Proposal_Information Title: Parallel high resolution imaging of diffuse objects in the Magellanic Clouds Proposal_Category: GO Scientific_Category: Interstellar Medium Cycle: 5 Investigators PI_name: Dr. Jeremy Walsh PI_Institution: Space Telescope European Coordinating Facility CoI_Name: Dr. Marc Azzopardi CoI_Institution: Observatoire de Marseille CoI_Name: Dr. You-Hua Chu CoI_Institution: University of Illinois CoI_Name: Dr. Donald Garnett CoI_Institution: University of Minnesota CoI_Name: Dr. Mohammad Heydari-Malayeri CoI_Institution: Institut d'Astrophysique CoI_Name: Dr. Barry Lasker CoI_Institution: Space Telescope Science Institute Contact: Y CoI_Name: Prof. James Lequeux CoI_Institution: Observatoire de Paris, Meudon CoI_Name: Prof. John Meaburn CoI_Institution: University of Manchester CoI_Name: Dr. George Meylan CoI_Institution: European Southern Observatory CoI_Name: Dr. Nicole Meyssonnier CoI_Institution: Observatoire de Marseille Abstract: The Magellanic Clouds, because of their well-determined distance and small extinction, allow an unprecedented opportunity to observe many ISM phenomena occurring in a whole galaxy. The HST resolution (0.1" = 0.025 pc) offers detail hitherto poorly studied in the extragalactic context on the morphology and spatial relationships in various ISM processes associated with the evolution of Population I and Population II systems. This long term (11 cycles) parallel program exploits these opportunities by obtaining WFPC2 images of appropriate targets that are accessible at the same time as primary pointings. The number of parallel observations per Cycle is estimated at ~15; and our intent is to accumulate a significant archive of Magellanic Cloud direct images over the life of the program. The parallel targets, to be specified in Phase II of each HST Cycle, will include (or search for) compact H II regions and young clusters, proto-stellar and maser regions, reflection nebulae, Herbig-Haro objects, stellar ejecta, SNR and wind-driven shells, supershells, planetary nebulae, Very Low Excitation nebulae and candidate proto-planetary nebulae. The observations will be primarily in the Balmer lines and the stronger forbidden lines, with supplemental continuum images. Questions Observing_Description: Pure parallel images of a variety of diffuse nebular objects in the Small and Large Magellanic Clouds are to be obtained with WFPC2. The primary pointings of HST in the Magellanic Clouds will provide the basis for this project. For each primary (FOS or FOC) pointing listed in the approved primary target list of a given Cycle, we will (in Phase II) survey an appropriate annulus around the target (against catalogs and direct images) for possible nebular and stellar targets as detailed in the scientific justification. If an object of interest occurs within the WFPC2 field at an accessible roll angle, emission line images in narrow bands and continuum images in broad band filters will be requested. (The default roll-angle must be used in our object selection but we will delimit ranges of roll-angles of particular advantage to our program dependent on the pointing position.) The targets of interest cover a broad range - to ensure a strong probability of obtaining images - from proto-stellar regions, through HII regions, supernova remnants, shells and supershells to evolved objects around high mass stars to planetary nebulae. Depending on the object and the exposure time of the primary pointing, a variety of emission line and or continuum images will be taken. Example objects are given in the Observing Summary. These are not program targets as the target selection is entirely dictated by the primary pointings. The program relies heavily on the primary pointings which clearly will differ from cycle to cycle. However we do not expect our methods or proposed targets to change substantially from year to year. On the basis of planning in previous cycles, there were about 30 hours of FOS and FOC pointings in the Magellanic Clouds, from which we selected the most promising fields (eliminating short primary exposures), giving >=10 hours of parallel imaging. Similar estimates hold for further cycles dependant on the pattern of primary observations. Over the envisaged lifetime of this program, a potentially valuable archive of 300 images of Magellanic Cloud nebulae will accrue. In Cycles 2-4 we have had many parallel opportunities but only a few observations (Six images in Cycle 2 and four in Cycle 3). With the improvements in scheduling we anticipate that a larger number of parallel images of the Magellanic Clouds will result, leading to new scientific results. Additional_Comments: CRAFTING RULES -------------- Decision has been taken to give continuum exposures the lowest priority. Assume that we can test for previous exposures in same SMS, but not in other ones. Definitions and rules H-alpha = F656N O-III = F502N red-cont = F675W grn-cont = F547M N1 = number of previous H-alpha exposures, ie, total taken on this primary target, in this SMS. It is a reasonable approximation to to use no roll angle constraint in this test. N2 = number of previous O-III exposures, as above N3 = number of previous red-cont exposures, as above N4 = number of previous grn-cont exposures, as above All continuum exposures are of duration two minutes and these are CR-split, approximately 50/50. All H-alpha and O-III exposures are to be of duration 1000-2000 sec, with a soft maximum around 2700 sec. All such exposures are CR-split whenever possible (ie, if two shorter exposures impossible because of readout constraints, take one longer one). Priorities (these are not time sequences, simply priorities). They apply to each object SEPARATELY. First obtain at least an hour of exposure in H-alpha Next obtain at least an hour of exposure in O-III. But if there is opportunity for only one O-III exposure, it's better to use the time on H-alpha, unless one somehow knows that there is another O-III in another SMS. If this can't be computed, it's better to do the O-III and run the risk that it will be an orphan. Next continuum exposures as follows one red-cond one grn-cont second red-cont second grn-cont do not take more than two exposures in each continuum Finally, continue to take H-alpha and O-III exposures, keeping the total exposure times approximately the same. Data_Distribution Medium: 8MM ! 8MM or 6250BPI or 1600BPI Blocking_Factor: 10 ! 10 or 1 Ship_To: Dr. D. Garnett ! STSCI or PI_Address or Astronomy Department 116 Church Street, S.E. Minneapolis, Minn. 55455 Ship_Via: UPS ! UPS (2-day) or OVERNIGHT