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"23574 results found.
- EP260806a: COLIBRÍ optical observations
- EP260806a: OSIRIS+/GTC redshift z=0.089
- GRB 260715A: cubesat Avion detection
- GRB 260708A: cubesat Avion detection
- SN 2026stf / GRB 260708A: ATLAS forced photometry
- GRB 260730B: Glowbug gamma-ray detection
- GRB 260805C: Glowbug gamma-ray detection
- GRB 260805B: Glowbug gamma-ray detection
- Fermi GRB 260805A: Global MASTER-Net observations report
- GRB 260804A: Glowbug gamma-ray detection
- AT 2026wki: EP/FXT follow-up observations
- GRB 260730B: CALET Gamma-Ray Burst Monitor detection
- GRB 260708A: LCO further optical observations show supernova features
- Fermi GRB 260802B: Global MASTER-Net observations report
- GRB 260802A: SVOM/VT optical upper limits from VHF data
- GRB 260802A / EP J223759.5+531421: SVOM/COLIBRÍ (FM-GFT) optical upper limit
- EP260731a: COLIBRÍ optical upper limit
- GRB 260727A: SVOM/ECLAIRs refined analysis
- GRB 260726A: SVOM/ECLAIRs refined analysis
- EP260728a: COLIBRÍ optical upper limit
- EP260727a: VLT/X-shooter spectroscopic redshift z = 2.817
- EP 260729a: Ondrejov D50 optical detection supports stellar flare origin
- EP260727a: SAO RAS optical observations
- GRB 260727A: AbAO and SAO RAS optical observations
- GRB 260726A: Fermi GBM Observation
- EP260727a: 1.5m OSN optical counterpart detection
- Konus-Wind detection of GRB 260727A
- EP260727a: NUTTELA-TAO Early Optical Limits
- GRB 260727A: Glowbug gamma-ray detection
- GRB 260726A: J-band upper limit with WINTER
- GRB 260727A: J-band upper limit with WINTER
- GRB 260726A: SVOM ECLAIRs improved position and MXT possible detection of a counterpart
- GRB 260727A / SVOM sb26072702: RAPAS optical non-detection
- EP260723a: SVOM/ECLAIRs Upper Limit
- GRB 260727A: GOTO early optical upper limit
- GRB 260727A: Kilonova-Catcher optical upper limit
- Fermi GRB 260726A: Global MASTER-Net observations report
- GRB 260616A: cubesat Avion detection
- GRB 260718A: SVOM/ECLAIRs refined analysis
- EP260723a: COLIBRÍ optical observations
- IceCube-260722A: One candidate from the Zwicky Transient Facility (ZTF)
- IceCube Alert 260722A: Global MASTER-Net observations report
- Konus-Wind detection of GRB 260721A
- GRB 260721A: NuSTAR detection of prompt emission
- Konus-Wind detection of GRB 260714B
- Fermi trigger No 806104130: Global MASTER-Net observations report
- Fermi GRB 260718A: Global MASTER-Net observations report
- GRB 260710A: SVOM/GRM observation
- GRB 260718A : GRANDMA and KNC upper limits
- GRB 260718A: SVOM/VT optical upper limits from VHF data
- GRB 260618B: EP-FXT follow-up observation upper limit
- GRB 260714B: COLIBRÍ optical counterpart candidate
- SVOM sb26071506: Global MASTER-Net observations report
- GRB 260710A: AstroSat CZTI detection
- GRB 260714B: AstroSat CZTI detection
- IceCube-260712A: LAST optical follow-up observations of the IceCube neutrino candidate
- EP260713a: Einstein Probe detection of an X-ray transient
- GRB 260708A: slowly decaying X-ray emission observed by EP/FXT
- EP260623a: KAIT optical observations
- GRB 260708A: GRANDMA Optical Observations
- GRB 260710A: Fermi GBM Detection
- IceCube-260708A: Observations with the Vera C. Rubin Observatory
- EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
- GRB 260708A: Glowbug gamma-ray detection
- GRB 260706A : GRANDMA Upper limits
- GRB 260708A: Kilonova-Catcher optical afterglow detection
- Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
- IceCube Alert 260709A: Global MASTER-Net observations report
- LAT GRB260708.42: Global MASTER-Net observations report
- GRB260708B: MAXI/GSC detection
- GRB 260706A: Further EP-FXT follow-up observation
- GRB 260706A: SVOM/VT optical upper limits
- EP260707a: TRT optical upper limit
- 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: REM optical/NIR observations
- GRB 260706A: LCO optical upper limit
- 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
- IceCube260704A: OHP/T193 optical observations
- GRB 260629A: AstroSat CZTI detection
- Fermi trigger No 804738310: Global MASTER-Net observations report
- Fermi GRB 260703A: Global MASTER-Net observations report
- GRB 260623A: Glowbug gamma-ray detection
- GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
- Fermi trigger No 804552016: Global MASTER-Net observations report
- Fermi GRB 260628A: Global MASTER-Net observations report
- EP260626a: COLIBRÍ optical upper limit
- Konus-Wind detection of GRB 260623B / EP260623a
- EP260623a: TNG NIR afterglow detection
- Konus-Wind detection of GRB 260618B
- EP260623a: WINTER J-band observations
- GRB 260617A: Glowbug gamma-ray detection of a short burst
- EP260623a: Optical follow-up observations with Kinder
- EP260623a: TRT optical observations
- EP260623a: REM optical/NIR afterglow detection
- EP 260623a: COLIBRÍ optical observations