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"3746 results found.
- GRB 260916A: MAXI/GSC detection
- EP Alert 260914.53: Global MASTER-Net observations report
- SVOM GRB260914.47: Global MASTER-Net observations report
- GRB 260907A: SVOM/GRM observation
- GRB 260907A: Glowbug gamma-ray detection of a likely short burst
- Fermi GRB 260907A: Global MASTER-Net observations report
- GRB 260907A: Fermi GBM Final Real-time Localization
- EP Alert 260903.62: Global MASTER-Net observations report
- SVOM GRB260903A: Global MASTER-Net observations report
- Konus-Wind detection of GRB 260829A
- GRB 260829A: SVOM/GRM observation
- IceCube-260827A: No transient candidates from the Zwicky Transient Facility
- NuSTAR 260828: a 1100s hard X-ray transient
- EP260727a: ATCA 10 GHz detection
- IceCube-260827A: Upper limits from a search for additional neutrino events in IceCube
- GRB 260818B: TNG NIR observations
- MAXI GRB260827.40: Global MASTER-Net observations report
- EP Alert 260820.31: Global MASTER-Net observations report
- IceCube Alert 260825A: Global MASTER-Net observations report
- GRB 260822A: GOTO optical counterpart detection
- GRB260822B: Fermi GBM Final Localization
- GRB 260818B: VLA radio observations
- EP260806a: SAO RAS multicolor optical observations
- EP260812a: SVOM/C-GFT optical upper limit
- GRB 260808B: SVOM/VT optical afterglow confirmation
- GRB 260808B: SVOM/VT optical candidate from VHF data ( localization correction for GCN 45317 )
- GRB 260808B: SVOM/VT optical candidate from VHF data
- EP260806a: Einstein Probe detection of an X-ray transient
- SN 2026stf / GRB 260708A: ATLAS forced photometry
- Fermi GRB 260805A: Global MASTER-Net observations report
- GRB 260803A: Fermi GBM Final Real-time Localization
- Fermi GRB 260802B: Global MASTER-Net observations report
- GRB 260802A / EP J223759.5+531421: SVOM/VT optical upper limit
- GRB260730A: Fermi GBM Final Localization
- EP260727a: VLT/X-shooter spectroscopic redshift z = 2.817
- GRB 260727A: AbAO and SAO RAS optical observations
- EP260728a: EP-FXT follow-up observation
- EP260727a: 1.5m OSN optical counterpart detection
- GRB 260726A: Liverpool Telescope optical observations
- GRB 260727A: Liverpool Telescope optical upper limits
- EP260727a: Liverpool Telescope confirmation of optical counterpart
- GRB 260728A: Fermi GBM Final Localization
- GRB 260726A: SVOM/VT optical candidate
- EP260723a: SVOM/VT optical observation
- SVOM trigger sb26071506: SVOM/VT confirmation of a stellar flare
- Fermi GRB 260718A: Global MASTER-Net observations report
- GRB260708B: MAXI/GSC detection
- Fermi GBM Sub-Threshold Detection of GRB 260705A
- GRB 260705A: SVOM detection of a burst
- 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
- GRB 260628A: Fermi GBM Final Real-time Localization
- Konus-Wind detection of GRB 260623B / EP260623a
- IPN triangulation of GRB 260605A
- GRB 260604A: 239Alferov CubeSat detection
- GRB 260506B: cubesat Avion detection
- EP260616a/GRB260616B: COLIBRÍ optical upper limit
- GRB 260614A: AstroSat CZTI detection
- The EP-WXT trigger 01709269893 is likely a flaring star
- The EP-WXT trigger 01709269488 is likely a flaring star
- GRB 260610B / AT2026owq: SVOM/VT optical observations
- GRB 260515A: SOAR optical observations
- GRB 260604C: OPD1.6m - GRANDMA observations - detection
- GRB 260604C: GOTO detections of the optical afterglow
- Fermi GRB 260604C: Global MASTER-Net observations report
- Fermi GRB 260604C: Global MASTER-Net observations report
- EP260602d: Optical Upper limits with kinder observations
- Fermi GRB 260602B: Global MASTER-Net observations report
- Fermi GRB 260602B: Global MASTER-Net observations report
- Fermi GRB 260601A: Global MASTER-Net observations report
- Fermi trigger No 801900520: Global MASTER-Net observations report
- GRB 260527A / EP260527a: VLA radio detection
- Fermi GRB 260529A: Global MASTER-Net observations report
- EP260527a: COLIBRÍ optical detection
- Fermi trigger No 801580882: Global MASTER-Net observations report
- Fermi GRB 260525A: Global MASTER-Net observations report
- GRB 260523B: AstroSat CZTI detection
- Fermi GRB 260522A: Global MASTER-Net observations report
- Fermi GRB 260516C: Global MASTER-Net observations report
- GRB 260516D: SVOM possible detection of a burst
- GRID detection of GRB 260507A
- SVOM GRB 260515A: Global MASTER-Net observations report
- Fermi GRB 260514A: Global MASTER-Net observations report
- Fermi GRB 260512A: Global MASTER-Net observations report
- GRB 260506A: Glowbug gamma-ray detection of a short burst
- GRB 260511B : MITSuME Akeno optical afterglow candidate detection
- Fermi GRB 260510A: Global MASTER-Net observations report
- GRB 260507A: Fermi GBM Final Real-time Localization
- GRB 260506A: Fermi GBM Final Real-time Localization
- Fermi GRB 260504A: Global MASTER-Net observations report
- Fermi GRB 260429A: Global MASTER-Net observations report
- GRB 260428A: AstroSat CZTI detection
- Fermi GRB 260428A: Global MASTER-Net observations report
- GRB 260424B: COLIBRÍ optical upper limit
- GRB 260428A: Fermi GBM Final Real-time Localization
- GRB 260401A: cubesat Avion detection
- GRB 250328A: VLT host galaxy discovery and redshift z = 1.250
- EP260416a: Mondy optical observations
- GRB 260419A: AstroSat CZTI detection