GCN Circulars
GCN Circulars are rapid bulletins submitted by and distributed to the community. See the documentation for help with subscribing to or submitting Circulars.
Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
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"- EP detected a brightening of LMXB 1ES 1735-26.9
- GRB260820A: Fermi GBM Final Real-Time Localization
- GRB 260818B: Insight-HXMT detection
- GRB 260818B: EP-FXT follow-up observation
- GRB 260818A: J-band observations with WINTER
- GRB 260818B: SVOM/ECLAIRs refined analysis
- GRB 260818A: SVOM/ECLAIRs refined analysis
- GRB 260818B: NOT optical upper limits
- GRB 260810A: SVOM/GRM observation
- GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
- GRB260818A: EP-FXT follow-up observation
- GRB 260818B: LCO optical upper limits
- GRB 260818B: SVOM detection of a short burst
- SVOM trigger sb26081806 is not a GRB
- EP260806a: SAO RAS multicolor optical observations
- GRB 260818A: LCO optical upper limits
- EP260812a: AbAO optical upper limit
- GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
- GRB 260810A: Insight-HXMT/HE detection
- GRB 260818A: SVOM possible detection of a long and faint GRB
- EP260806a: SVOM/ECLAIRs detection through targeted search
- EP260806a: NUTTELA-TAO optical observations
- The EP-WXT trigger 01709281429 is likely a flaring star
- EP260812a: AZT-22 optical upper limit
- EP260812b: GTC/OSIRIS+ tentative spectroscopic redshift z = 2.034
- EP260806a: WFST optical observations
- The EP-WXT trigger 01709280562 is likely a flaring star
- EP260812b: Optical upper limit with Kinder
- The EP-WXT trigger 01709279838 is likely a flaring star
- GRB 260805D: SVOM/GRM detection of a possible magnetar burst
- GRB 260808B: Liverpool Telescope further optical observations
- GRB 260808B: GTC/OSIRIS+ spectroscopic redshift z = 1.295
- GRB 260813A: BALROG localization (Fermi Trigger 808341387 / GRB 260813803)
- GRB 260813A: Fermi GBM Final Real-time Localization
- EP260812a: NOT and Liverpool Telescope upper limits:
- EP260812b: Liverpool Telescope observations
- EP260812b: GOTO detection of the optical counterpart
- EP260812a: refined analysis of the EP-WXT and autonomous EP-FXT observation
- EP260812a: SVOM/C-GFT optical upper limit
- EP260812b: COLIBRÍ optical observations
- EP260812b: SVOM/VT optical observation
- GRB 260808A: SVOM/GRM observation
- EP260812b: Einstein Probe detection of an X-ray transient
- EP trigger #01709278129 (EP260812b?): NOT optical counterpart
- Fermi GBM Sub-Threshold Detection of GRB 260809A
- GRB 260810A: Glowbug gamma-ray detection
- GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
- GRB 260810A: AstroSat CZTI detection of a long burst
- EP260812a: Einstein Probe detection of an X-ray transient
- GRB 260809A: SAO RAS optical observations
- GRB 260808B: SAO RAS optical observations
- GRB 260808B: SVOM/VT optical re-brightening at day 3
- GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
- GRB 260806A: CALET Gamma-Ray Burst Monitor detection
- GRB 260808A: GECAM-B observation
- GRB 260807A: SVOM/ECLAIRs refined analysis
- EP260806a: MAO/AZT-22 optical observations
- IceCube-260807A: Upper limits from a search for additional neutrino events in IceCube
- GRB260808B: MAO/AZT-22 optical observations
- GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
- GRB 260809A: J-band upper limit with WINTER
- EP260809a: VLT/X-shooter spectroscopic redshift z = 3.07
- GRB 260806A: Glowbug gamma-ray detection
- GRB 260808A: CALET Gamma-Ray Burst Monitor detection
- GRB 260805C: CALET Gamma-Ray Burst Monitor detection
- GRB 260804A: CALET Gamma-Ray Burst Monitor detection
- GRB260809A/EPF_J234751.2+210212: EP-FXT follow-up observation
- The EP-WXT trigger 01709278015 is likely a flaring star
- GRB 260809A: SVOM/COLIBRÍ (FM-GFT) optical observation
- GRB 260808B: SVOM/COLIBRÍ (FM-GFT) optical observation
- GRB 260809A: NOT optical observations
- GRB260809A: MAO/AZT-22 optical observations
- GRB260809A: OHP/T193 optical observations
- IceCube-260805A: Upper limits from a search for additional neutrino events in IceCube
- GRB 260809A: SVOM/VT optical counterpart
- EP260809a: J-band upper limit with WINTER
- GRB 260808B: J-band upper limit with WINTER
- GRB 260808B: SVOM/ECLAIRs refined analysis
- EP260809a:refined analysis of the EP-WXT and autonomous EP-FXT observation
- GRB 260809A: SVOM detection of a faint burst
- GRB 260808B: Liverpool Telescope optical observations
- GRB 260808B: NOT optical observations
- GRB 260808B: LCO optical observations
- GRB 260808A: NuSTAR detection of prompt emission
- EP260809a: COLIBRÍ optical observations
- EP260809a: LCO optical observation
- EP260809a: OHP/T193 optical observations
- GRB260808B: OHP/T193 optical observations
- GRB 260808B / EPF_J230056.0+082842: EP-FXT follow-up observation
- EP260809a: Einstein Probe detection of an X-ray transient
- GRB 260808B: SVOM/VT optical afterglow confirmation
- GRB 260808C: Fermi GBM Final Real-time Localization
- GRB 260808B: SVOM/VT optical candidate from VHF data ( localization correction for GCN 45317 )
- GRB 260808B: SVOM/VT optical candidate from VHF data
- GRB 260808B: SVOM detection of a faint burst
- GRB 260808A: BALROG localization (Fermi Trigger 807850307 / GRB 260808119)
- Fermi GRB 260808A: Global MASTER-Net observations report
- GRB 260808A: Fermi GBM Final Real-time Localization
- EP260806a: ZTF serendipitous detection of ZTF26abmjjnm / AT 2026yeh
- IceCube Alert 260807A: Global MASTER-Net observations report