Äîêóìåíò âçÿò èç êýøà ïîèñêîâîé ìàøèíû. Àäðåñ îðèãèíàëüíîãî äîêóìåíòà : http://www.stsci.edu/hst/wfc3/documents/ISRs/2000/WFC3-2000-08.pdf Äàòà èçìåíåíèÿ: Fri Sep 26 03:21:20 2008 Äàòà èíäåêñèðîâàíèÿ: Thu Jan 15 04:53:41 2009 Êîäèðîâêà: Ïîèñêîâûå ñëîâà: ionization front

Instrument Science Report WFC3-2000-008

Wide Field Camera #3 Filter Selection Process - Part IICompendium of Community Input
O. Lupie, C. Hanley, J. Nelan May 12, 2000

ABSTRACT This is the second part of a series documenting the WFC3 Filter Selection Process. For the sake of historical documentation, this series of reports presents a summary of the selection process and the final filter lists. Part I documents relevant studies of historical HST filter usage, Part II provides a brief synopsis of the WFC3 Filter Workshop during which the astronomical community responded to the solitication of their inputs. Parts III and IV present the IR and UVIS filter specifications and compare the suite of WFC3 filters to the those of ACS, NICMOS and WFPC2.

1.0 Introduction
Wide Field Camera #3 is a radial bay instrument slated to replace the WFPC2 during the final servicing mission to Hubble in late 2003. The WFC3 is a dual-channel instrument and its panchromatic capabilities make it unique among the HST pantheon of instruments. Besides the advances in technology that the WFC3 will bring to Hubble, there are other ways that WFC3 is unique among HST instruments: the instrument definition team as defined by all previous instrument-building philosophies has been replaced by a consortium of scientists and engineers at GSFC, STScI, Ball Aerospace, JPL, and other contractors. A Scientific Oversight Committee (SOC) provides scientific feedback to STScI and GSFC. It is composed of scientists from the astronomical community who are

Copyright© 1999 The Association of Universities for Research in Astronomy, Inc. All Rights Reserved.


Instrument Science Report WFC3-2000-008 experts in the near UV, IR, ground-based and spaced-based observing, and who cover many relevant astronomical areas of interest. The role of the STScI WFC3 team is multifaceted, providing both scientific input and operational experience to the project, supporting and facilitating the SOC in their endeavors, and carrying the information to the community. The design of the instrument is a multi-bounded problem: budgets, technology limits, time limits, science-needs versus available resources, etc. Detailed reviews of these issues may be found at the GSFC WFC3 web site and in other WFC3 publications. Also, details of the WFC3 optical channels may be found in Part I of this series and also in the WFC3 "Science White Paper "(ed M. Stiavelli and R. O'Connell, 2000), and on the GSFC website (http://wfc3.gsfc.nasa.gov).

2. WFC3 Filter Workshop
Adopting the philosophy that the WFC3 is a community instrument, the main goal of the filter selection process is to address as many types of astronomical research as feasible. Three strategic initiatives have provided the information needed to arrive at a filter list for the WFC3: 1. a special filter workshop was held on July 14, 1999 at STScI where community astronomers were invited or volunteered to discuss their filter priorities with the SOC in several areas of astronomy; 2. GSFC, on its website, hosted a "Discussion Board" where astronomers who could not attend the meeting could still provide their opinions and priorities; 3. the SOC put out a strawman filter list (on the web site) prior to the workshop to encourage response from the community, i.e., laying the foundation of the filter priority and selection philosophy.

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Instrument Science Report WFC3-2000-008

2.1 Workshop Agenda The following is the agenda of the Filter Workshop. In addition to providing the list of speakers and talks, we also wish to emphasize the discussion sessions in the afternoon where the meeting participants constructed the preliminary filter lists. I. Introduction and WFC3 Overview (J. MacKenty, STScI and R. O'Connell, SOC) II. Science Needs: Galaxy and Galactic: 9:00-10:30 Chair [Bob O'Connell, SOC Chair]

Nino Panagia: "Photometric Studies of Stars and Stellar Systems" George Wallerstein: "Stromgren Photometry " Jon Morse: "Narrowband Imaging of Shock-excited Environments" Paul Scowen: "HST Narrow Band Science in HII Regions" Pat Harrington: "Filters for Extracting the Physics of Emission Line Objects" Ken Mighell: "Populations, Evolution, and Washington Photometry" Alex Storrs: "Planetary Observations and Filter Choice" Extra Galactic: 10:50-11:45 Chair [Jay Frogel, SOC] Ben Dorman: "Stellar Populations in the UV with WFC3" Alan Uomoto: "SDSS Filters" Harry Ferguson: "Filters for Studying Galaxy Evolution" Peter Garnevich: "High Redshift Supernovae" Special Infrared - 11:45-12:30 Chair [Jay Frogel, SOC] Marcia Rieke: "Optimum Choices for the Near IR Channel" Pat McCarthy: "IR Grisms" Special ACS Review: Z. Tsvetanov [ACS Filters] III. Discussion Sessions 1. Broad Band, Medium [chairs J. Holtzman/R. Windhorst, SOC] 2. Narrow Band, Continuum [chair B. Balick, SOC] 3. Special Elements [chair John Trauger, SOC and UVIS Filters]

