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The ING filter database

The ING filter database has an entry for all filters that are interchangeble between different instruments. The database, which is displayed under the following links, is updated every time somebody logs a filter movement into our FILTER ORGANIZER program. This program is consulted by members of the Support Astronomy Group and by others that bring filters from one place to another.

For this database to be of any use, it is vital that all filter movements are logged into the database immediately after the filter was accessed.

  • The complete filter database
  • Broad band filters only (excluding Taurus/WFC filters)
  • Broad band filters only, sorted on wavelength (excluding Taurus/WFC filters)
  • Narrow band filters only (excluding Taurus/WFC filters)
  • Narrow band filters only, sorted on wavelength (excluding Taurus/WFC filters)
  • Taurus filters only
  • Taurus filters only, sorted on wavelength
  • Wide Field Camera filters only
  • There is also the possibility to use filters available at the NOT, some of which are complementary to our filters (e.g., NOT has a collection of 51-mm square redshifted Hbeta and OIII filters, and ING has a collection of 51-mm square redshifted Halpha filters). If your are interested in using any filter from the NOT you will need to contact them (staff@not.iac.es) for permission (in all cases priority will go to use of the filters at the NOT itself). You should also contact the ING staff before your observing run to see if the filter can be fitted and/or needs a special adapter.

    Legend of the database.

    Filter throughput plots and tables.

    These can be obtained by clicking the links in columns 3 (PostScript plot) and 4 (ASCII table). Mariet Broxterman is currently measuring the filter throughput of our filters; for the filters that haven't been measured yet see the plots provided by the filter document of Reynier Peletier.

    Note that the filter scanner uses a rectangular beam of light to measure the throughput. In one dimension this beam has a f/9.0 focal ratio, in the other dimension it has a f/26.1 focal ratio. For interference filters this will affect the measured central wavelength; please consult Appendix D of the Observers Guide for more information regarding the central wavelength of interference filters in an uncollimated beam.

    The scanner can only measure up to about 9000 Angstroms. Around this wavelength noise is apparent in the throughput scans. Some I and Z band scans show local throughputs of more than 100% because of this.

    AUX Port filters

    As of semester 99A the AUX port filters cannot be changed anymore. The filter setup is as follows: RGO U #202, Harris B #25, Harris V #30, Harris R #36, Harris I #41. The sixth slot is taken up by the focus mask with a Kitt Peak V filter (#49) attached to it: this slot cannot be used for regular observations.

    What filters fit in which instruments?

    Many of the ING filters are easy to move from one instrument to another. Often, filters that originally did not fit in an instrument, can now be put in holders that do fit in that particular instrument. Knowing this, please note that many filters labelled as 'TAURUS' filters also fit in other instruments such as the UES.

    When marked with an * the filters give rise to vignetting. Note that for TAURUS it depends on where in the instrument the filters are put whether they vignet or not. Also note that the round 25mm and 38mm filters (serial #1 and #2) are fitted in 50x50mm holders.

    Maarten Blanken