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"37412 results found.
- GRB 260714B: Insight-HXMT/HE detection
- GRB 260718A: EP-FXT follow-up observation
- Fermi trigger No 806104130: Global MASTER-Net observations report
- Fermi GRB 260718A: Global MASTER-Net observations report
- GRB 260718A: LCO optical upper limits
- GRB 260711A: SVOM/GRM observation
- GRB 260710A: SVOM/GRM observation
- GRB 260718A: Fermi GBM Observation
- GRB 260718A : GRANDMA and KNC upper limits
- GRB 260718A: SVOM/VT optical upper limits
- GRB 260718A: SVOM/VT optical upper limits from VHF data
- GRB 260718A: SVOM detection of a burst
- GRB 260714B: SVOM/GRM observation
- GRB 260310A / AT2026fgk: Late-time Chandra Detection
- GRB 260714B: GECAM-B observation of a burst
- GRB 260618B: EP-FXT follow-up observation upper limit
- GRB 260714B: COLIBRÍ optical counterpart candidate
- GRB 260715A: Fermi GBM Final Real-time Localization
- GRB 260710A: AstroSat CZTI detection
- GRB 260709A: AstroSat CZTI detection
- GRB 260714B: AstroSat CZTI detection
- GRB 260714B: Fermi-LAT detection
- GRB 260714B: Fermi GBM Detection
- GRB 260714B: BALROG localization (Fermi Trigger 805746211 / GRB 260714766)
- GRB 260714B: Fermi GBM Final Real-time Localization
- GRB 260706A: ATCA detection of possible radio counterpart
- GRB 260705A: ATCA radio observations
- GRB 260714A: Fermi GBM Final Real-time Localization
- GRB 260619A: SVOM/VT continuous optical observations
- GRB 260618B: SVOM/VT optical observations indicate shallow decay and reddening
- GRB 260708A: slowly decaying X-ray emission observed by EP/FXT
- EP260623a: KAIT optical observations
- GRB 260708A: GRANDMA Optical Observations
- Fermi-LAT Gamma-ray Observations of IceCube-260712A
- Fermi-LAT Gamma-ray Observations of IceCube-260708A
- GRB 260710A: Insight-HXMT/HE detection
- Fermi-LAT Gamma-ray Observations of IceCube-260704A
- IceCube-260712A - IceCube observation of a high-energy neutrino candidate track-like event
- GRB 260708A: LCO optical observations
- GRB 260710A: Fermi GBM Detection
- GRB 260709A: SVOM/GRM detection
- GRB 260709A: GECAM-B observation
- GRB 260705C: AstroSat CZTI detection
- GRB 260710A: Fermi GBM Final Real-time Localization
- GRB 260708A: Glowbug gamma-ray detection
- GRB 260704A: SVOM/ECLAIRs refined analysis
- GRB 260706A : GRANDMA Upper limits
- GRB 260708A: Kilonova-Catcher optical afterglow detection
- GRB 260708A: GECAM-B observation of a burst
- GRB 260708A: Fermi-GBM observation
- Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
- GRB 260709A: Fermi GBM Final Real-time Localization
- IceCube-260708A - IceCube observation of a high-energy neutrino candidate track-like event
- GRB 260708A: Fermi-LAT detection
- GRB 260705B: SVOM/GRM observation
- GRB 260708A: Fermi-GBM detection
- GRB 260706A: Further EP-FXT follow-up observation
- GRB 260706A: SVOM/VT optical upper limits
- Fermi GBM trigger 805087514/260707142 (GRB 260707A) is not a GRB
- GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
- GRB 260705C: Glowbug gamma-ray detection of a short burst
- GRB 260706A: SVOM/ECLAIRs refined analysis
- GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
- GRB 260706A: SVOM/GRM observation
- GRB 260706A: REM optical/NIR observations
- GRB 260706A: LCO optical upper limit
- GRB 260706A: EP-FXT follow-up observation
- GRB 260707A: Fermi GBM Final Real-time Localization
- GRB 260706A: Fermi GBM Observation
- IPN triangulation of GRB 260627A
- GRB 260705A: SVOM/ECLAIRs refined analysis
- GRB 260706A: SVOM detection of a burst
- GRB 260706A: Fermi GBM Final Real-time Localization
- The EP-WXT trigger 01709274014: KAIT confirmation of a stellar flare
- GRB 260705A: LCO optical upper limits
- GRB 260704A: NOT optical upper limits
- GRB 260705C: Fermi GBM Final Localization
- GRB 260705B: Fermi GBM Final Real-time Localization
- Fermi GBM Sub-Threshold Detection of GRB 260705A
- GRB 260705A: SVOM detection of a burst
- GRB 260704A: EP-FXT follow-up observation
- GRB 260629A: SVOM/GRM observation of a short burst
- GRB 260629A: GECAM-A observation of a short burst
- IceCube-260704A - IceCube observation of a high-energy neutrino candidate track-like event
- GRB 260629A: AstroSat CZTI detection
- GRB 260704A: SVOM detection of a possible GRB
- GRB 260703B: Fermi GBM Final Localization
- Fermi trigger No 804738310: Global MASTER-Net observations report
- Fermi GRB 260703A: Global MASTER-Net observations report
- GRB 260703A: Fermi GBM Final Localization
- GRB 260610B: VLA detection
- GRB 260623A: Glowbug gamma-ray detection
- GRB 260614B: ATCA Radio Upper Limits
- GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
- Fermi trigger No 804552016: Global MASTER-Net observations report
- GRB 260701A: Fermi GBM Final Real-time Localization
- Fermi GBM trigger 804552016/260630945 is not a GRB
- Fermi-LAT Gamma-ray Observations of IceCube-260622A
- GRB 260629A: Fermi GBM Final Real-time Localization
- Fermi GRB 260628A: Global MASTER-Net observations report