# S250206dm: a intriguing multi-messenger event
**URL:** https://forum.astro-colibri.science/t/s250206dm-a-intriguing-multi-messenger-event/330
**Category:** Latest transients
**Tags:** gw, neutrino
**Created:** [February 7, 2025, 3:50pm UTC](https://forum.astro-colibri.science/t/s250206dm-a-intriguing-multi-messenger-event/330 "2025-02-07T15:50:01Z")
**Posts on this page:** 5
**Page:** 1
### Author:  [@Fabian.Schussler](https://forum.astro-colibri.science/u/Fabian.Schussler)
#### Post date: [February 7, 2025, 3:50pm UTC](https://forum.astro-colibri.science/t/s250206dm-a-intriguing-multi-messenger-event/330/1 "2025-02-07T15:50:01Z")
An intriguing chain of events has been detected on February 6, 20205:
It all started with [S250206dm](https://astro-colibri.com/event:S250206dm), a gravitational wave detected by both LIGO interferometers. It has rapidly been classified as being either a merger of a neutron star with a black hole (55% probability) or a merger of a binary neutron start system (37%). There remains a roughly 8% probability that the event was due to noise background. The event has been fairly well localized (910 deg² at 90% containement) and is not too far way at 348 ± 114 Mpc .
A scan of the probable sky region in various wavelength has started to search a counterpart.
One such search has been performed automatically within the IceCube neutrino observatory. And it turned out a positive result! Named [S250206dm NuTracks](https://astro-colibri.com/event:icecube_lvk_S250206dm), two neutrino tracks have been found in spatial and temporal coincidence with the GW. The full report by IceCube is available here: [GCN - Circulars - 39176 - LIGO/Virgo/KAGRA S250206dm: Two counterpart neutrino candidates from IceCube neutrino searches](https://gcn.nasa.gov/circulars/39176)
At this moment no new source has been found (e.g. [GCN 39204](https://gcn.nasa.gov/circulars/39204)) but we invite everybody to participate in this exciting endeavour!
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### Author:  [@marc.serrau2](https://forum.astro-colibri.science/u/marc.serrau2)
#### Post date: [February 7, 2025, 4:31pm UTC](https://forum.astro-colibri.science/t/s250206dm-a-intriguing-multi-messenger-event/330/2 "2025-02-07T16:31:58Z")
Last night I tried to observe this event targetting one of the tile given by AstroColibri during 45mn reaching mag 20.5 (19.9 at SNR=5). Unfortunately, I have no tool to compare automatically the resutling image and more, this tile position does not coincide to one of the new target list given by GCN 39206 (see : [GCN Circular 39206](https://gcn.nasa.gov/circulars/39206)).
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### Author:  [@Fabian.Schussler](https://forum.astro-colibri.science/u/Fabian.Schussler)
#### Post date: [February 7, 2025, 6:42pm UTC](https://forum.astro-colibri.science/t/s250206dm-a-intriguing-multi-messenger-event/330/3 "2025-02-07T18:42:58Z")
Covering these large uncertainty regions is indeed challenging!
In addition, the localisation region provided by the gravitational wave observatories has been updated several times yesterday evening/night, as soon as new analysis results became available. You can reproduce these changes by going through the archive within Astro-COLIBRI:
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### Author:  [@Fabian.Schussler](https://forum.astro-colibri.science/u/Fabian.Schussler)
#### Post date: [February 11, 2025, 4:37pm UTC](https://forum.astro-colibri.science/t/s250206dm-a-intriguing-multi-messenger-event/330/4 "2025-02-11T16:37:42Z")
A very nice article summarizing these events:
> **[Did LIGO just see its most important gravitational wave ever?](https://bigthink.com/starts-with-a-bang/ligo-most-important-gravitational-wave-ever/)**
>
> The ultimate multi-messenger astronomy event would have gravitational waves, particles, and light arriving all at once. Did that just occur?
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### Author:  [@Fabian.Schussler](https://forum.astro-colibri.science/u/Fabian.Schussler)
#### Post date: [February 14, 2025, 12:50pm UTC](https://forum.astro-colibri.science/t/s250206dm-a-intriguing-multi-messenger-event/330/5 "2025-02-14T12:50:17Z")
Improved analyses of the gravitational wave data have led to significant shifts and reductions of the localisation region derived from that data. The best-fit neutrino position given as [S250206dm\_NuTracks](https://astro-colibri.com/event:icecube_lvk_S250206dm) seems now no longer compatible with the [GW region](https://astro-colibri.com/event:S250206dm).
It could well be that this was a chance coincidence after all…