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"12332 results found.
- GRB 250129A: 7DT Detection and Medium-band SED of Afterglow
- Swift GRB250129A: MASTER 4 days observations report
- LIGO/Virgo/KAGRA S250201i: Coverage and upper limits from MAXI/GSC observations
- EP250108A / SN 2025kg: Upper limits from a neutrino search with IceCube
- GRB 250127A: EP-FXT second observation epoch and confirmation of the x-ray afterglow fading
- GRB 250128B: SAO RAS Zeiss-1000 and CrAO ZTSh optical upper limits
- GRB 250128B: VLA radio upper limit
- Ep250125A: 1.3m DFOT optical upper limit
- GRB 250128B: TNG optical upper limit
- GRB 250127A: CrAO and Terskol optical upper limits
- GRB 250128B: NOT optical upper limit
- GRB 250128B: OHP/T193 optical upper limit
- Swift GRB 250129A: Global MASTER-Net observations report
- Fermi GRB 250128B: Global MASTER-Net observations report
- Swift GRB 250129A: Global MASTER-Net OT detection
- GRB 250128B: GOTO optical upper limit
- Swift GRB 250128B: Global MASTER-Net observations report
- EP250125a: Upper limits from Swift/BAT-GUANO
- GRB 250128B: Swift detection of a short burst
- GRB 250127A: Swift-XRT observations
- GRB 250127B: DDOTI Upper Limit on the Afterglow
- Fermi-LAT Gamma-ray Observations of IceCube-250102A
- Fermi GRB 250128A: Global MASTER-Net observations report
- Fermi GRB 250127B: Global MASTER-Net observations report
- Fermi-LAT Gamma-ray Observations of IceCube-250101A
- GRB 250127A: SVOM/VT upper limit
- GRB 250127A: LCO optical upper limit
- GRB 250126A: MAXI/GSC detection
- EP250108a / SN 2025kg: Refined Analysis of EP-WXT Detection
- EP250125a: Optical upper limit with Kinder observations
- EP250108a: AbAO, CMO and Terskol optical upper limits
- LIGO/Virgo S250119cv: Swift XRT observations, 5 X-ray sources
- Fermi-LAT Gamma-ray Observations of IceCube-241224A
- EP250108a / SN2025kg: Non-detection from ATCA radio follow-up observations
- EP250108a / AT2025kg: VLA radio upper limit
- GRB 250114B: SVOM/VT upper limit
- EP250108a: MeerKAT radio upper limit
- Konus-Wind detection of GRB 250113A
- GRB 250114B: Liverpool Telescope optical upper limit
- GRB 250114B : MITSuME Akeno optical afterglow candidate detection
- GRB 250114B: Swift-XRT observations
- GRB 250114B: OHP/T193 optical upper limit
- Integral GRB250114.55: Global MASTER-Net observations report
- GRB 250114B : GIT optical upper limit
- EP250111a: SAO RAS optical upper limit
- Swift GRB250114A: Global MASTER-Net OT detection
- Swift GRB 250114A: Global MASTER-Net observations report
- EP241021a: SMA radio observation
- EP250109b: optical upper limits with the Liverpool Telescope
- Fermi trigger No 758442826: Global MASTER-Net observations report
- GRB 250109A / EP250109a: Mephisto optical upper limits
- EP250108a: Mephisto detection
- EP250111a: Global MASTER-Net observations report
- EP250108a / AT 2025kg: Swift UVOT detections
- EP250108a: EP-FXT follow-up observation
- GRB 250109a: GMG Optical Upper Limit
- EP250109a: Swift/UVOT non-detection
- GRB 250108B: 1.3m DFOT upper limit
- GRB 250108B: REM optical/NIR upper limits
- EP250109a: SVOM/VT optical candidate
- EP250109a: Global MASTER-Net observations report
- EP250109a: GOTO optical upper limits
- EP250109a: Swift/XRT non-detection
- GRB 250108A: Swift/UVOT Upper Limits
- EP250108a: Global MASTER-Net observations report
- GRB 250108A: NOT optical upper limit
- Swift GRB 250108B: Global MASTER-Net observations report
- GRB 250103A: 1.6m Mephisto optical observations
- GRB 250108A: Swift-XRT afterglow detection
- GRB 250108B: Swift/UVOT Upper Limits
- GRB 250108B: Swift detection of a burst
- Fermi GRB 250107B: Global MASTER-Net observations report
- GRB 250101A: J band upper limit by SYSU 80cm telescope
- GRB 250103B: REM optical/NIR upper limits
- GRB 250106A: Swift-XRT observations
- Fermi trigger No 757753930: Global MASTER-Net observations report
- GRB 250103A: Bassano Bresciano Observatory upper limit
- GRB 250103A: Swift-XRT observations
- GRB 241229A: 1.3m DFOT upper limit
- GRB 241228A: 1.3m DFOT upper limit
- GRB 250103A: TSHAO optical upper limit
- GRB 250103B: LCOGT Optical Upper Limit
- IceCube-250102A: Upper limits from a search for additional neutrino events in IceCube
- Swift GRB 250103B: Global MASTER-Net observations report
- EP250101a: Liverpool Telescope optical upper limit
- IceCube-250101A: Upper limits from a search for additional neutrino events in IceCube
- Fermi GRB 250102A: Global MASTER-Net observations report
- GRB 250103A: GOTO optical upper limit
- GRB 250103A: SVOM/C-GFT optical upper limit
- GRB 250101A: NUTTelA-TAO / BSTI Optical Limits
- IceCube Alert 250102.58: Global MASTER-Net observations report
- EP241231b: optical upper limit with the Liverpool Telescope
- EP250101a: Xinglong optical upper limit
- LIGO/Virgo/KAGRA S241230bd: Upper limits from Swift/BAT-GUANO
- GRB 250101A: Swift/UVOT Detection
- Fermi GRB 250101B: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S250101k: Upper limits from Fermi-GBM Observations
- Swift GRB250101.56: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S241231du: Coverage and upper limit from MAXI/GSC observations
- EP241217A: J band upper limit by SYSU 80cm telescope