This is a Director's Discretionary Time proposal, to be executed in any of the natural observing windows prior to June 2020. In the second submission, I corrected the type from GO to GO/DD. -1830306419 Assigned ID: 1102 ----- Attempting Submission 1 (Thu Aug 29 19:43:49 GMT 2019) ----- HST Phase I Proposal 1102 (SN2019ein.apt) successfully submitted. Receipt: # 1102-1 ----- Attempting Submission 2 (Thu Aug 29 20:01:00 GMT 2019) ----- HST Phase I Proposal 1102 (SN2019ein.apt) successfully submitted. Receipt: # 1102-2 2nd submission -1144039164 ----- Attempting Submission 1 (Wed Nov 06 14:45:13 GMT 2019) ----- HST Phase II Proposal 16047 (SN2019ein.apt) successfully submitted. Receipt: # 16047-1 ----- Attempting Submission 2 (Mon Nov 18 21:58:05 GMT 2019) ----- A SN Ia Event in a Globular Cluster of a Nearby Galaxy The path to a SN Ia is not observationally known as we have never observed the progenitor or its properties: mass, age, and metallicity. These shortcomings are removed when a SN Ia occurs in a globular cluster, an old population with near-uniform metallicity. Previous efforts to discover a SN Ia in globular cluster have failed, but a recent Ia event, SN 2019ein, lies within 0.5 arcseconds of a globular cluster candidate in the early-type galaxy NGC 5353 (D = 28 Mpc) on a pre-SN WFC3/IR F110W image (SN is 5.5 kpc from the galaxy center). To establish that this SN Ia-GC association is real and not due to chance, we propose observations that will reduce the error circle for the SN by a factor of 50 to 0.01 arcsec (1.4 pc, less than the half-light radii for a typical globular cluster). This is accomplished by obtaining an HST image while the supernova is still visible and registering that image on the pre-SN image; we propose to use the ACS/WFC F475W and F814W. These observations can also show the location of SN 2019ein within the GC, and as the binary is relatively heavy, it should lie toward the center. A confirmation of the SN-GC association would be powerful evidence for the double-degenerate path, and once the SN has faded, further properties of the globular cluster can be obtained. This program constitutes images in two filter on the ACS/WFC, W475W and F814W, of approximate equal observing time, and for a total of 1 orbit. The target is a fading SN Ia, SN2019ein, which lies about 5 kpc from the center of NGC 5353. The image should be dithered to achieve the highest spatial resolution. There are no particularly bright objects in the field, being mostly 20-27 mag plus some diffuse emission from the elliptical galaxy. Joel N. Bregman has been interested in this issue for over a decade and published the null results of a search for the association between SN Ia and globular clusters (Washabaugh and Bregman 2013). He and Seitzer have continued to search for associations in the outer parts of galaxies (where the galaxy surface brightness level and object confusion is low) using ground-based techniques (also null results). He will be responsible for leading the project and bringing it to a conclusion with a published result. Patrick Seitzer has published a number of papers on globular clusters. He has been the lead observer in the ground-based efforts to find associations between SN Ia and globular clusters in nearby galaxies. He also has extensive HST experience and will participate in the analysis of the images. Oleg Gnedin is a theorist who has worked on the formation and evolution of globular clusters and their populations. He will assist in the interpretation of the observations. Stellar Populations 6 false false false false false false false SUPPORTED GALAXY ELLIPTICAL Target should not be placed near the chip gap of the detectors. J2000 J2000 ACS/WFC Imaging No No F814W ACS/WFC Imaging No No F475W POS-TARG DITHER 0.262 LINE false false 2 18.39 ACS-WFC-DITHER-LINE 1 false The scheduling data was generated by CASM 27.2. 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