User's Guide Contents
	Return to ETC Welcome SYNPHOT SNR and Exposure Time SNR Time Optimal SNR Spectroscopy Target Acquisition Basic Use Page Heirarchy Reference Extraction Regions Spectral Distribution User Spectra Other Spectra Extinction Normalization Background CCD Parameters ID Number Calculations SYNPHOT Calls Call Descriptions Call Parameters NICMOS Spectroscopic Extraction Regions Tables Spectral Elements NICMOS Filters NICMOS Dispersers ACS Filters and Dispersers COS Dispersers WFC3 Filters and Dispersers STIS Filters and Dispersers NICMOS Tables COS Tables STIS Tables and Topical Help

STIS Grating Summary

Grating/ Prism	Spectral Range (Å)		Dispersion (Å/pix)	Resolution	Detector	Plate Scale ("/pix)
	Full	Per Tilt				Spatial	Spectral
First Order Gratings
G140L	1150-1736	610	0.6	935-1440	FUV-MAMA	0.024
G140M	1150-1740	55	0.05	11500-17400		0.029	0.036
G230L	1570-3180	1610	1.58	500-1005	NUV-MAMA	0.024
G230M	1640-3175	90	0.09	9110-17500		0.029	0.035
G230LB	1685-3065	1380	1.35	615-1135	CCD	0.051
G230MB	2000-3100	155	0.15	5550-10335		0.051
G430L	2900-5700	2900	2.73	530-1040		0.051
G430M	3025-5615	286	0.28	5330-10270		0.051
G750L	5240-11490	5030	4.92	535-1170		0.051
G750M	5450-11150	570	0.56	4870-9950		0.051
Echelle Gratings
E140M	1150-1700	600	l/91,700	45,800	FUV-MAMA
E140H	1150-1700	210	l/228,000	114,000^1		0.029	0.047
E230M	1575-3110	800	l/60,000	30,000	NUV-MAMA
E230H	1650-3000	267	l/228,000	114,000^1		0.029	0.047
Prism
PRISM	1150-3000	1950	1.2-20	1000-26	NUV-MAMA

¹ Resolution of up to 200,000 may be obtained when using this grating with the 0.1 X 0.03 aperture and specialized data reduction techniques.

For gratings with more than one supported central wavelength value, the user is also allowed to choose which central wavelength to use for the calculation. Whenever the grating or central wavelength value is changed, the wavelength value which specified in section 2 as the wavelength for at which the calculation is to be performed is checked to see if it is within the valid range for that grating and cental wavelength value. If the wavelength specified here is out of the allowed range, then its value is reset to the mid-point wavelength of the allowed range. Users should check this value carefully, as the value already in this field may depend on prior selections made in the web interface.

To simplify instrument operation and calibration, only specific grating tilts with corresponding central wavelengths are implemented. There are also a few unsupported or unavailable central wavelengths.

Approximate wavelength solutions for the prism settings at 1200 and 2125 Å are available.

Issues to consider when choosing between G230LB and G230L or choosing between G230MB and G230M include relative sensitivity, read noise, plate scale, bright object limits, and detector PSF.

G750L and G750M are subject to long wavelength fringing for wavelengths > 7500 Å.

Spectral format plots for each combination of detector, optical element and central wavelength are available.

Only a portion of the full spectral range falls on the detector for the intermediate-resolution first-order and the echelle (except E140M) gratings. Therefore separate exposures must be taken for these gratings for full wavelength coverage.

STIS Filter Summary

STIS/CCD FILTERS
Name	Filter	Central Wavelength (Å)	FWHM (Å)	Field of View (arcsec^2)
plate scale 0.05071 ± 0.00007 arcseconds per pixel
50CCD^1	Clear	5850	4410	52 x 52
F28X50LP^1	longpass > 5500 Å	7230	2720	28 x 52
F28X50OIII^2	[O III]	5007	5	28 x 52
F28X50OII	[O II]	3740	80	28 x 52
50CORON^3	Clear + Coronagraphic fingers	5850	4410	Special

¹red halo, ²red leak, ³The 50CORON aperture is an unfiltered aperture with a number of occulting bars and wedges which functions as a coronagraphic mask. A number of separate aperture positions have been defined for use within 50CORON, ad may be individually specified in Phase 2 proposals.

