A bystander's view of how the detection of first neutron star merger seen by LIGO Scientific Collaboration and Virgo was followed up by electromagnetic observations. Timeline curated from discovery papers, twitter threads and GCN's

1. © amruta jaodand
GW170817
1 9 / 1 1 / 2 0 1 7
A m r u t a J a o d a n d
Binary Neutron
Star Merger
The Dawn of Multi-messenger Astronomy

2. © amruta jaodand
GW170817The arrival
Stardate:
14/08/17 12:39:45-12:41:04 UTC
O2 : November 30, 2016 to August 25, 2017
117 days of LIGO-Virgo joint run
SNR 18.4
DH: 107 Mpc
1 in 9000yrs
SNR 26.4
DH: 218 Mpc
SNR 2
DH: 58 Mpc
-C.Berry
Images:
Gravityspy
by Zooinverse
@barbika71

3. © amruta jaodand
GW170817
Glitch occurs 1.1 s before coalescence,
saved by the BNS merger
SNR 26.4
DH: 218 Mpc
Fermi-GBM GRB170817A
Detected 12:41:06 UTC
GCN circular sent out :
50-300keV, 12:41:20 UTC
The arrival
Stardate:
14/08/17 12:39:45-12:41:04 UTC
Rapid Response Call
GCN circular sent out about :
13:08:16 UTC

4. © amruta jaodand
GW170817
Fermi-GBM GRB170817A
Detected 12:41:06 UTC
GCN circular sent out :
50-300keV, 12:41:20 UTC
The arrival
Stardate:
14/08/17 12:39:45-12:41:04 UTC
Rapid Response Underway
GCN circular about temporally
coincident BNS merger LSC+VC:
13:21:42 UTC
ApJ, 848, 2, L13

5. © amruta jaodand
GW170817
Fermi-GBM GRB170817A
Detected 12:41:06 UTC
GCN circular sent out :
50-300keV, 12:41:20 UTC
The arrival
Stardate:
14/08/17 12:39:45-12:41:04 UTC
Rapid Response Call
GCN circular sent out about :
13:08:16 UTC
GCN circular about temporally
coincident BNS merger LSC+VC:
13:21:42 UTC
Astronomers
on alert!

6. © amruta jaodand
GW170814
Fermi-GBM GRB170817A
Detected 12:41:06 UTC
GCN circular sent out :
50-300keV, 12:41:20 UTC
The arrival
Stardate:
14/08/17 12:39:45-12:41:04 UTC
Rapid Response Call
GCN circular sent out about :
13:08:16 UTC
GCN circular about temporally
coincident BNS merger LSC+VC:
13:21:42 UTC
False alarm rate:
A: 1 in 1.1 Million years
B: 0.08 Million years
Phys. Rev. Lett. 119, 161101

7. © amruta jaodand
GW170814
First three instrument Sky Map
17:54:51 UTC
Fermi-GBM GRB170817A
Detected 12:41:06 UTC
GCN circular sent out :
50-300keV, 12:41:20 UTC
The arrival
Stardate:
14/08/17 12:39:45-12:41:04 UTC
Rapid Response Call
GCN circular sent out about :
13:08:16 UTC
GCN circular about temporally
coincident BNS merger LSC+VC:
13:21:42 UTC
First Coherent Analysis produces Sky Map
sent out at 23:54:40 UTC
Phys. Rev. Lett. 119, 161101

8. © amruta jaodand
GW170817
PC: Josh Simon
@joshuadsimon
Folks at UCSC (Dave Coulter et al) -
preparing a list of targets in the afternoon
for Swope: Las Campanas+Lick observatory team
Only visible for start of the night (2 hrs) and clock is ticking!
18 mins before the observation start , a target list is ready.
Swope FOV: 29.7*29.8 arcmins
47 galaxies in 12 images
Transfer, reduce and examine each galaxy by EYE
Fermi-GBM GRB170817A
Detected 12:41:06 UTC
GCN circular sent out :
50-300keV, 12:41:20 UTC
The arrival
Stardate:
14/08/17 12:39:45-12:41:04 UTC
Rapid Response Call
GCN circular sent out about :
13:08:16 UTC
GCN circular about temporally
coincident BNS merger LSC+VC:
13:21:42 UTC
First three instrument Sky Map
17:54:51 UTC
First Coherent
Analysis produces
Sky Map
sent out at 23:54:40 UTC

9. © amruta jaodand
GW170817
Fermi-GBM GRB170817A
Detected 12:41:06 UTC
GCN circular sent out :
50-300keV, 12:41:20 UTC
The arrival
Stardate:
14/08/17 12:39:45-12:41:04 UTC
Rapid Response Call
GCN circular sent out about :
13:08:16 UTC
GCN circular about temporally
coincident BNS merger LSC+VC:
13:21:42 UTC
First three instrument
Sky Map
17:54:51 UTC
First Coherent
Analysis produces
Sky Map
sent out at 23:54:40 UTC
Coulter et al GCN
23:33 UTC (tc + 10.87 hr)

