Neutron Star Collision VSS

[Nick White]

A friend of mine at Southampton Uni is a member of the team that detected gravitational waves and optical emission from a neutron star merger event, reported today in the news. We’re meeting up soon and I hope to find out more about the discovery when I see him. In the meantime, I note that one of the papers available on the Nature website provides details about the optical emission from the event. Alas, although some of these events might be within reach of amateur telescopes and CCDs, their annual all-sky frequency of occurrence is predicted to be very low. Does the VSS have any plans in this new area of research? 

[Robin Leadbeater]

Interestingly the detection by several pro supernova survey teams of the optical transient was submitted  to the Transient Name Server, (which generates alerts for possible supernovae and which  I monitor it for potential candidates for spectroscopic classification.)

https://wis-tns.weizmann.ac.il/object/2017gfo

It was mag 17.3 at discovery which would have been just bright enough for a spectrum with my setup.  The TNS submissions and subsequent spectrum which showed it to be something unusual, was embargoed for 2 months though so it only appeared on TNS today giving no chance to observe it.  Had an amateur picked it up in the meantime though (eg as part of a supernova patrol) and posted it on TNS, they would have been credited with the discovery as IAU recognise the first to publish as the discoverer.

Robin

[Gary Poyner]

Hi Nick,

The VSS hasn’t discussed this at all – but…

You might find this interesting…

http://iopscience.iop.org/journal/2041-8205/page/Focus_on_GW170817?utm_medium=email&utm_source=iop&utm_term=&utm_campaign=12734-36073&utm_content=FI

Gary

[Robin Leadbeater]

About 10 years ago I was interested in trying to image a Gamma Ray Burst optical counterpart and subscribed  to alerts from the Gamma-ray Coordinates Network (GCN) Circulars.   Having caught one I then lost interest.  http://www.threehillsobservatory.co.uk/astro/astro_image_81.htm

I’ve just had a look in the GCN circular archives around the time of this GW event and there was a lot of chatter there about it eg https://gcn.gsfc.nasa.gov/gcn3/21505.gcn3 so that could be a good place to monitor for future events.

Robin

[Nick White]

Hi Robin, I see that GRB 080603 appeared at m~14 a few seconds after detection, a surprise to me having not looked into this kind of thing before. Would the position error reported within the GCN circular not present a problem?

Thanks Gary, looks like my reading is sorted for the rest of this week while I’m off work.

[Robin Leadbeater]

Hi Nick,

Yes the Fermi coordinate uncertainty left a lot of sky to search but one of the papers in Gary’s reference describes how this was managed by one of the teams.

http://iopscience.iop.org/article/10.3847/2041-8213/aa8edf/meta

Remarkably the combined data from the three operational GW detectors constrained the location considerably (and more accurately) compared with just the Fermi data. (fig 1 in the above paper). The DLT40 supernova survey team then prioritised  imaging their 20 target galaxies which fell in that region. 

Robin

[Grant Privett]

At a conference I am at, some observers from a small university observatory in the Virgin Islands reported visual counterpart observations from a system that is in the 0.5m league – though their sky is rarely below 20.5mag and despite the fact a cat 5 hurricane was about to hit.

They – and several other teams – caught it reasonably quickly via the alert system.

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