Cycle 11 Abstract catalog (based on Phase I submissions) Generated on: Mon Dec 10 08:39:48 EST 2001 ============================================================================= Proposal Category: GO Scientific Category: Quasar Absorption Lines and IGM ID: 9350 Title: Intergalactic HeII absorption in CSO 118 = HS 1157+3143 PI: Dieter Reimers PI Institution: Hamburger Sternwarte We propose to observe the HeII Gunn-Peterson effect in the z = 3 quasar CSO 118, which has been discovered in our SNAPSHOT survey to have a transparent line of sight. The aim is in particular to extend our knowledge about HeII reionization which has been observed to take place in the range z = 3.1 to z = 2.8. While existing and future FUSE observations will cover the redshift range z < 2.9, redshifts above 2.9 have been covered by HST with only 2 lines of sights. ================================================================================ Proposal Category: GO Scientific Category: Cosmology ID: 9351 Title: Determining Hubble's Constant from Observations of Cepheids in the Host Galaxy of SN Ia 1994ae PI: Adam Riess PI Institution: Space Telescope Science Institute We propose to determine the luminosity of the type Ia supernova (SN Ia) 1994ae by observing Cepheids in the host spiral galaxy NGC 3370. Modern CCD photometry has yielded an extremely tight Hubble diagram for SNe Ia with a precisely determined intercept (i.e., Delta H_0/H_0 ~ 1) measurement of the true Hubble constant is still limited by the calibration. The HST calibration of all but a few SNe Ia observed to date is significantly compromised by the systematics of photographic photometry and host galaxy extinction, as well as by the photometric uncertainties associated with WFPC2. In contrast, SN 1994ae is one of the very best-observed SNe Ia with CCD photometry. The exquisite B, V, $R, and I light curves are well-sampled beginning 10 days before maximum brightness, and they indicate little reddening. From our supernova photometry and the current provisional SN Ia calibration we would find a distance of 30 +/- 2.1 Mpc, well within the range where ACS can accurately observe Cepheid light curves and distinguish Cepheids from nonvariable stars. ================================================================================ Proposal Category: GO Scientific Category: Cosmology ID: 9352 Title: The Deceleration Test from Treasury Type Ia Supernovae at Redshifts 1.2 to 1.6 PI: Adam Riess PI Institution: Space Telescope Science Institute Type Ia supernovae (SNe Ia) provide the only direct evidence for an accelerating universe, an extraordinary result that needs a rigorous test. The case for cosmic acceleration rests on the observation that SNe Ia at z ~ 0.5 are ~ 0.25 mag fainter than they would be in a universe without acceleration. A powerful and straightforward way to assess the reliability of the SN Ia measurement and the conceptual framework of its interpretation is to look for cosmic deceleration at z >= 1. This would be a clear signature of a mixed dark-matter and dark-energy universe. Systematic errors in the SN Ia result attributed to grey dust or cosmic evolution of the SN Ia peak luminosity would not show this change of sign. We have demonstrated proof of this concept with a single SN Ia, SN 1997ff at z = 1.7, found and followed by HST. The results suggest an early epoch of deceleration, but this is too important a conclusion to rest on just one object. Here we propose to use HST for observations of six SNe Ia in the range 1.2 <= z <= 1.6, that will be discovered as a byproduct from proposed Treasury programs for high-latitude ACS surveys. Six objects will provide a much firmer foundation for a conclusion that touches on important questions of fundamental physics. ================================================================================ Proposal Category: GO Scientific Category: Hot Stars ID: 9353 Title: Direct imaging of the progenitors of massive, core- collapse supernovae PI: Stephen Smartt PI Institution: Institute of Astronomy Modern supernovae searches in the nearby Universe are discovering vast numbers of SNe which have massive star progenitors (Types II, Ib and Ic). The extensive HST (and ground-based) image archives of galaxies within ~20 Mpc enables their individual bright stellar content to be resolved. As massive, evolved stars are the most luminous single objects in a galaxy, the progenitors of core-collapse SNe should be directly detectable on pre- explosion images. Within the last year we have set direct mass limits on the progenitors of two SNe Type II-P by analysing pre-explosion archive images and follow up HST exposures. We have now identified six other recent, nearby SNe which have WFPC2 archive exposures of the site taken before explosion. Additionally, our