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"3103 results found.
- 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
- GRB 260512A: AstroSat CZTI detection
- GRB 260514A: Fermi GBM Final Real-time Localization
- Fermi GRB 260512A: Global MASTER-Net observations report
- Konus-Wind detection of GRB 260511B
- GRB 260511B: AstroSat CZTI detection
- GRB 260510C: AstroSat CZTI detection
- GRB 260511A: SVOM/VT optical observation with VHF data
- Fermi GRB 260511A: Global MASTER-Net observations report
- GRB 260510C: MAXI/GSC detection
- SVOM GRB 260509A: MASTER-OAFA optical observation
- GRB 260504B: AstroSat CZTI detection
- EP260502a is likely a flaring star
- IceCube Alert 260505A: Global MASTER-Net observations report
- GRB 260430B: AstroSat CZTI detection of a long burst
- SVOM GRB 260504B: MASTER-OAFA optical observations
- EP260502a: BOOTES-7 observations of a fading catalogued source close to the X-ray position
- GRB 260429B / EP260429a: AstroSat CZTI detection
- SN 2026kid: Optical follow-up with small-aperture telescopes in Spain and China
- GRB 260424B: AstroSat CZTI detection
- GRB 260429B / EP260429a: COLIBRÍ optical upper limit
- GRB 260428A: AstroSat CZTI detection
- Fermi GRB 260428A: Global MASTER-Net observations report
- EP260321a/SN 2026gzf: spectroscopy at Mondy observatory
- IceCube Alert 260425A: Global MASTER-Net observations report
- GRB 260424A: AstroSat CZTI detection of a long burst
- EP260416a: ZTSh R band observations
- GRB 260419A: AstroSat CZTI detection
- GRB 260421A: AstroSat CZTI detection
- GRB 260310A: Late-time Chandra X-ray Detection
- Fermi GRB 260421C: Global MASTER-Net observations report
- Fermi GRB 260421B: Global MASTER-Net observations report
- Fermi trigger No 798275385: Global MASTER-Net observations report
- EP260417a: Global MASTER-Net observations report
- Fermi GRB 260417A: Global MASTER-Net observations report