Suprime-Cam filter acceptance policy

  1. We accept user filters for Open Use observations.
    1. A preparation period is necessary for observatory staff to become skilled in accepting user filters. During this period, only a limited number of user filters will be accepted.
    2. Once the system for accepting user filters is well organized, we will increase the number of filters we can accept. However, we may be unable to accept all user filters if the demand is too large.
  2. Please contact the Suprime-Cam support astronomer before starting the manufacture of a new filter. We may already have, or be expecting, a similar filter which will be suitable for your needs.
  3. The properties of the user filters must be provided before their acceptance can be considered. If you are an Open Use proposer, please read the following notices very carefully.
    1. All filters must satisfy the physical specifications (Appendix A) and their actual size measurements must be submitted.
    2. An evaluation of optical characteristics is required. Measurements of transmission curve under f/1.9 beam, homogeneity of optical characteristics, etc., are recommended (these measurements can be done at NAOJ in Mitaka, Japan). At a minimum, evaluation data based on actual measurements by the manufacturer must be submitted.
    3. The certificate of actual size measurement and inspection data of optical characteristics must be submitted to the Suprime-Cam Support Astronomer by the date specified in the Call for Proposals of the semester. The proposal will not be accepted if the certificate is not submitted.
    4. If your proposal is accepted, send the filter(s) immediately to the observatory.
  4. Suprime-Cam can only hold 10 filters at a time and it is necessary to remove the instrument from the Prime Focus Unit to replace the filter cassettes. Because of this and additional scheduling constraints, we may be unable to accommodate all the user filters, or schedule all proposals at the preferred times. Note that previous acceptance of a user filter does not guarantee preferential treatment or favorable scheduling.
  5. Subaru Telescope will prepare the filter holders, glue the filters to the filter holders, and perform the filter exchange test. Experienced staff will be assigned to these works. However, Subaru Telscope and its staff do not accept responsibility for any damage to the filters.
  6. If requested, the filter(s) can be returned a month after the observations. However, all filters will be sturdily glued to their holders and may be difficult to use at other facilities. We are happy to accept unwanted filters and will allow them to be used by other observers.

  1. Specification of the filters
    1. Dimension: (205.0 +/- 0.5)mm x (170.0 +/ -0.5)mm x (15.0 +/- 0.2)mm @0 deg C. Corner cuts of C5-C8 (mm) are necessary for 4 corners of 205x170 surface. Front and back surfaces must be parallel with an accuracy of 1 arcmin. [See figure above]
    2. Clear Aperture Size: 192mm x 158mm (centered on the filter center). Since the beam passes through this area, optical characteristics must be uniform inside the area.
    3. The uncoated edges of the filter must be less than 3mm in width. We will cover this area with black adhesive rubber to avoid light leak through this area.
    4. The four sides of the filter must be frosted to increase the adhesive strength when these sides are glued to the filter holder.
  2. Nota bene when manufacturing the filters
    1. Anti-reflection coating is necessary.
    2. Coating must resist wiping with alcohol.
    3. Must withstant temperatures of -10 deg C.
    4. Ghosts tend to be made between filter surface and corrector lens and are very strong when a highly-reflective surface (such as the surface with interference coating) of a filter faces the corrector lens. Therefore, the reflectivity of this surface must be reduced and use of color-glass which absorbs light is recommended.
    5. There is a coating method available for which the operating humidity is assumed. If a filter is coated with this method, changes in humidity cause changes in the transparency curve. Please contact your manufacturer in advance about this issue.

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