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Instrument Science Report WFC3-2000-008 4. Summary and Other Issues [chair J. Holtzman, SOC]

2.2 Abstracts/Summaries
In this section, informal abstracts or brief summaries of the talks are documented. Note that if abstracts were not available, summaries compiled by WFC3 Science Integrated Product Team (IPT) members are included for completeness. To see figures and actual presentations, please refer to the STScI WFC3 web site at http://www.stsci.edu/instruments/wfc3/wfc3-filter_workshop.html. 1. Title: Stellar Populations in the Ultraviolet with WFC3 Speaker: Ben Dorman (Raytheon ITSS-NASA/GSFC) ABSTRACT: The precise study of both resolved and integrated stellar populations at ultraviolet wavelengths promises to allow accurate assessment of the integrated from galaxies at significant (z > 1) redshifts. For Galactic globular clusters, UV colour-magnitude diagrams can be used to measure stellar populations of interest, in particular the blue stragglers and advanced evolutionary stages (Horizontal-branch and later), without significant crowding problems as seen in the visual. The hot populations of local group systems may be also be accurately measured. An important new application possible with WFC3 arises as the UV also strongly differentiates against metallicity. This can be used to obtain an accurate record of the history of Galactic halo metallicity enrichment. Integrated light from old stellar populations is dominated by the main-sequence turnoff with potential contamination from hot HB stars. Two colour UV diagrams can be used to gain information concerning the age-metallicity "degeneracy" problem since the turnoff is sensitive to both. The UV spectral range in populations dominated by cool stars has three significant wavelength ranges which may have differential behavior with population parameters: lambda <~ 250 nm, lambda < 250nm, lambda < 290, lambda >~ 290nm. Requirements for these projects are: a) most importantly, strong red rejection longward of ~ 320nm, b) filters with peak response in each of the above mentioned regimes. 2. Title: Filters For Studying Galaxy Evolution Speaker: Harry Ferguson (STScI) ABSTRACT: For most studies of distant galaxies, the choice of filter is a delicate trade-off of throughput and bandwidth. I will provide examples of specific applications that illus-

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Instrument Science Report WFC3-2000-008 trate the criteria that should enter in to the filter selection for both narrow and broadband filters. SUMMARY NOTES: · · · · · · · · · filters for detections: very broad f300x, f475x, f800x filters for morphological structure: SLOAN or WFPC2 UV filter at 2500A for deep field work Lyman-break galaxies - wavelengths 2280,2735,3650A Medium-band filters for field galaxies Red-leak suppression critical. Redshifted SLOAN filters Grism for emission line searches Rounded Overlapping filter shapes are preferable to sharp non overlapping filters transformations are easier (Young 1994 A&A288,687).

3. Title: High Redshift Supernovae Speaker: Peter Garnevich (Center for Astrophysics) SUMMARY NOTES: For low redshift supernovae, a filter is needed at about 4000A. To observe supernovae at z=0.9-1.3, a high QE IR channel is needed with filters at 1 micron with widths from 2030%. The best case to support this filter is an observation set of LP850 with NICMOS F110M. 4. Title: Beyond Pretty Pictures- Key Filters for Extracting the Physics of Emission Line Objects. Speaker: Pat Harrington (Univ. of Maryland) ABSTRACT: The wealth of new and unexpected morphological detail seen with the high spatial resolution of the WFPC2 in planetary nebulae and other emission line nebulae have revolutionized our ideas of these objects. Narrow-band filters were key to revealing this fine structure. But a proper set of filters is even more important in understanding the physical processes which shape these structures. To achieve such an understanding, we must be able to map such parameters as temperature on the same 0.1 arcsec scale. Such programs are just getting under way as they necessarily lag the morphological studies; it important that the WFC3 have a filter set that is well chosen for such analysis. Ratios of narrowband images are ideal for such work. We discuss the most important filters, and the requirements which image-ratio studies place on them, such as out-of-band rejection and the need for filters to subtract the continuum background.

