Astrodon Photometrics Sloan U-Filter 50mm unmounted
The Sloan Digital Sky Survey (SDSS) filters were designed by Fukugita et al. to include five mostly non-overlapping filters covering 300nm to the sensitivity limit of silicon CCD cameras near 1100 nm. They combined colored glass filters and short-pass dielectric coatings to steepen the low wavelength side of the bandpass. The [O I] skyline at 557.7nm occurs between the g' and r' filters, and is thus reduced.
The SDSS photometric system is the most common filter set used today. The Hubble Space Telescope is equipped with an SDSS set that provides a large reference database for research. Much of photometry up to magnitude 23 will be done in this system with meter-class telescopes. The upcoming large collaborative survey projects (Large Synoptic Survey Telescope - LSST; Panoramic Survey Telescope and Rapid Response System - Pan-Starrs) will also use SDSS filters.
The Astrodon Photometrics Sloan filters use only dielectric coatings to achieve steep cut-on and cut-offs and peak transmissions in excess of 95%.
The image shows a spectral compilation of actual scans of the Astrodon Photometrics Sloan filter set.
These filters are parfocal with all Astrodon LRGB and narrowband filters.
- 50% transmission points provided above (+/- 3nm typical)
- Peak transmission guaranteed > 95% (>90% for u')
- <0.1%T out-of-band 300 - 1100 nm
- Striae-free, single fused silica substrates
- 1/4-wave propagated wavefront prior to coating
- <0.5 arcminute substrate parallelism
- 3.000 +/-0.025mm substrate thickness
- 1.25" mounted
- 49.7mm dia. unmounted
- 49.7 x 49.7mm square unmounted
- Proudly made in the U.S.A.