15465(  3) - 01-Jun-2018 15:47:06 - [  1]

                  HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 15465

Version:   3  Check-in Time: 01-Jun-2018 15:47:06       STScI Edit Number: 1     

Title
Resolving Extreme High-Ionization UV Emission-Line Diagnostics in Preparation for JWST
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Type             Cycle
GO               25       
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Investigators                                                                   
                                                                                     Contact?
    PI: Dr. Danielle Berg                 The Ohio State University                     Y 
   CoI: Dr. John Chisholm                 University of California - Santa Cruz         N 
   CoI: Prof. Dawn K. Erb                 University of Wisconsin - Milwaukee           N 
   CoI: Dr. Richard W. Pogge              The Ohio State University                     N 

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Abstract

The recent observations of extreme ultraviolet (UV) emission lines with complex line
profiles in a z~2 lensed galaxy (Berg et al. 2018a) suggest our ability to          
characterize sources using their UV emission lines may be biased by the unaccounted 
for stellar and interstellar medium (ISM) contributions. This is of particular      
concern for the imminent window onto reionization-era sources allowed by the James  
Webb Space Telescope (JWST), where extreme UV emission lines may be the only        
diagnostic probes available. Because the CIII], OIII], CIV, and HeII high-ionization
emission lines are rarely seen in lower redshift galaxies (0<z<3), the promising UV 
diagnostic diagrams combining these lines (e.g., Feltre et al. 2016; Nakajima et al.
2017; Byler et al. 2018) lack observational confirmation or calibration.            
Fortunately, recent UV spectral campaigns have identified a sample of nearby        
galaxies with analogous emission-line features to reionization-era systems,         
including the strongest CIV (Berg et al. 2016) and HeII (Berg et al. 2018b) emitters
in the local Universe. We therefore propose high resolution, high signal-to-noise   
HST/COS spectral observations of two reionization-era analogues that will allow us  
to robustly model the massive star populations and resolve the stellar and nebular  
components of the high-ionization emission lines. These data will provide the first 
stringent test of the high-ionization UV emission line diagnostics critical to the  
interpretation of distant sources accessible with JWST.                             
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  Observations Description
  ------------------------

     Goal:                                                                          
     We will obtain NUV target aquisiton images and high-resolution, high           
     signal-to-noise HST/COS spectral observations of two reionization-era analogues
     that will allow us to robustly model the massive star populations and resolve  
     the stellar and nebular components of the high-ionization emission lines.      
                                                                                    
     Targets:                                                                       
     Our targets were selected from previous low-resolution HST/COS obsevations for 
     their large CIV and HeII equivalent widths. These targets have high [OIII]     
     optical emission line surface brightnesses, large ionizations, low             
     metallicities (12+log(O/H) < 8.0), and compact morphologies in order to achieve
     maximum flux through the 2.5" COS aperture. We use the coordinates from our    
     target's SDSS optical spectra, which are in the ICRS reference frame.          
                                                  15465(  3) - 01-Jun-2018 15:47:06 - [  2]

                                                                                    
     Target Acquisition:                                                            
     Since all sources have SDSS positions, which are generally accurate to 0.1", we
     do not do an ACQ/SEARCH routine. With such excellent input coordinates from the
     SDSS, we aquire our targets using the ACQ/IMAGE mode with the PSA aperture and 
     MirrorA for the COS/NUV configuration. Following the successful target         
     acquisition method of our previous HST-GO14628 program, we have determined     
     integration times necessary to reach a S/N = 25 for our targets. We assume a   
     flat spectral distribution normalized by the GALEX FUV surface brightnesses.   
     Both galaxies are compact in the SDSS imaging with a FWHM PSF diameter of ~2". 
     We then divide the GALEX FUV fluxes by the area of the 2" PSF to determine the 
     FUV surface brightnesses. Note that Target 18 required us to use Mirror B to   
     ensure safe levels when using the BOT.                                         
                                                                                    
