UNIONS Memorandum Of Understanding








The Canada-France Imaging Survey (CFIS) team is a group of astrophysicists primarily based in Canada and France who have joined together to design and enable the CFIS observing campaign at the Canada-France Hawaii Telescope (CFHT),


the Pan-STARRS Team, a small group of astrophysicists at the Institute for Astronomy at the University of Hawaii responsible for the funding and scientific operation of Pan-STARRS including the Pan-STARRS1 and Pan-STARRS2 Telescopes, instruments, and associated cyber-infrastructure,


the Wide Imaging with Subaru HSC of the Euclid Sky (WISHES) team, a group of astrophysicists primarily based in Japan who have joined together to design and enable the WISHES observing campaign at the Subaru Telescope,

hereinafter individually referred to as a “Party” and jointly referred to as the “Parties,”

CONSIDERING that cooperation between their respective collaborations will enhance the science impact of each survey, enable new and exciting science on which members of each consortia will work, and will provide other mutual benefits:

HAVE AGREED as follows:

  1. The purpose of this Memorandum of Understanding (hereinafter referred to as the “MOU”) is to define the terms and conditions under which collaboration between the Parties will be conducted.

  1. This MOU sets forth the major collaborative principles and any relevant managerial, technical, and operational interfaces between the Parties that are necessary to ensure compatibility between their respective activities, including the major roles and responsibilities of the Parties.

  1. The Canada-France Imaging Survey (CFIS) is a MegaCam Large Program at the Canada-France-Hawaii Telescope (CFHT) that has been allocated 271 nights over six semesters (17A to 19B, from Feb. 1st 2017, to Jan. 31st 2020 in the current CFHT planning (this original allocation has been extended up to July 31st 2022 for a total of 314 nights as part of the CFHT Large Program completion policy). CFIS has two survey components:

    • CFIS-r plans to image ~5000 square degrees over 154 nights in the r-band. Covering the sky above a declination of 30 degrees, and outside the galactic plane (Galactic latitude |b|>25 degrees), it will produce a panoramic survey with exquisite image quality (~0.7 arcsecond median) to a depth of 24.1 (point source, SNR=10, 2 arcseconds diameter aperture).

    • CFIS-u plans to survey ~10000 square degrees over 117 nights, covering the region above a declination of 0 degrees, and outside the galactic plane (Galactic latitude |b|>25 degrees), to a u-band depth of 23.6 (point source, SNR=10, 2 arcseconds diameter aperture, ~0.9 arcsecond median image quality).

  1. The CFIS observations, like all others at CFHT, are conducted on a best effort basis.

  1. All science data and associated calibration data and metadata obtained as part of CFIS will be shared with the Pan-STARRS and WISHES teams as covered by the terms in this MOU.

  1. The CFIS Steering Group (5 Canadian and 5 French members) oversees all CFIS science activities and is responsible for advising the CFIS Principle Investigators (Alan McConnachie and Jean-Charles Cuillandre, also in the Steering Group) on all aspects of the collaboration.

  1. The list of current members in the CFIS team is included as an Appendix. Membership of CFIS is open to any astronomer working in Canada and France. In special circumstances, non-Canadian and French astronomers may join CFIS. In these cases, the CFIS Steering Group will consult with the Pan-STARRS and WISHES leads prior to approving the new member to ensure there are no collaborative conflicts with Pan-STARRS and WISHES.

  1. The Pan-STARRS NEO Survey is a NASA funded SSO Near Earth Object Observations Program with the expectation of ongoing support. The cadence and the area of the Pan-STARRS NEO Survey are determined by the NEO program, but includes the CFIS footprint. The depth in the CFIS footprint will grow over time, and will grow differently in different bands. The Pan-STARRS NEO Survey has three components:

    • Pan-STARRS-w survey for NEOS in dark time which has uneven sky coverage that is most heavily weighted on the ecliptic but which will be roughly uniform going forward. The mode of the PSF distribution in w-band is 1.2 arcsec. Pan-STARRS-w is within the CFIS-u footprint.

    • Pan-STARRS-i survey for NEOS in grey time has uneven sky coverage. The mode of the distribution in i-band is 1.0 arcsec. Pan-STARRS-i is within the CFIS-u footprint.

    • Pan-STARRS-z survey for NEOS in bright time will have roughly uniform coverage, and is entirely in the northern 1000 square degree CFIS-r footprint between a declination of +30 and +38 degrees to complement the WISHES effort.