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Instrument Science Report WFC3-2000-008 SUMMARY NOTES: Filters for studying various processes: · · · · · · · basic morphology: H-alpha, H-beta (reddening); H-alpha leak <1% basic ionization structure: HeI 5876A, HeII 4686A advanced ionization structure: OI]6300A at H0/H
+

physical conditions from ratios OIII and OIII/OII. density in low ionization regions [NII]6584A is strong line for shocks, [SII], [CII]; higher ionization regions [OIII]5007A (strongest), [NeIII]3869A,[SII]9532A; highest ionization [NeV]3426A.

5. Title: IR GRISMS Speaker: Pat McCarthy (Carnegie Obs, Pasadena and WFC3 SOC member) SUMMARY NOTES: An IR grism allows observations out to z=4 (might have to deal with overlapping spectrum). The recommended grisms are: · · J-band at 0.9-1.3 microns R=300 per pix H-band at 1.3-1.8 microns R=300

· Hi-Resolution band at 1.4-1.6 microns R=800 Note: [redder version of G096, shorter version of G141 and a grism at z=1-1.5 at 1.4 microns.] 6. Populations, Evolution, and Washington Photometry Speaker: Ken Mighell (NOAO) ABSTRACT: Analysis of WFC3 observations of Local Group stellar populations in star clusters will be greatly simplified if the filter set includes filters designed since the Johnson-Cousins BVRI and Washington C because the community understands the interpretation of data in these filters and stellar evolution models are not available for unique HST filters. The [original] strawman list surprisingly does not contain the WFPC2 F555W or any other filter which would transform well to V without color terms. T. has been shown that using F606W color magnitude diagrams is problematical. User community support is quite strong. Geisler and Sarajedini (1999 AJ 117, 308) have recently shown that observations of Population II red giants with the Washington C system (C-T1) color have 3 times the metallicity sensitivity in comparison with the standard (V-I) color. The T1 filter is frequently [and successfully] replaced with the R filter. Usage of the R and Washington C

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Instrument Science Report WFC3-2000-008 filters may well suffice for precise metallicity determination. However, unambiguous interpretation of stellar ages within the complex populations in the Local Group has suffered from the degeneracy of red giant branch colors. The Washington C filter can break the degeneracy by combining (C-R) and (C-I). The strawman F380W should be replaced with a Washington C filter with a higher peak throughput.

7. Title: Narrowband Imaging Diagnostics of Shock-excited Environments Speaker: Jon A. Morse (University of Colorado) ABSTRACT: HST studies of shock structures in the interstellar medium have led to new insights into many astrophysical phenomena that harbor supersonic flows, from protostellar jets, to nebulae surrounding Luminous Blue Variables, to supernova remnants. High spatial resolution images from WFPC, WFPC2, FOC, and STIS in the light of various emission lines have been combined to allow the first detailed tests of radiative shock models. Narrowband images of nebular objects are also among the most stunning from HST, and have engendered significant public interest. I will discuss important emission-line diagnostics of shock-excited environments that can be observed with WFC3 through narrowband filters. Future WFC3 studies will make use of the improved throughput (especially at blue and NUV wavelengths), larger field of view, and smaller pixel size compared to WFPC and WFPC2. SUMMARY NOTES: Ionization Structure: · need access to wide range of ionization stages in ionized environments to measure ionization parameter, structure and cooling distance in post shock regions, degree of completeness in radiative shocks. Example SNR N132D]. HST Resolves bow-shock Mach disk structures in Jets (H alpha isolated from neighboring NII).

·

Proper Motions: HST resolution allows us to track gaseous motions over short time scales, e.g., multi-epoch images of protostellar jets to test models of hydrodynamic flow, transverse kinematics can be combined with LOS kinematics to deduce 3-D flow geometries. Electron Densities and Temperatures [equations on web]: Densities from H recombination and forbidden line fluxes (e.g., [OII]5007), densities from ratio [SII]6717/6731 Temperatures from line ratio maps (7000-35000K) [OIII]4959,5007/[OII]4363, [NII]6548,6583/[NII]5755

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Instrument Science Report WFC3-2000-008 Elemental Abundances - origin of heavy elements and nucleosynthesis; Wide range of elements H, He, C, N, O, Ne, Mg, Si, S, Ar, Ca, Fe, and molecular. NIR Filters: Stellar Jets from [FeII]1.644 microns and other tracers. Off-band continuum filters desirable to eliminate dust scattered light.

