8399( 5) - 04/19/99 10:53 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 8399 Version: 5 Check-in Date: 19-Apr-1999 10:52:31 1.Proposal Title: Hubble Heritage observations of NGC 4650A ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO/DD 7 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Keith Noll Space Telescope Science Institute CoI: Jay Gallagher University of Wisconsin-Madison N CoI: Lynn Matthews NRAO-Charlottesville N CoI: Anne Kinney Space Telescope Science Institute N CoI: Lisa Frattare Space Telescope Science Institute Y CoI: Howard Bond Space Telescope Science Institute N CoI: Carol Christian Space Telescope Science Institute N CoI: Jayanne English Space Telescope Science Institute N CoI: Forrest Hamilton Space Telescope Science Institute N CoI: Zolt Levay Space Telescope Science Institute N ------------------------------------------------------------------------------------ 5. Abstract NGC 4650A is a classic example of a polar ring galaxy in which an outer disk orbits in approximately the polar plane of an inner, high surface brightness S0 galaxy. Polar ring (PR) galaxies are astrophysically important as highly visible examples of the e ffects of interactions and/or gas capture in galaxy evolution. Because they have two planes of rotation, they also provide unique opportunities to explore the extent and structures of `dark matter halos'. In this Hubble Heritage project we will provide a superb color image of NGC4650A obtained through a combination of observations in the blue, visual, and near infrared WFPC2 bandpasses. The resoltuion provided by WFPC2 will provide the first close-up view of the mysterious inner S0 disk system, as well as allowing us to explore the structural details of the larger polar disk. In this object we will search for evidence of effects of gravitational instabilities within the polar disk, ranging in spatial scale from dark cloud co mplexes to spiral arms, as a m eans to assess the importance of self-gravity within this subsystem. A dynamical analysis by Sackett and Sparke (1990, ApJ, 361, 408) as well as later imaging and kinematic investigations (Arnaboldi et al. 1997, AJ, 113, 585) suggest that the polar ring d isk could be more massive than suggested by HI and optical observations. This information will lead to a better understanding of the degree to which the dark matter is dominant far above the midplane of the central galaxy in NGC4650A. Our program is also designed to explore characteristics of small scale features within this unusual galaxy. For example, since PRs may result form mergers or interactions between galaxies, we need to be alert to the presence of aging super star clusters (or younger globular clusters) as well as the possibility of nuclear region anomalies. ------------------------------------------------------------------------------------ 8399( 5) - 04/19/99 10:53 - [ 2] Observations Description ------------------------ This program uses a stepped series of exposures times to avoid the possibility of saturation. The shortest exposures are designed to measure a possible nuclear point source with magnitude equal to the observed central surface brightness in one square arcs econd from Schweizer et al. (1983, AJ, 88, 909). The next step is to allow for potential super star clusters in the southern outer disk OB association visible in the VLT image. Finally deep exposures are needed to reveal the structure of the outer ring, i ncluding its dust lanes which are useful indicators of dynamical influences in the ISM (e.g. spiral arm compression waves), and to map the faint but small interaction zone between the two disks. These data will also be essential for exploring globular or other star clusters within this extraordinary galaxy. Exposure times are chosen to allow us to reach surface brightnesses of \mu_V=25 mag/arcsecond**2 with a S/N of 4 or greater per pixel, in F606W and F814W and about 3 in F 450W. These data will enable u s to map the main body of the galaxy to a surface brightness limit equivalent to the normal definition of the ``optical radius'' of a galaxy, and will produce an image that is fully competitive