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.
- GRB 260616B/EP260616a: Insight-HXMT/HE detection
- EP260623a: OSIRIS+/GTC redshift z = 0.703
- EP260623a: Las Cumbres discovery of the optical counterpart
- GRB 260614B: EP-FXT follow-up observation
- GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
- GRB 260619A: TRT optical counterpart confirmation
- GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
- GRB 260604B: 239Alferov CubeSat detection
- GRB 260604A: 239Alferov CubeSat detection
- GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
- Konus-Wind detection of GRB 260617A
- GRB 260616B: AstroSat CZTI detection
- GRB 260619A: Kilonova-Catcher optical upper limit
- GRB 260617A: CALET Gamma-Ray Burst Monitor detection
- EP260618a: COLIBRÍ optical counterpart candidate
- IPN triangulation of GRB 260617A (short)
- GRB 260506B: cubesat Avion detection
- Konus-Wind detection of GRB 260616B/EP260616a
- Konus-Wind detection of GRB 260616A
- GRB 260616B: CALET Gamma-Ray Burst Monitor detection
- EP260616a/GRB260616B: COLIBRÍ optical upper limit
- GRB 260610B / AT2026owq: SAO RAS optical observations of possible re-brightening
- GRB260616C: MAXI/GSC detection
- GRB 260616A: Fermi-LAT detection
- GRB 260610B / AT 2026owq: COLIBRÍ further observations and confirmation of the rebrigthening
- GRB 260614A: AstroSat CZTI detection
- GRB 260610B / AT 2026owq: Possible re-brightening identified from Pan-STARRS observations
- GRB 260604C: GRANDMA late observations with CFHT/MegaCam
- GRB 260614B: SVOM/ECLAIRs refined analysis
- GRB 260610B: SVOM/GRM observation
- GRB 260614B: SVOM/VT optical afterglow confirmation
- GRB 260614B: Fermi GBM Observation
- GRB 260614A: GECAM-B observation
- GRB 260614B: SVOM/VT optical candidate from VHF data
- GRB 260614B: SVOM detection of a burst
- GRB 260611B: SVOM/GRM detection
- The EP-WXT trigger 01709269488 is likely a flaring star
- GRB 260610B / AT2026owq: GRANDMA optical observations
- GRB 260610B / AT2026owq: further SAO RAS optical observations
- EP260605a: COLIBRÍ optical upper limits
- GRB 260611B: CALET Gamma-Ray Burst Monitor detection
- GRB 260610B / AT2026owq: OASDG optical observations
- GRB 260610B: IAC-80 Optical observations
- GRB 260610B / AT2026owq: SAO RAS optical observations
- GRB 260610B: optical counterpart shows spectroscopic redshift of z=0.473
- GRB 260610B / AT2026owq: Early ATLAS observations
- GRB 260610B: TRT optical observation
- GRB 260610B: DDOTI optical observations
- GRB 260610B: GOTO optical counterpart candidate
- Konus-Wind detection of GRB 260601A
- IPN triangulation of GRB 260601A (short/hard)
- EP260610a: COLIBRÍ optical upper limits
- Konus-Wind detection of GRB 260604C
- GRB 260604C: AstroSat CZTI detection
- IPN triangulation of GRB 260601B / EP260601a
- GRB 260604C: SVOM/ECLAIRs refined analysis
- GRB 260608A: SVOM/ECLAIRs refined analysis
- Konus-Wind detection of GRB 260607B
- GRB 260604C: further SAO RAS optical observations
- GRB 260607A / GOTO26fqf / AT2026ong: COLIBRÍ optical observations
- GRB 260604C: SVOM/COLIBRÍ (FM-GFT) colour evolution and confirmation of the late rebrightening
- GRB 260608A: SVOM detection of a burst
- EP260605a: EP-FXT follow-up observation
- GRB 260607A: TRT optical observations
- GRB 260604C: GRANDMA further observations
- GRB 260607A: GOTO tentative optical counterpart candidate GOTO26fqf / AT2026ong
- GRB 260604C: Mondy optical observations: evidence of a possible brightening
- GRB 260607B: Fermi GBM Final Localization Correction
- GRB 260604C: Simeiz Zeiss-1000 optical observations of the afterglow
- GRB 260604C: OPD1.6m - GRANDMA observations - detection
- GRB 260604C: 6 GHz VLA observations
- GRB 260604C: SAO RAS optical observations
- GRB 260604C: GRANDMA observations
- GRB260603A: SVOM/ECLAIRs refined analysis
- EP260603a: COLIBRÍ optical upper limit
- GRB 260604A: Glowbug gamma-ray detection
- GRB 260601B / EP260601a: AstroSat CZTI detection
- GRB 260527A/EP260527a: 6 GHz VLA observations
- GRB 260604C: GOTO detections of the optical afterglow
- GRB 260604C: Correction to GCN 44828
- GRB 260604C: Kilonova-Catcher optical afterglow detection
- GRB 260604C: SVOM/COLIBRÍ (FM-GFT) optical observations
- EP260602d: J-band upper limit with WINTER
- EP260602b: J-band upper limit with WINTER
- GRB 260604C: LAST detection of optical counterpart candidate
- Fermi GRB 260604C: Global MASTER-Net observations report
- Fermi GRB 260604C: Global MASTER-Net observations report
- SVOM GRB260604.85: Global MASTER-Net observations report
- GRB 260601A: CALET Gamma-Ray Burst Monitor detection
- EP260602a: EP-FXT follow-up observation
- EP260603a: Global MASTER-Net observations report
- EP260602d: Optical Upper limits with kinder observations
- GRB 260603B: Fermi GBM Final Localization
- Konus-Wind detection of GRB 260601B/EP260601a
- GRB 260601B/EP260601a: Glowbug gamma-ray detection
- GRB 260603A: Kilonova-Catcher optical upper limit
- GRB 260603A: SVOM/VT optical observations
- GRB 260603A: SVOM/COLIBRÍ (FM-GFT) photometric redshift z = 3.57
- Fermi trigger No 802141998: Global MASTER-Net observations report
- GRB 260603A: SVOM/COLIBRÍ (GFT-FM) optical counterpart candidate