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SUMMARY:Mapping the Faint Frontier: Improved Local Group Kinematics with J
 WST + Gaia + HST Astrometry
DTSTART;VALUE=DATE-TIME:20261028T182300Z
DTEND;VALUE=DATE-TIME:20261028T182400Z
DTSTAMP;VALUE=DATE-TIME:20261023T011145Z
UID:indico-contribution-3710@nyx.physics.mcgill.ca
DESCRIPTION:Speakers: Liwen Chen (University of Toronto)\nStellar proper m
 otions (PMs) are fundamental for reconstructing the Local Group dynamics\,
  understanding the Milky Way accretion history\, and constraining the natu
 re of dark matter. While Gaia is powerful for measuring PMs\, its performa
 nce is limited for faint sources (G > 20 mag). Previous studies on Gaia + 
 Hubble Space Telescope (HST) astrometry have shown that combining telescop
 es achieved more precise PM measurements than Gaia alone.\n\nMotivated by 
 GaiaHub\, a previous Gaia + HST tool\, we have developed GaiaWebb\, which 
 combines Gaia and James Webb Space Telescope (JWST) observations. GaiaWebb
  retrieves JWST images\, extracts stellar positions and magnitudes\, cross
 -matches JWST sources with Gaia stars\, aligns JWST images to the Gaia ref
 erence frame\, and then measures the improved PMs using large JWST-to-Gaia
  time baselines. We have also expanded another Gaia + HST tool\, BP3M (Bay
 esian Positions\, Parallaxes\, and Proper Motions)\, to simultaneously com
 bine JWST + Gaia + HST measurements. The enhanced BP3M differs from GaiaWe
 bb in that it uses Gaia data as priors while jointly aligning images and m
 aking measurements. We tested our new tools on the Large Magellanic Cloud 
 and Draco dwarf galaxy\, and the resulting PMs are consistent with the lit
 erature measurements. GaiaWebb and BP3M improve PM precision by factors of
  5-20 compared to Gaia DR3 alone\, with faint stars (G > 19 mag) seeing th
 e largest improvement. \n\nOur future work will include producing publicly
  available catalogues of improved PMs\, calibrating those catalogues throu
 gh comparisons with the literature\, and measuring new bulk motions of Loc
 al Group structures.\n\nhttps://nyx.physics.mcgill.ca/event/587/contributi
 ons/3710/
LOCATION:Online 
URL:https://nyx.physics.mcgill.ca/event/587/contributions/3710/
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