  1. The Pan-STARRS observations are conducted on a best effort basis;

  1. All Pan-STARRS static sky science data (stacks, mean exposure photometry, mean forced photometry) and associated calibration data and metadata will be shared with the CFIS and WISHES teams as covered by the terms in this MOU.

  1. It is expected that Pan-STARRS will request ongoing support from NASA and ongoing data obtained under proposal will automatically be considered part of the Pan-STARRS dataset and subject to the terms in this MOU.

  1. The leads of the Pan-STARRS Team are Kenneth Chambers, Eugene Magnier, and Richard Wainscoat.

  1. The Pan-STARRS team includes all IfA scientists that work on Pan-STARRS data. The current members of the Pan-STARRS team are included as an Appendix.

  1. The Wide Imaging Survey with Subaru HSC of the Euclid Sky (WISHES) is an approved Subaru Open Use Intensive Program that has been allocated 40 nights (200.9 hours on source) over six semesters from S20B through S23A. It plans to take z-band images over ~4500 square degree of the sky above a declination of 30 degrees that fully overlaps with a planned Euclid Wide survey footprint. The expected depth is 23.4 (point source within 2 arcseconds diameter aperture, SNR=10) and the images will be taken under the seeing better than 1.0 arcsecond.
  1. WISHES is conducted on a best effort basis.

  1. All science data and associated calibration data and metadata obtained as part of WISHES will be shared with CFIS and the Pan-STARRS team as covered by the terms in this MOU.

  1. It is possible that WISHES will request more observing time from the Subaru Telescope in order to ensure the completeness of the survey. Any new data obtained under a new proposal will automatically be considered part of the WISHES dataset and subject to the terms in this MOU.
  1. The leads of the WISHES team are Masamune Oguri, Satoshi Miyazaki, and Hisanori Furusawa.

  2. The list of current members in the WISHES team is included as an Appendix. Membership of WISHES is open to any astronomer working in Japan. In special circumstances, non-Japanese astronomers may join WISHES. In these cases, the WISHES leads consult with CFIS and Pan-STARRS leads prior of the approval to ensure there are no collaborative conflicts

The collaboration between CFIS, Pan-STARRS and WISHES is expected to enable new scientific discoveries and scientific opportunities for the members of each collaboration. They are expected to cooperate in a manner consistent with this aim. As new opportunities and ideas develop, it is expected that all Parties will be proactive in enabling the science, to the mutual scientific benefit of all Parties.

  1. The joint effort will be referred as the “Ultraviolet Near-Infrared Optical Northern Survey” (UNIONS)

  2. In order to preserve the identity of the individual teams, the CFIS, Pan-STARRS and WISHES components will remain clearly identified throughout UNIONS wherever practical e.g., UNIONS (CFIS/Pan-STARRS/WISHES), CFIS/Pan-STARRS/WISHES (UNIONS).

  3. The CFIS, Pan-STARRS and WISHES teams will keep operating under their own collaboration rules, ensuring that all terms of this present MoU are implemented.

  4. Once this MOU is in effect, WISHES will publish their own specific pages in the UNIONS internal Wiki, which also hosts CFIS and PanSTARRS pages. The “Who is doing what” pages will encompass all science activities from WISHES, Pan-STARRS and CFIS pertaining to the joint dataset as listed below (ARTICLE 6.1).

  5. The CFIS Steering Group (10 representatives), the Pan-STARRS leads (3 representatives), and the WISHES leads (3 representatives) will work together as a single group leading the UNIONS (the UNIONS Steering Group), including hosting monthly telecons. The email alias for this UNIONS leading group (handled by CFHT) will include the WISHES, the CFIS and Pan-STARRS leads.

  6. CFHT will continue to support a mailing list for the UNIONS community, adding the WISHES team to the Pan-STARRS team and the CFIS team.

  7. A CFIS type approach consisting of a light procedure by the CFIS Steering Group checking papers based on the joint dataset to be submitted, and the equivalent on the Pan-STARRS and WISHES sides, will ensure that the respective publications policies are fully respected by all sides for UNIONS papers (ARTICLE 6).

  8. A key original rule of the CFIS holds for all members of this new collaboration: there is no reserved science but every scientist must list intentions on the UNIONS Wiki early on and collaborations are encouraged.


The following publication policy is derived from and supersedes the original CFIS publication policy, with the addition of considerations specific to the collaboration between CFIS, Pan-STARRS and WISHES.

