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"27552 results found.
- 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
- GRB 260117A: SVOM detection of a long faint burst
- Swift triggered on the HMXB 1A 1118-61
- EP260116A: 1.3m DFOT optical upper limit
- GRB 260114A: VLT/MUSE spectroscopic observations
- GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
- EP260116a: Xinglong optical upper limit
- EP260116a: Einstein Probe detection of an X-ray transient
- GRB 260114A: VLT/HAWK-I further near-infrared upper limits
- IceCube-260115A - IceCube observation of a high-energy neutrino candidate track-like event
- GRB 260115A: Fermi GBM Final Real-time Localization
- 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: Mondy optical observations
- GRB 260114A: GMG Optical Observation
- GRB 260114A: Swift detection of a short burst
- GRB 260114A: Fermi GBM Final Real-time Localization
- EP260110a: TRT optical upper limits
- 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
- Swift Trigger 1434591 is not a GRB
- GRB 260112B: Fermi GBM Final Real-time Localization
- GRB 260111A: Swift ToO observations
- GRB 260111A: Swift/BAT-GUANO arcminute localization of a burst
- GRB 260112A: Fermi GBM Final Real-time Localization
- IceCube-260111A - IceCube observation of a high-energy neutrino candidate track-like event
- GRB 260111A: Fermi GBM Final Real-time Localization
- Swift trigger 1436759 is not an astrophysical event
- EP260110a: BOOTES-5/JGU optical upper limit
- EP260110a: Einstein Probe detection of an X-ray transient
- GRB 260109C: LCO optical upper limits
- EP260105b / GRB 260105C : Fermi-GBM Sub-Threshold Detection
- Swift Trigger 1434591: possible GRB 260109C
- GRB 260109B: Fermi GBM Final Real-time Localization
- GRB 260102A: Swift-XRT afterglow detection
- GRB 260109A: Fermi GBM Final Real-time Localization
- Swift GRB 251230A: Global MASTER-Net OT detection
- GRB 260107A: Fermi GBM Final Real-time Localization
- EP260105b/EP-WXT trigger 01709251028: Einstein Probe detection of an X-ray transient
- GRB 260105B: Fermi GBM Detection
- EP260105a: FTW optical observations
- EP260104a: FTW optical observations
- GRB 260105B: Fermi GBM Final Real-time Localization
- GRB 260105A: Fermi GBM Final Real-time Localization
- FRB 20251229A: A potentially hyperactive repeating fast radio burst source
- EP260104a: Einstein Probe detection of a fast X-ray transient
- GRB 260101A: COLIBRÍ optical upper limits
- EP260105a: Einstein Probe detection of an X-ray transient
- GRB 260103A: Insight-HXMT/HE detection
- GRB 260104A: COLIBRÍ optical upper limits
- GRB 260104C: Fermi GBM Final Real-time Localization
- GRB 260104A: Swift-XRT refined Analysis
- GRB 260104A: Enhanced Swift-XRT position
- GRB 260101A: Swift/UVOT Detection
- GRB 260104B: Fermi GBM Final Localization
- GRB 260104A: Swift detection of a burst
- GRB 260101A: COLIBRÍ optical observations
- GRB 260102B: Fermi GBM Final Real-time Localization
- Fermi GBM Sub-Threshold Detection of GRB 260102A
- 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 260102A: SVOM detection of a burst
- GRB 260101A: GECAM-B detection
- GRB 260101A: NOT spectroscopic observations
- GRB 260101A: SVOM/GRM observation
- GRB 260101A: Swift-XRT refined Analysis
- GRB 260101A: Enhanced Swift-XRT position
- EP260101a: Einstein Probe detection of an X-ray transient
- 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 260101A: Fermi GBM Final Real-time Localization
- 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
- EP251229a: Optical upper limit with Kinder observations
- GRB 251230A: 1.3m DFOT optical upper limit
- GRB 251230A: Swift-XRT refined Analysis
- GRB 251231A: Fermi GBM Final Real-time Localization
- GRB 251230A: Swift/UVOT detection