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"- Konus-Wind detection of GRB 260921A (possible merger-origin)
- GRB 260924A: Fermi-LAT detection of a bright burst
- GRB 260924A: AstroSat CZTI detection
- GRB 260920A: SVOM/GRM observation
- GRB 260924A: NOT optical counterpart confirmation
- GRB 260924A: detection of a bright optical afterglow by the 1.5m OSN telescope
- GRB 260922A: CALET Gamma-Ray Burst Monitor detection
- GRB 260924A: Enhanced Swift-XRT position
- The EP-WXT trigger 01709319842 is likely a flaring star
- GRB 260924A: Swift detection of a burst
- GRB 260924A: Fermi GBM Final Real-time Localization
- Fermi GRB 260923A: Global MASTER-Net observations report
- GRB 260923A: Fermi GBM Final Real-time Localization
- Trigger_21914: Swift ToO observations (retracted)
- EP260806a: e-MERLIN detection at 5 GHz
- GRB 260922A: Ondrejov D50 optical limit
- Fermi-LAT Gamma-ray Observations of IceCube-260919A
- Fermi-LAT Gamma-ray Observations of IceCube-260916A
- ATCA observations of GRB 260909A
- GRB 260922A: Swift-BAT refined analysis
- EP260920a: VLT/HAWK-I near-infrared counterpart confirmation
- GRB 260922A: J-band upper limit with WINTER
- GRB 260922A: Swift/UVOT Upper Limits
- GRB 260922A: COLIBRÍ Optical Counterpart Candidate (correction to GCN 45698)
- GRB 260922A: COLIBRÍ optical upper limits
- GRB 260922A: Swift-XRT refined Analysis
- GRB 260922A: Enhanced Swift-XRT position
- Fermi-LAT Gamma-ray Observations of IceCube-260805A
- Konus-Wind detection of GRB 260810A
- GRB 260920A: Glowbug gamma-ray detection
- GRB 260918A: SVOM/ECLAIRs refined analysis
- GRB 260922A: SVOM/C-GFT optical upper limit
- GRB 260922A: Swift detection of a burst
- GRB 260917C: AstroSat CZTI detection
- GRB 260920B/EP260920b: GECAM-B detection of a burst
- GRB 260921A: AstroSat CZTI detection
- GRB 260921A: Swift-BAT refined analysis
- GRB 260921B: Fermi GBM Final Localization
- GRB 260921A: Fermi GBM Observation
- EP260920b: 2.2m CAHA optical afterglow detection and 10.4m GTC redshift confirmation
- EP Alert 260921.58: Global MASTER-Net observations report
- GRB 260917B:: SVOM/ECLAIRs refined analysis
- The EP-WXT trigger 01709319528 is likely a flaring star
- EP260920a: VLT/HAWK-I near-infrared candidate
- Swift GRB 260921A: MASTER OT J094129.58+025052.5 possible optical counterpart detection with host galaxy (z=1.3)
- Swift GRB 260921A: Global MASTER-Net observations report
- GRB 260921A: Swift detection of a burst
- EP260920b: VLT/X-shooter spectroscopic redshift z = 3.582
- GRB 260921A: Fermi GBM Final Real-time Localization
- EP260920b: LCO observations
- GRB 260920A: AstroSat CZTI detection
- EP260920b: SVOM/VT optical observation
- EP260920b: refined analysis of the EP-WXT and EP-FXT observations
- EP260920b: COLIBRÍ optical observations
- EP260920b: LCO optical counterpart detection
- The EP-WXT trigger 01709318601 is likely a flaring star
- EP Alert 260921.01: Global MASTER-Net observations report
- EP260920b: Global MASTER-Net observations report
- EP260920b: Einstein Probe detection of an X-ray transient
- IceCube-260919A: Upper limits from a search for additional neutrino events in IceCube
- EP Alert 260920.66: Global MASTER-Net observations report
- EP-WXT detected a brightening of HMXB LS V +44 17
- EP260920a: NOT early time optical upper limits
- EP260920a: NOT optical upper limits
- GRB 260920A: Fermi GBM Final Real-time Localization
- EP260920a: SVOM/VT optical upper limits
- EP260917a: Global MASTER-Net observations report
- EP260920a: refined analysis of the EP-WXT and autonomous EP-FXT observations
- EP260920a: COLIBRÍ optical upper limits
- EP260920a: Update of the LCO optical counterpart candidate
- EP260917b: EP-FXT non-detection and upper limit
- IceCube Alert 260919A: Global MASTER-Net observations report
- EP260920a: LCO optical counterpart candidate
- EP260920a: Einstein Probe detection of an X-ray transient
- EP Alert 260919.40: Global MASTER-Net observations report
- GRB 260915A: VLT optical and near-infrared upper limits
- EP260917a: refined analysis of the EP-FXT observations
- IceCube-260919A - IceCube observation of a high-energy neutrino candidate track-like event
- The EP-WXT trigger 01709318491 is likely a flaring star
- EP260806a: Yamaguchi Interferometer radio detections
- EP260917a: SVOM/VT optical upper limits
- GRB 260918A: SVOM/C-GFT optical upper limits
- EP Alert 260918.62: Global MASTER-Net observations report
- Fermi GBM Sub-Threshold Detection of GRB 260918A
- EP Alert 260918.24: Global MASTER-Net observations report
- SVOM GRB260918.16: Global MASTER-Net observations report
- Konus-Wind detection of GRB 260916B (short/hard)
- The EP-WXT trigger 01709318279 is likely a flaring star
- GRB 260918A: SVOM/VT optical upper limits
- GRB 260916B: Glowbug gamma-ray detection of a short burst
- GRB 260918A: EP-FXT follow-up observation
- GRB 260917B: Mondy optical upper limit
- IPN triangulation of GRB 260916B (short)
- EP260917b: EP-WXT detection of an X-ray transient
- EP260917A: J-band upper limit with WINTER
- IPN triangulation of GRB 260810A
- EP Alert 260917.32: Global MASTER-Net observations report
- GRB 260917B: EP-FXT follow-up observation
- EP260917a: COLIBRÍ optical upper limits
- GRB 260915A: Swift-XRT afterglow detection