ACS Filters and Dispersers

The following tables show the three cameras’ ‘filters’ properties. The definitions of the columns below are those of the stsdas.synphot BANDPAR task. These definitions are summarized here. For further details please see the on-line help on BANDPAR. Here ‘INT’ refers to an integral over wavelength, and ‘THRU’ is the throughput of the filter at that wavelength. ‘LAM’ is wavelength.

Central Wavelength = bandpar.pivwv
   defined as PIVWV = SQRT(INT(THRU * LAM) / INT (THRU / LAM))
Mean Wavelength = bandpar.avgwv
   defined as AVGWV = INT(THRU * LAM) / INT(THRU)
Peak Wavelength = bandpar.wpeak
   defined as wavelength at peak throughput (WPEAK)
FWHM = bandpar.fwhm
   defined as FWHM = SQRT(8 * LOG(2)) * BANDW
Max Transmission = maximum transmission OF THE FILTER ONLY
   (no other optical components) as measured pre-launch in the lab
Max Throughput = bandpar.tpeak
   defined as peak bandpass throughput

The Range column describes the total range in wavelength where the filter throughput (by itself, no other optical components) is larger than 0.05%. For low-pass filters, the range is open-ended; the table lists in this case the range as the maximum range listed in the SYNPHOT/pysynphot throughput reference files.

The rightmost column, Fraction, is the fraction of light falling on the central pixel, assuming the point source PSF is centered on that pixel as estimated by Tiny Tim PSF simulations (3-gyro mode).

All data in these tables (except for the PSF-related ‘Fraction’) are generated from the STScI CDBS tables, which are updated as more accurate information is obtained. The observer is strongly advised to regenerate these tables from the most up-to-date data in CDBS if the exact values are critical to planning observations. The SYNPHOT user’s guide (Bushouse, 1998) is the best guide on how to do this.

HRC Filters

Filter	Central	Mean	Peak	FWHM	Range	Trans	Thru	Fraction
F475W	4775.7	4794.0	5000.2	986.23	1800	0.913701	0.24735	0.17
F502N	5022.9	5023.0	5005.5	85.867	145	0.7135654	0.19196	0.169
F550M	5579.9	5582.4	5550.3	389.02	740	0.8770255	0.24687	0.153
F555W	5356.0	5368.0	5059.8	841.13	1720	0.885	0.24037	0.159
F606W	5888.0	5926.1	6689.8	1565.5	2570	0.9517956	0.27447	0.143
F625W	6295.5	6309.2	6479.9	977.51	1720	0.915	0.26496	0.134
F658N	6583.8	6584.0	6592.0	136.27	180	0.9118735	0.26505	0.128
F775W	7665.1	7677.5	7320.1	1017.4	1910	0.947	0.23605	0.107
F850LP	9145.2	9161.6	8859.5	1269.1	>3080	0.976	0.13813	0.086
F892N	8916.1	8916.4	8915.4	237.98	320	0.9182586	0.13461	0.091
F220W	2255.4	2264.4	2219.9	441.03	1350	0.361	0.050401	0.175
F250W	2715.9	2727.4	2520.1	563.76	1980	0.48071	0.061124	0.166
F330W	3362.7	3367.2	3460.3	409.16	790	0.751	0.10714	0.156
F344N	3433.7	3433.8	3430.2	64.922	95	0.67994	0.10093	0.156
F435W	4311.0	4322.0	4760.1	728.95	8780	0.92799	0.22602	0.17
F660N	6599.1	6599.3	6595.4	175.72	100	0.7178267	0.20719	0.128
F814W	8115.3	8146.9	7459.5	1656.6	2870	0.991	0.23965	0.099
POL_UV	6231.7	6607.0	7399.7	4943.9	>18000	1.0	0.088816	0.135
POL_V	6943.2	7184.0	9206.6	4134.8	>16500	1.0	0.086172	0.121
PR200L	5650.2	6051.9	6460.4	4830.5	>9392	0.93	0.26908	0.151
CORON	5472.0	5926.3	6460.4	4926.1		0.475	0.13743	0.156
G800L	7506.4	7594.9	7000.0	2614.3	>6000	0.902	0.22724	0.110

