Difference between "Events" and "Superevents"

[jonah]

I got this great question, and wanted to share it:

“When I look at gracedb for searching events, there are two choices: “Event” and “Superevent”.
Would you please let me know what is the difference between the two and why the list under the choice of “Event” is empty?”

Here’s my answer:

The GraceDB terms event and superevent are described on the GraceDB data models documentation and the Public Alerts User Guide.

“Events” correspond to triggers from individual pipelines, while a “superevent” corresponds to a collection of events that are at the same GPS time, so that each superevent is intended to represent a single astrophysical source.

People looking at the gracedb page without LVK credentials don’t have access to individual pipeline triggers, only the superevents. So, if you’d like to search for “Events” in GraceDB, you need to first login using your LVK credentials by clicking the Login button in the menu bar.

Good luck!

[Maryam]

Thanks for your explanation.
After login and using proper query form, now I can search for the events.
But the events and superevents id are different from the publicly known ids.
For instance, I can not find GW170817 by this name and I needed to use its actual GPS time to find it (them).
Would you please let me know how can I make an association between the known id of an event/superevent and its id in GraceDB to search for it?

[martinberoiz]

Hi Maryam,

Those GW*** ID’s are given after confirmation in “offline” analysis and publication.

One way to find the graceDB ID is to locate the event in gwosc’s event portal. In your case it would be this detail page.

It would usually appear in the first info box, but for this particular event, it seems it’s missing. I’m not sure why.

[jonah]

Thanks, @martinberoiz ! There’s no GraceID for GW170817 because this is an O2 event. The public alerts program didn’t begin until O3.

[lupinlin]

I joined the RRT lv0 shift last week, and Sawada-san plotted a figure to illustrate the event identification for me. Hopefully it is also helpful.