  1. UNIONS publications are considered those publications that are based wholly or partly on any proprietary data that is shared as part of the UNIONS collaboration, including papers based on any of the individual datasets (CFIS, Pan-STARRS or WISHES) or any combination of 2 or more of these datasets, and in which the UNIONS data are a significant component of the analysis.

  1. Exceptions to this are papers that are specifically describing an individual survey or survey component (e.g., the WISHES observing strategy or the CFIS-r data processing pipeline).

  1. If it is unclear if the UNIONS data are a significant or ancillary component of the analysis (and so whether the paper is formally a “UNIONS paper”), the UNIONS Steering Group, in consultation with the relevant lead authors and any other relevant parties, will decide on the appropriate action.

  1. Papers based on UNIONS data will list by default the entire Pan-STARRS team (builders), CFIS-SG members (builders) and WISHES leadership (builders) as co-authors, although each of them has right of refusal. Only Steering Group members who contact the lead author of a paper to request authorship should be listed as authors.

  1. Other UNIONS collaborators who contribute significantly to a given UNIONS paper will be granted authorship. “Contributing” could be any of: proposal writing, data reduction, analysis, interpretation, writing, etc, as long as it is deemed a significant contribution to the project.

  1. It is expected that some UNIONS members have and will contribute more than others to the project and/or specific papers, and will therefore deserve to be on a paper when they so request. For the purposes of clarity, these members include individuals or groups responsible for acquiring and generating high level (collaboration-wide) data products such as images, stacks or object catalogs that are widely used. At the level of specific Science Projects, these members also include individuals or groups responsible for the creation of advanced products that may be used by the Science Project (e.g., galaxy shape catalogues for weak lensing, stellar metallicity catalogues, etc.).

  1. It is expected that there will be a at least one UNIONS overview paper that will discuss the broad goals of UNIONS, including details of data reduction. This paper (and any similar papers) will offer authorship to the entire UNIONS Collaboration, who must individually confirm that they want to be listed as a coauthor.

  1. It is expected that a paper will be written by a core group of authors who agree among themselves how they are to be ordered after the lead author, possibly followed by one or more UNIONS Collaboration members, as appropriate while respecting the guideline 6.3 (builders). These other authors are to be listed in alphabetical order. If there is disagreement as to whom should be included as authors, the UNIONS Steering Group should be consulted by the lead author.

  1. All UNIONS papers to be submitted will be first posted on the UNIONS internal pages once the draft is at a stage where it could be submitted to the journal. A notice will be circulated to the entire collaboration. UNIONS members who are not already a co-author have a 3-week period from date of circulation to make a contribution significant enough to the draft and make the case to the lead author for authorship. The lead author will give full consideration to coauthors’ inputs to the paper. Note that it is generally expected that all people who are interested in the science will already have been identified as coauthors through their participation in the relevant science projects, and this present guideline is intended as a failsafe mechanism. As such, extensions to the 3 week period will not in general be considered.

  1. All UNIONS papers for which the UNIONS dataset forms a significant component of the analysis on which the paper is based will include UNIONS in the title. Additionally, the abstract will include the acronyms (or full names) of the individual surveys that contribute the specific data analyzed in the paper (i.e., some combination of CFIS/Pan-STARRS/WISHES). The text of the paper will include a few sentences to make explicit the relationship between UNIONS and CFIS/Pan-STARRS/WISHES (the UNIONS Wiki will propose a few appropriate sentences).

  1. UNIONS papers will include the acknowledgement texts for CFIS, Pan-STARRS and WISHES. Appropriate credit to the UNIONS collaboration for running the survey and producing the data set is expected along the usual required acknowledgment text for MegaCam and the CFHT funding agencies (c.f. UNIONS internal pages for the relevant texts, including the relevant text for Pan-STARRS and WISHES).

  1. The UNIONS leadership (Article 5.5) will act as a form of light-handed editorial board for UNIONS papers, for example, ensuring the publications comply with the present rules and are using the most up-to-date data. It will have final right of approval over all UNIONS publications based on the UNIONS dataset to be submitted to peer-reviewed journals, which they will convey to the lead author during the 3-week pre-submission period. The default answer will be positive and no publications will be blocked based on scientific analysis or interpretation; rather, consideration will only be given to respecting the collaboration rules and guidelines, and ensuring the integrity of the dataset (e.g., in case of fundamental misinterpretation of catalogues or incorrect versions of the dataset being used).

  1. All articles for publication in peer-reviewed journals should be posted to the arXiv. It is left to the lead authors, in consultation with their coauthors, to decide if the first posting of an article should occur after submission or acceptance of the paper to the journal.

