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"- IBAS Alert 7313 is SGR J1935+2154
- GRB 151221A: INTEGRAL detection of a short burst or possible SGR
- Fermi GBM trigger 472166503/151218890 is not a GRB
- LIGO/Virgo G184098: Fermi-LAT search for high-energy gamma-ray counterpart
- GRB 151215A: TSHAO optical observations
- GRB151215A: Continued P60 Observations
- GRB 151212B: CALET Gamma-Ray Burst Monitor detection
- GRB 151216A: MAXI/GSC detection
- GRB 151210B: Fermi GBM observation
- GRB151215A: Early optical light curve from pt5m, La Palma
- GRB 151215A: MITSuME Akeno optical upper limits
- GRB 151210B: CALET Gamma-Ray Burst Monitor detection
- GRB 151215A: Swift-XRT refined Analysis
- GRB 151215A: Swift-BAT refined analysis
- GRB151215A: Swift/UVOT detection
- GRB 151215A: MASTER early OT detection and light curve
- GRB 151215A: NOT spectroscopy and redshift
- GRB 151215A: Enhanced Swift-XRT position
- GRB 151215A: GROND Detection of the Optical/NIR Afterglow
- GRB 151215A: Prompt enhanced Swift-XRT position
- GRB151215A: P60 Optical Afterglow Candidate
- GRB 151215A: Swift detection of a burst
- LIGO/Virgo G184098: LOFAR follow-up
- GRB151212A: Swift/UVOT observations
- GRB 151212A: GROND Optical Afterglow Candidate
- GRB 151212A: Swift-XRT afterglow detection
- GRB 151212A: Tiled Swift observations
- GRB 151212A: MAXI/GSC detection
- GRB 151210A: Swift/UVOT Upper Limits
- GRB 151210A: Swift-BAT refined analysis
- GRB 151210A: Swift-XRT refined Analysis
- GRB 151210A: Enhanced Swift-XRT position
- GRB 151210A: GROND Afterglow Confirmation
- GRB 151210A: Optical afterglow candidate from LCOGT-Cerro Tololo
- GRB 151210A: Swift detection of a burst
- GRB 151205C: Optical follow-up observations at Kiso
- GRB 151205A: Khureltogot upper limit
- Swift detection of 4U 1850-03
- GRB 151205B: Deep GROND Upper limits
- GRB 130831A: MASTER early OT detection and LC
- GRB 151205B: further Swift-XRT observations
- GRB 151205C: Swift-XRT observations
- GRB 151205B, Swift-BAT refined analysis
- GRB 151205A: Swift-XRT refined Analysis
- GRB 151205A, Swift-BAT refined analysis
- GRB 151205C: Tiled Swift observations
- GRB 151205C: MAXI/GSC detection
- GRB 151205B: MASTER-NET early optical observations
- GRB 151205A: Fermi GBM detection
- GRB 151205A: Garching Telescope Upper Limit
- GRB151205B: Initial UVOT observations
- GRB 151205B: Swift-XRT observations
- GRB 151205A: Swift/UVOT Upper Limits
- GRB 151205B: Swift detection of a burst
- GRB 151205A: Enhanced Swift-XRT position
- GRB 151205A: Swift detection of a burst
- GRB 151127A iTelescope observation
- LIGO/Virgo G184098: Results of of 2nd epoch of ASKAP follow-up
- Fermi GBM trigger 470712580/151202062 is not a GRB
- Fermi GBM trigger 470290196/151127174 is not a GRB
- GRB 151122A: Further Swift-XRT observations, no afterglow detected.
- Fermi GBM trigger 470375959/151128166 is not a GRB
- GRB 151127A: Swift/UVOT Upper Limits
- GRB 151127A: Swift-XRT refined Analysis
- GRB 151127A: Swift-BAT refined analysis
- GRB 151127A: Enhanced Swift-XRT position
- GRB151127A: Planned XMM-Newton observation
- GRB 151127A: GROND K-band upper limit
- GRB 151127A: LCOGT-SSO optical upper limits
- GRB 151127A: Swift detection of a short burst
- GRB 151118A iTelescope observation
- GRB 151122A: Swift/UVOT Observations
- GRB 151122A: Swift-XRT observations
- GRB 151122A: Fermi GBM detection
- GRB 151122A: Swift ToO observations
- GRB 151122A: Swift detection of a burst
- Konus-Wind observation of GRB 151120A
- GRB 151027A: Maidanak optical observations
- Swift-BAT refined analysis of trigger 664624 from SGR J1819-1600
- Swift Trigger 664610 is not astrophysical
- Swift-BAT probable detection of an outburst from SGR J1819-1600 (AX J1818.8-1559)
- Swift Trigger 664610: is unlikely a GRB
- GRB 151118A: MITSuME Akeno optical upper limits
- GRB 151120A: Swift-XRT afterglow detection
- GRB 151120A: Fermi GBM observation
- GRB 151118A: AAO optical upper limit
- LIGO/Virgo G194575: Updated significance from offline GW analysis
- GRB 151120A: Swift ToO observations
- GRB 151120A: GROND optical/NIR afterglow
- GRB 151120A: A long GRB detected by INTEGRAL
- GRB 151118A, Swift-BAT refined analysis
- LIGO/Virgo G194575: Fermi GBM Observations
- 610 MHz detection of GRB 151027A with the GMRT
- GRB 151118A: Early optical limit from pt5m, La Palma
- GRB 151118A: ISON-NM early optical limit
- GRB 151118A: Swift-XRT refined Analysis
- GRB 151027A: SAO RAS and Mt. Terskol observations
- GRB 151118A: Swift/UVOT Upper Limits
- GRB 151118A: Enhanced Swift-XRT position
- GRB GRB 151118A: MASTER-NET optical observations