! Proposal 6780, submission 5 ! PI: George Jacoby ! Received Mon Sep 9 16:06:14 EDT 1996 ! From: morsey@casa.Colorado.EDU ! Hubble Space Telescope Cycle 6 (1996) Phase II Proposal Template ! $Id: 6780,v 7.1 1996/09/10 13:46:30 pepsa Exp $ ! ! Refer to the HST Phase II Proposal Instructions to fill this out ! ! Anything after a "!" is ignored, and may be deleted ! ! All keywords with multiple entries are comma delimited except the ! Visit_Requirements and Special_Requirements keywords which can be ! delimited with carriage returns or semi-colons, but not commas ! ! For help call your Program Coordinator: Sleiman ! Phone: 410-338-4753 , E-mail: sleiman@stsci.edu ! ! This partially completed template was generated from a Phase I proposal. ! Name of Phase I Proposal: archive-1003.jacoby.prop ! Date generated: Fri Dec 22 18:23:01 EST 1995 ! Proposal_Information ! Section 4 Title: Spectroscopy and Imaging of a New Globular Cluster Planetary Nebula Proposal_Category: GO Scientific_Category: INTERSTELLAR MEDIUM Cycle: 6 Investigators PI_name: George Jacoby PI_Institution: National Optical Astronomy Observatories CoI_Name: Laura Fullton CoI_Institution: Space Telescope Science Institute Contact: ! Y or N (designate at most one contact) CoI_Name: Jon Morse CoI_Institution: University of Colorado Contact: ! Y or N (designate at most one contact) Abstract: ! Free format text (please update) We found the third (and probably last) PN to be associated with a Galactic globular cluster in NGC 6441. Optical spectra indicate an unexpectedly severe oxygen depletion (O/Fe ~ - 0.8). Ionization models (CLOUDY) indicate that oxygen at higher ionization stages may account for half of the depletion. HST observations are requested to (1) obtain UV spectra of the nebula to constrain models further and to determine directly the contributions from unseen higher stages of ionization of oxygen, while measuring carbon and nitrogen abundances, and (2) image the nebula at high resolution to ascertain its degree of disruption by the ISM. Neither the UV spectra nor the high resolution imaging can be done with ground-based telescopes. The optically derived O/Fe is 30-40* smaller than seen in the M15 PN or in field stars. This ratio impacts the ages derived for clusters where the field star assumption is used. Stellar dredge-up theory does not account for a depletion of oxygen this extreme. There is a small chance that the NGC 6441 PN is NOT a member of the cluster; its velocity differs from the cluster by ~ 20 km/s. This difference could be due to an interaction with the ISM. Direct images of the nebula are requested to examine the morphology. An interaction will be evident by the presence of a bow shock or by displacement of the ``central'' star from the nebula center. Questions ! Free format text (please update) Observing_Description: We will obtain HAlpha (F656N) and [OIII] (F502N) images of the PN in NGC 6441 with the PC to (1) provide EARLY ACQUISITION images for pointing information, and (2) ascertain its degree of distortion that might result from an interaction with the ISM, (3) identify any ionization dependent structures. We choose to image primarily in HAlpha rather than OIII since the flux is slightly higher and the throughput better at the red wavelength, resulting in a 2* improvement and the primary goal of the imaging is to prepare for the spectroscopy. Short continuum exposures (F675W, F547M) are required to subtract stellar sources from the faint nebular image. The images are necessary for the spectroscopy since we wish to avoid as many stars as possible while collecting as much nebular light as we can. Stars can be the limiting noise source if the aperture is poorly placed. Exposure times for the PC imaging (assuming 7.1 min for acquisition and 5.25 min for orbit 2 and 3 re-acquisition) allow for 6 exposures at Halpha of 600s each in orbits 1 and 2, 5 F675W red continuum exposures of 23s each at the end of orbits 1 and 2. Two exposures of 2s through F675W are also needed to avoid saturating our FOS offset star. Orbit 3 was