SBC Filters

Filter	Central	Mean	Peak	FWHM	Range	Trans	Thru	Fraction
F115LP	1406.1	1415.0	1260.2	354.53	>8850	0.92705	0.057976	0.101
F122M	1273.7	1277.5	1216.0	213.97	1170	0.143	0.0095276	0.078
F125LP	1437.5	1445.2	1320.0	334.09	>8780	0.91	0.0529	0.108
F140LP	1527.0	1532.6	1390.1	294.08	>8650	0.89	0.04167	0.125
F150LP	1610.7	1614.7	1490.0	258.52	>8600	0.86812	0.029992	0.141
F165LP	1757.9	1760.1	1700.1	203.2	>8500	0.85	0.0090218	0.162
PR110L	1429.4	1438.1	1320.1	355.49	>8800	0.89444	0.045411	0.106
PR130L	1438.7	1446.6	1299.9	336.48	>8780	0.89611	0.053365	0.108

WFC Filters

Filter	Central	Mean	Peak	FWHM	Range	Trans	Thru	Fraction
F475W	4744.4	4763.0	4999.6	989.27	1800	0.913701	0.3736	0.213
F502N	5023.0	5023.1	5005.5	68.042	145	0.7135654	0.28985	0.210
F550M	5581.2	5583.5	5550.4	384.47	740	0.8770255	0.38211	0.216
F555W	5359.6	5371.8	5499.8	847.79	1720	0.885	0.37093	0.214
F606W	5917.7	5956.3	6689.8	1583.2	2570	0.9517956	0.46516	0.219
F625W	6310.5	6324.1	6479.9	978.32	1720	0.915	0.44337	0.22
F658N	6584.0	6584.4	6591.6	87.487	180	0.9118735	0.44498	0.22
F775W	7693.0	7705.4	7380.3	1023.4	1910	0.947	0.42868	0.206
F850LP	9054.8	9071.6	8610.3	1270.3	>3080	0.976	0.24829	0.147
F892N	8914.9	8915.1	8914.9	171.78	320	0.9182586	0.21473	0.154
F435W	4317.4	4327.3	4569.9	691.08	8780	0.92799	0.3807	0.217
F660N	6599.4	6599.5	6595.2	83.666	100	0.7178267	0.34844	0.0.22
F814W	8059.8	8087.4	7460.2	1541.6	2870	0.991	0.44092	0.197
POL_UV	6634.5	6874.9	7640.4	4053.7	>1800	1.0	0.16482	0.22
POL_V	6910.0	7134.4	7209.6	4017.0	>16500	1.0	0.1386	0.22
G800L	7480.7	7559.1	7199.8	2473.0	>6000	0.902	0.40081	0.210

Ramp Filters

Filter	Central	Range	Camera
FR388N	3710-4050	2%	WFC/HRC
FR423N	4050-4420	2%	WFC
FR462N	4420-4820	2%	WFC
FR656N	6270-6850	2%	WFC/HRC
FR716N	6850-7470	2%	WFC
FR782N	7470-8160	2%	WFC
FR914M	7570-10710	9%	WFC/HRC
FR853N	8160-8910	2%	WFC
FR931N	8910-9720	2%	WFC
FR459M	3810-5370	9%	WFC/HRC
FR647M	5370-7570	9%	WFC
FR1016N	9720-10610	2%	WFC
FR505N	4820-5270	2%	WFC/HRC
FR551N	5270-5750	2%	WFC
FR601N	5750-6270	2%	WFC

Please refer to Bohlin and Tsvetanov (ISR ACS 00-05) for details about calculation of peak transmission for ramp filters.