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"- Integral GRB221012.53: Global MASTER-Net observations report
- GRB 221009A/Swift J1913.1+1946: eMERLIN observations
- Fermi trigger No 687205006: Global MASTER-Net observations report
- INTEGRAL detection of a burst from SGR J1935+2154
- GRB 220829A: Detection by GRBAlpha
- GRB 220826B: Detection by GRBAlpha
- GRB 221009A: NuSTAR Detection
- GRB 221009A: NICER follow-up observations
- GRB 221009A: LCOGT Optical Afterglow Detection
- GRB 221009A: COATLI Detection of the Afterglow
- GRB221009A: INTEGRAL detection of Hard X-ray emission up to 38 hours after trigger
- GRB 221009A: planned observation with the Imaging X-ray Polarimetry Explorer (IXPE)
- Fermi trigger No 687190301: Global MASTER-Net observations report
- GRB 221009A (Swift J1913.1+1946): Swift-BAT refined analysis
- Fermi Gamma-ray Burst Monitor trigger 221011452/687178284 is not a GRB
- GRB 221009A: 10.4m GTC spectroscopic redshift confirmation
- GRB 221009A: Detection by GRBAlpha
- GRB 221009A: Sintez-Newton/CrAO optical observations
- GRB 221009A: Upper limits from HAWC 8 hours after trigger
- GRB 221006A: Swift ToO observations
- GRB 221011A: Fermi GBM Final Real-time Localization
- Swift/XRT discovery of multiple dust-scattering X-ray rings around GRB 221009A
- GRB 221009A (Swift J1913.1+1946): iTelescope optical observation
- GRB 221009A: BlackGEM optical observations
- LHAASO observed GRB 221009A with more than 5000 VHE photons up to around 18 TeV
- GRB 221009A: NOEMA mm detection
- INTEGRAL detection of a burst from SGR J1935+2154
- GRB 221006A: CALET Gamma-Ray Burst Monitor detection
- Integral GRB221010.89: Global MASTER-Net observations report
- Fermi trigger No 687077239: Global MASTER-Net observations report
- GRB 221009A: Continued Swift/XRT observations
- GRB 221009A/Swift J1913.1+1946: Assy optical afterglow observation
- GRB 221009A/Swift J1913.1+1946: Lick/Nickel telescope optical observations
- Konus-Wind detection of GRB 221009A
- GRB 221009A: Lulin SLT-40cm optical observations
- Swift J1913.1+1946: New Photometry
- GRB 221009A: Upper limits from a neutrino search with IceCube
- GRB 221009A (Swift J1913.1+1946): Burke-Gaffney Observatory optical observations
- GRB221009A/Swift J1913.1+1946: SRG/ART-XC observation
- GRB 221009A / Swift J1913.1+1946: GIT detection of the optical afterglow
- GRB221009A/Swift J1913.1+1946: Solar Orbiter STIX measurements
- GRB221009A/Swift J1913.1+1946: INTEGRAL SPI/ACS observations
- GRB 221009A: Multi-color detection of the optical
- GRB 221009A: Fermi-LAT refined analysis
- GRB 221009A (Swift J1913.1+1946): AGILE/GRID detection
- GRB 221009: Swift/UVOT Detection
- GRB221009A/Swift J1913.1+1946: ATA follow-up observations
- GRB 221009A or Swift J1913.1+1946: PRIME near-infrared detection
- GRB 221009A/Swift J1913.1+1946: AMI-LA observations
- GRB 221009A: REM optical and NIR detection of the afterglow
- GRB 221009A: Swift-XRT refined Analysis
- GRB 221009A (Swift J1913.1+1946): AGILE/MCAL detection
- Swift J1913.1+1946: Early Optical Photometry
- GRB 221009A: Redshift from X-shooter/VLT
- GRB 221009A: Nanshan/NEXT photometry and Xinglong-2.16m spectroscopy
- GRB 221009A (Swift J1913.1+1946): MeerLICHT observations
- GRB 221009A (Swift J1913.1+1946): Mondy optical observations
- GRB 221009A BOOTES-2/TELMA and OSN optical detections
- Swift J1913.1+1946 : Pre-discovery limits from ZTF
- GRB 221009A: Fermi GBM observation
- IPN triangulation of extremely bright GRB 221009A
- Swift J1913.1+1946: Optical photometry
- Fermi trigger No 687014224: Global MASTER-Net observations report
- Swift J1913.1+1946: Liverpool Telescope imaging and spectroscopy
- GRB 221009A or Swift J1913.1+1946: Fermi-LAT detection
- GRB 221009A: Fermi GBM detection of an extraordinarily bright GRB
- GRB 221009A: Swift detected transient may be GRB
- Swift GRB221009.59: Global MASTER-Net OT detection
- GRB 221008A: Swift-XRT observations
- Swift J1913.1+1946 a new bright hard X-ray and optical transient
- GRB 221008A: Tiled Swift observations
- GRB 221008A: MAXI/GSC detection
- GRB 220915A: Detection by GRBAlpha
- GRB 221006A: Swift-XRT observations
- GRB 221006A: Tiled Swift observations
- GRB 221006A: MAXI/GSC detection
- GRB 220930A: MITSuME Akeno optical upper limits
- GRB 220912A: Detection by VZLUSAT-2
- Fermi trigger No 686588176: Global MASTER-Net observations report
- GRB220927A: Detection by GRBAlpha
- Fermi GBM trigger 686565116/221004355 is not a GRB
- Fermi GBM trigger 686435254/221002852 is not a GRB
- Fermi GBM trigger 686350260/221001869 is not a GRB
- GRB 220921A: ATCA detection of radio counterpart
- GRB 220930A: AbAO Optical Upper Limit
- Fermi trigger No 686403226: Global MASTER-Net observations report
- Fermi trigger No 686350260: Global MASTER-Net observations report
- Konus-Wind detection of GRB 220930A
- GRB 220930A: AstroSat CZTI detection
- GRB 220930A: Swift-BAT refined analysis
- GRB 220930A: Swift-XRT refined Analysis
- GRB 220930A: LCOGT Optical Upper Limits
- GRB 220930A: Swift/UVOT Upper Limits
- GRB 220930A: Enhanced Swift-XRT position
- Swift GRB 220930A: Global MASTER-Net observations report
- GRB 220930A: BOOTES-5/JGT early optical upper limit
- GRB 220930A: Prompt enhanced Swift-XRT position
- GRB 220930A: COATLI Upper Limits
- GRB 220930A: Swift detection of a burst
- Fermi-LAT gamma-ray observations of IceCube-220928A