Cycle 10 SNAP program will double the WFPC2 image archive of nearby galaxies which significantly increases the chances of having multi- colour photometry of pre-explosion sites for future SNe. In this Cycle, we request time on two fronts. Firstly we require imaging of the six SNe with existing pre-explosion data in order to perform exact astrometry of the SNe positions to around 0.05". Secondly, as a follow on from our two successful Cycle 10 programs, we request ToO status for any nearby core-collapse SN which explodes during Cycle 11 and which has pre-explosion HST images. The goal of this proposal is to directly identify the progenitor stars of core-collapse SNe. ================================================================================ Proposal Category: GO Scientific Category: Solar System ID: 9354 Title: Saturn's Atmospheric Structure at Solstice PI: Erich Karkoschka PI Institution: University of Arizona We propose to image Saturn near its solstice with the same 22 WFPC2/NICMOS filters which we imaged Saturn near its equinox about six years ago. Additionally, we propose to use the ACS/HRC with its high ultraviolet throughput and its superior spatial resolution. All filters span a wavelength range of a factor of 10, they cover methane band strengths over several orders of magnitude, and they include the center and wings of the hydrogen dipole absorption near 2 Mum. Thus, they probe many atmospheric levels over five scale heights. The 22 WFPC2/NICMOS filters have proven to provide an excellent probe of Saturn's vertical aerosol structure. The spatial resolution yields several hundred resolution elements in latitude which can be grouped into 10-15 distinct zones. The best viewing of Saturn high southern latitudes occurs at its winter solstice which happens during Cycle 11. The three spacecraft which have visited Saturn flew by near Saturn's equinox, and Cassini will miss the solstice too. HST acquired comprehensive data of Saturn near its last equinox in 1995. The proposed observations will expand this data set to Saturn's solstice and thus provide a unique record of its seasonal variation. ================================================================================ Proposal Category: GO Scientific Category: Solar System ID: 9355 Title: Test of Efficient Subsampling for NIC3 by Smearing Images of Jupiter PI: Erich Karkoschka PI Institution: University of Arizona Several camera/filter combinations of HST do not sample the point spread function with a sufficiently small sampling interval to retrieve the full spatial resolution possible at the wavelength of the filter. This is especially true for the NIC3 camera. Dithering observations by sub-pixels is the standard solution. However, the extra overhead time of dithering can be too long to make dithering feasible for many solar system targets where rotation or relative motion is noticeable during the overhead time. I suggest to test a new method where a single exposure yields 10 dithered images which provide sufficient subpixel information to recover the whole spatial capabilities of HST. I suggest to test this method with Jupiter imaged by eight NIC3 filters. The same eight filters of NIC1 or NIC2 provide the standard for comparison with still exposures. The method lets Jupiter smear across NIC3 by about three pixels during the whole exposure by changing HST's tracking rates. Each interval between readouts of NIC3 provides a dithered image. It is difficult to predict how well the reduced NIC3 images will compare with the still NIC1 images with respect to spatial resolution, but one orbit of HST can test the method. If this method works well, it could be applied to many other future observations. ================================================================================ Proposal Category: SNAP Scientific Category: ISM and Circumstellar Matter ID: 9356 Title: SNAPSHOT survey of the Planetary Nebulae population of the Galactic Bulge PI: Albert Zijlstra PI Institution: Department of Physics The spectacular structures seen in HST images of planetary nebulae (PNe) are generally accepted as originating from hydrodynamical interactions between stellar winds: the interacting-stellar wind model (ISW). Traditionally, the shaping is thought to occur after the star becomes hot enough to ionize the PN. But recent HST images indicate that the shaping may occur earlier, and the newer GISW model puts the shaping during the pre-planetary nebula evolution. The relative importance of both models is not known: GISW shaping will account for some fraction of PNe, but estimates range from 15--100 during the PN phase, especially for the youngest PNe. We here propose an HST SNAPshot survey of compact PNe in the Galactic Bulge, to test these predictions. The