originally intended to begin the FOS spectroscopy in a second visit, but the SAA limits our 9 orbits for spectroscopy to 8 orbits; consequently, we have moved one orbit to enhance the imaging science. Orbit 3 provides for 2 [OIII] exposures of 1000s each and 2 green continuum exposures of 80s and 2 of 20s each. For a nebula flux of F_HAlpha = 3* 10^-15 ergs/cm^2/s/arcsec^2, based on our spectroscopy, the S/N per PC pixel over the 3900s of Halpha on- band exposures will exceed 2.5 per pixel. The total continuum exposures have an effective throughput 50* higher, so only 1.3 minutes are required to match the on-band image; however, 2 minutes total are requested to avoid degradation of the on-band image when subtracting the continuum. Similar arguments apply at [OIII], although the final S/N will be about 30% lower due to the lower system throughput at 5007A. Three spectral setups are needed to tie into the ground-based spectra. Only the blue spectrum (grating G160L) is time consuming, as a consequence of the weak lines of nitrgoen and the lower system throughput. This region of the spectrum, requiring 5 orbits, is crucial: it provides the most constraints on the photo-ionization models through the lines of NV (1240), OIV (1402), NIV (1487), CIV (1549), NIII (1747), HeII (1640), OIII (1663), CIII (1909), and NeIV 2422. Shorter exposures with gratings G270H and G400H will tie into the optical spectrum via NeIII (3868), HGamma (4340), and HeII (4686) which are all strong lines. The exposure time in the blue (1150-2510) is calculated to yield a good measurement (SNR ~ 5) for extinction (E(B-V)=0.5) affected lines as weak as 25\% of HBeta (F^obs_HBeta = 0.6 * 10^-15 ergs/cm^2/s/arcsec) integrated over aperture 1.0 (0.86" round). Photo-ionization models indicate that the high excitation nitrogen lines will be this weak. With this goal, all FOS data can be obtained in 1 visit. Acquisition for FOS can be performed by a peak-up on a nearby star, followed by a small blind offset to the nebula position. Absolute positioning is not critical. Peaking up on the nebula is NOT desired, as the aperture may be pulled off the optimum nebular position to a continuum source. \medskip begintabularlll WFPC2 & Primary Orbits:3 & Exposures:10 (3900s in HAlpha,2.3 min in R, 2800s in [OIII], 320s in Green, total) , FOS Acq + G400H & Primary Orbits:1 & Exposures:2 1700s, FOS G400H + G270H (ReD) & Primary Orbits:1 & Exposures:3 (1000s + 1220s) , FOS G270H (ReD) & Primary Orbits:1 & Exposures:1 (2480s) , FOS G160L (BLue) & Primary Orbits:1 & Exposures:1 (2110s) , FOS G160L (BLue) & Primary Orbits:1 & Exposures:1 (2500s) , FOS G160L (BLue) & Primary Orbits:1 & Exposures:2 2500s, FOS G160L (BLue) & Primary Orbits:2 & Exposures:2 (2500s each orbit) , endtabular \medskip The switch from red to blue detectors can be done at the end of target visibility for the G270H grating to minimize loss of exposure time during the orbit commencing the G160L grating observations. Real_Time_Justification: None We are submitting a proposal to CTIO for deeper optical spectra and near-IR spectra (out to 9532 Angstrom) to assist in constraining the photo-ionization models at the low excitation species end. Calibration_Justification: ! Move appropriate text from Real_Time_Justification Additional_Comments: Please ensure that WFPC-2 EARLY/ACQ imaging is scheduled well in advance of FOS spectroscopy. Fixed_Targets ! Section 5.1 Target_Number: 1 Target_Name: NGC6441-PN Alternate_Names: Description: STELLAR CLUSTER,GLOBULAR CLUSTER,ISM,PLANETARY NEBULA Position: RA=17H50M10.88S +/- 0.1S, DEC=-37D03'27.1" +/- 1", PLATE-ID=060H Equinox: 2000 RV_or_Z: V=+30 Flux: V=19.8 +/- 0.5, SURF-LINE(4861)=6+/-2 E-16 Comments: Target_Number: 2 Target_Name: NGC6441-OFFSET Alternate_Names: Description: STAR Position: RA=17H50M11.2916S +/- 0.05S, DEC=-37D03'35.71" +/- 1", PLATE-ID=060H Equinox: 2000 RV_or_Z: V=+30 Flux: V=16.3 +/- 0.1, ! Include at least V and B-V B-V=1.60 +/- 0.1 Comments: Magnitude, color and position determined from EARLY/ACQ images. Target_Number: 3 Target_Name: