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.
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"
- IceCube-210922A: No neutrino counterpart candidates in ANTARES search
- GRB 210923B: GECAM detection
- Retraction of Fermi GBM GRB 210923A: the trigger is not a GRB
- IceCube-210922A: Upper limits from a search for additional neutrino events in IceCube
- IceCube-210922A: Upper limits from Fermi-GBM Observations
- IceCube-210922A: No Candidate Counterparts from the Zwicky Transient Facility
- GECAM observations of a series of bursts from SGR J1935+2154 (2021-09-15T14 to 2021-09-23T14)
- GRB 210919A: DECam Upper Limits
- Fermi-LAT Gamma-ray Observations of IceCube-210922A
- Konus-Wind detection of a burst from SGR 1935+2154 on 2021 September 22
- GRB 210923A: Fermi GBM Final Real-time Localization
- IceCube Alert 210922.76: Global MASTER-Net observations report
- GRB 210919A: Swift-BAT refined analysis
- IceCube-210922A - IceCube observation of a high-energy neutrino candidate track-like event
- GRB 210912A: LBT optical observations
- GRB 210919A: Lowell Discovery Telescope upper limits (correction to GCN 30859)
- GRB 210919a: Lowell Discovery Telescope upper limits
- GRB210919A: Keck NIRC2 Kp band upper limits
- GRB 210919A: Swift/UVOT Upper Limits
- GRB 210919A: LOAO and LSGT optical upper limits
- GRB 210919A: MITSuME Akeno optical upper limits
- GRB 210919A: Swift-XRT refined Analysis
- GRB 210919B: Fermi GBM Final Real-time Localization
- GRB 210919A: NOT upper limits
- GRB 210919A: AbAO optical upper limit
- GRB 210919A: Enhanced Swift-XRT position
- GRB 210919A: LCO Optical Upper Limit
- GRB 210919A: BOOTES-2/TELMA optical upper limit
- Swift GRB 210919A: Global MASTER-Net observations report
- GRB 210919A: Swift detection of a short burst
- Swift trigger 1073821: detection of IGR J16418-4532
- GRB 210912A: BOOTES-5/JGT optical afterglow candidate (Correction to GCNC 30823)
- GRB 210917A: Fermi GBM Final Real-time Localization
- GRB 210812A is not a compelling example of a lensed GRB
- GECAM observations of bursts from SGR J1935+2154 (2021-09-13T01 to 2021-09-15T14)
- GRB 210909A: Detection by GRBAlpha
- GRB 210912A: Swift-BAT refined analysis
- Konus-Wind observation of the recent SGR 1935+2154 activity
- GRB 210912A: Tautenburg observations
- GECAM observations of bursts from SGR J1935+2154 (2021-09-12T05 to 2021-09-13T01)
- AGILE observations of two bright bursts from SGR 1935+2154
- GRB 210912A: CAHA 2.2m Detection
- GRB 210912A: Swift-XRT refined Analysis
- GRB 210912A: Swift/UVOT Detection
- Fermi GBM observation of another bright burst in the direction of SGR 1935+2154
- GRB 210912A: Enhanced Swift-XRT position
- GRB 210912A: Host-galaxy candidate in PanSTARRS
- Fermi trigger No 653151835: Global MASTER-Net observations report
- Fermi trigger No 653124492: Global MASTER-Net observations report
- Fermi trigger No 653122278: Global MASTER-Net observations report
- GRB 210912A: Mondy optical afterglow confirmation
- Swift GRB 210912A: Global MASTER-Net observations report
- GRB 210912A: BOOTES-5/JGT optical afterglow candidate
- GECAM observations of bursts from SGR J1935+2154 (2021-09-11T07 to 2021-09-12T08)
- GRB 210912B: Fermi GBM Final Real-time Localization
- GRB 210912A: Swift detection of a burst
- Fermi trigger No 653093506: Global MASTER-Net observations report
- Fermi trigger No 653066776: Global MASTER-Net observations report
- Fermi trigger No 653084584: Global MASTER-Net observations report
- Fermi trigger No 653083551: Global MASTER-Net observations report
- Fermi trigger No 653079281: Global MASTER-Net observations report
- Fermi trigger No 653066130: Global MASTER-Net observations report
- Fermi trigger No 653072474: Global MASTER-Net observations report
- Fermi trigger No 653071808: Global MASTER-Net observations report
- Fermi trigger No 653054042: Global MASTER-Net observations report
- Fermi trigger No 653049776: Global MASTER-Net observations report
- Fermi trigger No 653022153: Global MASTER-Net observations report
- Fermi trigger No 653031163: Global MASTER-Net observations report
- Swift GRB210910.42: Global MASTER-Net observations report
- Fermi GBM observation of a bright flare in the direction of SGR 1935+2154
- Fermi trigger No 653010039: Global MASTER-Net observations report
- Konus-Wind detection of the second intermediate flare from SGR 1935+2154
- IPN triangulation of a bright burst from SGR 1935+2154
- Fermi trigger No 652957973: Global MASTER-Net observations report
- Fermi trigger No 652944960: Global MASTER-Net observations report
- Fermi trigger No 652981861: Global MASTER-Net observations report
- GRB 210826A: further Swift-XRT observations
- GRB 210909B: GECAM detection
- GECAM observations of a series of bursts from SGR J1935+2154
- Swift detection of a burst from SGR Swift J1555.2-5402
- Fermi trigger No 652934203: Global MASTER-Net observations report
- GECAM observation of a burst from SGR J1935+2154
- GECAM observation of a burst from SGR J1935+2154
- Fermi trigger No 652927551: Global MASTER-Net observations report
- GRB 210619B: Maidanak and Assy optical observations, broken power law parametrization
- Fermi trigger No 652911693: Global MASTER-Net observations report
- Fermi trigger No 652906639: Global MASTER-Net observations report
- Fermi GRB 210909A: Global MASTER-Net observations report
- GECAM observation of a burst from SGR J1555.2-5402
- GRB 210909A: Fermi GBM Final Real-time Localization
- GRB 210905A: Swift/UVOT Upper Limits
- GRB 210905A: ATCA detection
- GRB 210905A: ALMA detection
- GRB 210905A: AstroSat CZTI detection
- GRB 210905A, GROND observations
- Konus-Wind detection of GRB 210905A
- Fermi GBM Sub-Threshold Detection of GRB 210905A
- Fermi GBM trigger 652585475 / 210906073 is not a GRB
- Fermi trigger No 652585475: Global MASTER-Net observations report
- GRB 210905A: Swift-XRT refined Analysis