GCN Circulars
GCN Circulars are rapid bulletins submitted by and distributed to the community. 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 251222A / EP251222b: Kilonova-Catcher optical afterglow detection
- GRB 251129A / EP251129a: VLA detection of a radio counterpart
- EP251222a: VLT/FORS2 spectroscopic redshift z = 0.505
- GRB 251222A: ZTSH BVRI optical observations
- GRB 251222A: SVOM/COLIBRÍ (FM-GFT) optical observations
- GRB 251222A: Continued 1.3m DFOT optical observation
- EP251220a: 3.6m DOT optical afterglow detection
- GRB 251222A: Fermi GBM Observation
- EP251220a: CrAO ZTSh optical observations
- EP251221a: PRIME upper limit
- EP251222a: Global MASTER-Net observations report
- GRB 251222A / EP251222b: GECAM-B observation
- EP251221a: Liverpool Telescope upper limits
- EP251222a: refined analysis of the EP-WXT and EP-FXT observations
- EP251222b/GRB 251222A: refined analysis of the EP-WXT and EP-FXT observations
- Konus-Wind detection of GRB 251222A / EP251222b
- GRB 251222A: Swift-XRT afterglow detection
- GRB 251222A / EP251222b: LCO detection of the optical counterpart
- EP251222a: NTT/ULTRACAM optical observations
- EP251222a: GOTO optical upper limit
- GRB 251222A / EP251222b: GOTO optical counterpart detection
- GRB 251222A / EP251222b: LCO optical observations
- GRB 251222A: 1.3m DFOT optical detection
- GRB251221A: 7DT optical upper limits
- EP251222a: GSP Optical Counterpart Detection
- GRB 251222A / EP251222b: VLT/X-shooter spectroscopic redshift z = 3.171
- GRB 251222A / EP251222b: SVOM/VT optical rebrightening
- EP251222b/GRB 251222A: SVOM/GRM observation
- EP251222b/GRB 251222A: Einstein Probe detection of an X-ray transient
- EP251222a: Einstein Probe detection of an X-ray transient
- The EP-WXT trigger 01709250397 is likely a flaring star
- EP251221a: Global MASTER-Net observations report
- GRB 251222A: PRIME near-infrared detection
- EP251221a: NOT optical upper limit
- GRB 251222A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
- GRB 251222A: NOT optical observations
- IceCube-251218A: No Candidate Transients from the Zwicky Transient Facility
- IPN triangulation of GRB 251220B (short)
- GRB 251222A: Swift ToO observations
- GRB 251222A: BALROG localization (Fermi Trigger / GRB 251222712)
- GRB 251222A: SVOM/VT optical candidate
- GRB 251222A: SVOM detection of a long burst
- SVOM GRB251222A: Global MASTER-Net observations report
- GRB 251222A: Fermi GBM Final Real-time Localization
- EP251220a: PRIME upper limit
- EP251220a: VLT/FORS2 spectroscopic redshift z = 2.375
- GRB 251221A: PRIME near-infrared observation
- EP251220a: NOT optical observations
- EP251220a: FTW optical and NIR observations
- GRB 251221A: UAFO and Mondy optical upper limit
- GRB 251221A: Swift-XRT refined Analysis
- EP251221a: Einstein Probe detection of a fast X-ray transient
- GRB 251221A: Swift/UVOT Upper Limits
- Fermi Gamma-ray Burst Monitor trigger 788028118/251221696 is not a GRB
- GRB 251221A: Enhanced Swift-XRT position
- GRB 251221A: Fermi GBM Observation
- GRB 251221B: Fermi GBM Final Real-time Localization
- EP251220a: EP-FXT follow-up observation
- GRB 251220B: SVOM/GRM observation of a short burst
- EP251220a: COLIBRÍ confirmation of fading and photometric redshift upper limit of z < 3.4
- EP 251220a: GOTO optical counterpart detection
- GRB 251221A: COLIBRÍ detection of the optical counterpart
- EP 251220a: COLIBRÍ detection of the optical counterpart
- GRB 251221A: Swift detection of a burst
- Swift GRB251221A: Global MASTER-Net observations report
- GRB 251221A: Fermi GBM Final Real-time Localization
- EP251220a: Global MASTER-Net observations report
- EP251220a: EP detection of a fast X-ray transient
- SVOM GRB251220.98: Global MASTER-Net observations report
- GRB 251220B: Fermi GBM Final Real-time Localization
- GRB 251219A: SVOM/GRM observation of a short burst
- GRB 251219A: GECAM-B detection of a possible magnetar X-ray burst from SGR 1830-0645
- Fermi-LAT Gamma-ray Observations of IceCube-251218A
- GRB 251220A: MAXI/GSC detection
- GRB 251215A: Swift-XRT afterglow detection
- IceCube-251218A: Upper limits from a search for additional neutrino events in IceCube
- IceCube-251218A: COLIBRÍ optical upper limits
- SVOM GRB251219.11: Global MASTER-Net observations report
- IceCube-251218A - IceCube observation of a high-energy neutrino candidate track-like event
- IceCube Alert 251218.85: Global MASTER-Net observations report
- GRB 251214B: VIRT Optical Upper Limit
- Fermi trigger No 787736968: Global MASTER-Net observations report
- Fermi GRB 251217A: Global MASTER-Net observations report
- GRB 251217A: Fermi GBM Final Real-time Localization
- GRB 251215A: Swift/UVOT Upper LImits
- GRB 251215A: Fermi GBM Observation
- Fermi GRB 251216A: Global MASTER-Net observations report
- GRB 251202A/EP251202a: Koshka optical upper limit
- GRB 251214B: Mondy optical upper limit
- GRB 251215A: COLIBRÍ optical upper limit
- GRB 251216A: Fermi GBM Final Real-time Localization
- EP251214b: KAIT optical upper limit
- GRB 251215A: Swift-XRT observations
- Fermi GRB 251215A: Global MASTER-Net observations report
- EP251214a: Optical upper limit with Kinder observations
- GRB 251214B: 1.6m Mephisto observations with newly installed mosaic cameras
- GRB 251215A: Glowbug gamma-ray detection
- GRB 251214B: UAFO optical upper limit
- GRB 251214B: VLT/X-shooter observations
- GRB 251213A: GRID-10B observation