15596( 3) - 06-Jul-2018 18:46:09 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 15596 Version: 3 Check-in Time: 06-Jul-2018 18:46:09 STScI Edit Number: 0 Title Directors Discretionary observations of shock excitation around Eta Carinae with WFC3 ------------------------------------------------------------------------------------ Type Cycle GO/DD 25 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Nathan Smith University of Arizona Y CoI: Dr. Jon A. Morse BoldlyGo Institute N ------------------------------------------------------------------------------------ Abstract In cycle 25, time was awarded to obtain a UV image of Mg II 2800 emission in the nebula around the massive star Eta Carinae, using the F280N filter with WFC3/UVIS. This was the first WFC3 imaging of Eta Car, the first image of Mg II around a massive star, and the first deep UV image of the nebulosity around Eta Carinae. That image revealed strong Mg II emission, but with very unexpected morphology. The Mg II is essentially anticorrelated with the other line emission seen previously in H-alpha, [N II], or [Fe II] emission. The Mg II emission provides an entirely new view of Eta Carinae, revealing a significant reservoir of additional ejecta mass and kinetic energy outside the main bipolar nebula, which has been invisible in all other imaging filters used so far. To accomplish the originally stated goal of using Mg II as a diagnostic of shocks in the ejecta, we need to understand the alignment of the Mg II emission as compared to other tracers like H-alpha, and the Mg II image needs to be continuum subtracted to separate line emission from dust-scattered starlight. This DD proposal requests images in the F336W (continuum subtraction) and F658N ([N II]) filters at the current epoch. This is urgently needed because the nebula is expanding rapidly and differentially; WFPC2 images from more than a decade ago are inadequate for proper alignment. These additional images (1 orbit) will permit a quantitative analysis of the shock conditions that give rise to the separation of Mg II and H-alpha, and will allow us to separate shocked gas from photoionized ejecta. We also request a very short exposure in F280N to patch saturated pixels in the existing F280N image. ------------------------------------------------------------------------------------ Observations Description ------------------------ Our proposed observations have two immediate objectives: (1) to obtain F336W and F658N images at the present epoch to align with our new F280N Mg II image, and (2) to obtain a pair of very short exposures in the F280N lter to patch saturated pixels around the bright central star. F336W and F658N: We will image continuum emission from Eta Car at blue/near-UV wavelengths (F336W) and H+[N ii] 6583 line emission from shocked gas (F658N). We will use a similar observing strategy as in previous sequences of images taken with WFPC2 in 1999 and 2001, with a range of integration times to accommodate the factor of > 10^5 in dynamic range between the central star and the faintest structures in the extended nebula. In the longest exposures needed to see the fainter outer condensations in the nebula, the central star 15596( 3) - 06-Jul-2018 18:46:09 - [ 2] and its immediate surroundings will badly saturate and bleed onto adjacent pixels. The range of shorter exposure times are necessary to provide unsaturated images that can be used to patch the overexposed sections of the images. For F336W and F658N, a suitable series of exposures can be obtained in one orbit, including overheads. For WFC3, the red sensitivity is similar to WFPC2, but blue sensitivity is signifcantly better. We will therefore use a similar range of exposures in the F658N filter, and somewhat shorter exposures in F336W than in previous cycles. The main requirement is to achieve good signal to noise in the fainter outer regions of the nebula to compare with the F280N emission. F280N short exposures: We will also obtain two short-exposure images in the F280N filter, with exposure times of a few to tens of seconds. The purpose of these images is to patch the saturated pixels in the F280N image obtained in March 2018. A central region of roughly 20x200 pixels was badly saturated with bleeding onto adjacent pixels around the central star. For this program, we had obtained a CR-split pair of images with a total exposure time of about 3900 s, because we were primarily interested in detecting faint outer MgII emission. Not knowing what to expect, we maximized the exposure time in one orbit. To carefully register the F280N image with the F336W and F658N images proposed here, and to investigate the morphology of any MgII emission or absorption near the central star that may be different from the continuum emission, we need unsaturated exposures of the central star in the F280Nfilter. ------------------------------------------------------------------------------------ 15596( 3) - 06-Jul-2018 18:46:09 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 ETA-CAR EXT-STAR, EJECTA, RA=10H45M3.5460S, J2000 V = 6.21 EMISSION LINE NEBULA, DEC=-59D41'3.95" ETA CARINAE STAR, LUMINOUS BLUE VARIABLE Reference Frame: Other: SIMBAD Extended: YES Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. In previous cycles we noted that special catalog ZZZQ may be needed because GSC is poor in this field. It