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"12320 results found.
- Swift GRB 260101A: Global MASTER-Net observations report
- SVOM GRB251231.57: Global MASTER-Net observations report
- GRB 251230A / EP251230a: SVOM/VT optical continued observations and upper limit
- GRB 251230A / EP251230a: further NOT optical observations revealing shallower decay or possible rebrightening
- GRB 251230A/EP251230a: Optical upper limit with Kinder observations
- EP251229a: Optical upper limit with Kinder observations
- GRB 251230A: 1.3m DFOT optical upper limit
- GRB251230A: 7DT optical upper limits
- GRB 251230A / EP251230a: NOT observations and spectroscopic redshift upper limit z < 2.2
- EP251229a: BOOTES-2 early optical upper limit
- GRB 251230A: GOTO optical upper limit
- EP251229a: NOT optical upper limits
- Swift GRB 251230A: Global MASTER-Net observations report
- EP251229a: Global MASTER-Net observations report
- Fermi GRB 251228A: Global MASTER-Net observations report
- SVOM GRB251227.07: Global MASTER-Net observations report
- IceCube-251225A: Upper limits from a search for additional neutrino events in IceCube
- IceCube Alert 251225.84: Global MASTER-Net observations report
- EP251222a: Optical upper limit with Kinder observations
- GRB 251129A / EP251129a: VLA detection of a radio counterpart
- EP251221a: PRIME upper limit
- EP251222a: Global MASTER-Net observations report
- EP251221a: Liverpool Telescope upper limits
- GRB 251222A: Swift-XRT afterglow detection
- EP251222a: GOTO optical upper limit
- GRB251221A: 7DT optical upper limits
- EP251221a: Global MASTER-Net observations report
- EP251221a: NOT optical upper limit
- IceCube-251218A: No Candidate Transients from the Zwicky Transient Facility
- SVOM GRB251222A: Global MASTER-Net observations report
- EP251220a: PRIME upper limit
- EP251220a: VLT/FORS2 spectroscopic redshift z = 2.375
- GRB 251221A: UAFO and Mondy optical upper limit
- GRB 251221A: Swift/UVOT Upper Limits
- EP251220a: COLIBRÍ confirmation of fading and photometric redshift upper limit of z < 3.4
- GRB 251221A: Swift detection of a burst
- Swift GRB251221A: Global MASTER-Net observations report
- EP251220a: Global MASTER-Net observations report
- SVOM GRB251220.98: Global MASTER-Net observations report
- Fermi-LAT Gamma-ray Observations of IceCube-251218A
- GRB 251220A: MAXI/GSC detection
- IceCube-251218A: Upper limits from a search for additional neutrino events in IceCube
- IceCube-251218A: COLIBRÍ optical upper limits
- SVOM GRB251219.11: Global MASTER-Net observations report
- IceCube Alert 251218.85: Global MASTER-Net observations report
- GRB 251214B: VIRT Optical Upper Limit
- Fermi trigger No 787736968: Global MASTER-Net observations report
- Fermi GRB 251217A: Global MASTER-Net observations report
- GRB 251215A: Swift/UVOT Upper LImits
- Fermi GRB 251216A: Global MASTER-Net observations report
- GRB 251202A/EP251202a: Koshka optical upper limit
- GRB 251214B: Mondy optical upper limit
- GRB 251215A: COLIBRÍ optical upper limit
- EP251214b: KAIT optical upper limit
- GRB 251215A: Swift-XRT observations
- Fermi GRB 251215A: Global MASTER-Net observations report
- EP251214a: Optical upper limit with Kinder observations
- GRB 251214B: 1.6m Mephisto observations with newly installed mosaic cameras
- GRB 251214B: UAFO optical upper limit
- EP251214b: Global MASTER-Net observations report
- EP251214a: KAIT optical upper limit
- GRB 251214B: Swift/UVOT Detection
- EP251214a: EP-FXT non-detection and upper limit
- EP251214a: Global MASTER-Net observations report
- Fermi trigger No 787396657: Global MASTER-Net observations report
- EP251214a: COLIBRÍ optical upper limit
- Swift GRB 251214B: Global MASTER-Net observations report
- EP251214.305: COLIBRÍ optical upper limit
- Fermi GRB 251214A: Global MASTER-Net observations report
- EP251212a: Global MASTER-Net observations report
- EP251212a: KAIT optical upper limit
- EP251212a : COLIBRÍ optical upper limit
- Fermi-LAT Gamma-ray Observations of IceCube-251210A
- IceCube-251210A: Upper limits from a search for additional neutrino events in IceCube
- Fermi GRB 251211B: Global MASTER-Net observations report
- IceCube-251210A: DDOTI Optical Upper Limit
- SVOM GRB251211.12: Global MASTER-Net observations report
- GRB 251205A: 1.3m DFOT optical upper limit
- IceCube Alert 251210.46: Global MASTER-Net observations report
- EP251124a: Mondy optical upper limit
- GRB 251208B: COLIBRÍ optical upper limits
- Fermi GRB 251209A: Global MASTER-Net observations report
- Fermi GRB 251208C: Global MASTER-Net observations report
- GRB 251206A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
- GRB 251208D: LAST optical upper limit
- GRB 251208B: GROWTH-India Telescope optical upper limits
- GRB 251208D: Swift-XRT observations
- GRB 251129A: e-MERLIN C-band observations
- LAT GRB251208.43: Global MASTER-Net observations report
- GRB 251208D: LCO optical upper limits
- SVOM GRB251208D: Global MASTER-Net observations report
- SVOM GRB251206.86: Global MASTER-Net observations report
- GRB 251203C: Swift/UVOT Upper Limit
- Konus-Wind detection of GRB 251118A
- Swift GRB251205A: Global MASTER-Net observations report
- GRB 251203C: SVOM/COLIBRÍ (FM-GFT) optical upper limit
- GRB 251201B: SALT spectroscopic redshift z = 1.599
- GRB 251203C: J-band observations with WINTER
- GRB 251203C: LCO optical afterglow confirmation
- GRB 251203B: Swift-XRT observations