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"26038 results found.
- EP260119a: KAIT optical observations
- GRB 260117A: Swift-XRT afterglow detection
- EP260119a: LCO optical observations
- 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
- GRB 260101A: COLIBRÍ optical upper limits
- GRB 260104A: COLIBRÍ optical upper limits
- 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 260101A: COLIBRÍ optical observations
- 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
- GRB 260101A: Fermi GBM Observation
- GRB 260101A: GECAM-B detection
- GRB 260101A: NOT spectroscopic observations
- GRB 260101A: SVOM/GRM observation
- GRB 260101A: Swift-XRT refined Analysis
- Swift GRB 260101A: Global MASTER-Net observations report
- GRB 260101A: Enhanced Swift-XRT position
- GRB 260101A: OSIRIS+ redshift z = 2.623 for the new year burst
- GRB 260101A: LCO detection of the optical counterpart
- GRB 260101A: Swift detection of a burst with an 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
- GRB 251230A: 1.3m DFOT optical upper limit
- GRB 251230A: Swift-XRT refined Analysis
- 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
- GRB 251230A: GOTO optical upper limit
- GRB 251230A / EP251230a: SVOM/VT optical observation
- GRB 251230A: Enhanced Swift-XRT position
- GRB 251230A: Early optical counterpart detection by LCO.
- EP251230a / GRB 251230A: Einstein Probe detection of an X-ray transient
- GRB 251230A/EP#01709250693 (likely EP251230a): FTW optical and NIR observations
- Swift GRB 251230A: Global MASTER-Net observations report
- GRB 251230A: Swift detection of a burst with a bright optical counterpart
- GRB 251129A: redshift correction and SN detection at z = 0.505 with GTC
- GRB 251222A/EP251222b: Optical detection with Kinder observations
- GRB 251221A: Swift-BAT refined analysis
- GRB 251205A: Kilonova-Catcher optical afterglow detection
- GRB 251222A / EP251222b: Kilonova-Catcher optical afterglow detection
- GRB 251129A / EP251129a: VLA detection of a radio counterpart
- GRB 251222A: SVOM/COLIBRÍ (FM-GFT) optical observations