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"32501 results found.
- GRB 251222A: radio detection with the VLA
- GRB 260114A: VLT/HAWK-I near-infrared upper limits
- Konus-Wind detection of GRB 260114A
- GRB 260114A: 6 GHz VLA observations
- GRB 260114A: VLT/X-shooter redshift of the putative host galaxy
- GRB 260114A : MITSuME Akeno optical upper limits
- GRB 260114A: COLIBRÍ optical upper limits
- GRB 260114A: TNG NIR upper limit
- GRB 260114A: NOT optical observations
- Konus-Wind detection of GRB 251230A / EP251230a
- GRB 260114A: SVOM/GRM observation of a short burst
- Swift GRB 260114A: Global MASTER-Net observations report
- GRB 260114A: GECAM-B observation of a short burst
- GRB 260114A: Mondy optical observations
- GRB 260114A: Fermi GBM observation
- GRB 260112B: GECAM-B observation
- GRB 260114A: GMG Optical Observation
- Fermi-LAT Gamma-ray Observations of IceCube-260111A
- EP-WXT trigger 01709251266: SVOM/C-GFT confirmation of a stellar flare
- IceCube-260111A: Upper limits from a search for additional neutrino events in IceCube
- EP260110a: NOT and GTC Optical and Near-Infrared Observations
- EP260110a: TRT optical upper limits
- Konus-Wind detection of GRB 260101A
- GRB 260111A: Swift-XRT observations
- GRB 260111A: COLIBRÍ optical afterglow candidate
- GRB 260111A: GECAM-B observation of a burst
- GRB 260111A: Fermi GBM Observation
- Swift Trigger 1434591 is not a GRB
- GRB 260111A: GOTO optical upper limits
- GRB 260111A: Swift ToO observations
- GRB 251230A: Mondy Optical Observations
- GRB 260111A: Swift/BAT-GUANO arcminute localization of a burst
- EP260110a: SVOM/VT optical upper limits
- EP260110a: Global MASTER-Net observations report
- Fermi GRB 260111A: Global MASTER-Net observations report
- EP260110a: KAIT optical upper limit
- EP260110a: refined analysis of the EP-WXT and EP-FXT observations
- EP 260110a: COLIBRÍ optical observations
- EP260110a: SVOM/C-GFT upper limit
- EP260110a: BOOTES-5/JGU optical upper limit
- GRB 260109C: LCO optical upper limits
- GRB 260109C: Kilonova-Catcher optical upper limit
- EP260105b / GRB 260105C : Fermi-GBM Sub-Threshold Detection
- GRB 260104A: Swift-BAT refined analysis
- GRB 260101A: Swift-BAT refined analysis
- Swift GRB 251230A: Global MASTER-Net OT detection
- Fermi GRB 260107A: Global MASTER-Net observations report
- GRB 260102A: AbAO optical observations
- EP260105b/EP-WXT trigger 01709251028: Einstein Probe detection of an X-ray transient
- Fermi GRB 260105A: Global MASTER-Net observations report
- EP260105a: FTW optical observations
- EP260104a: FTW optical observations
- GRB 260105A: SVOM/GRM observation
- GRB 260105B: SVOM/GRM observation
- FRB 20251229A: COLIBRÍ optical upper limits
- Fermi GRB 260105B: Global MASTER-Net observations report
- EP260105a: SVOM/VT optical upperlimit
- EP260105a: refined analysis of the EP-WXT and EP-FXT observations
- EP260105a: LCO Optical Upper limit
- EP260104a: Global MASTER-Net observations report
- GRB 260101A: COLIBRÍ optical upper limits
- EP260105a: Global MASTER-Net observations report
- GRB 260103A: Insight-HXMT/HE detection
- GRB 260104A: COLIBRÍ optical upper limits
- Fermi GRB 260104B: Global MASTER-Net observations report
- Swift GRB 260104A: Global MASTER-Net observations report
- GRB 251230A/EP-WXT trigger 01709250693: Mephisto optical upper limits
- GRB 260101A: Swift/UVOT Detection
- GRB 260103A: GECAM-B observation of a burst
- Fermi-LAT Gamma-ray Observations of IceCube-251225A
- GRB 260101A: COLIBRÍ optical observations
- Fermi GBM Sub-Threshold Detection of GRB 260102A
- GRB 260102A: EP-FXT follow-up observation
- EP260101a: Global MASTER-Net observations report
- GRB 260102A: LCO optical upper limits
- GRB 260102A: Swift-XRT observations
- GRB 260102A: SVOM/COLIBRÍ (FM-GFT) optical observations
- GRB 251230A / EP251230a: GECAM-B detection
- GRB 260102A: SVOM/VT optical counterpart
- GRB 251230A / EP251230a: Insight-HXMT/HE detection
- GRB 260102A: Swift ToO observations
- GRB 260101A: Fermi GBM Observation
- EP260101a: refined analysis of the EP-WXT and EP-FXT observations
- GRB 260101A: GECAM-B detection
- GRB 260101A: NOT spectroscopic observations
- GRB 260101A: SVOM/GRM observation
- Swift GRB 260101A: Global MASTER-Net observations report
- GRB 260101A: OSIRIS+ redshift z = 2.623 for the new year burst
- GRB 260101A: LCO detection of the optical counterpart
- GRB 251230A / EP251230a: SVOM/VT optical continued observations and upper limit
- GRB 251230A: GRANDMA/TAROT Early Detection
- 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
- GRB 251222A: Mondy Optical Observations
- EP251230a / GRB 251230A: refined analysis of the EP-WXT and EP-FXT observations
- GRB 251230A: Swift/UVOT detection
- GRB251230A: 7DT optical upper limits
- GRB 251230A / EP251230a: NOT observations and spectroscopic redshift upper limit z < 2.2