     Science Exposures:                                                             
     We will use COS with the G160M grating with a central wavelength of 1589       
     angstroms in TIMETAG mode in order to simultaneously observe the CIV 1548, 1550
     and HeII 1640 spectra features. In order to resolve the stellar and nebular    
     components of the CIV and HeII features, we use the ETC to determine the total 
     science integration times necessary to achieve a S/N >~ 7 per resolution in the
     continuum for our targets using input continuum fluxes at 1500 A from our      
     previous HST/COS observations. We will observe our targets for 3 and 5 orbits  
     each though the PSA aperture with the COS/FUV configuration. With the G160M    
     grating we use FP-POS=ALL, which takes 4 images offset from one another in the 
     dispersion direction and increases S/N. These 4 positions allow a flat to be   
     created and cosmic rays to be eliminated.                                      
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                                                  15465(  3) - 01-Jun-2018 15:47:06 - [  3]

TARGET LIST    Fixed Targets
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Tar|   Target   |         Target        |            Target              |Coord   | Radial |             Flux data
No |    Name    |       Description     |           Position             |Eqnx    |  Vel.  |
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1   SDSSJ104457  GALAXY, DWARF COMPACT   RA=10H44M57.7900S +/- 0.1",      J2000             V = 17.55 g = 17.49, r = 17.76          
                                         DEC=+03D53'13.10" +/- 0.1"                                                                 
    Reference Frame: ICRS    Extended: YES
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2   J141851      GALAXY, DWARF COMPACT   RA=14H18M51.1194S +/- 0.1",      J2000             V = 17.77 SDSS r-band = 17.65           
                                         DEC=+21D02'39.84" +/- 0.1"                                                                 
    Reference Frame: ICRS    Extended: YES
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                                                  15465(  3) - 01-Jun-2018 15:47:06 - [  4]

Visit: 01
     Visit Requirements:  <none>                                                                                      
     On Hold Comments:    <none>                                                                                      
     Additional Comments: <none>                                                                                      


Exposures
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Exp |   Target  | Instr  | Oper. | Aper    |Spectral|Central|           Optional           |Num|   Time   |       Special
Num |    Name   | Config | Mode  | or FOV  |Element |Waveln.|          Parameters          |Exp|  (Total) |     Requirements
------------------------------------------------------------------------------------------------------------------------------------
1    SDSSJ104457 COS/NUV  ACQ/IMA PSA       MIRRORA                                         1   183 S (183                          
                          GE                                                                    S)                                  
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2    SDSSJ104457 COS/FUV  TIME-TA PSA       G160M    1589    SEGMENT=BOTH, FLASH=YES,       1   1846 S                              
                          G                                  FP-POS=ALL, BUFFER-TIME=27581      see below                           
                                                                                                (1832 S)                            
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3    SDSSJ104457 COS/FUV  TIME-TA PSA       G160M    1589    SEGMENT=BOTH, FLASH=YES,       1   1846 S                              
                          G                                  FP-POS=ALL, BUFFER-TIME=27851      see below                           
                                                                                                (2600 S)                            
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4    SDSSJ104457 COS/FUV  TIME-TA PSA       G160M    1589    SEGMENT=BOTH, FLASH=YES,       1   1846 S                              
                          G                                  FP-POS=ALL, BUFFER-TIME=27851      see below                           
                                                                                                (2600 S)                            
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Sub Exposures
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Target             | Exp |Instr   | Oper. |  Aper  |Spectral|Cent.|Primary     |Secondary   |Iteration |CR-SPLIT  |Orbit  |Duration
Name               | Num |Config  | Mode  | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num       |Num       |Number |
------------------------------------------------------------------------------------------------------------------------------------
SDSSJ104457         1     COS/NUV  ACQ/IMA PSA      MIRRORA        none         none         none       none       1       N/A      
                                   GE                                                                                               
SDSSJ104457         2     COS/FUV  TIME-TA PSA      G160M    1589  none         none         none       1          1       458.0 S  
                                   G                                                                                                
SDSSJ104457         2     COS/FUV  TIME-TA PSA      G160M    1589  none         none         none       2          1       458.0 S  
                                   G                                                                                                
SDSSJ104457         2     COS/FUV  TIME-TA PSA      G160M    1589  none         none         none       3          1       458.0 S  
                                   G                                                                                                
SDSSJ104457         2     COS/FUV  TIME-TA PSA      G160M    1589  none         none         none       4          1       458.0 S  
                                   G                                                                                                
SDSSJ104457         3     COS/FUV  TIME-TA PSA      G160M    1589  none         none         none       1          2       650.0 S  
                                   G                                                                                                
SDSSJ104457         3     COS/FUV  TIME-TA PSA      G160M    1589  none         none         none       2          2       650.0 S  
                                   G                                                                                                
SDSSJ104457         3     COS/FUV  TIME-TA PSA      G160M    1589  none         none         none       3          2       650.0 S  
                                   G                                                                                                
SDSSJ104457         3     COS/FUV  TIME-TA PSA      G160M    1589  none         none         none       4          2       650.0 S  
                                   G                                                                                                
SDSSJ104457         4     COS/FUV  TIME-TA PSA      G160M    1589  none         none         none       1          3       650.0 S  
                                   G                                                                                                
                                                  15465(  3) - 01-Jun-2018 15:47:06 - [  5]


