This page gives the filter specs and a report on the status of the various orders. There are also links to the filter profiles.
Information about the Gemini Consortium filter sepcifications are here

Useful technical background on the choice of Gemini filter specifications is here . Gemini recommended a narrow J than standard to avoid OH lines and water vapour absprption edges. They claimed that the J sky would be 0.5 magnitudes fainter in their J filter which is 40% narrower than the standard Barr J.

Plots of Eric Persson's LCO Filters are here

Barr Associates have useful online information about filters and general and their own filter sets. The division of Barr Associates that deals with Astronomical Filters is the Scientific Products Devision.

They have a useful page which summarises their astronomical filters , including their IR filter specifications.

Filter Specifications Common to all Filters

• Size: 32 x 32 mm square
• Minimum clear aperture: 28 x 28 mm square
• Coating Quality: F,F per MIL-C-48497 (i.e. 60/40)
• Operating Environment: 77K under vacuum
• Blocking: T < 0.05% from 600 to 2800 nm
• Flatness: l/4 over the usable aperture
• Edge slopes: < 2% narrowband, < 4% broadband

Name	Number	Center l	Bandwidth	Short HPP	Long HPP	Peak T (%)	Status
OCLI blocker	6	1.55	1.50	0.80	2.30	95	received Sept 98
OCLI J	6	1.250	0.141	1.179	1.320	83	.
OCLI H	6	1.624	0.288	1.480	1.768	94	.
OCLI K	6	2.194	0.333	2.028	2.361	97	.
OCLI K'	6	2.110	0.319	1.950	2.269	95	.
BARR z	6	0.954	0.204	0.852	1.056	80	.
BARR J	8	1.250	0.280	1.110	1.390	Unknown	Cancelled
BARR H	8	1.626	0.303	1.474	1.777	75	.
OCLI OII	6	1.235	0.014	1.228	1.242	70	.
OCLI [FeII]	6	1.638	0.020	1.628	1.648	77	.
OCLI H2	6	2.116	0.026	2.103	2.129	90	.
OCLI Brg	6	2.167	0.028	2.153	2.181	75	.
OCLI CH4s	6	1.574	0.083	1.533	1.616	80	.
OCLI CH4l	6	1.696	0.089	1.652	1.741	90	.
BARR JOH	6	1.186	0.010	1.181	1.191	80	mid-Nov
BARR HOH	6	1.573	0.012	1.567	1.579	80	mid-Nov

Notes: Numbers for yet to be received filters are design expectations. Numbers for received filters are achieved performances. All performances given for 77K operating temperature and a collimated beam.

For further information and detailed filter profiles, click on the filter name you are interested in.

Original page by François Piché

Last Revision: Febuary 25, 1999 by rgm