Suprime-Cam filter acceptance policy
- We accept user filters for Open Use observations.
- 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.
- 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.
- 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.
- 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.
- All filters must satisfy the physical specifications (Appendix A)
and their actual size measurements must be submitted.
- 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.
- 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
- If your proposal is accepted, send the filter(s) immediately to
- 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.
- 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.
- 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
- Specification of the filters
- 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]
- 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.
- 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.
- The four sides of the filter must be frosted to increase the
adhesive strength when these sides are glued to the filter holder.
- Nota bene when manufacturing the filters
- Anti-reflection coating is necessary.
- Coating must resist wiping with alcohol.
- Must withstant temperatures of -10 deg C.
- 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.
- 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.