Sub Exposures
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Target             | Exp |Instr   | Oper. |  Aper  |Spectral|Cent.|Primary     |Secondary   |Iteration |CR-SPLIT  |Orbit  |Duration
Name               | Num |Config  | Mode  | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num       |Num       |Number |
------------------------------------------------------------------------------------------------------------------------------------
SDSSJ104457         4     COS/FUV  TIME-TA PSA      G160M    1589  none         none         none       2          3       650.0 S  
                                   G                                                                                                
SDSSJ104457         4     COS/FUV  TIME-TA PSA      G160M    1589  none         none         none       3          3       650.0 S  
                                   G                                                                                                
SDSSJ104457         4     COS/FUV  TIME-TA PSA      G160M    1589  none         none         none       4          3       650.0 S  
                                   G                                                                                                
                                                  15465(  3) - 01-Jun-2018 15:47:06 - [  6]

Visit: 02
     Visit Requirements:  <none>                                                                                      
     On Hold Comments:    <none>                                                                                      
     Additional Comments: <none>                                                                                      


Exposures
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Exp |   Target  | Instr  | Oper. | Aper    |Spectral|Central|           Optional           |Num|   Time   |       Special
Num |    Name   | Config | Mode  | or FOV  |Element |Waveln.|          Parameters          |Exp|  (Total) |     Requirements
------------------------------------------------------------------------------------------------------------------------------------
1    J141851     COS/NUV  ACQ/IMA PSA       MIRRORA                                         1   153 S (153 GS ACQ SCENARIO BASE1B3  
                          GE                                                                    S)                                  
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2    J141851     COS/FUV  TIME-TA PSA       G160M    1589    SEGMENT=BOTH, FLASH=YES,       1   1846 S                              
                          G                                  FP-POS=ALL, BUFFER-TIME=31682      see below                           
                                                                                                (1908 S)                            
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3    J141851     COS/FUV  TIME-TA PSA       G160M    1589    SEGMENT=BOTH, FLASH=YES,       1   1846 S                              
                          G                                  FP-POS=ALL, BUFFER-TIME=31682      see below                           
                                                                                                (2616 S)                            
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4    J141851     COS/FUV  TIME-TA PSA       G160M    1589    SEGMENT=BOTH, FLASH=YES,       1   1846 S                              
                          G                                  FP-POS=ALL, BUFFER-TIME=31682      see below                           
                                                                                                (2616 S)                            
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5    J141851     COS/FUV  TIME-TA PSA       G160M    1589    SEGMENT=BOTH, FLASH=YES,       1   1846 S                              
                          G                                  FP-POS=ALL, BUFFER-TIME=31682      see below                           
                                                                                                (2616 S)                            
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6    J141851     COS/FUV  TIME-TA PSA       G160M    1589    SEGMENT=BOTH, FLASH=YES,       1   1846 S                              
                          G                                  FP-POS=ALL, BUFFER-TIME=31682      see below                           
                                                                                                (2616 S)                            
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Sub Exposures
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Target             | Exp |Instr   | Oper. |  Aper  |Spectral|Cent.|Primary     |Secondary   |Iteration |CR-SPLIT  |Orbit  |Duration
Name               | Num |Config  | Mode  | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num       |Num       |Number |
------------------------------------------------------------------------------------------------------------------------------------
J141851             1     COS/NUV  ACQ/IMA PSA      MIRRORA        none         none         none       none       1       N/A      
                                   GE                                                                                               
J141851             2     COS/FUV  TIME-TA PSA      G160M    1589  none         none         none       1          1       477.0 S  
                                   G                                                                                                
J141851             2     COS/FUV  TIME-TA PSA      G160M    1589  none         none         none       2          1       477.0 S  
                                   G                                                                                                
J141851             2     COS/FUV  TIME-TA PSA      G160M    1589  none         none         none       3          1       477.0 S  
                                   G                                                                                                
J141851             2     COS/FUV  TIME-TA PSA      G160M    1589  none         none         none       4          1       477.0 S  
                                   G                                                                                                
J141851             3     COS/FUV  TIME-TA PSA      G160M    1589  none         none         none       1          2       654.0 S  
                                   G                                                                                                
                                                  15465(  3) - 01-Jun-2018 15:47:06 - [  7]