STIS/NUV MAMA FILTERS
Aperture Name	Filter	Central Wavelength (Å)	FWHM (Å)	Field of View (arcsec^2)
plate scale ~0.0248 arcseconds per pixel
25MAMA ^4	Clear	2220	1200	25 x 25
F25QTZ ^5	longpass > 1475 Å	2320	1010	25 x 25
F25SRF2^6	longpass > 1275 Å	2270	1110	25 x 25
F25MGII	Mg II	2800	70	25 x 25
F25CN270	~2700 Å Continuum	2700	350	25 x 25
F25CIII	[C III]	1909	70	25 x 25
F25CN182	~1800 Å Continuum	1820	350	25 x 25
F25ND3	ND=10^-3	2344	1345	25 x 25
F25ND5	ND=5 x 10^-6	2621	1515	25 x 25
F25NDQ1 F25NDQ2 F25NDQ3 F25NDQ4	ND=10^-1 ND=10^-2 ND=10^-3 ND=10^-4	2277 2318 2417 2450	1126 1036 756 607	~12 x 12 ~12 x 12 ~12 x 12 ~12 x 12

STIS/FUV MAMA FILTERS
Aperture Name	Filter	Central Wavelength (Å)	FWHM (Å)	Field of View (arcsec^2)
plate scale ~0.0248 arcseconds per pixel
25MAMA ^7	Clear	1370	320	25 x 25
F25QTZ ^5	longpass > 1475 Å	1590	220	25 x 25
F25SRF2 ^6	longpass > 1275 Å	1480	280	25 x 25
F25LYA ^8	Ly-alpha	1216	85	25 x 25
F25ND3	ND=10^-3	1376	316	25 x 25
F25ND5	ND=7 x 10^-7	1385	336	25 x 25>
F25NDQ1 F25NDQ2 F25NDQ3 F25NDQ4	ND=10^-1 ND=10^-2 ND=10^-3 ND=10^-4	1416 1404 1407 1437	384 384 401 391	~12 x 12 ~12 x 12 ~12 x 12 ~12 x 12

⁴not well focused, ⁵excludes O I 1302, ⁶excludes Ly-alpha, ⁷high airglow, ⁸low throughput

Note that MAMA imaging observations are subject to especially strict bright object limits, and will not be performed unless ALL objects in or near the aperture can be shown to be below these limits.

As STIS filters are located in the STIS slit wheel they must be listed as apertures in Phase II proposals and cannot be used in combination with other apertures. The STIS filters can, however, be used together with a grating to do filtered slitless first order spectroscopy. This can be especially useful when it is necessary to exclude contamination due to geocoronal lines.

STIS has a relatively limited set of filters. However its imaging capabilities do include some unique advantages that make it worth considering as an alternative to WFPC2 or ACS for some UV and optical imaging projects.

Comparisons of Imaging Mode Throughputs:

· CCD, FUV-MAMA and NUV-MAMA Clear and Filtered Throughputs

· STIS CCD Clear vs. WFPC2

· STIS vs. ACS Imaging

· Color Corrections from Johnson V to AB Magnitude

Choosing a filter for imaging observations or slitless spectroscopy:

· CCD Ghosts and Reflections

· CCD Red Light Halo

· Filter Choice for Target ACQ Observations

· Other Caveats for STIS Imaging

· MAMA Longpass Filters and Geocoronal Lines

· MAMA Imaging Bright Object Limits

· STIS Imaging, Spectroscopic, and Target ACQ ETCs