0 Assigned ID: 3442 ----- Attempting Submission 1 (Fri Mar 25 19:21:06 GMT 2022) ----- We propose an archival project to investigate the origin of large astrometric offsets between the radio and optical positions of the celestial reference frame sources (ICRF3) used to register the Gaia optical celestial reference frame. We selected a subsample of ICRF3 sources with astrometric radio-optical error normalized offsets exceeding 10 standard deviations, and were able to find suitable archival WFPC2, WFC3, ACS and NICMOS images for 85 of them (~30% of the subsample). These observations will be used to investigate the origin of these offsets, and explore the possibility that they are due to dual or dislodged AGNs. Dr. Schmitt is the PI, he will be the point of contact on technical issues that may arise during the development of the project. He is a specialist in the imaging of AGNs at both optical and radio wavelengths, including the fitting of PSFs and light profiles. He is a member of the USNO/NRL working group on issues related to the registration of the optical and radio reference frames. Dr. Satyapal is the Co-PI of this project and will oversee the work of the PhD student, Ms. Schwartzman. She is a specialist in AGN physics, including the detection of dual AGNs and the interpretation of their relations. Dr. Secrest is a specialist in the field of astrometry, and AGN physics. Currently he is the lead of the USNO/NRL working group on issues related to the registration of the optical and radio references frames. Dr. Clarke is a specialist in the field of radio interferometry, including the detailed analysis and interpretation of images of quasars and radio galaxies. Ms. Schwartzman is a graduate student at George Mason University. She will work on this project as part of her PhD dissertation. Supermassive Black Holes and Active Galaxies Galaxies 0 Regular false false false false false false SUPPORTED