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.
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"19501 results found.
- GRB 250204A: SVOM/VT optical candidate
- GRB 251230A: MeerLICHT afterglow detection
- GRB 260127A: GECAM-B observation
- GRB 260127B: AstroSat CZTI detection
- IPN triangulation of GRB 260121A
- GRB 260127A: Swift-BAT refined analysis
- GRB 260127B: Swift-XRT observations
- GRB 260127A: INASAN-Kislovodsk, SAO RAS, and Terskol K-800 optical observations
- GRB 260127A: Fermi GBM Observation
- GRB 260127A: COLIBRÍ optical observations
- GRB 260127B: Swift ToO observations
- GRB 260127A : MITSuME Akeno optical afterglow candidate detection
- GRB 260127A: Swift-XRT refined Analysis
- GRB 260127A: SVOM/C-GFT optical observations
- GRB 260127A: Enhanced Swift-XRT position
- GRB 260127A: Prompt enhanced Swift-XRT position
- Swift GRB 260127A: Global MASTER-Net observations report
- GRB 260127A: Swift detection of a burst
- GRB 260125A: Swift-XRT observations
- Konus-Wind detection of GRB 260120B
- GRB 260125A: Swift ToO observations
- GRB 260114A: SVOM/VT optical upper limits
- GRB 260122B: Swift-BAT refined analysis
- GRB 260120B: SVOM/GRM observation
- GRB 260120B: AstroSat CZTI detection
- GRB 260114A: Insight-HXMT/HE detection
- GRB 260122B: Swift detection of a burst
- Swift GRB260122.97: Global MASTER-Net observations report
- GRB 260120B: Swift-BAT refined analysis
- GRB 260120B: Swift-XRT refined Analysis
- GRB 260120B: Fermi GBM Observation
- GRB 260120B: Swift/UVOT Detection
- GRB 260120B: COLIBRÍ optical upper limits
- GRB 260120B: Enhanced Swift-XRT position
- GRB 260120B: SVOM/C-GFT optical counterpart detection
- GRB 260101A: 239Alferov CubeSat detection
- GRB 260120B: Swift detection of a burst
- Swift GRB260120B: Global MASTER-Net observations report
- GRB 260114A: Swift/UVOT Upper Limits
- Trigger 1442421: Swift detection of HMXB 1A 1118-61
- GRB 260117A: Swift-XRT afterglow detection
- GRB 260117A: ZTSh optical upper limit
- Swift GRB260118.48: Global MASTER-Net observations report
- GRB 260117A: SVOM/COLIBRÍ (FM-GFT) optical observations
- Swift trigger on the HMXB 1A 1118-61
- GRB 260117A: SVOM/VT optical candidate
- GRB 260117A: SVOM/C-GFT upper limit
- GRB 260117A: Swift-XRT observations
- GRB 260117A: Swift ToO observations
- Swift triggered on the HMXB 1A 1118-61
- GRB 260114A: VLT/MUSE spectroscopic observations
- GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
- GRB 260114A: VLT/HAWK-I further near-infrared upper limits
- GRB260114A: STEP/T80S optical limits
- GRB 251222A: radio detection with the VLA
- GRB 260114A: VLT/HAWK-I near-infrared upper limits
- Konus-Wind detection of GRB 260114A
- GRB 260114A: Swift-XRT refined Analysis
- 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 260114A: GMG Optical Observation
- GRB 260114A: Swift detection of a short burst
- Swift GRB260113.43: Global MASTER-Net observations report
- Konus-Wind detection of GRB 260101A
- GRB 260111A: Swift-XRT observations
- Swift Trigger 1439093: is probably not GRB 260113A
- GRB 260111A: COLIBRÍ optical afterglow candidate
- GRB 260111A: Fermi GBM Observation
- Swift Trigger 1434591 is not a GRB
- GRB 260111A: Swift ToO observations
- GRB 260111A: Swift/BAT-GUANO arcminute localization of a burst
- Swift trigger 1436759 is not an astrophysical event
- GRB 260109C: LCO optical upper limits
- GRB 260109C: Kilonova-Catcher optical upper limit
- Swift Trigger 1434591: possible GRB 260109C
- GRB 260102A: Swift-XRT afterglow detection
- GRB 260104A: Swift-BAT refined analysis
- GRB 260101A: Swift-BAT refined analysis
- Swift GRB 251230A: Global MASTER-Net OT detection
- Swift GRB 260104A: Global MASTER-Net observations report
- GRB 260104A: Swift-XRT refined Analysis
- GRB 260104A: Enhanced Swift-XRT position
- GRB 260101A: Swift/UVOT Detection
- GRB 260104A: Swift detection of a burst
- GRB 260102A: LCO optical upper limits
- GRB 260102A: Swift-XRT 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