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 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
- GRB 260918A: LCO optical upper limits
- EP260917a: Einstein Probe detection of an X-ray transient
- GRB 260918A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
- GRB 260918A: SVOM detection of a burst
- GRB 260917C: Fermi GBM Final Real-time Localization
- GRB 260917B: FRAM-Auger optical limits
- GRB 260916B: Fermi GBM Detection
- IceCube-260916A: Upper limits from a search for additional neutrino events in IceCube
- GRB 260916B: Fermi GBM Final Localization
- GRB 260917A: Glowbug gamma-ray detection
- GRB 260915A: SVOM/ECLAIRs refined analysis
- GRB 260917B: WINTER J-band observations
- GRB 260917B: SVOM/VT optical observations
- SVOM GRB260917.16: Global MASTER-Net observations report
- GRB 260917B: LCO optical observation
- GRB 260917B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
- GRB 260917B: SVOM detection of a faint burst
- GRB 260914A: 2.2m CAHA optical afterglow detection and 10.4m GTC redshift confirmation
- GRB 260917A: BALROG localization (Fermi Trigger 811304653 / GRB 260917100)
- GRB 260917A: Fermi GBM Final Real-time Localization
- Fermi trigger No 811304653: Global MASTER-Net observations report
- The EP-WXT trigger 01709317235 is likely a flaring star
- GRB 260915A: J-band upper limit with WINTER
- Fermi trigger No 811264269: Global MASTER-Net observations report
- IceCube-260916A - IceCube observation of a high-energy neutrino candidate track-like event
- GRB 260909A: NOEMA detection
- GRB 260914A: SVOM/GRM observation
- GRB 260914A: Mondy and TShAO optical observations
- GRB 260914A: SVOM/ECLAIRs refined analysis
- GRB 260909A: Swift-XRT observations
- GRB 260916A: MAXI/GSC detection
- MAXI GRB260916.37: Global MASTER-Net observations report
- GRB 260915A: Swift ToO observations
- GRB 260915A: J-band upper limit by SYSU 80cm infrared telescope
- GRB 260915A: SVOM/C-GFT optical upper limits
- GRB 260915A: EP-FXT follow-up observation
- GRB 260915A: SVOM/VT refined early optical upper limits