Astrodon

The Sloan Digital Sky Survey (SDSS) filters were  designed by Fukugita et al. (Ast. J., 411/4, April 1996, p. 1748-1756) to include five mostly non-overlapping filters covering 300 nm 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 557.7 nm 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 following is a summary of the 50% transmission points of a variety of SDSS filters from the Large Filter Consortium. The new Astrodon Photometrics Sloan set is included for comparison.

The Astrodon Photometrics Sloan filters use only dielectric coatings to achieve steep cut-on and cut-offs and peak transmissions in excess of 95%. 

 

	WIYN	DES	LSST	Pan-Starrs	Fukugita	Astrodon
u'						320/385
g'	402/550	400/550	402/552	402/552	410/551	401/550
r'	560/710	560/710	552/691	552/691	556/695	555/695
i'	700/820	700/850	690/819	691/818	690/814	690/820
z'	830/980	830/1000	818/922	818/922	841/982	820/-

 
 

 

 

 

 

The following is a spectral compilation of actual scans of the Astrodon Photometrics Sloan filter set.

These filters are parfocal with all Astrodon LRGB and narrowband filters.

Specifications:

• 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 +/-0.025 mm substrate thickness
• 1.25" mounted
• 49.7 mm dia. unmounted
• 49.7 x 49.7 mm square unmounted
• Proudly made in the U.S.A.