10. © amruta jaodand
GW170817
Fermi-GBM GRB170817A
Detected 12:41:06 UTC
GCN circular sent out :
50-300keV, 12:41:20 UTC
The arrival
Stardate:
14/08/17 12:39:45-12:41:04 UTC
Rapid Response Call
GCN circular sent out about :
13:08:16 UTC
GCN circular about temporally
coincident BNS merger LSC+VC:
13:21:42 UTC
First three instrument
Sky Map
17:54:51 UTC
First Coherent
Analysis produces
Sky Map
sent out at 23:54:40 UTC
Coulter et al GCN
23:33 UTC (tc + 10.87 hr)
ESO - launched
one of the biggest ToO campaign

11. © amruta jaodand
GW170817
Fermi-GBM GRB170817A
Detected 12:41:06 UTC
GCN circular sent out :
50-300keV, 12:41:20 UTC
The arrival
Stardate:
14/08/17 12:39:45-12:41:04 UTC
Rapid Response Call
GCN circular sent out about :
13:08:16 UTC
GCN circular about temporally
coincident BNS merger LSC+VC:
13:21:42 UTC
First three instrument
Sky Map
17:54:51 UTC
First Coherent
Analysis produces
Sky Map
sent out at 23:54:40 UTC
Coulter et al GCN
23:33 UTC (tc + 10.87 hr)
ApJ, 848, 2, L12

12. © amruta jaodand
GW170817
Fermi-GBM GRB170817A
Detected 12:41:06 UTC
GCN circular sent out :
50-300keV, 12:41:20 UTC
The arrival
Stardate:
14/08/17 12:39:45-12:41:04 UTC
Rapid Response Call
GCN circular sent out about :
13:08:16 UTC
GCN circular about temporally
coincident BNS merger LSC+VC:
13:21:42 UTC
First three instrument
Sky Map
17:54:51 UTC
First Coherent
Analysis produces
Sky Map
sent out at 23:54:40 UTC
Coulter et al GCN
23:33 UTC (tc + 10.87 hr)
tc + 12.8 hr, GeminiSouth FLAMINGO2
first near-infrared Ksband
Constrains the early optical to infrared color
At tc + 15.3 hr, the Swift - bright, UV emission
Constrains the effective temperature
Swift and Hubble Space Telescope monitoring
UV evolution
GeminiSouth FLAMINGO2
IR (tc + 12.8 hr)
Swift (tc + 15.37 hr)
ApJ, 848, 2, L12

13. © amruta jaodand
GW170817
Fermi-GBM GRB170817A
Detected 12:41:06 UTC
GCN circular sent out :
50-300keV, 12:41:20 UTC
The arrival
Stardate:
14/08/17 12:39:45-12:41:04 UTC
Rapid Response Call
GCN circular sent out about :
13:08:16 UTC
GCN circular about temporally
coincident BNS merger LSC+VC:
13:21:42 UTC
First three instrument
Sky Map
17:54:51 UTC
First Coherent
Analysis produces
Sky Map
sent out at 23:54:40 UTC
Coulter et al GCN
23:33 UTC (tc + 10.87 hr)
GeminiSouth FLAMINGO2
IR (tc + 12.8 hr)
Swift (tc + 15.37 hr)
UV, optical, and IR observations
• Mapped the emission from the sub-relativistic ejecta,
Next two days, a rapid dimming of UV–blue
Unusual brightening of the nearinfrared
|
After roughly a week, the redder optical and
near-infrared bands began to fade
|
Unusual rapid luminosity decline.
In bluer optical bands (i.e., in the g band),
Fast decay between daily photometric
measurements
ApJ, 848, 2, L12

14. © amruta jaodand
GW170817
Fermi-GBM GRB170817A
Detected 12:41:06 UTC
GCN circular sent out :
50-300keV, 12:41:20 UTC
The arrival
Stardate:
14/08/17 12:39:45-12:41:04 UTC
Rapid Response Call
GCN circular sent out about :
13:08:16 UTC
GCN circular about temporally
coincident BNS merger LSC+VC:
13:21:42 UTC
First three instrument
Sky Map
17:54:51 UTC
First Coherent
Analysis produces
Sky Map
sent out at 23:54:40 UTC
Coulter et al GCN
23:33 UTC (tc + 10.87 hr)
GeminiSouth FLAMINGO2
IR (tc + 12.8 hr)
Swift (tc + 15.37 hr)
Fermi-GBM
• Persistent emission limits for the 48 hr period
• Constraining upper limits on
precursor and extended emission
ApJ, 848, 2, L12