  1. Any UNIONS member presenting a poster, talk, communication, etc. is encouraged to report it on the UNIONS internal pages, as well as posting afterward on those pages a PDF of their presentation or proceeding.

  1. Confidentiality regarding unpublished results is expected from the UNIONS Collaboration.

  1. Consultation should be made with the science lead in situations where unpublished material is going to be shown.

  1. The CFIS-u and CFIS-r data, as processed by the CFIS team, will be available on a rolling basis (essentially after each observing run for the MegaPipe products) to all members of UNIONS:

  • CFIS rolling basis:

    • Single detrended images (CFHT Elixir products)
    • Stack images & MegaPipe detections
    • u & r-bands
    • Metadata
  1. Pan-STARRS data will come in processing waves as described below by the UNIONS internal data releases. These release dates are understood to be on a best-effort basis:

  • DR1

    • February 2019
    • Pan-STARRS, all Pan-STARRS Medium-Deep fields within the CFIS footprint, the following products will be produced independently of the CFIS dataset:
      • g, r, i, z, y-band stack images (full depth available)
      • stack source catalogs (photometry, astrometry, galaxy models)
  • DR2

    • April 2020
    • Pan-STARRS, within the CFIS sky coverage only, the following products will be produced independently of the CFIS dataset:
      • i & z-band stack images (full depth available)
      • w-band stack images from best image quality subset, using ~⅓ of w-band exposures
      • Stack source catalogs (photometry, astrometry, galaxy models)
      • Mean Forced Warp Photometry
      • Metadata
  • DR3 (extra versus DR2 besides gain in sky coverage and overall depth)

    • April 2021
    • Pan-STARRS:
      • Forced chips (mean of the individual frame photometry)
      • Includes Pan-STARRS photometry of CFIS-u, CFIS-r
  • DR4 (extra versus DR2/3 besides gain in sky coverage and overall depth)

    • April 2022
    • Pan-STARRS:
      • The Tractor or equivalent forced photometry
  1. The WISHES data, as processed by the WISHES team, will be made available to all members of UNIONS. The products include stacked images and the source catalog produced by hscPipe. The data release plan is not yet determined, but it is expected that WISHES data will be processed approximately once a year.
  1. The UNIONS dataset will be made available to the CFIS, Pan-STARRS and WISHES teams through the CADC-CANFAR infrastructure, expanding on the current CFIS implementation.

  1. Public releases of the Pan-STARRS data covered by this MOU may be performed by the Pan-STARRS team, using STScI or other partners as a portal, on timescales earlier than the UNIONS data release dates. It is anticipated that a subset of the UNIONS data may be used in future Pan-STARRS 3pi releases to improve uniformity. In addition, public release of the data may be mandated by the Pan-STARRS sponsor on an earlier timescale.

  2. Internal or public releases of the WISHES data may also be performed by the WISHES team via an NAOJ portal.

  3. CFIS, Pan-STARRS and WISHES will coordinate and plan observations to attempt to obtain at least 1250 square degrees (goal: 2000 square degrees) of contiguous sky coverage in common by Summer 2022, in the general area of the north ecliptic pole. This is to help ensure a sufficient area will be covered that can be targeted by the Euclid space mission as part of its first data release.

  4. There will be a UNIONS public data release of all data in the region of the north ecliptic pole (point 7) no later than Summer 2023, that will match the final preparations of the 2022 launch of the Euclid space mission.

  5. The UNIONS final public release will be driven by the release dates of the CFIS and WISHES. CFIS is estimated to be released on August 1, 2023 considering the last CFIS photons are expected to be gathered by July 31, 2022. WISHES is estimated to have completed observations by the end of Semester 2023A. Intermediate public releases may occur prior to these dates upon approval from the UNIONS leadership, and will involve some subset of the data or surveys.

  1. CADC-CANFAR will handle an overall effort for the world release of the UNIONS.


This MOU may be amended by written agreement of the Parties.


The Parties will consult with each other promptly when events occur or matters arise that may question the interpretation or implementation of the terms of this MOU. Any dispute in the interpretation or implementation of the terms of this MOU will be referred to the CFIS Steering Group,the leads of Pan-STARRS, and the leads of WISHES. Failing agreement at that level, the Parties may agree to submit the dispute to an agreed-upon form of dispute resolution.


This MOU will enter into force upon signature by all Parties. It will remain in force through the final public release of the optimized joint CFIS,Pan-STARRS, and WISHES dataset.