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 210724A: Swift-XRT refined Analysis
- GRB 210725A: Swift-BAT refined analysis
- GRB 210724A: Swift-BAT refined analysis
- Swift GRB 210725B: Global MASTER-Net observations report
- GRB 210724A: Afterglow candidate from OSIRIS/GTC
- GRB 210725B: Enhanced Swift-XRT position
- GRB 210725A: MITSuME Akeno optical upper limits
- GRB 210725B: Swift detection of a burst
- GRB 210725A: CALET Gamma-Ray Burst Monitor detection
- GRB 210723A: CALET Gamma-Ray Burst Monitor detection
- GRB 210722A: continued Assy optical observations
- GRB 210722A: Nanshan/NEXT further optical observations
- GRB 210725A: KAIT Optical Upper Limit
- Fermi trigger No 648868114: Global MASTER-Net observations report
- GRB 210725A: Swift detection of a burst
- Swift GRB210725.16: Global MASTER-Net observations report
- GRB 210723A: Fermi GBM Observation
- GRB210724A: MeerLICHT upper limits
- GRB 210724A: Swift detection of a burst
- Swift GRB210724.84: Global MASTER-Net observations report
- GRB 210723A: Swift-BAT refined analysis
- GRB 210722A: continued Assy optical observations
- GRB 210723A: Swift-XRT refined Analysis
- GRB 210722A: D50 optical detection
- Swift GRB 210723A: Global MASTER-Net observations report
- GRB 210722A: Fermi GBM observation
- GRB 210722A: Swift-BAT refined analysis
- GRB 210722A: Kitab optical observations, light curve
- GRB 210722A: Redshift from OSIRIS/GTC
- GRB 210723A: Prompt enhanced Swift-XRT position
- GRB 210723A: Swift detection of a burst
- GRB 210722A: RATIR Optical Observations
- GRB 210722A: Swift-XRT refined Analysis
- GRB 210722A: Swift/UVOT Detection
- GRB 210722A: GIT optical detection and preliminary analysis
- Swift GRB 210722A: Global MASTER-Net observations report
- GRB 210702A: ALMA detection of mm-band rebrightening
- GRB 210722A: Assy optical detection
- GRB 210702A: ATCA detection of radio rebrightening
- GRB 210722A: Nanshan/NEXT optical afterglow observations
- GRB 210722A: Swift detection of a burst with a bright optical counterpart
- Fermi trigger No 648602917: Global MASTER-Net observations report
- Fermi-LAT Gamma-ray Observations of IceCube-210717A
- GRB 210719A: GECAM detection
- IceCube-210717A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
- Fermi trigger No 648359752: Global MASTER-Net observations report
- Fermi trigger No 648278666: Global MASTER-Net observations report
- IceCube-210717A: IceCube observation of a high-energy neutrino candidate track-like event
- Konus-Wind detection of GRB 210714A
- Fermi trigger No 647942198: MASTER optical afterglow detection
- GRB 210704A: Zeiss-1000/SAO-RAS optical observations
- GRB 210715B: DDOTI Upper Limits on the Afterglow
- Fermi trigger No 648033323: Global MASTER-Net observations report
- Fermi trigger No 648024201: Global MASTER-Net observations report
- Fermi trigger No 647942198: Global MASTER-Net observations report
- GRB 210712A: Swift-BAT refined analysis
- GECAM detection of a short burst from SGR J1935+2154
- Recent activity of SGR 1935+2154 as observed by CGBM
- GRB 210712A: Swift-XRT refined Analysis
- GRB 210712A: Swift/UVOT Upper Limits
- GRB 210712A: BOOTES-3/YA optical upper limit
- Fermi trigger No 647805873: Global MASTER-Net observations report
- GRB 210712A: Enhanced Swift-XRT position
- GRB 210704A: classification as long GRB and redshift estimating
- GRB 210704A: Lowell Discovery Telescope Optical Observations
- Konus-Wind detection of a burst from SGR 1935+2154 on 2021 July 10
- GECAM detection of a short burst from SGR J1935+2154
- Fermi trigger No 647775795: Global MASTER-Net observations report
- GRB 210712A: Swift detection of a burst
- GRB 210709A: AstroSat CZTI detection
- GRB 210704A: Continued Gemini-North NIR K-band Detections
- GRB 210704A: INTEGRAL observations
- GRB 210704A: NOT optical observations and color change
- GRB210704A: Gemini near-infrared upper limits
- Fermi trigger No 647653174: Global MASTER-Net observations report
- GRB 210704A: Assy optical afterglow upper limit
- Fermi trigger No 647641569: Global MASTER-Net observations report
- Fermi trigger No 647624281: Global MASTER-Net observations report
- GECAM detection of a short burst from SGR J1935+2154
- GRB 210704A: OSIRIS/GTC Observations and Archival Detection of the Possible Host Galaxy
- MAXI GRB210709.93: Global MASTER-Net observations report
- Fermi trigger No 647522278: Global MASTER-Net observations report
- GRB 210704A: Gemini-North Infrared Source Detection
- GRB 210704A: further TNG optical observations
- GRB 210706A: Swift/XRT afterglow confirmation
- GECAM detection of a short burst from SGR 1935+2154
- GRB 210708B: Swift-BAT refined analysis
- Fermi GRB 210709A: Global MASTER-Net observations report
- GRB 210709A: Fermi GBM Final Real-time Localization
- Swift GRB 210708B: Global MASTER-Net observations report
- GRB 210708A: Swift/UVOT Upper Limits
- GRB 210702A: ATCA detection
- GRB 210702A: ALMA detection
- GRB 210708A: Swift-BAT refined analysis
- Fermi GBM Sub-Threshold Detection of GRB 210708A
- Fermi GBM Sub-Threshold Detection of GRB 210707A
- IceCube-210629A - Spectroscopic observation of AT2021osi
- Konus-Wind detection of a burst from SGR 1935+2154 on 2021 July 7
- GRB 210708B: Swift detection of a possible burst
- GRB 210708A: Swift-XRT refined Analysis