8. Title: Photometric Studies of Stars and Stellar Systems Speaker: Nino Panagia (STScI) ABSTRACT: I will review the quantities that characterize a stellar spectrum, focusing mostly on the continuum. On this basis, I will discuss criteria to select and define photometric bands suited for the identification of the surface parameters of a star, i.e. effective temperature, angular radius and, possibly, gravity. Some applications to the case of young populations and the identification of special types of stars will be presented and discussed. Finally, I will extend these considerations to the study of more distant stellar systems, in which blending of several stars into one apparent stellar image is a problem. SUMMARY NOTES: 1) For each star, measure in at least 3 bands with high signal and separation between bands to be long enough to measure the flux gradient accurately and short enough to make all observations near the peak of the stellar flux curve, and to retain comparable angular resolution in all bands; 2) Have filters just shortward and just longward of the Balmer discontinuity; 3) maximize width but minimize overlap; filter group that allows photometric measurements for all stars. 4) A possible list of central wavelengths: 1100,1600,2250,3150(300w),4450(f450w),6300(f606w),8900(f814w),12600,17800. 9. Title: Optimum Choices for the Near-Infrared Channel Speaker: Marcia Rieke (Univ. of Arizona Steward Observatory) ABSTRACT: Based on both NICMOS and groundbased experience, the optimum filter set for the IR channel will be discussed. Calibration issues and photometric accuracy will be considered as well as scientific needs ranging from detection of Solar System ices to emission lines in extragalactic objects. SUMMARY NOTES: 1. Suggested Infrared Complement: Narrowband: F108N,F113N: HeI 1.083 microns F128N, F130N: Paschen Beta 1.282 microns

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Instrument Science Report WFC3-2000-008 F131N: Redshifted Paschen Beta F164N, F167N: [FeII] 1.644 microns F187N,F190N: Paschen alpha 1.875 microns Broadband: filter F110M F124W F125M F145M Broad cont: filter F158M F160W F165M F172M F180M
c

FWHM(micr) 0.20 0.23 0.10 0.19

R

Comments

1.1 1.24 1.25 1.45

5.5 5.4 J 12.5 Brown Dwarf /CH4 07.6 H20,Brown Dwarf Comments Brown Dwarf H and Grism filter Ice Brown Dwarf Ice

c FWHM(micr) R 1.58 1.59 1.65 1.72 1.80 0.10 0.40 0.10 0.07 0.07 15.8 4.0 16.5 24.6 25.7

2. NICMOS most used filters include F160W, F110W 3. Photometric Issues: Very broad filters should be avoided because: 1) color corrections make accurate photometric transformations difficult if R < 4; 2) Flat fielding is compromised for broad filters because of color-dependent terms in the FF response; and 3) Background over 0.9-1.9 microns has a minimum at 1.6 microns so broadening a filter's response may not necessarily improve S/N. 10. Title: HST Narrow-Band Science in HII regions Speaker: Paul Scowen (Arizona State Univ) ABSTRACT: Over the past 5 years the study of HII regions has enjoyed a Renaissance due almost entirely to the remarkable spatial resolution afforded by the WFPC-2 on HST using its complement of narrow band filters. Observations using these facilities have allowed us access, for the first time, to the spatial scales critical to successful modeling of the physics and dynamics of the ionization fronts in these objects. Such modelling has yielded a new picture of how these objects evolve. Another important part of this new view is the erosionary effect of photo evaporation and the implications it has for uncovering protostellar and protoplanetary systems, and in addition the effect it might have on secondary star formation. The importance of access to narrow-band filters at Space Telescope resolutions will be emphasized. SUMMARY NOTES: The author reviewed typical targets in HII regions (protostellar objects, Ionization front shocks, bubbles, chaotic structure.

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Instrument Science Report WFC3-2000-008 · · · · · · ACS has only a couple of narrowband filters; ground-based cameras do not have the resolution; STIS has sensitivity but a limited set of filters; Enough filters need to be chosen to sample the range of ionization conditions in HII regions and the ISM; Line-free filters are needed for accurate continuum subtraction; Some filters are needed to remove contaminating flux e.g., [NII] from Halpha.

11. Title: Planetary Observations and Filter Choice Speaker: Alex Storrs, STScI ABSTRACT: Observations of solar system objects have some special considerations. I will review the different major types of planetary observations that have been made with WF/PC and WFPC2 and that may be made with WFC3, and the types of filters that have been used and that may be used in the future. SUMMARY by author: 1. The F1042M filter has been very useful for defining the width of the 1 micron silicate feature,when used in connection with the F953N and other filters shortward of the feature. While the IR arm of WFC3 may well be more sensitive than the CCD in this region, there may be some time constraints on shifting from one to the other. For a time variable object (say, a rotating planet) the time lost may prevent a good comparison between filters. Also, wouldn't it be good to be able to directly compare the performance of the two sides of WFC3? 2. In looking at the long wavelength end of the mineral reflectivity spectrum, there are areas around 1.25 microns and 1.05 microns which would best be defined by medium band filters (say, 0.1 microns wide) and the intervening inflections at 1.125 microns and 1.400 microns could be investigated with medium- or narrowband filters at those wavelengths. This set would allow the refinement of the orthopyroxene/clinopyroxene and feldspar content of the surfaces studied. 3. Lacking an LRF, a grism would be very useful on small sources. There has not been a whole lot about the NICMOS grism in the news primarily because the software to reduce the data has only recently (like last week) become available. A grism will necessarily give you coverage across telluric absorptions, which has already been discussed (see P. Eisen hardt's posting) as a place of strength for WFC3. WFC3 will look at atmospheres, surfaces and aurorae and Io (torus).

