WFC3 offers slitless spectroscopy with both the ultra-violet/optical (UVIS) and infrared (IR) channels. The UVIS channel is equipped with the G280 grism, which has a resolving power of R~70 in the wavelength range ~ 0.19-0.55 microns. The IR channel includes the G102 and G141 grisms with resolving powers R~210 in the range 0.8-1.15 microns and R~130 in the range 1.1-1.7 microns, respectively.

If you encounter any problems related to the WFC3 Grism, please contact our Help Desk.

I. Proposal Information & Documentation

Provides links to Manuals and Web pages to help with preparing your Phase 1 & Phase 2 proposals.

II. Data Analysis Information & Documentation

Provides links to Manuals and Web pages for retrieving and analysing WFC3 Grism data. aXe is the Grism reduction software supported by STScI.

III. Calibration Files & Calibration Information

Links for obtaining the newest calibration files for the UVIS and IR Grisms.

IV.Grism-related Instrument Science Reports (ISRs)

List of ISRs directly relevant to the WFC3/Grism. ISRs are in-house refereed technical papers which address specific topics related to instrument and telescope performance or data analysis techniques. This grouping of ISRs has been compiled to provide additional information to observers beyond what is found in the Instrument Handbook.

V. Frequently Asked Questions (FAQ)

List of FAQs related to everything from Proposal Preparation to Data Analysis. This guide is based on questions submitted to the Help Desk as well as feedback from our recent WFC3 Grism survey. The FAQ page will continually evolve over time to include more Q&As as we receive feedback from users.

VI. Other Useful Resources

Here you will find links to other useful webpages, including those of the 2010 STScI Slitless Spectroscopy Workshop, and from teams carrying out large surveys with the WFC3 grisms.

I. Proposal Information & Documentation

WFC3 Instrument Handbook	Overview of instrument capabilities. Useful for Phase 1 & 2 planning. (pdf version)
WFC3 Data Handbook	Guide to using the data obtained with WFC3. Useful for post-observations. (pdf version)
Phase 2 Proposal Instructions	Guide (pdf format) for Preparing Phase 2 proposals. WFC3 information is located in Chapter 14.
Astronomer's Proposal Tool (APT) Training Tools	A collection of video tutorials for using APT. See the APT homepage for obtaining the latest version. Aladin is the default sky atlas used with APT. See the Aladin homepage for more information on using this software.
aXesim - a WFC3 Grism Simulator	A software package which allows you to simulate WFC3/Grism observations. A browsable version of the User Manual is available here, there is also a pdf version available. Detailed information for grism simulation software (Pyraf version).
aXesim on the Web	The web-based version of aXesim. This is a more limited version of the standalone aXesim.
Exposure Time Calculator (ETC) User Manual	Provides general overview of the ETC for all instruments.
WFC3 Grism Exposure Time Calculator (UVIS)	Used for estimating the exposure time for UVIS Grism observations.
WFC3 Grism Exposure Time Calculator (IR)	Used for estimating the exposure time for IR Grism observations.
WFC3 Dithering Strategies	Web based guide for designing dithering patterns for WFC3.
Activating a Target of Opportunity (ToO) Proposal	Describes how an HST observer activates a ToO proposal.

II. Data Analysis Information & Documentation

Retrieving your Data: Multimission Archive Starview Duplication Checker	These three links all provide access to proprietary data for PIs as well as publicly available data.
WFC3 Pipeline Information	Provides a brief description of the WFC3 data pipeline, along with notes on updates.
Do I Need to Recalibrate?	Web guide on how to check if calibration files for your datasets have changed recently.
Hubble Observation Problem Reports	Guidelines for submitting a Hubble Observation Problem Report (HOPR). This is used for: 1) Problems with implementation, scheduling execution, or data processing of your observations; 2) Requests for failed observations to be repeated.
aXe Spectral Extraction Software	Detailed information on installation of the Grism data reduction software aXe, including methodology, tasks and parameters. The latest version is 2.3, and is available as part of STSDAS 3.14 (released August 2011). A detailed User Manual is available in pdf or postscript, however the cookbook (see below) is recommended for a first overview of the reduction process. IMPORTANT for SUB-ARRAY MODE: if your data (grism and/or direct image) were taken in this mode, you must embed it in a full-frame before analysing with aXe. A python script to do this is available here along with instructions.
aXe Cookbook (IR)	Step-by-step guide to reducing G141 (IR) grism data using aXe. Includes link to download Grism data from the WFC3 ERS Program. This data is used as an example in the guide. A UVIS Cookbook is coming soon.
aXe2web	Software which produces an html summary of each reduced object which includes: 1) direct image; 2) 2D spectrum; 3) 1D raw extracted spectrum; 4) 1D flux calibrated spectrum. Documentation can be found here. The software package can be found here, along with the README, and example parameter file.
Space Telescope Analysis Newsletters (STANs)	Archive of newsletters sent to observers with updates which may affect observation planning or analysis.
WFC3 Advisories	Important advisories regarding the status of the WFC3 instrument.
Publication Guidelines for HST Observations	Short summary of what to include in your publications once your data analysis has been completed.