NGC6441-POSN1 Alternate_Names: Description: ISM,PLANETARY NEBULA,KNOT Position: R=10.91", PA=328.188D, FROM 2 Equinox: 2000 RV_or_Z: V=+30 Flux: SURF-LINE(4861)=6+/-2 E-16 Comments: Knot determined from WFPC2 EARLY/ACQ images. ! This is a template for a single visit containing a single exposure ! Repeat exposure and visit blocks as needed Visits ! Section 6 Visit_Number: 1 Visit_Requirements: ! Section 7.1 Visit_Comments: EARLY/ACQ images to identify target for FOS spectroscopy. Best ORIENT is 210D but this may be unschedulable and is NOT critical! Put target in middle of PC1. WFPC2 observations must be scheduled as early as possible to allow time for analysis and scheduling of FOS orbits in the August or October windows, the last chances before FOS disappears. We therefore request the WFPC2 images to be obtained in the April/May cycle 5 window. Exposure_Number: 1 ! Section 6.5 Target_Name: NGC6441-PN Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F656N Wavelength: Optional_Parameters: CR-SPLIT=0.5 Number_of_Iterations: 1 Time_Per_Exposure: 1200S Special_Requirements: ! Section 7.2 Exposure_Number: 2 ! Section 6.5 Target_Name: NGC6441-PN Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F656N Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 600S Special_Requirements: ! Section 7.2 Exposure_Number: 3 ! Section 6.5 Target_Name: NGC6441-PN Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F675W Wavelength: Optional_Parameters: CR-SPLIT=0.5 Number_of_Iterations: 1 Time_Per_Exposure: 46S Special_Requirements: ! Section 7.2 Exposure_Number: 4 ! Section 6.5 Target_Name: NGC6441-PN Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F675W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 23S Special_Requirements: ! Section 7.2 Exposure_Number: 5 ! Section 6.5 Target_Name: NGC6441-PN Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F656N Wavelength: Optional_Parameters: CR-SPLIT=0.5 Number_of_Iterations: 1 Time_Per_Exposure: 1200S Special_Requirements: ! Section 7.2 Exposure_Number: 6 ! Section 6.5 Target_Name: NGC6441-PN Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F656N Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 600S Special_Requirements: ! Section 7.2 Exposure_Number: 7 ! Section 6.5 Target_Name: NGC6441-PN Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F675W Wavelength: Optional_Parameters: CR-SPLIT=0.5 Number_of_Iterations: 1 Time_Per_Exposure: 46S Special_Requirements: ! Section 7.2 Exposure_Number: 8 ! Section 6.5 Target_Name: NGC6441-PN Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F675W Wavelength: Optional_Parameters: CR-SPLIT=0.5 Number_of_Iterations: 1 Time_Per_Exposure: 6S Special_Requirements: ! Section 7.2 Exposure_Number: 9 ! Section 6.5 Target_Name: NGC6441-PN Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F547M Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 80S Special_Requirements: ! Section 7.2 Exposure_Number: 10 ! Section 6.5 Target_Name: NGC6441-PN Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F547M Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 80S Special_Requirements: ! Section 7.2 Exposure_Number: 11 ! Section 6.5 Target_Name: NGC6441-PN Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F547M Wavelength: Optional_Parameters: CR-SPLIT=0.5 Number_of_Iterations: 1 Time_Per_Exposure: 40S Special_Requirements: ! Section 7.2 Exposure_Number: 12 ! Section 6.5 Target_Name: NGC6441-PN Config: WFPC2 Opmode: IMAGE Aperture: PC1-FIX Sp_Element: F502N Wavelength: Optional_Parameters: Number_of_Iterations: 1 Time_Per_Exposure: 2000S Special_Requirements: ! Section 7.2 Visit_Number: 2 Visit_Requirements: ON HOLD FOR 1 ! Section 7.1 ! Uncomment or copy visit level special requirements needed ! Most of these requirements (including ORIENT) will limit scheduling ! PCS MODE [Fine | Gyro] ! GUIDing TOLerance ! DROP TO GYRO IF NECESSARY [NO REACQuisition] ! ORIENTation TO ! ORIENTation TO FROM ! ORIENTation TO FROM NOMINAL ! SAME ORIENTation AS ! CVZ ! PARallel ! SCHEDulability ! AFTER [BY [TO ]] ! AFTER ! BEFORE ! BETWEEN AND ! GROUP WITHIN