GCN Circulars
GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.
Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search
To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.
Advanced Search Examples (click to copy):
subject:"Swift"body:"GRB"submitter:"Judith Racusin"- Swift Trigger 748858: MASTER-OAFA early optical observations
- GRB 170419A: Swift detection of a burst
- Swift Trigger 748858: Zadko observatory - Gingin optical observations
- Swift Trigger 748858: a possible GRB
- LIGO/Virgo G275404: DLT40 follow-up observation
- LIGO/Virgo G277583: DLT40 follow-up observation
- GRB 170409A: TAROT Reunion observatory optical observations
- Konus-Wind observation of GRB 170409A
- GRB 170402A: AstroSat CZTI detection
- GRB 170409A: Fermi GBM Observation
- GRB 170409A: Fermi-LAT detection
- GRB 170405A: SMARTS optical/IR afterglow observations
- GRB 170403B CALET Gamma-Ray Burst Monitor detection
- GRB 170317A: SAO RAS optical observations
- GRB170405A, Swift-UVOT Detection
- GRB 170405A, Swift-BAT refined analysis
- GRB 170405A: Etelman observatory optical observations
- GRB 170405A: Swift-XRT refined Analysis
- GRB 170405A: RATIR Optical and NIR Observations
- Konus-Wind observation of GRB 170405A
- GRB 170405A: LCO FTN observations
- Trigger 745966: Swift detection of 4U1850-03
- GRB 170405A: ISON/Terskol optical observations
- GRB 170405A: Watcher optical detection
- GRB 170405A: Redshift from OSIRIS/GTC
- GRB 170405A: TAROT Reunion observatory optical observations
- GRB 170405A: NOT optical observations
- GRB 170405A: Fermi-LAT detection
- GRB 170405A: Fermi GBM observation
- GRB 170405A: Enhanced Swift-XRT position
- GRB 170405A: Swift detection of a burst with an optical counterpart
- LIGO/Virgo G275697: Update on significance from offline analyses
- LIGO/Virgo G275404: Update on significance from offline analyses
- LIGO/Virgo G275404: European VLBI Network (EVN) follow-up of the near-IR transient in the AGL J1914+1043 field
- GRB 170402A CALET Gamma-Ray Burst Monitor detection
- GRB 170330A CALET Gamma-Ray Burst Monitor detection
- GRB 170325A: optical observations, possible OT/host detection
- Konus-Wind observation of GRB 170403A (short/hard)
- IPN Triangulation of GRB 170403A (short)
- GRB 170403A: Fermi GBM observation
- Konus-Wind observation of GRB 170330A
- IceCube-170321A: Konus-Wind upper limits
- Swift Trigger 745090 is a noise trigger near NGC 5195
- Fermi-LAT Gamma-ray Observations of IceCube-170321
- Swift triggered on SAX J1806.5-221
- GRB 170330A: AstroSat CZTI detection
- GRB 170330A: Swift-BAT refined analysis
- GRB 170331A: Swift-BAT refined analysis
- DOAO 1m telescope V, R, I observation of GRB 170317A
- GRB 170331A: Swift/UVOT Upper Limits
- IceCube-170321A: Swift-XRT observations
- GRB 170330A: Swift-XRT refined Analysis
- GRB 170331A: Swift-XRT refined Analysis
- GRB 170330A: Enhanced Swift-XRT position
- GRB 170331A: Enhanced Swift-XRT position
- GRB 170330A: Swift/UVOT Detection of a Fading Afterglow
- GRB 170325A: 15 GHz upper limits from AMI
- GRB 170318B: 15 GHz upper limits from AMI
- GRB 170318A: 15 GHz upper limits from AMI
- GRB 170317A: 15 GHz upper limits from AMI
- GRB 170330A: LCO Cerro Tololo observations
- LIGO/Virgo G275697: LOFAR follow-up
- Konus-Wind observation of GRB 170329A
- GRB 170329A: AstroSat CZTI detection
- IBAS trigger 7789 is not a GRB
- GRB 170331A: LCO Sutherland observations
- GRB 170331A: Prompt enhanced Swift-XRT position
- Fermi trigger 512347439/GRB 170327A: MASTER-SAAO possible OT detection
- GRB 170331A: Swift detection of a burst
- GRB 170330A: Prompt enhanced Swift-XRT position
- GRB 170330A: Swift detection of a burst
- GRB 170329A: Fermi GBM detection
- GRB 170329A: Fermi-LAT detection
- GRB 170325B: POLAR Observation
- GRB 170325A: Fermi GBM observation
- LIGO/Virgo G277583: Konus-Wind observations
- GRB 170325A, Swift-BAT detection of a short GRB
- INTEGRAL pointed follow-up of IceCube-170321A
- LIGO/Virgo G277583: Fermi GBM Observations
- Konus-Wind observation of GRB 170320A
- GRB 170320A: POLAR Observation
- LIGO/Virgo G277583: INTEGRAL search for an X-ray and gamma-ray counterpart
- Fermi GBM Observation of IceCube-170321A
- LIGO/Virgo G275697: AMI Large Array Search for a Radio Afterglow
- Fermi GBM trigger 511851891/170322212 is not a GRB
- IceCube-170321A - IceCube observation of a high-energy neutrino candidate event
- INTEGRAL SPI-ACS observation of AMON IceCube EHE 80305071 129307
- IPN Triangulation of GRB 170320A (long/intense)
- Search for counterpart to IceCube-170321A with ANTARES
- GRB 170318A: KAIT Optical Upper Limit
- GRB 170317A: Mondy optical observations
- GRB 170318B: Swift-BAT refined analysis
- GRB 170317A: POLAR observation
- GRB 170318B: RATIR Optical and NIR Observations
- GRB 170317A: RATIR Optical and NIR Observations
- GRB 170318B: Swift/UVOT Upper Limits
- GRB 170318B: Swift-XRT refined Analysis
- GRB 170318A: Swift-XRT refined Analysis
- LIGO/Virgo G277583: CALET Observations
- GRB 170318A: RATIR Optical and NIR Observations