with that taken with the VLT. [Note: Reduction of the program to 7 orbits would require dropping one F814W exposure and thereby reducing our ability to map the outer disk where we would have S/N<3; a 6 orbit program would drop an F450W exposure, and lead to a further loss in information about the outer polar disk a nd colors of any faint star clusters.] Real Time Justification ----------------------- Calibration Justification ------------------------- Real_Time_Justification Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Paper Products: NO Media: ELECTRONIC Blocking Factor: 10 Ship To: STSCI Ship Via: Email: frattare@stsci.edu ------------------------------------------------------------------------------------ 8399( 5) - 04/19/99 10:53 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC4650A GALAXY RA=12H 44M 49.2S +/- 0.1S, DEC=- J2000 V = 2910 B = 14.2 40D 42' 52.0" +/- 1", PLATE- B-R = 0.92 ID=00ZD Comments: V, B-V not available; exposures based on surface brightness. 8399( 5) - 04/19/99 10:53 - [ 4] Visit: 01 Visit Priority: Visit Requirements: ORIENT 25.00D TO 35.00D BETWEEN 01-Apr-1999 AND 01-May-1999 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 NGC4650A WFPC2 IMAGE WF4-FIX F450W 2 100 S POS TARG -30.0, 0 ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC4650A WFPC2 IMAGE WF4-FIX F450W CR-SPLIT=0.5,CR-TOLERANCE=0.1 1 2000 S SAME POS AS 1 EXPAND ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC4650A WFPC2 IMAGE WF4-FIX F450W CR-SPLIT=0.5,CR-TOLERANCE=0.1 1 2600 S POS TARG -30.2, 0.2 EXPAND ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC4650A WFPC2 IMAGE WF4-FIX F450W CR-SPLIT=0.5,CR-TOLERANCE=0.1 1 2600 S POS TARG -30.4, 0.4 EXPAND ------------------------------------------------------------------------------------------------------------------------------------ 8399( 5) - 04/19/99 10:53 - [ 5] Visit: 02 Visit Priority: Visit Requirements: SAME ORIENT AS 01 BETWEEN 01-Apr-1999 AND 01-May-1999 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 NGC4650A WFPC2 IMAGE WF4-FIX F606W 2 20 S POS TARG -30.4, 0.4 ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC4650A WFPC2 IMAGE WF4-FIX F606W CR-SPLIT=0.5,CR-TOLERANCE=0.1 1 2200 S SAME POS AS 1 EXPAND ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC4650A WFPC2 IMAGE WF4-FIX F606W CR-SPLIT=0.5,CR-TOLERANCE=0.1 1 2600 S POS TARG -30.0, 0 EXPAND ------------------------------------------------------------------------------------------------------------------------------------ 8399( 5) - 04/19/99 10:53 - [ 6] Visit: 03 Visit Priority: Visit Requirements: SAME ORIENT AS 01 BETWEEN 01-Apr-1999 AND 01-May-1999 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 NGC4650A WFPC2 IMAGE WF4-FIX F814W 2 30 S POS TARG -30.0, 0 ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC4650A WFPC2 IMAGE WF4-FIX F814W CR-SPLIT=0.5,CR-TOLERANCE=0.1 1 2200 S SAME POS AS 1 EXPAND ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC4650A WFPC2 IMAGE WF4-FIX F814W CR-SPLIT=0.5,CR-TOLERANCE=0.1 1 2600 S POS TARG -30.2, 0.2 EXPAND ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC4650A WFPC2 IMAGE WF4-FIX F814W CR-SPLIT=0.5,CR-TOLERANCE=0.1 1 2600 S POS TARG -30.4, 0.4 EXPAND ------------------------------------------------------------------------------------------------------------------------------------ 8399( 5) - 04/19/99 10:53 - [ 7] Summary Form for Proposal 8399 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures WF4-FIX ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=0.5 CR-TOLERANCE=0.1 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO/DD ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 25.00D TO 35.00D BETWEEN 01-Apr-1999 AND 01-May-1999 POS TARG -30.0, 0 SAME POS AS 1 EXPAND POS TARG -30.2, 0.2 EXPAND POS TARG -30.4, 0.4 EXPAND SAME ORIENT AS 01 BETWEEN 01-Apr-1999 AND 01-May-1999 POS TARG -30.4, 0.4 POS TARG -30.0, 0 EXPAND ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F450W F606W F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC4650A ------------------------------------------------------------------------------------------------------------------------------------