Sub Exposures
------------------------------------------------------------------------------------------------------------------------------------
Target             | Exp |Instr   | Oper. |  Aper  |Spectral|Cent.|Primary     |Secondary   |Iteration |CR-SPLIT  |Orbit  |Duration
Name               | Num |Config  | Mode  | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num       |Num       |Number |
------------------------------------------------------------------------------------------------------------------------------------
J141851             3     COS/FUV  TIME-TA PSA      G160M    1589  none         none         none       2          2       654.0 S  
                                   G                                                                                                
J141851             3     COS/FUV  TIME-TA PSA      G160M    1589  none         none         none       3          2       654.0 S  
                                   G                                                                                                
J141851             3     COS/FUV  TIME-TA PSA      G160M    1589  none         none         none       4          2       654.0 S  
                                   G                                                                                                
J141851             4     COS/FUV  TIME-TA PSA      G160M    1589  none         none         none       1          3       654.0 S  
                                   G                                                                                                
J141851             4     COS/FUV  TIME-TA PSA      G160M    1589  none         none         none       2          3       654.0 S  
                                   G                                                                                                
J141851             4     COS/FUV  TIME-TA PSA      G160M    1589  none         none         none       3          3       654.0 S  
                                   G                                                                                                
J141851             4     COS/FUV  TIME-TA PSA      G160M    1589  none         none         none       4          3       654.0 S  
                                   G                                                                                                
J141851             5     COS/FUV  TIME-TA PSA      G160M    1589  none         none         none       1          4       654.0 S  
                                   G                                                                                                
J141851             5     COS/FUV  TIME-TA PSA      G160M    1589  none         none         none       2          4       654.0 S  
                                   G                                                                                                
J141851             5     COS/FUV  TIME-TA PSA      G160M    1589  none         none         none       3          4       654.0 S  
                                   G                                                                                                
J141851             5     COS/FUV  TIME-TA PSA      G160M    1589  none         none         none       4          4       654.0 S  
                                   G                                                                                                
J141851             6     COS/FUV  TIME-TA PSA      G160M    1589  none         none         none       1          5       654.0 S  
                                   G                                                                                                
J141851             6     COS/FUV  TIME-TA PSA      G160M    1589  none         none         none       2          5       654.0 S  
                                   G                                                                                                
J141851             6     COS/FUV  TIME-TA PSA      G160M    1589  none         none         none       3          5       654.0 S  
                                   G                                                                                                
J141851             6     COS/FUV  TIME-TA PSA      G160M    1589  none         none         none       4          5       654.0 S  
                                   G                                                                                                
                                                  15465(  3) - 01-Jun-2018 15:47:06 - [  8]

            Summary Form for Proposal  15465

  Item                         Used in this proposal                                                                              
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  Apertures                    PSA                                                                                                 
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  Configurations               COS/FUV, COS/NUV                                                                                    
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  Opmodes                      ACQ/IMAGE, TIME-TAG                                                                                 
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  Optional Parameters          BUFFER-TIME=27581, BUFFER-TIME=27851, BUFFER-TIME=31682, FLASH=YES, FP-POS=ALL, SEGMENT=BOTH        
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  Special Requirements         GS ACQ SCENARIO BASE1B3                                                                             
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  Spectral Elements            G160M, MIRRORA                                                                                      
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  Target Names                 J141851, SDSSJ104457                                                                                
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