does not appear that the predecessor program 15289 used the special catalog. Visit 1 of 15289 successfully imaged with WFC3 through the F280N UVIS filter, but Visit 2 appears to have had tracking issues with a couple of exposures in the IR channel. ------------------------------------------------------------------------------------------------------------------------------------ 15596( 3) - 06-Jul-2018 18:46:09 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-UVIS-DITHER-LINE Pattern_Purpose DITHER Number_Of_Points 2 Point_Spacing 0.145 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 46.84 Angle_Between_Sides Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 2 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-UVIS-DITHER-LINE-3PT Pattern_Purpose DITHER Number_Of_Points 3 Point_Spacing 0.135 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 46.84 Angle_Between_Sides Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 15596( 3) - 06-Jul-2018 18:46:09 - [ 5] Visit: 01 (Visit1) Visit Requirements: BEFORE 01-SEP-2018:00:00:00 On Hold Comments: Additional Comments: Any ORIENT could suffice for these observations, however duplicating the orientation of program 15289 UVIS F280N observations would be helpful for data analysis and directs the diffraction spikes and CCD saturation bleeding away from important outer emission. The image header states that PA_V3 = 169.08 degrees for the previous F280N images. Please duplicate this orientation (or use 349.08 degrees) if possible. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 ETA-CAR WFC3/UVI ACCUM UVIS2-C1K F280N FLASH=2.0, BLADE=A 1 3 S (6 S) PATTERN 1 1-6 S 1C-SUB ------------------------------------------------------------------------------------------------------------------------------------ 2 ETA-CAR WFC3/UVI ACCUM UVIS2-C1K F280N FLASH=2.0 1 20 S (40 S 1C-SUB S) ------------------------------------------------------------------------------------------------------------------------------------ 3 ETA-CAR WFC3/UVI ACCUM UVIS2-C1K F336W FLASH=2.0, BLADE=A 1 0.5 S (1 S 1C-SUB S) ------------------------------------------------------------------------------------------------------------------------------------ 4 ETA-CAR WFC3/UVI ACCUM UVIS2-C1K F336W FLASH=2.0 1 8 S (16 S) S 1C-SUB ------------------------------------------------------------------------------------------------------------------------------------ 5 ETA-CAR WFC3/UVI ACCUM UVIS2-C1K F658N FLASH=2.0, BLADE=A 1 0.5 S (1 S 1C-SUB S) ------------------------------------------------------------------------------------------------------------------------------------ 6 ETA-CAR WFC3/UVI ACCUM UVIS2-C1K F658N FLASH=2.0 1 8 S (16 S) S 1C-SUB ------------------------------------------------------------------------------------------------------------------------------------ 7 ETA-CAR WFC3/UVI ACCUM UVIS2-2K2 F336W FLASH=2.0 1 120 S (240 PATTERN 1 7 S C-SUB S) ------------------------------------------------------------------------------------------------------------------------------------ 8 ETA-CAR WFC3/UVI ACCUM UVIS2-2K2 F658N FLASH=2.0 1 180 S (540 PATTERN 2 8 S C-SUB S) ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ ETA-CAR 1 WFC3/UVI ACCUM UVIS2-C1 F280N 1 none none none 1 N/A S K1C-SUB ETA-CAR 1 WFC3/UVI ACCUM UVIS2-C1 F280N 2 none none none 1 N/A S K1C-SUB ETA-CAR 2 WFC3/UVI ACCUM UVIS2-C1 F280N 1 none none none 1 N/A S K1C-SUB ETA-CAR 2 WFC3/UVI ACCUM UVIS2-C1 F280N 2 none none none 1 N/A S K1C-SUB 15596( 3) - 06-Jul-2018 18:46:09 - [ 6] 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 | ------------------------------------------------------------------------------------------------------------------------------------ ETA-CAR 3 WFC3/UVI ACCUM UVIS2-C1 F336W 1 none none none 1 N/A S K1C-SUB ETA-CAR 3 WFC3/UVI ACCUM UVIS2-C1 F336W 2 none none none 1 N/A S K1C-SUB ETA-CAR 4 WFC3/UVI ACCUM UVIS2-C1 F336W 1 none none none 1 N/A S K1C-SUB ETA-CAR 4 WFC3/UVI ACCUM UVIS2-C1 F336W 2 none none none 1 N/A S K1C-SUB ETA-CAR 5 WFC3/UVI ACCUM UVIS2-C1 F658N 1 none none none 1 N/A S K1C-SUB ETA-CAR 5 WFC3/UVI ACCUM UVIS2-C1 F658N 2 none none none 1 N/A S K1C-SUB ETA-CAR 6 WFC3/UVI ACCUM UVIS2-C1 F658N 1 none none none 1 N/A S K1C-SUB ETA-CAR 6 WFC3/UVI ACCUM UVIS2-C1 F658N 2 none none none 1 N/A S K1C-SUB ETA-CAR 7 WFC3/UVI ACCUM UVIS2-2K F336W 1 none none none 1 N/A S 2C-SUB ETA-CAR 7 WFC3/UVI ACCUM UVIS2-2K F336W 2 none none none 1 N/A S 2C-SUB ETA-CAR 8 WFC3/UVI ACCUM UVIS2-2K F658N 1 none none none 1 N/A S 2C-SUB ETA-CAR 8 WFC3/UVI ACCUM UVIS2-2K F658N 2 none none none 1 N/A S 2C-SUB ETA-CAR 8 WFC3/UVI ACCUM UVIS2-2K F658N 3 none none none 1 N/A S 2C-SUB 15596( 3) - 06-Jul-2018 18:46:09 - [ 7] Summary Form for Proposal 15596 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures UVIS2-2K2C-SUB, UVIS2-C1K1C-SUB ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BLADE=A, FLASH=2.0 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BEFORE 01-SEP-2018:00:00:00, PATTERN 1 1-6, PATTERN 1 7, PATTERN 2 8 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F280N, F336W, F658N ------------------------------------------------------------------------------------------------------------------------------------ Target Names ETA-CAR ------------------------------------------------------------------------------------------------------------------------------------