7874( 2) - 11/21/97 09:18 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 7874 Version: 2 Check-in Date: 21-Nov-1997 09:16:47 1.Proposal Title: The shells of NGC 5128: debris from a recent merger ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 7 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: TIMOTHY BEDDING UNIVERSITY OF SYDNEY CoI: Dante Minniti Lawrence Livermore National Laboratory Y CoI: Roberto Soria Mount Stromlo Observatory N CoI: Arjun Dey Kitt Peak National Observatory N ------------------------------------------------------------------------------------ 5. Abstract At a distance of about 3.6 Mpc, NGC 5128 (= Cen A) is the closest high-luminosity AGN, the closest radio galaxy, the closest giant elliptical and one of the closest and best examples of a merger remnant. The galaxy has prominent dust lanes and shells which, according to several theoretical studies, are the result of a merger with a small satellite galaxy. Here, we propose to obtain deep NICMOS images of one of the outer shells in order to investigate in detail the debris of the accreted satellite. We will use JHK color- magnitude and color-color diagrams of the component stars in the shell to determine the ages and metal abundances of the stellar populations of the cannibalized satellite. Our HST imaging study will be complemented by existing archival WFPC2 images of the halo and nuclear regions of NGC 5128, which will provide an excellent differential comparison with the shell population. This study should provide us with a unique database to directly investigate the timescale of the merger process and place powerful constraints on the theoretical merger models. ------------------------------------------------------------------------------------ 7874( 2) - 11/21/97 09:18 - [ 2] Observations Description ------------------------ The proposed images need to be deep enough in J, H and K to resolve the RGB tip for the old stellar component (M_H = - 7.2, J-H_0 = 0.9, H-K_0 = 0.3). The corresponding limiting apparent magnitudes depend on the distance; we adopt D = 3.6 Mpc (Soria et al.\\ 1996). The required limiting magnitudes for accurate photometry are are thus S/N=10 at H=22.0 and J=23.0, and S/N=5 at K = 20.4. These correspond to total exposure times of about 700 sec, 500 sec and 3000 sec, respectively, with NIC2. We require that the JH color- magnitude diagram be complete down to about 1.5 mag below the RGB tip, similar to Figure reffig.cmd. Also, the K images down only to the RGB tip would allow us to make a color-color diagram deep enough to identify the AGB stars and to determine the C/M star ratio. Similar exposures are needed for both fields (the NE shell and the halo control, chosen to be that observed by Soria et al. 1996 in V and I). An additional 3000 sec is required for a background field in K. Thus, using NICMOS Camera 2 require a total of 6 orbits. CAM1 and CAM3 will be used in parallel for visit 1. CAM3 is chosen for the K observations for visit 2, with CAM1 and CAM2 in parallel Our first attempt to obtain photometry of the halo of NGC 5128 using adaptive optics was unsuccessful (see above and Bedding et al.\\ 1997). Those data were taken under poor seeing conditions in which fast variations prevented good correction. We have since obtained observations in better seeing which we hope will allow us to detect the brightest stars. The luminosity function and color-magnitude diagram should allow us to estimate ages for the youngest stellar populations in the halo. These will complement the proposed NICMOS observations of the shell region of NGC 5128, which is much too crowded for adaptive optics. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: ELECTRONIC Blocking Factor: 10 Ship To: PI_Address Ship Via: Email: ------------------------------------------------------------------------------------ 7874( 2) - 11/21/97 09:18 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC5128-POS1 GALAXY, ELLIPTICAL RA=13H 26M 18.00S +/- 0S, DEC=- J2000 V = +300 V = 6.98 42D 53' 48.0" +/- 0", PLATE- B-V = 0.98 ID=00AK 2 NGC5128-POS2 GALAXY, ELLIPTICAL RA=13H 26M 24.50S +/- 0S, DEC=- J2000 V = +300 V = 6.98 42D 50' 10.0" +/- 0", PLATE- B-V = 0.98 ID=00AK 3 NGC5128-POS3 GALAXY, ELLIPTICAL RA=13H 25M 24.323S +/- 0S, DEC=- J2000 V = +300 V = 6.98 43D 09' 58.53" +/- 0", PLATE- B-V = 0.98 ID=00AK 7874( 2) - 11/21/97 09:18 - [ 4] Visit: 01 Visit Priority: Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC5128-POS NIC2 MULTIAC NIC2-FI F160W CAMERA-FOCUS=1-2 , 1 DEF PAR 2-3 WITH 1 1 CUM X SAMP-SEQ=SPARS64 ,NSAMP=5 , PATTERN=SQUARE-WAVE-DITH , NUM-POS=6 ,DITH-SIZE=0.712 , PATTERN-ORIENT=215.0 ------------------------------------------------------------------------------------------------------------------------------------ 2 ANY NIC1 MULTIAC NIC1-FI F160W SAMP-SEQ=SPARS64 ,NSAMP=5 1 DEF CUM X ------------------------------------------------------------------------------------------------------------------------------------ 3 ANY NIC3 MULTIAC NIC3-FI F160W SAMP-SEQ=SPARS64 ,NSAMP=5 1 DEF CUM X ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC5128-POS NIC2 MULTIAC NIC2-FI F110W CAMERA-FOCUS=1-2 , 1 DEF PAR 5-6 WITH 4 1 CUM X SAMP-SEQ=SPARS64 ,NSAMP=5 , PATTERN=SQUARE-WAVE-DITH , NUM-POS=6 ,DITH-SIZE=0.712 , PATTERN-ORIENT=215.0 ------------------------------------------------------------------------------------------------------------------------------------ 5 ANY NIC1 MULTIAC NIC1-FI F110W SAMP-SEQ=SPARS64 ,NSAMP=5 1 DEF CUM X ------------------------------------------------------------------------------------------------------------------------------------ 6 ANY NIC3 MULTIAC NIC3-FI F110W SAMP-SEQ=SPARS64 ,NSAMP=5 1 DEF CUM X ------------------------------------------------------------------------------------------------------------------------------------ 21 NGC5128-POS NIC2 MULTIAC NIC2-FI F160W CAMERA-FOCUS=1-2 , 1 DEF PAR 22-23 WITH 21 2 CUM X SAMP-SEQ=SPARS64 ,NSAMP=5 , PATTERN=SQUARE-WAVE-DITH , NUM-POS=6 ,DITH-SIZE=0.712 , PATTERN-ORIENT=215.0 ------------------------------------------------------------------------------------------------------------------------------------ 22 ANY NIC1 MULTIAC NIC1-FI F160W SAMP-SEQ=SPARS64 ,NSAMP=5 1 DEF CUM X ------------------------------------------------------------------------------------------------------------------------------------ 23 ANY NIC3 MULTIAC NIC3-FI F160W SAMP-SEQ=SPARS64 ,NSAMP=5 1 DEF CUM X ------------------------------------------------------------------------------------------------------------------------------------ 24 NGC5128-POS NIC2 MULTIAC NIC2-FI F110W CAMERA-FOCUS=1-2 , 1 DEF PAR 25-26 WITH 24 2 CUM X SAMP-SEQ=SPARS64 ,NSAMP=5 , PATTERN=SQUARE-WAVE-DITH , NUM-POS=6 ,DITH-SIZE=0.712 , PATTERN-ORIENT=215.0 ------------------------------------------------------------------------------------------------------------------------------------ 25 ANY NIC1 MULTIAC NIC1-FI F110W SAMP-SEQ=SPARS64 ,NSAMP=5 1 DEF CUM X ------------------------------------------------------------------------------------------------------------------------------------ 7874( 2) - 11/21/97 09:18 - [ 5] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 