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SUMMARY:Observing Black Holes from the Stratosphere: Engineering a Balloon
 -borne VLBI Station and its Future Prospects
DTSTART:20260427T103000Z
DTEND:20260427T113000Z
DTSTAMP:20260503T112400Z
UID:indico-event-9332@scitalks.tifr.res.in
DESCRIPTION:Speakers: Mayukh Bagchi (Queen's University)\n\nIn 2019\, the 
 Event Horizon Telescope (EHT) produced the first image of a supermassive b
 lack hole shadow by combining simultaneous observations from radio telesco
 pes across the Earth using a technique called Very Long Baseline Interfero
 metry (VLBI). The EHT is limited by two factors: the diameter of the Earth
  and atmospheric absorption and phase fluctuations\, which worsen rapidly 
 at sub-millimeter wavelengths. A space-based VLBI station would address bo
 th\, but at an enormous cost. A balloon-borne station floating at ~35 km a
 bove 99% of the atmosphere is a much cheaper intermediate step\, giving ac
 cess to higher (sub-millimeter) observing frequencies and improving the UV
  coverage as the balloon drifts across a campaign.The Balloon-borne VLBI E
 xperiment (BVEX) launched from Timmins\, Ontario on 29 August 2025. BVEX i
 s a K-band (22 GHz) balloon-borne radio telescope\, built to demonstrate V
 LBI between a balloon-borne and a ground-based telescope. The payload pair
 s a single-sideband heterodyne front-end with a Radio Frequency System-on-
 Chip (RFSoC) backend that runs a high resolution spectrometer and a VLBI p
 acketizer\, streaming baseband data over 100 GbE to an onboard NVMe SSD st
 orage system. Phase stability and timing synchronization are anchored on a
 n ultra stable Oven Controlled Crystal Oscillator (OCXO) housed inside a t
 emperature controlled pressure vessel. Getting millimetre level position a
 nd attitude knowledge under stratospheric thermal and mechanical condition
 s is one of the hardest engineering problems on the platform.In this talk\
 , I will walk through the instrumental design\, flight implementation\, an
 d lessons learned from the first BVEX flight\, along with the upgrades pla
 nned for BVEX 2.0\, launching from Brazil in 2027. I will close by outlini
 ng the science a station like this could enable when paired with the EHT (
 230 GHz) and ngEHT (345 GHz and above).\n\nhttps://scitalks.tifr.res.in/ev
 ent/9332/
LOCATION:A269 (Hybrid)
URL:https://scitalks.tifr.res.in/event/9332/
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