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"24378 results found.
- GRB 251028A: SVOM/GRM observation
- IceCube-251025A: Two Transient Candidates from the Zwicky Transient Facility
- GRB 251028A: Fermi GBM Observation
- GRB 251022A: Swift-XRT confirmation of fading
- GRB 250926B: VZLUSAT-2 detection
- GRB 250926A: VZLUSAT-2 detection
- GRB 250925A: VZLUSAT-2 detection
- GRB 251026B: Fermi GBM Observation
- GRB 251026A/EP251026a: SVOM/VT optical counterpart
- GRB 251026A/EP251026a: EP-FXT follow-up observation
- The EP-WXT trigger 01709247588 is likely a flaring star
- GRB 251028B: Fermi/GBM observation
- GRB 251028B: Swift/BAT-GUANO localization skymap of a burst
- GRB 251028B: CALET Gamma-Ray Burst Monitor detection
- Fermi GRB 251028B: Global MASTER-Net observations report
- GRB 251028B: Fermi GBM Final Localization Correction
- GRB251025B: 3.6m DOT Optical Observations
- GRB 251028A: BALROG localization (Fermi Trigger 783314796 / GRB 251028143)
- GRB 251028A: Fermi GBM Final Real-time Localization
- The EP-WXT trigger 01709247525 is not a real source
- IceCube-251025A: Upper limits from a search for additional neutrino events in IceCube
- Fermi-LAT Gamma-ray Observations of IceCube-251025A
- Konus-Wind detection of GRB 251022A
- GRB 251022A: SVOM/GRM observation
- Konus-Wind detection of GRB 251016A (short/hard)
- GRB 251027A: SVOM detection of a faint burst
- GRB 251025C: CALET Gamma-Ray Burst Monitor detection
- LIGO/Virgo/KAGRA S251026bn: Updated Sky localization
- Fermi GRB 251026B: Global MASTER-Net observations report
- Fermi GRB 251025C: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S251026bn: Identification of a GW compact binary merger candidate
- IceCube-251025A: DDOTI Optical Upper Limit
- GRB 251026B: Fermi GBM Final Localization
- GRB 251026A: SVOM detection of a long burst
- GRB 251025B: SVOM/VT optical bump
- GRB 251023A: SVOM/GRM observation
- GRB 251025C: Fermi GBM Final Real-time Localization
- Konus-Wind detection of GRB 251016B
- GRB 251024A: Swift-BAT refined analysis
- IceCube Alert 251025.57: Global MASTER-Net observations report
- GRB 251024A: Swift-XRT refined Analysis
- GRB 251025B: SVOM/C-GFT optical counterpart detection
- GRB 251025B: SVOM detection of a burst
- IceCube-251025A - IceCube observation of a high-energy neutrino candidate track-like event
- GRB 251025A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
- GRB 251025A: SVOM/VT VHF optical upper limit
- GRB 251025A: SVOM detection of a faint burst
- GRB 251023C: Glowbug gamma-ray detection
- GRB 251024A: LCOGT Optical Afterglow Detection
- GRB 251022A: KAIT optical observations
- Swift GRB 251024A: Global MASTER-Net observations report
- EP251023b/GRB 251023B: JinShan optical observation
- GRB 251022A: Swift-XRT detection of GOTO25iym
- EP251023b: Global MASTER-Net observations report
- GRB 251023C: CALET Gamma-Ray Burst Monitor detection
- GRB 251023C: Swift/BAT-GUANO localization skymap of a burst
- GRB 251022A: Fermi GBM Observation
- GRB 251022A: Swift/BAT-GUANO localization skymap of a burst
- EP251023a: Global MASTER-Net observations report
- IPN triangulation of GRB 251016B
- EP251023a: Keck/LRIS spectroscopic redshift z=2.232
- GRB 251022A: MASTER OT detection
- EP251021b/GRB 251021A: SVOM/VT optical candidate
- EP251023a: NOT optical counterpart detection
- Fermi GRB 251023A: Global MASTER-Net observations report
- GRB 251022A: GOTO optical counterpart detection
- GRB 251023A: Fermi GBM Final Localization Correction
- GRB 251022A: Fermi-LAT detection
- GRB 251016B: Fermi GBM Detection
- LAT GRB251022A: Global MASTER-Net observations report
- GRB 251022A: Fermi GBM Final Real-time Localization
- GRB 251021A/EP251021b: Fermi-GBM Sub-Threshold Detection
- EP251021b: BOOTES-7 optical upper limit
- LIGO/Virgo/KAGRA S251021u: Updated Sky localization
- GRB 251016A: SVOM/ECLAIRs refined analysis
- LIGO/Virgo/KAGRA S251021u: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S251018bi: Updated Sky localization
- Fermi-LAT gamma-ray observations of IceCube-251018A
- IceCube-251018A: Upper limits from a search for additional neutrino events in IceCube
- GRB 251017A: Swift-BAT refined analysis
- GRB 251016A: Fermi GBM Observation
- GRB 251018A: Fermi GBM Observation
- Fermi trigger No 782500909: Global MASTER-Net observations report
- IceCube-251018A: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S251018bi: Identification of a GW compact binary merger candidate
- IceCube-251018A - IceCube observation of a high-energy neutrino candidate track-like event
- GRB 251017A: VLT/MUSE spectroscopic redshift z = 4.327
- GRB 251016A: VLT/FORS2 Optical Observation
- GRB 251017A: Swift-XRT refined Analysis
- GRB 251018A: MASTER OT detection
- Swift GRB 251018A: Global MASTER-Net observations report
- GRB 251018A: Fermi GBM Final Real-time Localization
- GRB 251017A: SVOM/VT optical observation
- GRB 251011A: Fermi GBM Observation
- GRB 251017A: OHP/T193 i-band observations
- GRB 251013C: OHP/T193 third epoch optical observations and detected rebrightening
- LIGO/Virgo/KAGRA S251017di: Retraction of GW compact binary merger candidate
- Fermi GRB 251016B: Global MASTER-Net observations report
- Swift GRB 251017A: Global MASTER-Net observations report
- GRB 251017A : MITSuME Akeno optical afterglow candidate detection