0 ----- Attempting Submission 4 (Mon Oct 07 03:28:01 GMT 2013) ----- ----- Attempting Submission 5 (Tue Oct 15 19:11:30 GMT 2013) ----- ----- Attempting Submission 6 (Wed Oct 16 18:44:19 GMT 2013) ----- How Low Can They Go? Detecting low luminosity supernova progenitors While we now discover thousands of supernovae (SNe) per year, in the history of astronomy a little more than a dozen SN progenitors have been identified, and all of these have been from Type II SNe. This dearth is largely due to the fact that the progenitors are destroyed in the SN, and so to study them one must have fortuitously taken data on them prior to their explosion. However, the fault may also partially lie with the methods employed to search for progenitors. In the past, searches have generally relied on looking at the location of a SNe in an archival image to see if a noticeable point source is at the right location. This method requires that the background field of the galaxy be relatively uniform, and if one wants an accurate estimate of the progenitor mangitude, that the star was not in an association or binary. Here we propose to take WFC3 images several years post explosion so that we can subtract them from archival WFPC2 images. We show that we can do this with extraordinary fidelity. We will apply this method to a well-chosen sample of three Type II SNe and two Type Ibc SNe, which lie on messy galaxy fields that may have camouflaged the presence of a progenitor. This method has the potential to detect or substantially deepen the limits on the progenitors of these objects, which already appear too faint for theoretical models. In this program, we ask for time to image a number of hosts of nearby SNe using WFC3, which were also observed by HST with WFPC2 prior to the explosion. In all cases we know the location of the SNe on the host to better than an arc second from ground-based imaging, and in a few cases we have post-explosion HST observations which show the light of the Sne on the host, giving us a sub-pixel position. In these cases, the light of the SNe prevents us from seeing the environment of the SN post explosion. However, we will be returning to SNe four or more years after explosion, when the light of the SN will have faded magnitudes below the expected luminosity of the original progenitor star. We will attempt to locate and determine the actual luminosity of the SN progenitors by subtracting the images we will acquire now from the images taken prior to the explosion. Although we will be using a different instrument from that used to take the initial image, we have found that we can nonetheless perform a very high fidelity image subtraction. The excellent image subtraction is made possible by a number of propitious factors. First the WFC3 was placed in the same location on the focal plane of HST as WFPC2, so the two instruments share the same optics along most of their light path. In addition they share very similar filter sets, minimizing color terms. Thus the primary diferences in their point-spread functions (PSFs) arise through diferences in the detectors. A dithered WFC3 image however, has essentially all of the information contained in a WFPC2 image and more, and its PSF can in principle be convolved to closely match that of the WFPC2. HOT STARS Default false false false false false SUPPORTED EXT-STAR SUPERNOVA TYPE II J2000 J2000 EXT-STAR SUPERNOVA TYPE II J2000 J2000 EXT-STAR SUPERNOVA J2000 J2000 EXT-STAR SUPERNOVA J2000 J2000 EXT-STAR SUPERNOVA TYPE II J2000 J2000 WFC3/UVIS Imaging No No F606W WFC3/UVIS Imaging No No F475W WFC3/UVIS Imaging No No F300X WFC3/UVIS Imaging No No F606W WFC3/UVIS Imaging No No F606W WFC3/UVIS Imaging No No F475W WFC3/UVIS Imaging No No F606W WFC3/UVIS Imaging No No F475W WFC3/UVIS Imaging No No F475W WFC3/UVIS Imaging No No F814W POS-TARG DITHER 0.173 LINE 0.112 false false 81.785 4 23.884 WFC3-UVIS-DITHER-BOX 1 false The scheduling data was generated by CASM 21.2. CASM was run in Phase II mode. 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