UV spectroscopy and imaging of the transient Swift J221951-484240 discovered in the follow-up of GW S190930t.
Abstract
Swift/UVOT detected J221951-484240 on the 30th September 2019 as part of the search for an electromagnetic counterpart to the LIGO/VIRGO Gravitational Wave (GW) trigger S190930t; after the cycle 27 proposal deadline. Compared to archival UV images, J221951-484240 is brighter by over 3 magntidues. The nature of this blue-slowly evolving source remains unclear following Swift and ground-based follow-up. It is possible this transient is associated with S190930t or alternatively it may be a new class of UV-bright transient. HST UV data is the only means to constrain the distance to the source and its true nature. Determining this now will allow us to plan additional observations using Swift, HST and other resources to follow its evolution. Observations in the present cycle would also facilitate rapid publication, which is of particular importance as this source was identified during follow-up of a GW alert. Only HST has the UV spectroscopic capability to obtain the key data needed to identify the nature of this 19th magnitude u-band transient before it fades away. Owing to the unique nature of this source, these observations will lead to a timely and high-impact publication whether or not it is connected to the GW emission.
- Publication:
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HST Proposal
- Pub Date:
- February 2020
- Bibcode:
- 2020hst..prop16076O