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"3137 results found.
- Swift Trigger 1513439 is probably not a GRB
- GRB 260924A: Optical follow-up observations with Kinder
- GRB 260924A: AstroSat CZTI detection
- Fermi GRB 260923A: Global MASTER-Net observations report
- GRB 260917C: AstroSat CZTI detection
- GRB 260921A: AstroSat CZTI detection
- EP260920b: VLT/X-shooter spectroscopic redshift z = 3.582
- GRB 260920A: AstroSat CZTI detection
- EP260920b: LCO optical counterpart detection
- EP Alert 260921.01: Global MASTER-Net observations report
- EP260917a: Global MASTER-Net observations report
- EP Alert 260918.24: Global MASTER-Net observations report
- SVOM GRB260918.16: Global MASTER-Net observations report
- Konus-Wind detection of GRB 260916B (short/hard)
- IPN triangulation of GRB 260916B (short)
- IceCube-260916A: Upper limits from a search for additional neutrino events in IceCube
- GRB 260915A: SVOM/ECLAIRs refined analysis
- MAXI GRB260916.37: Global MASTER-Net observations report
- GRB 260915A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
- GRB 260915A: LCO optical upper limits
- EP Alert 260914.53: Global MASTER-Net observations report
- GRB 260915A: SVOM detection of a burst
- GRB 260914A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
- SVOM GRB260914.47: Global MASTER-Net observations report
- GRB 260910B: GOTO tentative optical counterpart candidates
- GRB 260910B: Fermi GBM Final Real-time Localization
- EP Alert 260909.53: Global MASTER-Net observations report
- Fermi GRB 260907A: Global MASTER-Net observations report
- GRB260903A: Liverpool Telescope optical observations
- GRB 260903A: SVOM/VT optical candidate
- EP260901a: Global MASTER-Net observations report
- GRB 260829A: AstroSat CZTI detection
- GRB 260827A: Glowbug gamma-ray detection
- GRB 260825A: AstroSat CZTI detection
- GRB 260827A: Fermi GBM Final Real-time Localization
- IceCube Alert 260825A: Global MASTER-Net observations report
- The EP-WXT trigger 01709287395 is likely a flaring star
- EP260806a: SVOM/ECLAIRs detection through targeted search
- EP260806a: NUTTELA-TAO optical observations
- GRB 260810A: AstroSat CZTI detection of a long burst
- GRB 260808A: BALROG localization (Fermi Trigger 807850307 / GRB 260808119)
- GRB 260808A: Fermi GBM Final Real-time Localization
- SN 2026stf / GRB 260708A: ATLAS forced photometry
- GRB 260803A: Fermi GBM Final Real-time Localization
- GRB 260802A/EP J223759.5+531421: SVOM detection of a possible magnetar burst
- GRB 260731A: AstroSat CZTI detection of a long burst
- GRB 260730B: AstroSat CZTI detection
- GRB 260727A: AstroSat CZTI detection
- Fermi GRB 260726A: Global MASTER-Net observations report
- GRB 260723A: Fermi GBM Final Localization
- GRB 260718A: SVOM/VT optical upper limits
- SVOM sb26071506: Global MASTER-Net observations report
- GRB 260710A: AstroSat CZTI detection
- GRB 260709A: AstroSat CZTI detection
- GRB 260714B: AstroSat CZTI detection
- GRB 260714B: Fermi GBM Final Real-time Localization
- GRB 260708A: GRANDMA Optical Observations
- GRB 260705C: AstroSat CZTI detection
- Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
- LAT GRB260708.42: Global MASTER-Net observations report
- GRB 260706A: SVOM/VT optical upper limits
- GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
- GRB 260707A: Fermi GBM Final Real-time Localization
- IPN triangulation of GRB 260627A
- GRB 260629A: AstroSat CZTI detection
- GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
- Fermi trigger No 804552016: Global MASTER-Net observations report
- GRB 260616B: AstroSat CZTI detection
- GRB 260616A: AstroSat CZTI detection
- GRB 260506B: cubesat Avion detection
- GRB 260610B / AT2026owq: SAO RAS optical observations of possible re-brightening
- GRB260616C: MAXI/GSC detection
- GRB 260614A: AstroSat CZTI detection
- GRB 260603C: AstroSat CZTI detection
- EP260605a: COLIBRÍ optical upper limits
- GRB 260604C: AstroSat CZTI detection
- GRB 260607A / GOTO26fqf / AT2026ong: COLIBRÍ optical observations
- GRB 260607B: AstroSat CZTI detection
- The EP-WXT trigger 01709267001 is likely a flaring star
- GRB 260601B / EP260601a: AstroSat CZTI detection
- EP260603a: Global MASTER-Net observations report
- Fermi GRB 260602B: Global MASTER-Net observations report
- Fermi GRB 260602B: Global MASTER-Net observations report
- GRB 260602A: Fermi GBM Final Real-time Localization
- Fermi trigger No 801900520: Global MASTER-Net observations report
- GRB 260531A: MAXI/GSC detection
- GRB 260429B / EP260429a: COLIBRÍ optical counterpart candidate
- GRB 260526A: GECAM-B observation
- GRB 260525A: AstroSat CZTI detection
- Fermi GRB 260526A: Global MASTER-Net observations report
- GRB 260525A: Fermi GBM Final Real-time Localization
- GRB 260523B: AstroSat CZTI detection
- GRB 260511A: iTelescope T-75 optical detection
- GRB 260518A: AstroSat CZTI detection of a long burst
- GRB 260515A: further Liverpool Telescope observations
- Fermi GRB 260516C: Global MASTER-Net observations report
- GRB 260515A: Liverpool Telescope optical detection
- GRB 260515A: LCO optical observations
- SVOM GRB 260515A: Global MASTER-Net observations report
- EP260514a: Global MASTER-Net observations report