them into the public master catalogue.

If you have data in these fields and would be willing to contribute to the current effort, please USE THE FORM BELOW.

At some stage, we may request 2D and 1D products in order to re-assign redshifts and quality flag following the survey quality flag assessment.

Best regards,
Peter Capak (IPAC, Caltech, USA), Jean Coupon (University of Geneva, CH), Audrey Galametz (University of Geneva, CH), Daniel Masters (JPL, USA), Stéphane Paltani (University of Geneva, CH), Daniel Stern (JPL, USA), Francisco Castander (IEEC-CSIS, ES) - on behalf of the Euclid Organisation Unit for Photometric Redshifts (OU-PHZ).

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