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Instrument Science Report WFC3-2000-008 12. Title: ACS Filters Speaker: Z. Tsvetanov, ACS-JHU ABSTRACT: Advanced Camera for Surveys (ACS) is a third generation HST instrument and is currently scheduled to replace FOC during SM3b at the end of 2000. ACS is equipped with a large selection of spectral elements to support a wide variety of astronomical programs. In this presentation I will present the scientific requirements determining the astronomical choices and technical specifications as well as the predicted performance. SUMMARY NOTES: ACS will provide a gain in HST imaging capability over current instruments with a discovery efficiency factor of 10 (area x throughput). The science drivers for the selection of ACS filters included: 1) survey of high redshift galaxy clusters and their surroundings to map dark matter distribution. 2) Narrowband imaging of inner regions of environs of active galaxies (QSOs and AGNs) and strongly starbursting galaxies. 3) Coronographic surveys of nearby stars for protoplanetary disks, brown dwarf companions, and planets. 13. Title: SDSS Filters Speaker: Alan Uomoto (Johns Hopkins Univ) SUMMARY NOTES: The Sloan Digital Sky Survey will soon contain more photometry than all other photometric systems combined. Much of the sky will be surveyed to 23rd magnitude. The SDSS filters are used on ACS and therefore, in its role as backup to ACS, the WFC3 should carry the SDSS filters onboard. The use of Stromgren photometry to Derive Metallicties and Ages in Globular Clusters and Local Group Galaxies Speaker: George Wallerstein (Univ of Washington) ABSTRACT: The Stromgren system consists of 4 filters: y,b,v, and u whose effective wavelengths are 5470A, 4670A, 4110A, and 3500A respectively with passbands of 180 to 300 A (half-width. The color b-y is sensitive to temperature but not metallicity (because of comparable line blanketing in b-y). The v-b color is very sensitive to metallicity for F and G stars. As an example of the usefulness of the Stromgren system we have analysed stars at the main sequence turnoff of Omega Centauri using the m index [(v-b)-(b-y)] to estimate the metallicity of individual stars with an uncertainty of about +/- 0.2 in [Fe/H]. We have observed a field north of the core of the most massive globular cluster in our Galaxy, Omega Centauri, with Stromgren vby filters. We looked for a correlation of age 14. Title:

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Instrument Science Report WFC3-2000-008 and metallicity in a region that avoids the dense core and the inhomogeneous foreground dust emission shown by the IRAS satellite. By dividing the stars into three groups with [-2.2<[Fe/H]<-1.6, -1.6<[Fe/H]<-1.2, and -1.2<[Fe/H]<-0.5 we investigated the connection between age and metallicity. When we plotted a color-magnitude diagram for each metallicity group with the isochrones of VandenBerg et al (1998) superimposed, we found that the most likely age for the most metal-poor group is 14 Gyr. The group with intermediate metallicity has a likely age of 12 Gyr, and the most metal-rich group has an age near 10 Gyr. This clear correlation of metallicity with age shows that Omega Centauri has enriched itself over a time-scale of roughly 4 Gyr. Apparently star formation ceased approximately 10 Gyr ago as type Ia supernovae and stellar winds dispersed the interstellar matter. It is remarkable that ejecta from stellar winds failed to disperse the interstellar matter at an earlier time, but were captured by the cluster instead. Possibly Omega Cen was once a small galaxy in which all the activity occurred before it was captured by our Galaxy. Our observations reached magnitude 20 with a 0.9-m telescope. With HST we could reach mag. 25 thereby covering almost all systems in the Local Group and the dense cores of Galactic globular clusters. [Figures showing the passbands and our C-M diagrams may be found on the web.]

