6814( 3) - 02/05/96 11:40 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6814 Version: 3 Check-in Date: 05-Feb-1996 11:06:03 1.Proposal Title: The Nucleus and Stellar Populations of the dEn Galaxy NGC 5206 ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle GALAXIES & CLUSTERS GO 6 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Andrew Layden McMaster University CoI: Ata Sarajedini Kitt Peak National Observatory N CoI: Robert Schommer Cerro Tololo Inter-American Observatory N CoI: William Harris McMaster University N CoI: Patrick Durrell McMaster University N ------------------------------------------------------------------------------------ 6. Abstract Few detailed facts are known about nucleated dwarf elliptical galaxies (dEn's), yet they comprise a large, perhaps dominant fraction of the dwarf elliptical galaxies in the Universe. In particular, the nature of the nucleation and the mechanisms responsible for it are practically unstudied. There are suggestions that nuclei are the results of significant second epochs of star formation. The nuclei have also been suggested as the progenitors of the globular clusters seen in the Galaxy today; nuclei of accreted dEn's survive as globular clusters while the envelopes of the dEn's were mixed into the halo field. In an effort to obtain high quality data on a particular member of this class of galaxy, we propose to use WFPC2 to obtain "B", "V" and "I" images of the nucleus of the closest isolated dEn galaxy, NGC 5206. These images will enable us to investigate its light and color profiles at an angular resolution unobtainable from the ground. The size and detailed brightness profile of the nucleus will be compared with those of the Galactic globular clusters. Color gradients within the nucleus and relative to the surrounding envelope, for which we already posess wide-angle, ground-based images, will provide clues about the extent and intensity of any second epochs of star formation in NGC 5206. The WF images will allow us to search the innermost regions of the galaxy for star clusters. ------------------------------------------------------------------------------------ 6814( 3) - 02/05/96 11:40 - [ 2] Observations Description ------------------------ We will center the PC chip on the nucleus of NGC 5206, and will obtain a sequence of exposures in F439W ("B"), F555W ("V"), and F814W ("I"). The exposure times are designed to provide the maximum dynamic range, since the surface brightness ranges from B ~ 17.5 mag asec^2 for the central arcsec to B ~ 25 near the edges of the WF chips in this pointing. In particular, we do not know the light profile at the very center (does it have a cusp indicative of core-collapsed stellar system or a black shole?), so we require several very short exposures to ensure that we do not saturate these critical pixels. Orbit 1 will consist of the following exposures in F814W: 3x500s, 200s, 50s, 10s, and a 10s exposure in F555W. Orbit 2 will consist of the following exposures in F555W: 3x600s, 200s, 50s. Orbit 3 will consist of 2x900s, 450s, and 180s in F439W. Real Time Justification ----------------------- None. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 6814( 3) - 02/05/96 11:40 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC5206-NUC GALAXY,DWARF RA=13H 33M 43.88S +/- 0.3",DEC=- J2000. V = 14.5+/-0.3 ELLIPTICAL,GALAXY,NUCLE 48D 09' 03.9" +/- 0.3",PLATE- B = 15.3+/-0.2 US ID=02EX I = 13.4+/-1.0 E(B-V) = 0.17+/-0.03 SURF(V) = 21.0+/-0.1 SURF(B) = 21.8+/-0.1 SURF(I) = 19.9+/-0.5 Comments: The Broad Band Magnitudes are estimates of the total nuclear magnitude, derived from semi-resolved ground based images (1.5" seeing). The Surface Brightnesses are estimated at a radius of 17 arcsec, i.e., at the edge of the PC chip. 6814( 3) - 02/05/96 11:40 - [ 4] Visit: 01 Visit Requirements: ORIENT 300D TO 45D 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 ------------------------------------------------------------------------------------------------------------------------------------ 10 NGC5206-NUC WFPC2 IMAGE PC1 F814W 3 500S ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC5206-NUC WFPC2 IMAGE PC1 F814W 1 200S ------------------------------------------------------------------------------------------------------------------------------------ 30 NGC5206-NUC WFPC2 IMAGE PC1 F814W 1 50S ------------------------------------------------------------------------------------------------------------------------------------ 40 NGC5206-NUC WFPC2 IMAGE PC1 F814W 1 10S ------------------------------------------------------------------------------------------------------------------------------------ 45 NGC5206-NUC WFPC2 IMAGE PC1 F555W 1 10S ------------------------------------------------------------------------------------------------------------------------------------ 60 NGC5206-NUC WFPC2 IMAGE PC1 F555W 3 600S ------------------------------------------------------------------------------------------------------------------------------------ 70 NGC5206-NUC WFPC2 IMAGE PC1 F555W 1 230S ------------------------------------------------------------------------------------------------------------------------------------ 95 NGC5206-NUC WFPC2 IMAGE PC1 F555W 1 60S ------------------------------------------------------------------------------------------------------------------------------------ 100 NGC5206-NUC WFPC2 IMAGE PC1 F439W CR-SPLIT=no 2 900S ------------------------------------------------------------------------------------------------------------------------------------ 105 NGC5206-NUC WFPC2 IMAGE PC1 F439W 1 400S ------------------------------------------------------------------------------------------------------------------------------------ 110 NGC5206-NUC WFPC2 IMAGE PC1 F439W 1 160S ------------------------------------------------------------------------------------------------------------------------------------ 6814( 3) - 02/05/96 11:40 - [ 5] Summary Form for Proposal 6814 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=no ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category GALAXIES & CLUSTERS ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 300D TO 45D ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F814W F555W F439W ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC5206-NUC ------------------------------------------------------------------------------------------------------------------------------------