6578( 11) - 05/05/97 11:43 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6578 Version: 11 Check-in Date: 05-May-1997 10:46:40 1.Proposal Title: Optical Morphology of NGC 5128: X-ray Ridges and the Geometry of the Dust Lane ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle GALAXIES & CLUSTERS GO 6 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: ETHAN SCHREIER SPACE TELESCOPE SCIENCE INSTITUTE CoI: Alessandro Capetti Space Telescope Science Institute N CoI: Duccio Macchetto Space Telescope Science Institute N ------------------------------------------------------------------------------------ 6. Abstract We propose the first observations of NGC 5128 with WF/PC-2 to study the detailed morphology of the dust lane. We will resolve the stellar associations and determine the number, luminosities and spectral types of the sources seen along the edge of the dust lane in earlier observations with WF/PC-I. We will quantitatively check the interpretation that the X-ray ridges parallel to the dust lane are caused by massive X-ray binaries associated with young stars. Simultaneously, we will study the disk itself -- mapping the position of the stars and stellar associations along both north and south edges of the disk, possibly observing a significant number within the dust lane, and comparing the source distribution with the observed dust lane morphology, we will determine if the clustering of the bright sources is a projection of sources evenly distributed in or on a warped disk, or caused by interaction between the disk and the galaxy. Simultaneously, the possible scattering cloud near the nucleus will be studied using HST's highest available resolution in V and I. ------------------------------------------------------------------------------------ 6578( 11) - 05/05/97 11:43 - [ 2] Observations Description ------------------------ For the primary observations, we will use WF/PC-2 with three different filters, F336W, F555W and F814W. First, we will center the PC on a region of the northern edge of the dust lane so as to include a significant number of the bright sources seen by WF/PC-I. We will be able simultaneously to observe several arcminutes of the southern edge of the dust lane along the two diagonal WF chips. A second observation will include the nucleus and a region of the southern edge of the dust lane in the aperture of the PC while simultaneously observing several arcminutes of the northern edge of the dust lane in the WF chips. Note that both the north and south ridges will be observed, since there is evidence from infrared, X-ray and optical observations (and the models) that they differ. The PC provides the highest (0.046") resolution for determining the number of individual stars and cluster shapes in the crowded regions, while the WF observations will provide the necessary larger field of view. By cross- comparing these observations, we will be able to extrapolate the high resolution results to the larger FOV. The selected filters will provide the widest reasonable color range for discriminating the young blue objects, hypothesized to explain the X-ray emission, from older populations of objects. A color-color reddening-free diagram will be obtained in order to obtain spectral information independent of the dust absorption, which appears to be significant in the regions of interest. The exposure time is calculated to allow the detection of isolated stars of spectral type B3 or earlier. Given the distance modulus of Cen A, 27.7 mag assuming a distance of 3.5 Mpc, the magnitudes of a B3 star are 25.3, 26.1 and 26.3 in the U, V and I standard filters respectively. To reach these brightness limits two orbits are required with F336W, while one orbit is needed for each of the F555W and F814W filters. Thus, four orbits are required for each of the two different primary pointings, a total of 8 orbits. Real Time Justification ----------------------- None. None. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: ------------------------------------------------------------------------------------ 6578( 11) - 05/05/97 11:43 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC5128- GALAXY,Elliptical,Radio RA=13H 25M 30.3S +/- 0.1S, DEC= 2000 V = 550 V = 7.8+/-0.1 RIDGEN Galaxy -43D 00' 51" +/- 1" 11 NGC5128- GALAXY,Elliptical,Radio RA=13H 25M 27.8S +/- 0.1S, DEC= 2000 V = 550 V = 7.8+/-0.1 RIDGES Galaxy -43D 01' 07" +/- 1" 6578( 11) - 05/05/97 11:43 - [ 4] Visit: 01 Visit Requirements: ORIENT 115D TO 135D On Hold Comments: <none> Additional Comments: <none> Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 11 NGC5128-RID WFPC2 IMAGE PC1-FIX F336W CR-SPLIT=0.75 2 2420 S GES ------------------------------------------------------------------------------------------------------------------------------------ 21 NGC5128-RID WFPC2 IMAGE PC1-FIX F555W 1 300 S GES ------------------------------------------------------------------------------------------------------------------------------------ 22 NGC5128-RID WFPC2 IMAGE PC1-FIX F555W 1 2020 S GES ------------------------------------------------------------------------------------------------------------------------------------ 31 NGC5128-RID WFPC2 IMAGE PC1-FIX F814W 1 300 S GES ------------------------------------------------------------------------------------------------------------------------------------ 32 NGC5128-RID WFPC2 IMAGE PC1-FIX F814W 1 2020 S GES ------------------------------------------------------------------------------------------------------------------------------------ 6578( 11) - 05/05/97 11:43 - [ 5] Visit: 02 Visit Requirements: ORIENT 179D TO 181D FROM 1 On Hold Comments: <none> Additional Comments: <none> Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 11 NGC5128-RID WFPC2 IMAGE PC1-FIX F336W CR-SPLIT=0.75 2 2600 S GEN ------------------------------------------------------------------------------------------------------------------------------------ 21 NGC5128-RID WFPC2 IMAGE PC1-FIX F555W 1 300 S GEN ------------------------------------------------------------------------------------------------------------------------------------ 22 NGC5128-RID WFPC2 IMAGE PC1-FIX F555W 1 2200 S GEN ------------------------------------------------------------------------------------------------------------------------------------ 31 NGC5128-RID WFPC2 IMAGE PC1-FIX F814W 1 300 S GEN ------------------------------------------------------------------------------------------------------------------------------------ 32 NGC5128-RID WFPC2 IMAGE PC1-FIX F814W 1 2200 S GEN ------------------------------------------------------------------------------------------------------------------------------------ 6578( 11) - 05/05/97 11:43 - [ 6] Summary Form for Proposal 6578 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=0.75 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category GALAXIES & CLUSTERS ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 115D TO 135D ORIENT 179D TO 181D FROM 1 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F336W F555W F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC5128-RIDGES NGC5128-RIDGEN ------------------------------------------------------------------------------------------------------------------------------------