3. WFC3 Filter Discussion Board
In addition to information presented in these talks, we document some highlights placed on the Filter Discussion Board prior to the Filter Workshop: B. Woodgate, GSFC: WFC3 should have clear filters to provide a mode with maximum light gathering (faintest galaxies, Gamma ray bursts, protoplanetary disks, gravitational lens). Proved extremely useful on STIS and WFC3 will have a large field and higher sensitivity. P. Eisenhardt - repeat F110w and F160w because of the large archive of existing data, however have filters which better match ground-based J and H; include an open filter 0.91.9 microns to provide very deep images like STIS; tune some filters to just the atmospheric bishoprics bands - what we cannot get from the ground. J. Hutchings: put in a plug for ramp filters - filters tunable for studying randomly redshifted objects. T. Von Hippel: Much of my research with WFPC2 has been with the F555W and F814W filters. F606W transforms poorly to the Johnson V band. I have used WFPC2 to observe open clusters, white dwarfs, and globular clusters. Leaving out the F555W filter would be a mistake for comparisons with past WFPC2 data and comparisons with a large body of ground-based data. P. Stetson: The actual WFPC2 throughput of F555W and F814W filters should be duplicated for the sake of the Key Project Studies

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Instrument Science Report WFC3-2000-008 JP. Linde: Galactic Evolution & importance of uvby Standard Photometry - a unique set of filters for determination of high quality metallicities for individual stars. Data from ubvy photometry provide high accuracy (Me/H) data and ages for individual stars much fainter than possible with spectroscopy of a resolution necessary for corresponding accuracy. From wide band photometry, no really reliable data on (Me/H) can be obtained We envision a continuation of our studies of WFPC2 galactic evolution studies in other galaxies in the vicinity of the Galaxy. Given a reasonable sensitivity of the detector of the WFC3 (around 90 %), we can, without problems, reach a number of such galaxies with the HST, the WFC3 and uvby photometry. Suitable candidate galaxies are, with the corresponding limiting magnitudes for (Me/H) to an accuracy of 0.2 dex are Sculptor, Draco, Ursa Minor, Fornax, LeoII, LeoI. Stolovy: It is crucial that continuum filters for narrowbands are chosen to match each spectral line filter. T. Armandroff: Reproduce ground-based BV and I systems as closely as possible. (simple transformations with the smallest possible color terms. It is EXTREMELY IMPORTANT to be able to place the photometry on the ground-based system in order to be able to compare with existing photometry of comparison objects and stellar isochrones. The most important filters for such work, in my opinion, are B, V & I (Kron-Cousins). S. Pascarelle: I'd like to suggest that a series of medium-band (delta z~5%) filters be included with the IR filter set. As Esther Hu mentioned, the narrow-band WFPC2 filters were not well suited for searching for very high redshift emission-line objects, but medium-band filters have proven quite useful (Pascarelle et al., 1998, AJ, 116, 2659). As Peter Eisenhardt points out, it would be most useful to place these medium-band filters in wavelength regions inaccessible to ground-based telescopes due to strong night sky emission. I also support the idea of including an "open" filter in the R filter set (0.9-1.9um) the scientific returns would be numerous. A. Storrs: I too would like to put in a plug for the ramp filters. These can be used in planetary observations for which the frequency of use would be too low to justify a dedicated filter. LRFs have been used in the past for monitoring Mars, for distinguishing silicate mineralogies there and on other rocky bodies, for atmospheric studies (esp. across terrestrial absorption bands), and for icy surfaces (ozone comes to mind). These would be especially useful if they could be put in or near a focal plane, preferably after correction for spherical aberration. E. Hu: I'd like to follow up on Sam Pascarelle's comments on the issue of red filter selection, which is arguably the area which requires the most rethinking in the light of both very recent scientific discoveries (e.g., methane brown dwarfs, and new varieties of low-