15. © amruta jaodand
GW170817
Fermi-GBM GRB170817A
Detected 12:41:06 UTC
GCN circular sent out :
50-300keV, 12:41:20 UTC
The arrival
Stardate:
14/08/17 12:39:45-12:41:04 UTC
Rapid Response Call
GCN circular sent out about :
13:08:16 UTC
GCN circular about temporally
coincident BNS merger LSC+VC:
13:21:42 UTC
First three instrument
Sky Map
17:54:51 UTC
First Coherent
Analysis produces
Sky Map
sent out at 23:54:40 UTC
Coulter et al GCN
23:33 UTC (tc + 10.87 hr)
GeminiSouth FLAMINGO2
IR (tc + 12.8 hr)
Swift (tc + 15.37 hr)
X-RAY COUNTERPART
X-ray observations of GRB afterglows
• Geometry of the outflow
• Energy output
• Orientation of the system w.r.t. observers’ line
of sight
Earliest limits: MAXI GSC, no localisation
First pointed X-ray observations of GW170817
Swift - T0 0.6 + 2 days and NuStar - T0 0.70 + days.
No X-ray emission was detected
Swift continued to monitor and stacked several
epochs of observations
X-ray source near the location of GW170817
2.6x10^-14 erg cm−2 s−1
INTEGRAL - JEM-X - 1-6 days after
Chandra - Tc+2- non-detection +extended emission
Tc+9 days - 50ks exposure - X-ray counterpart
Tc+15 - still there!
ApJ, 848, 2, L12

16. © amruta jaodand
GW170817
Fermi-GBM GRB170817A
Detected 12:41:06 UTC
GCN circular sent out :
50-300keV, 12:41:20 UTC
The arrival
Stardate:
14/08/17 12:39:45-12:41:04 UTC
Rapid Response Call
GCN circular sent out about :
13:08:16 UTC
GCN circular about temporally
coincident BNS merger LSC+VC:
13:21:42 UTC
First three instrument
Sky Map
17:54:51 UTC
First Coherent
Analysis produces
Sky Map
sent out at 23:54:40 UTC
Coulter et al GCN
23:33 UTC (tc + 10.87 hr)
GeminiSouth FLAMINGO2
IR (tc + 12.8 hr)
Swift (tc + 15.37 hr)
RADIO COUNTERPART
Radio Emission
• Traces fast-moving ejecta from a neutron star
• Information on the energetics of the explosion
• Environment of the merger
ATCA : Blind survey,
2017 August 18 at 01:46 UTC
LWA : tc + 6.5 hr, then August 23 and 30
Four beams (one centered on NGC 4993, one off-center,
and two off NGC 4993)
3σ upper limits
NGC 4993, about 8 hours after the GW event, as ∼200 Jy at
25 MHz and ∼100 Jy at 45 MHz.
First detection : August 18 at
02:09:00 UTC (T0+13.5 hr)
ApJ, 848, 2, L12

17. © amruta jaodand
GW170817
Fermi-GBM GRB170817A
Detected 12:41:06 UTC
GCN circular sent out :
50-300keV, 12:41:20 UTC
The arrival
Stardate:
14/08/17 12:39:45-12:41:04 UTC
Rapid Response Call
GCN circular sent out about :
13:08:16 UTC
GCN circular about temporally
coincident BNS merger LSC+VC:
13:21:42 UTC
First three instrument
Sky Map
17:54:51 UTC
First Coherent
Analysis produces
Sky Map
sent out at 23:54:40 UTC
Coulter et al GCN
23:33 UTC (tc + 10.87 hr)
GeminiSouth FLAMINGO2
IR (tc + 12.8 hr)
Swift (tc + 15.37 hr)
SUMMARY
EM Counterpart Information
Prompt sGRB
BNS mergers are the progenitor of at least a
fraction of such bursts
Ultraviolet, optical, and infrared
Transient (kilonova),
Identification of the host galaxy and is associated with the aftermath of the BNS merger
Delayed X-ray and radio counterparts
provide information on the environment of the binary
ApJ, 848, 2, L12

18. © amruta jaodand
GW170817
Fermi-GBM GRB170817A
Detected 12:41:06 UTC
GCN circular sent out :
50-300keV, 12:41:20 UTC
The arrival
Stardate:
14/08/17 12:39:45-12:41:04 UTC
Rapid Response Call
GCN circular sent out about :
13:08:16 UTC
GCN circular about temporally
coincident BNS merger LSC+VC:
13:21:42 UTC
First three instrument
Sky Map
17:54:51 UTC
First Coherent
Analysis produces
Sky Map
sent out at 23:54:40
UTC
Coulter et al GCN
23:33 UTC (tc + 10.87 hr)
GeminiSouth FLAMINGO2
IR (tc + 12.8 hr)
Swift (tc + 15.37 hr)
Courtsey: @LIGO and
Karl Toland

19. © amruta jaodand
R E F E R E N C E S
• GW170817: Physical Review Letters 119, 161101 (2017)
• Multi-messenger Observations of a Binary Neutron Star Merger: The
Astrophysical Journal, Volume 848, Number 2, L12
• GW170817—The pot of gold at the end of the rainbow, blog account
C.Berry: https://cplberry.com/blog/
• Twitter thread by @joshuadsimon
https://twitter.com/joshuadsimon/status/920075788749217792
• Gravity Spy project at Zooinverse : Go check it out at
https://www.zooniverse.org/projects/zooniverse/gravity-spy/about/team
• Gravity Spy: integrating advanced LIGO detector characterization,
machine learning, and citizen science, Classical and Quantum Gravity,
Volume 34, Number 6