26 ANY NIC3 MULTIAC NIC3-FI F110W SAMP-SEQ=SPARS64 ,NSAMP=5 1 DEF CUM X ------------------------------------------------------------------------------------------------------------------------------------ 7874( 2) - 11/21/97 09:18 - [ 6] Visit: 02 Visit Priority: Visit Requirements: On Hold Comments: Additional Comments: Our observation plan for this visit has been coordinated with GO 7877. It would benefit both proposals if we use NIC3 for the K observations. As requested by P. Royle, the alternative plan is appended below (commented out with Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 31 NGC5128-POS NIC3 MULTIAC NIC3-FI F222M SAMP-SEQ=SPARS64 ,NSAMP=6 , 2 DEF PAR 32-33 WITH 31 1 CUM X PATTERN=SQUARE-WAVE-DITH , NUM-POS=5 ,DITH-SIZE=0.90 , PATTERN-ORIENT=215.0 ------------------------------------------------------------------------------------------------------------------------------------ 32 ANY NIC2 MULTIAC NIC2-FI F222M SAMP-SEQ=SPARS64 ,NSAMP=6 2 DEF CUM X ------------------------------------------------------------------------------------------------------------------------------------ 33 ANY NIC1 MULTIAC NIC1-FI F160W SAMP-SEQ=SPARS64 ,NSAMP=6 2 DEF CUM X ------------------------------------------------------------------------------------------------------------------------------------ 34 NGC5128-POS NIC3 MULTIAC NIC3-FI F222M SAMP-SEQ=SPARS64 ,NSAMP=6 , 2 DEF PAR 35-36 WITH 34 2 CUM X PATTERN=SQUARE-WAVE-DITH , NUM-POS=5 ,DITH-SIZE=0.90 , PATTERN-ORIENT=215.0 ------------------------------------------------------------------------------------------------------------------------------------ 35 ANY NIC2 MULTIAC NIC2-FI F222M SAMP-SEQ=SPARS64 ,NSAMP=6 2 DEF CUM X ------------------------------------------------------------------------------------------------------------------------------------ 36 ANY NIC1 MULTIAC NIC1-FI F160W SAMP-SEQ=SPARS64 ,NSAMP=6 2 DEF CUM X ------------------------------------------------------------------------------------------------------------------------------------ 37 NGC5128-POS NIC3 MULTIAC NIC3-FI F222M SAMP-SEQ=SPARS64 ,NSAMP=6 , 2 DEF PAR 38-39 WITH 37 3 CUM X PATTERN=SPIRAL-DITH-CHOP , NUM-POS=10 ,DITH-SIZE=0.90 , CHOP-SIZE=80.0 , PATTERN-ORIENT=215.0 ------------------------------------------------------------------------------------------------------------------------------------ 38 ANY NIC2 MULTIAC NIC2-FI F222M SAMP-SEQ=SPARS64 ,NSAMP=6 2 DEF CUM X ------------------------------------------------------------------------------------------------------------------------------------ 39 ANY NIC1 MULTIAC NIC1-FI F160W SAMP-SEQ=SPARS64 ,NSAMP=6 2 DEF CUM X ------------------------------------------------------------------------------------------------------------------------------------ 7874( 2) - 11/21/97 09:18 - [ 7] Summary Form for Proposal 7874 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations NIC2 NIC1 NIC3 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CAMERA-FOCUS=1-2 SAMP-SEQ=SPARS64 NSAMP=5 PATTERN=SQUARE-WAVE-DITH NUM-POS=6 DITH-SIZE=0.712 PATTERN-ORIENT=215.0 DITH-SIZE=0.90 NSAMP=6 NUM-POS=5 CHOP-SIZE=80.0 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PAR 2-3 WITH 1 PAR 5-6 WITH 4 PAR 22-23 WITH 21 PAR 25-26 WITH 24 PAR 32-33 WITH 31 PAR 35-36 WITH 34 PAR 38-39 WITH 37 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F160W F110W F222M ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC5128-POS1 ANY NGC5128-POS2 NGC5128-POS3 ------------------------------------------------------------------------------------------------------------------------------------