This is a list of filters usually available at Mt. Hamilton. It may not be complete in two ways; first, filters may have been missed in the initial listing or added since the list was compiled, and second, a few filters on hand are unidentified. This list does not include filters which are normally mounted within an instrument, and are therefore not available for borrowing. See the appropriate manual for the normal filter complement at a particular instrument. Few of these filters are owned by Lick Observatory. The majority belong to individual astronomers within the UC system who generously make them available to the rest of us. Please treat them with care. If you take a filter for use at any other telescope, leave a note where you took it from in case someone else looks for it, and be SURE to return it promptly when done. Do not take filters away from the mountain without explicit permission from the owners. People who add filters to the collection are urged to mark them clearly and in a permanent way. Commercial interference filters are usually adequately marked, although some manufacturers use obtuse (and even unintelligible) codes. Glass filters are the ones which we most commonly find completely unmarked. A good technique for marking such (relatively inexpensive glass) filters is to scratch their identity unobtrusively near the edge of the filter with a diamond tipped stylus. Interference filters and filter sandwiches are usually thick enough to write a description on the side. If you add filters to the collection, please inform Rem (rem@ucolick.org) so they can be added to this list. Priorities for the use of filters is owner, 120" observer, and then others. Practically speaking, this means that if you wish to use a particular filter at the 40", please verify first that it will not be needed at the 120. The following list is arranged by location on the mountain, and then in order of increasing wavelength, and with broadband, neutral density and blocking filters listed at the end. The values given are generally those provided by the manufacturer. In many instances passbands are available for the filters, but they are from many sources and were determined in many ways by many people, so we do not list them here. Most of the filters are 2" square, perhaps 10% are 2" round, and a few are 1" round. We have a few extra filter holders available at the telescopes for user filters. *************************************************************************** PLEASE DO NOT ATTEMPT TO CLEAN THESE FILTERS UNLESS YOU'RE SURE OF WHAT YOU'RE DOING. MANY HAVE VERY SOFT OVERCOATS!!!!! Thank you. *************************************************************************** 120" CASSEGRAIN (see also the gopher info on the Kast spectrograph for filters permanently mounted there) Narrow- and medium band filters wavelength FWHM 3380 ? 3380 30 3440 90 3500 50 3650 20 3662 70 3690 30 3700 ? 3734 60 3750 80 3804 65 3825 300 3870 30 3870 60 3875 62 3953 60 3972 60 4000 400 (Thuan-Gunn v) 4023 25 4043 60 4100 100 4200 250 4217 17 4220 60 4260 30 4265 ? 4300 60 4315 30 4360 ? 4380 20 4450 60 4479 60 4500 400 4512 60 4545 60 4550 80 4578 60 4614 20 4624 47 4625 100 4633 30 4644 60 4677 60 4710 60 4743 60 4750 400 4776 60 4809 60 4838 32 4861 40 4875 60 4900 800 (Thuan-Gunn g) 4908 60 4941 90 4974 60 4985 80 5000 100 5000 400 5030 80 5064 10(?) 5071 58 5103 59 5110 80 5156 36 5190 80 5199 60 5200 100 5232 60 5265 60 5298 61 5332 61 5350 80 5366 62 5382 62 5434 62 5500 400 5503 63 5538 64 5580 65 5610 65 5646 63 5682 65 5719 66 5735 250 5756 66 5780 65 5794 80 5826 80 5893 40 5920 60 5940 60 6000 70 6000 400 6067 70 6107 70 6147 71 6187 71 6199 40 6228 72 6250 400 6269 73 6300 45 6310 73 6351 74 6393 74 6435 74 6460 15 6477 75 6500 400 6500 700 (Thuan-Gunn r) 6518 359 6520 75 6563 45 (2 each) 6563 75 6567 15 6570 70 6606 75 6649 76 6685 50 6693 76 6710 100 6737 76 6750 500 6781 78 6826 78 6871 78 6916 78 6961 79 7000 400 7007 79 7053 79 7099 80 7141 50 7146 80 7193 80 7240 82 7246 50 7250 500 7288 82 7336 82 7384 84 7433 84 7482 84 7500 400 7531 84 7580 85 7620 ? 7630 85 7680 85 7730 85 7781 86 7832 86 7883 86 7935 88 7986 88 8000 100 8038 90 8091 90 8145 92 8225 90 8478 100 8570 90 8730 90 8750 650 8950 90 9000 400 9070 100 9160 100 9230 100 U liquid CuSO4 + 1mmUG2 U crystal CuSO4 + 2mmUG2 B Bessell* V Bessell* R Bessell* I Bessell* UG5 1mm B-350 2mm B-380 2mm BG14 2mm GG385 RG715 2mm RG850 2mm RG1000 2mm Rs Spinrad night sky NG 9 *************************************** 120" Coude CuSO4 liquid, no UG blocker UG 1 2mm UG 2 2mm UG 5 1mm BG 12 2mm BG 13 2mm BG 14 2mm BG 24 2mm GG 495 1mm RG 630 2mm NG 4 2mm NG 5 2mm NG 9 2mm NG 11 2mm diffusers **************************************** 40" Telescope U liquid CuSO4 + 1mm UG2 B Bessell* V Bessell* R Bessell* I Bessell* old B 1mm BG18 + 2mm GG385 + 1mm BG12 old V 2mmBG18 + 2mm GG495 alt I 7400/860 g 4900/800 (Gunn-Thuan) Rs Spinrad night sky RG 630 2mm RG 9 3mm GG 385 2mm GG 455 2mm GG 495 2mm ND 1 2.5 mag ND ND 2 5.0 mag ND ***************************************** *Bessell, M.S. PASP 1990, 102, 1181. These are Johnson-Cousins system for CCD's. End of List rem@ucolick.org Sept 96