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Instrument Science Report WFC3-2000-008 mass stars from IR surveys; very high redshift (z>5) galaxies; Kuiper Belt Objects and other outer Solar System bodies; etc.) and new instrumentation capabilities (IR detector side). For these programs a combination of medium bandpass filters spanning the far red wavelengths (from ~9000 Ang onwards) are important, and can be selected along with the J1, J2 filters to provide good general color discriminants, while also covering spectral diagnostic features (e.g., Alex Storrs' suggestion for 1.05 micron silicate feature in a medium bandpass filter). One can also include a filter placed in a region which inaccessible or difficult to study from the ground due to a combination of strong night sky emission and telluric absorption (following Peter Eisenhardt's suggestion). This would be an effective combination for a variety of programs. I would also favor a very broad JH filter. J. Trauger: on suggestions for Planetary and Brown-Dwarf Study: Here is a strawman filter proposal for the atmospheres of giant planets and brown dwarfs -- a set of three quad filters as follows -(1) UVIS CH4 abs/cntm pairs 619, 619(+/-), 893, 935 nm (2) UVIS CH4 narrowband 889, 904, 922, 937 nm (FWHM < 0.01*center wave). (3) NIR CH4 abs/cntm pairs 1080, 1130, 1580, 1710 nm This selection of planetary science passbands is offered for further discussion by the HST user community. It has been distilled from an informal email survey distributed in May 1999 to a number of planetary scientists who are past users of HST data. There were various opinions on the choice of continuum wavelength companion for the 1.71 micron filter, here we have taken Karkoschka's advice and selected 1.58 microns. The suggested broadband filters are already accounted in the WFC3 set of photometry filters in the UV and NIR. Bob West suggests a Cassini-style dual-passband continuum filter for the 619 nm band. The 619(+/-) filter simultaneously transmits the continuum wavelengths on both sides of the 619 absorption feature, while blocking the 619 absorption band itself. Since it is likely there will be space for up to two UVIS and one NIR filter for methane/planetary science, the list was reduced to 12 passbands distributed into three quad filters, each quad element covering an FOV larger than Jupiter. Multiple filter elements, four to each (quad) filter, each provide about 70 arcsecond square fields of view in the UVIS camera, and somewhat smaller (TBD) FOVs in the NIR camera. HST pointing offsets would be used to select among the four filter elements, as is done for the WFPC2 quads. Rapid absorption/continuum exposure pairs could be facilitated via filter selection, rather than telescope pointing, by placing each CH4 and its corresponding continuum passband in the same quad position on two different filters. Rapid subframe readouts of just one quadrant of the CCD can also be used to help keep the absorption/continuum pairs close together in time.

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Instrument Science Report WFC3-2000-008

B. Balick - list of high and medium priority narrow band filters: --------------------------------------------------2326 F233N CII], - reject SiII]2335 if possible 2425 F243N [NeIV], 2798 F280N MgII, 3078-3099 F309N OH(0,0) series 3426 F343N [NeV], 3726+3729F373N [OII] 3727 - nearby faint contaminating lines F375N [OII] redshifted - perhaps covered by medium filter? 3869 F387N [NeIII] - must reject H-epsilon and HeI lines F390N CN?, from WFPC2, F390N off CaII - perhaps covered by medium filter? 3945 F393N CaII, 4340 F434N H-gamma 4363 F437N [OIII] (must reject H-gamma) - must be used with F502N 4471 F447N HeI 4572 F457N [Mg I] 4686 F469N HeII, 4740 F474N [NeIV] (I added this to your list) 4861 F487N H-beta, 5007 F502N [OIII], 5199 F520N [NI]5198+5200 5303 F530N [Fe XIV], 5755 F575N [NII] - must be used with F658N 5876+5892 F588N HeI/NaI, 6300 F631N [OI], 6563 F656N H-alpha, 6584 F658N [NII], 6678 F668N HeI 6717+6731 F673N [SII], 6717 F673AN [SII] - must be used with but reject 6731 6731 F673BN [SII] - must be used with but reject 6717 7005 F701N [ArV], 7135 F714N [ArIII], 7387 F739N [NiII],

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Instrument Science Report WFC3-2000-008 7412 F741N [NiII], 9850 F985N [CI] Methane quad (543N, 619N, 727N, 893N), UV Narrow quad (376N, 384N, 392N, 399N) Unprioritized list of IR Narrowbands: 10320 F1032N [SII] - sum of [SII] 10284, 10317, 10336, 10370 probes S+ in very dusty regions; 10830 F1083N HeI 12400 F1240N H_2 12260+12327+12380+12416+12418+12470 mini forest of medium bright H_2 lines - must reject [FeII]12567 12818 F1282N Paschen-beta - not necessary of P-alpha is included 12567 F1257N FeII line; same upper state as 1.644 micron line Good for extinction and for HH objects. 16436 F1644N [FeII] Traces high density shocks at modest Excellent tracer of inner jets. 17470 F1748N H2 1-0 S(7) 18751 F1875N Paschen-alpha - use to probe H+ in very dusty regions

4. WFC3 FILTERS
Using their own expertise, inputs from the filter workshop and the Discussion Board, and several additional discussions, the SOC with help from the IPT prepared a list of filters that they recommend for inclusion into the WFC3. These are listed in the following table and discussed in more detail in Lupie and Boucarut, 2000 (ISR WFC3-2000-008, Part III).