III. Calibration Files and Information

UVIS Grism (G280)	G280 configuration & calibration files, primarily for aXe and aXesim. This includes sensitivity, flatfield cube, and trace information. Last Update: 2009-01-ISR.
I R Grism (G102)	G102 configuration & calibration files, primarily for aXe and aXesim. This includes sensitivity, flatfield cube, and trace information.
IR Grism (G141)	G141 configuration & calibration files, primarily for aXe and aXesim. This includes sensitivity, flatfield cube, and trace information.
Reference Files	This web page contains the current calibration and reference files used in the CALWF3 pipeline.
Zeropoints for WFC3 Filters	This table gives zeropoints for WFC3 UVIS & IR filters. This is important for the *.cat files used with aXe and aXesim. Note: aXe and aXesim only accept ST and AB MAG zeropoints.
Pivot Wavelengths for WFC3 UVIS filters	This table gives the pivot wavelengths for the WFC3 UVIS filters. This is important for the *.cat files used with aXe and aXesim.
Pivot Wavelengths for WFC3 IR filters	This table gives the pivot wavelengths for the WFC3 IR filters. This is important for the *.cat files used with aXe and aXesim.
HST Keyword Dictionary	Reference web page for looking up the meanings of all Keywords currently used for HST instruments.

IV. Grism-Related Instrument Science Reports (ISRs)

ISR 2012-06: Flux Calibration Monitoring - WFC3/IR G102 and G141 Grisms	Confirms stability in +1 order G102 and G141 flux calibrations to within 1% over WFC3 lifetime.
2011-09: IR Detector Timing & Persistence	Information on persistence in the IR detector for full & sub-arrays.
2011-05: Revised Flux Calibration of the WFC3 G102 & G141 Grisms	Update of flux calibrations, aperture corrections for the +1 order, and throughput variations across the FOV.
2011-04: WFC3/IR Banding	How to deal with background pixels a few DN above of the image in full & sub-array frames, including observing techniques to avoid.
2011-01: Master Sky Images for the WFC3 G102 & G141 Grisms	Details regarding construction of new master sky frames for data analysis and discussion of possible time-variations of background sky brightness.
2010-17: WFC3/IR Persistence as Measured in Cycle 17 using Tungsten Lamp Exposures	Measurement of persistence from internal Tungsten Lamps to assess impact of bright illumination on observations.
2010-16: IR Channel Subarray Dark Current Behavior	Discussion of the effects of, and how to deal with, dark current for sub-arrays.
2010-13: WFC3/IR Bad Pixel Table: Update Using Cycle 17 Data	Information regarding updated bad pixel tables, including values assigned to known bad areas (i.e. blob, death star, etc...)
2010-12: Proposal 11913-IR Filter Wedge Check	Information on offsets in pixel position for all IR filters. This ISR is important for programs using direct images obtained in filters other than F140W.
2010-09: Dithering Strategies for WFC3	Guidelines for dithering strategies. This ISR is useful for Phase 2 proposal preparation.
2010-07: First On-orbit Measurements of the WFC3-IR Count-rate Non-Linearity	Discussion of non-linearity in the WFC3 IR detector and comparison with similar phenomenon in ACS and NICMOS.
2010-06: The WFC3 IR "Blobs"	Discussion of blemishes which have appeared in the WFC3 IR detector. This ISR is useful for developing dithering strategies for Phase 2 proposal preparation.
2009-18: WFC3 SMOV proposal 11552: Calibration of the G102 Grism	Provides calibration information on the trace, resolution and wavelength solution of the G102 IR Grism.
2009-17: WFC3 SMOV proposal 11552: Calibration of the G141 Grism	Provides calibration information on the trace, resolution and wavelength solution of the G141 IR Grism.
2009-01: The ground calibration of the WFC3/UVIS G280 Grism	Provides calibration information on the trace, resolution and wavelength solution of the G280 UVIS Grism.
2007-03: Performance of the WFC3 Replacement IR Grisms	Summarizes the preformance of the G102 and G141 grisms. This report includes technical specicifications of the grisms, their installation, throughput, and dispersion.
2001-07: WFC3 Data Formats in OPUS & STSDAS	Describes content and structure of WFC3 science data files generated by OPUS and used in processing with STSDAS tasks.

VI. Other Useful Resources

2010 STScI Slitless Spectroscopy Workshop	The 2010 workshop highlighting scientific results of slitless spectroscopy and tutorials on using and analysing data from the WFC3 Grism. A direct link to the archived videos of the talks can be found here.
WISPS Team Page	WFC3 Infrared Spectroscopic Parallel Survey webpage. Includes access to reduced and drizzled direct near-IR imaging (F110W, F140W, & F160W), direct UVIS imaging (F475X & F600LP), and the near-IR grisms (G102 and G141).
3D-HST Team Page	"A Spectroscopic Galaxy Evolution Survey with the Hubble Space Telescope" webpage. Includes access F140W and G141 mosaics. Pipeline used by 3D-HST is available here.

Shortcuts

'Exposure Time Calculators'

'Instrument Comparisons'

'Instrument Handbook'

Data Handbook

aXe Cookbook

'Grism Spectroscopy'

Newsletters

ISRs

HST Primer

Call for Proposals

'Proposal Instructions'


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Spectroscopy

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