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"- GRB 220107A: Fermi GBM observations
- Fermi trigger No 663274898: Global MASTER-Net observations report
- GRB 220107A: Swift ToO observations
- Fermi GRB 220107A: Global MASTER-Net observations report
- GRB 220107A: Swift/BAT-GUANO arcminute localization
- GRB 220101A: Tautenburg observations
- GRB 220107A: BALROG localization (Fermi Trigger 663259536 / GRB 220107615)
- GRB 220107A: Fermi GBM Final Real-time Localization
- GRB 220101A: Continued Mondy optical observations
- GECAM observation of a burst from SGR J1555.2-5402
- GECAM detection of a short burst from SGR 1935+2154
- GRB 220101A: further TNG NIR observations
- GRB 220101A: continued 1.3m DFOT Optical Observations
- Fermi trigger No 663129379: Global MASTER-Net observations report
- GRB 220104A: Fermi GBM Observation
- GECAM observations of a series of bursts from SGR J1935+2154
- GRB 220101A: Mondy optical observations
- GRB 220101A: 3rd LCO Optical Observation
- GRB 220101A: 2.2m CAHA (+CAFOS) first day optical detection
- GRB 220101A: iTelescope optical observations
- GRB 211227A: Lijiang 2.4m Telescope Optical Observations
- GRB 220101A: VLA detection
- GRB 220101A: 1.3m DFOT observations
- GRB 220101A: LCO Continued Optical Observations
- GRB 220104A：GECAM detection
- Fermi GRB 220104A: Global MASTER-Net observations report
- GRB 220104A: Fermi GBM Final Real-time Localization
- GRB 211229B: Fermi GBM observation
- Fermi GRB 220103A: Global MASTER-Net observations report
- GRB 220103A: Fermi GBM Final Real-time Localization
- GRB 211227A: Gemini South Optical Observations
- GRB 211229B: Swift/BAT-GUANO detection outside the coded FOV
- Alert from the HAWC Burst Monitor HAWC-220103A
- GRB 220101A: TNG NIR afterglow detection
- GRB 220101A: ALMA detection
- GRB 220101A: LCO Optical Observations
- GRB 220101A: Tautenburg observations
- GRB 220101A: Swift-BAT refined analysis
- GRB 220101A: GMG observation (2nd epoch)
- GRB 211231A: AstroSat CZTI detection
- GRB 220101A: OASDG optical observations
- GRB 220101A : Eiso equals the maximum isotropic GRB energy
- GRB 220101A: GMG observation
- GRB 220101A: Asiago spectroscopic and photometric detection
- Fermi trigger No 662768315: Global MASTER-Net observations report
- GRB220101A: optical afterglow detection from Konkoly Observatory
- GRB 220101A: Fermi GBM Detection
- GRB 220101A: NOT redshift confirmation
- GRB 220101A: CAHA 2.2m/CAFOS detection
- GRB 220101A: Liverpool telescope imaging of a high-redshift afterglow
- GRB 220101A: THO optical observations
- GRB 220101A: Swift-XRT refined Analysis
- GRB 220101A: AGILE detection
- GRB 220101A: Xinglong-2.16m photometry and spectroscopy
- Swift GRB220101.22: Global MASTER-Net observations report
- GRB 220101: Swift/UVOT Detection
- GRB 220101A: Fermi-LAT detection
- GRB 220101A: Enhanced Swift-XRT position
- GRB 220101A: Correction to GCN 31347
- GRB 220101A: Swift detection of a burst with a bright optical counterpart
- IPN triangulation of GRB 211219A
- GRB 211231A: GECAM detection
- GRB 211229B: AGILE detection
- GRB 211231A: Fermi GBM Final Real-time Localization
- GRB 211229A: Swift-XRT and UVOT observations
- GRB 211227A: Deep early CAHA 2.2m/CAFOS observation
- GRB 211229A: Fermi GBM observation
- GRB 211229B: GECAM detection
- GRB 211229C: Swift/BAT-GUANO detection likely outside the coded FOV
- Fermi GRB 211229B: Global MASTER-Net observations report
- GRB 211229B: Fermi GBM Final Real-time Localization
- GRB 211229A: Swift ToO observations
- GRB 211229A: Swift/BAT-GUANO arcminute localization
- GRB 211227A: CALET Gamma-Ray Burst Monitor detection
- GRB 211225B: CALET Gamma-Ray Burst Monitor detection
- GRB 211229A: GECAM detection
- Fermi GRB 211229A: Global MASTER-Net observations report
- GRB 211229A: Fermi GBM Final Real-time Localization
- GRB 211227A: Swift/UVOT Upper Limits
- GRB 211227A: Swift-XRT refined Analysis
- GRB 211227A: Swift-BAT refined analysis
- Konus-Wind detection of the intermediate flare from SGR 1935+2154
- GRB 211227A: A possible short GRB with extended emission at z = 0.228?
- GRB 211227A: Liverpool Telescope upper limits
- GRB 211227A: Enhanced Swift-XRT position
- GRB 211227A: LCO Optical Observations
- GRB 211227A: Nanshan/NEXT optical observations and host galaxy candidate
- GRB 211227A: MAXI/GSC detection
- GRB 211227A: BOOTES-2/TELMA optical upper limit
- GRB 211221A: Swift/UVOT Upper Limits
- GRB 211227A: Swift detection of a burst
- Swift GRB211227.98: Global MASTER-Net observations report
- IceCube-20211216B: observations of SN2021gpw in the errorbox of the neutrino trigger
- GRB 211226A: Swift/BAT-GUANO detection outside the coded FOV
- GRB 211225B: Swift-BAT refined analysis
- Fermi trigger No 662216114: Global MASTER-Net observations report
- GRB 211225A: MITSuME Akeno optical upper limits
- GRB 211226A: AGILE/MCAL detection of a burst
- Swift GRB 211225B: Global MASTER-Net observations report
- Fermi GRB 211225C: Global MASTER-Net observations report