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WFC3 UVIS
#
UVIS-1 UVIS-2 UVIS 3 UVIS 4 UVIS 5 UVIS UVIS UVIS UVIS UVIS UVIS UVIS UVIS 6 7 8 9 10 11 12 13

Fname description
F218W F225W F275W F336W F390W F438W F555W F606W F814W F475W F625W F775W F850LP F350LP F300X F475X F600LP F390M F410M F467M F547M F621M F689M F763M F845M F280N F343N F373N F395N F469N F487N F502N F588N F631N F645N F656N F658N F665N F673N F680N F953N F191N F232N F243N F378N F387N F422M F437N F492N F508N F575N F672N F674N Stromgren v Stromgren b Stromgren y 11% fil 11% fil 11% fil 11% fil MgII 2795/2802 [NeV] 3426 [OII] 3726/29 CaII H&K HeII 4686 H-b 4861 [OIII] 5007 HeI 5876+NaI [OI] 6300+[SIII] Continuum H-a 6563 [NII] 6583 z (Ha +[NII]) [SII] 6717, 31 z (Ha +[NII]) [SIII] 9532 CIII] 1909 CII] 2326 [NeIV] 2425 z ([OII] 3727) [NeIII] 3869 continuum [OIII] 4363 z (H-b ) z ([OIII] 5007) [NII] 5755 [SII] 6717 [SII] 6731 U, Stromgren u Washington C WFPC2 WFPC2 WFPC2 WFPC2 SDSS g SDSS r SDSS i SDSS z B V Wide V Wide I ISM feature

lambda fwhm (A) (A)
2175 2250 2750 3375 3900 4320 5410 5956 8353 4750 6250 7760 8320 3500 2775 3800 6000 3900 4105 4675 5475 6212 6886 7630 8454 2798 3426 3732 3950 4686 4867 5013 5886 6306 6455 6563 6585 6654 6731 6902 9532 1909 2326 2425 3780 3869 4220 4364 4924 5081 5755 6716 6731 8890 9060 9240 9370 6194 6340 7270 7504 2775 6573 300 500 500 550 1000 695 1605 2340 2555 1520 1550 1470 2000 7000 1850 2200 4000 200 190 230 710 640 710 780 870 42 228 38 61 32 45 47 60 54 82 14 20 94 77 288 64 30 36 36 80 26 108 30 78 112 12 14 14 89 91 92 94 62 63 73 75 1850 94 F153M F128N F130N H_20 and NH_3 Paschen Beta Paschen Beta continuum F164N F167N [FeII] [FeII] continuum 1.6463 1.6677 0.0165 0.0167 F160W F125W G141 Broad H and Red Grism Ref Broad J "Red" Low Resolution Grism Fname

WFC3 IR
description
lambda (microns) 1.5450 1.2500 (1.4100) fwhm (microns) 0.2900 0.3000 (0.6000)

F127M F139M G102 F098M

Water/CH_4 continuum Water/CH_4 line "Blue" High Resolution Grating "Blue" Filter, Blue Grism Ref

1.2700 1.3850 (1.0250) 0.9850

0.0700 0.0700 (0.2500) 0.1700

UVIS-14 UVIS-15 UVIS 16 UVIS 17 UVIS 18 UVIS UVIS UVIS UVIS UVIS UVIS UVIS 19 20 21 22 23 24 25

very broad very broad very broad very broad

* * * *

1.5300 1.2839 1.3006

0.0700 0.0128 0.0130

F126N F132N F105W F140W

[FeII] Paschen Beta (redshifted) Wide "z" Wide Band spanning J-H bounda ( ) parenthesis indicates exact specs are still in work.

1.2590 1.3200 1.0450 1.4000

0.0126 0.0132 0.3100 0.4000

UVIS 26 UVIS 27 UVIS 28 UVIS 29 UVIS UVIS UVIS UVIS UVIS UVIS UVIS UVIS UVIS UVIS UVIS UVIS 30 31 32 33 34 35 36 37 38 39 40 41

Note:

Table: WFC3 IR and UVIS Filters

quads UVIS 42a UVIS 42b UVIS 42c UVIS 42d UVIS 43a UVIS 43b UVIS 43c UVIS 43d UVIS 44a UVIS 44b UVIS 44c UVIS 44d UVIS 45a UVIS 45b UVIS 45c UVIS 45d UVIS 46a UVIS 46b UVIS 46c UVIS 46d UVIS 47 UVIS 48

CH4A-a 25/km-agt CH4A-b 2.5/km-agt CH4A-c 0.25/km-agt CH4A-d 0.025/km-agt CH4B-a CH4 6194 CH4B-b 6194 cont.+ CH4B-c CH4 7270

CH4B-d 7270 cont. P200 F657N UV prism Wide Ha+[NIII]

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Instrument Science Report WFC3-2000-008

Acknowledgements

:

The FIlter Workshop required the dedication of the entire WFC3 Team at STScI and the WFC3 SOC. We thank P. Knezek and L. Cawley for their careful summary notes and for reviewing this report.

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