0 Assigned ID: 5393 ----- Attempting Submission 1 (Tue Mar 26 11:59:11 GMT 2024) ----- Changing aperture and dither step following PC advice. -524115784 ----- Attempting Submission 1 (Wed Aug 14 10:11:37 GMT 2024) ----- ----- Attempting Submission 2 (Tue Sep 10 11:26:58 GMT 2024) ----- The formation of Nuclear Star Clusters are a key ingredient to understand fundamental aspects in galaxy evolution, such as super massive black hole growth, physics of dense stellar systems and galaxy morphology evolution. However, direct observational evidence of NSC formation is still lacking. Roman et al. (2023; R23) proposed that the dwarf galaxy UGC 7346 is an exceptional first case in which the formation of a Nuclear Star Cluster (NSC) is caught in the act of forming. This dwarf galaxy, located in the outskirts of the Virgo Cluster, appears to be a merging system of two dwarf galaxies. R23 postulate that the dynamical friction produced by a 1:5 merger would be the mechanism triggering the collapse of the globular clusters (GCs) towards the centre. Ground-based imaging hints that the GC surface density is much higher in the centre of the galaxy than other dwarfs galaxies in the Virgo cluster with a bright tail in the GC luminosity function which could be explain as already merged GC. Our proposed observations will have the resolution and depth needed to resolve the full GC population and study the complete GC luminosity function, critical and sufficient requirements to prove this scenario. With the resolution of HST, we will be able to resolve the GCs and estimate the morphological components of the point sources improving the detection and filetring of GCs while reducing the fraction of interlopers. The proposed observations would constitute the first observational evidence of ongoing NSC formation, which could serve as a unique prove for the feasibility of dwarf mergers as a mechanism to produce an NSC. We aim to detect the whole GC luminosity function (GCLF) of UGC 7346 down to an absolute magnitude of -4 to ensure the detention of the fainter tail of GCs. At the assumed distance of ~16.5 Mpc this requirement translates into a source detection of ~27 magnitudes with an SNR>5 in two different bands (F814W and F606W). The APT indicates 53~minutes per orbit for the proposed observations. We will use a dithering pattern to fill the gap between the CCDs of the WFC/ACS and to correct for optical distortion. Withouth overhads we have 1920 seconds remain to observe. To optimise the overheads we use one filter per orbit. We expected a signal-to-noise ratio of 30 and 8 for point sources of 25.5 and 27 magnitudes in the i-band (AB system), respectively, which meet the requirements to study the full GCLF. We will observe UGC 7346 for two obrits, one for each filter, the F606W and F814W. In each orbit, 4 frames of 480 seconds will be taken using a dithering pattern. Pablo M. Sanchez-Alarcon, PI, will be in charge of leading the full analysis of the data and the publication of the results. He is a PhD student at the Instituto de Astrofisica de Canarias under the supervision of Johan Knapen, Javier Roman and Sebastien Comeron. His thesis is focused on deep imaging of galaxies, with a particular emphasis on the exploration of galaxy structures and evolution. He has full experience working with deep imaging, source detection, photometry analysis and morphological decomposition. He has a strong background in Bayesian statistics and data analysis techniques. Dr. Pamela M.I. Marcum, Admin-PI, provides overall management and leads tasks related to the retrieval of source photometry. She is currently a research scientist at NASA Ames Research Center and an expert in image analysis and photometry methods. As a former Program Scientist (Kepler, WISE) and Project Scientist (SOFIA), she has considerable experience in science management. Her experience in the study of extended extragalactic sources in astronomical images is strongly relevant to the goals of the proposed project. Dr. Javier Roman, Co-PI, is a former postdoctoral researcher at the Instituto de Astrofisica de Canarias. He will supervise the analysis of the data. He is an expert in observational astronomy, skilled in the use and operation of advanced telescopes and has a profound understanding of astronomical image analysis. He is the main author of the previous results of this galaxy, and his expertise and profound understanding of this specialized field are critical for the project. Dr. Johan Knapen, collaborator, is a senior staff researcher at the Instituto de Astrofisica de Canarias. He is a recognised observational astronomer and has wide experience in leading research groups. He will provide overall organization until the publication of the results. He has a strong background in the analysis of the morphological, structural and kinematic properties of galaxies. Dr. Sebastien Comeron, collaborator, is a professor at the Universidad de La Laguna. He is an expert in observational astronomy and has worked on plenty of studies related to deep imaging and photometric decompositions of galaxies. Dr. Alejandro S Borlaff, collaborator, will be responsible for all tasks related to image processing, calibration, and sky background estimation. He will implement state-of-the-art tools for background correction into the obtained mosaics. He is currently a researcher at NASA Ames Research Center / BAERI, and an expert in image analysis and photometry methods, particurarly from HST imaging. Dr. Reynier F. Peletier, collaborator, will support the interpretation of the results from the analyzed images. He is a professor at the University of Groningen and the Kapteyn Institute which has also been the Director for several years. He has an extended experience in the study of extragalactic globular clusters and stellar populations. Galaxies 6 false false false false false false false false SUPPORTED GALAXY DWARF ELLIPTICAL LSB YES This object was generated by the target selector and retrieved from the SIMBAD database. J2000 J2000 14.16 +- 0.02 (SDSS-g, AB), 13.36 +- 0.08 (SDSS-i, AB) ACS/WFC Imaging No No F606W ACS/WFC Imaging No No F814W POS-TARG DITHER 0.2637 LINE 0.1856 false false 69.02 4 20.7 ACS-WFC-DITHER-BOX 1 false 1725886460708 /Users/pmsa/Documents/PhD/Proposals/HST/UGC7346/Cycle32/Phase II/OP-cache/UGC7346_cycle32_phaseII_final-v01.xml The scheduling data was generated by CASM 32.1.1. CASM was run in Phase II mode. 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