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"5111 results found.
- IceCube Alert 260825A: Global MASTER-Net observations report
- IceCube-Cascade 260824A: Upper limits from a search for additional neutrino events in IceCube
- GRB 260822A: PRIME near-infrared upper limits from multiple epochs
- GRB 260820A: Insight-HXMT/HE detection
- GRB260820A: Fermi GBM Final Real-Time Localization
- GRB 260818B: NOT optical upper limits
- GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
- GRB 260808B: SVOM/VT optical afterglow confirmation
- GRB 260808C: Fermi GBM Final Real-time Localization
- EP260806a: Liverpool Telescope observations of the counterpart show a blue colour
- SN 2026stf / GRB 260708A: ATLAS forced photometry
- Fermi GRB 260802B: Global MASTER-Net observations report
- EP260731a: Einstein Probe detection of an X-ray transient
- GRB260730A: Fermi GBM Final Localization
- EP260728a: COLIBRÍ optical upper limit
- Fermi GRB 260726A: Global MASTER-Net observations report
- IceCube-260722A: Classification of ZTF26abjbxfs/SN 2026vts as a Type Ia Supernova
- GRB 260602B: cubesat Avion detection
- EP260723a: EP-FXT follow-up observation
- IPN triangulation of GRB 260706B
- Fermi Gamma-ray Burst Monitor trigger 806592752 / 260724564 is not a GRB
- EP260723a: Liverpool Telescope likely optical counterpart
- Fermi trigger No 806104130: Global MASTER-Net observations report
- IceCube Alert 260709A: Global MASTER-Net observations report
- GRB 260705B: SVOM/GRM observation
- EP260707a: Einstein Probe detection of an X-ray transient
- GRB 260706A: SVOM/ECLAIRs refined analysis
- GRB 260704A: SVOM detection of a possible GRB
- Fermi GRB 260703A: Global MASTER-Net observations report
- GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
- Fermi trigger No 804552016: Global MASTER-Net observations report
- GRB 260628A: Fermi GBM Final Real-time Localization
- EP260626a: Liverpool Telescope upper limits
- EP260623a: Liverpool Telescope optical observations
- Fermi GBM trigger 804010507/260624677 is not a GRB
- GRB 260624A: Fermi GBM Final Real-time Localization
- EP260623a: FRAM-ORM detection of the optical afterglow rise, peak and decay
- GRB 260623A: Fermi GBM Final Real-time Localization
- The EP-WXT trigger 01709271197 is likely a flaring star
- GRB 260604A: 239Alferov CubeSat detection
- GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection
- GRB 260429A: cubesat Avion detection
- GRB260616C: MAXI/GSC detection
- EP260610b: MAO/AZT-22 optical observations
- GRB 260610A: Fermi GBM Final Real-time Localization
- GRB 260604C: SVOM/COLIBRÍ (FM-GFT) colour evolution and confirmation of the late rebrightening
- GRB 260604A: SVOM/GRM detection
- GRB 260604C: 6 GHz VLA observations
- GRB 260604A: Glowbug gamma-ray detection
- Fermi GRB 260604C: Global MASTER-Net observations report
- Fermi GRB 260604C: Global MASTER-Net observations report
- GRB 260604A: Fermi GBM Final Real-time Localization
- GRB 260603A: SVOM/COLIBRÍ (FM-GFT) photometric redshift z = 3.57
- Fermi GRB 260602B: Global MASTER-Net observations report
- Fermi GRB 260602B: Global MASTER-Net observations report
- EP260530a/AT 2026nwl: COLIBRÍ optical follow up
- EP260530a/AT 2026nwl: COLIBRÍ optical observations
- Fermi GRB 260601A: Global MASTER-Net observations report
- Fermi trigger No 801900520: Global MASTER-Net observations report
- GRB 260531B: Fermi GBM Final Real-time Localization
- IPN triangulation of GRB 260527A / EP260527a
- EP260527a/GRB 260527A: optical upper limit with Kinder observations
- Fermi trigger No 801580882: Global MASTER-Net observations report
- Fermi GRB 260526A: Global MASTER-Net observations report
- Fermi GRB 260522A: Global MASTER-Net observations report
- GRB 260511A: iTelescope T-75 optical detection
- GRB 260520A: Fermi GBM Final Localization
- Konus-Wind detection of GRB 260518A
- GRB 260421B: radio detection with the VLA
- Fermi GRB 260516C: Global MASTER-Net observations report
- Fermi GRB 260516B: Global MASTER-Net observations report
- SVOM GRB 260515A: Global MASTER-Net observations report
- EP260514a: Global MASTER-Net observations report
- GRB 260513A: Fermi GBM Final Real-time Localization
- Konus-Wind detection of GRB 260511B
- GRB 260511B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
- GRB 260511B: SAO RAS optical observations
- GRB 260511B: SVOM/COLIBRÍ (FM-GFT) optical observations
- GRB 260510C: AstroSat CZTI detection
- Fermi GRB 260511A: Global MASTER-Net observations report
- GRB 260511A: LCO optical afterglow detection
- GRB 260510C: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
- GRB 260510C: MAXI/GSC detection
- SVOM GRB 260509A: MASTER-OAFA optical observation
- Fermi GRB 260510A: Global MASTER-Net observations report
- GRB 260509A: SVOM/COLIBRÍ (FM-GFT) observations
- EP260502a is likely a flaring star
- GRB 260421B: radio observation with the VLA
- IPN triangulation of GRB 260429A
- EP260502a: BOOTES-7 observations of a fading catalogued source close to the X-ray position
- GRB 260429A: SVOM/GRM observation of a short burst
- SN 2026kid: Optical follow-up with small-aperture telescopes in Spain and China
- GRB 260424B: AstroSat CZTI detection
- GRB 260429A: Fermi GBM Detection
- GRB 260429A: Fermi GBM Final Real-time Localization
- IceCube-260425A: Upper limits from a search for additional neutrino events in IceCube
- GRB 260424B: Glowbug gamma-ray detection of a short burst
- Konus-Wind detection of GRB 260424B
- GRB 260424C: Fermi GBM Final Localization
- IPN triangulation of GRB 260424B (short)