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"26922 results found.
- GRB 260807A: SVOM/ECLAIRs refined analysis
- 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
- 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
- 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
- IceCube Alert 260807A: Global MASTER-Net observations report
- GRB 260807A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
- GRB 260807A: SVOM possible detection of a faint burst
- EP260806a: COLIBRÍ optical observations
- EP260806a: refined analysis of the EP-WXT and autonomous EP-FXT observations
- EP260806a: SVOM/VT optical observation
- EP260806a: OSIRIS+/GTC redshift z=0.089
- EP260731a: refined analysis of the EP-WXT and autonomous EP-FXT observations
- EP260806a: LCO likely optical counterpart
- 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 260805B: Fermi GBM Final Localization
- GRB 260805B: BALROG localization (Fermi Trigger 807622617 / GRB 260805484)
- GRB 260805A: Fermi GBM Final Localization
- GRB 260730B: CALET Gamma-Ray Burst Monitor detection
- GRB 260708A / SN 2026stf: Spectroscopic host redshift z = 0.055 and confirmation of an associated type Ic-BL supernova
- GRB 260804A: Fermi GBM Final Real-time Localization
- GRB 260708A: LCO further optical observations show supernova features
- GRB 260803A: Fermi GBM Final Real-time Localization
- Fermi GRB 260802B: Global MASTER-Net observations report
- GRB 260802A / EP J223759.5+521421: EP-FXT follow-up observation
- GRB 260802A / EP J223759.5+531421: SVOM/VT optical upper limit
- GRB 260802A: SVOM/VT optical upper limits from VHF data
- GRB 260802A: LCO optical upper limits
- GRB 260802B: Fermi GBM Final Localization
- GRB 260802A / EP J223759.5+531421: SVOM/COLIBRÍ (FM-GFT) optical upper limit
- The EP-WXT trigger 01709277420 is likely a flaring star
- GRB 260802A/EP J223759.5+531421: SVOM detection of a possible magnetar burst
- GRB 260727A: EP-FXT further follow-up observations and candidate afterglow
- GRB 260618B: SVOM/VT continued optical observations indicated a steeper and redder decay
- GRB 260731A: AstroSat CZTI detection of a long burst
- EP260731a: COLIBRÍ optical upper limit
- EP260731a: NOT optical upper limit
- EP260731a: Einstein Probe detection of an X-ray transient
- GRB 260727A: SVOM/ECLAIRs refined analysis
- GRB 260726A: SVOM/ECLAIRs refined analysis
- GRB260730A: Fermi GBM Final Localization
- EP260728a: COLIBRÍ optical upper limit
- EP260727a: VLT/X-shooter spectroscopic redshift z = 2.817
- The EP-WXT trigger 01709277130 (EP260729a): refined EP-WXT analysis and association with a flaring star
- EP 260729a: Ondrejov D50 optical detection supports stellar flare origin
- EP260729a: Einstein Probe detection of an X-ray transient
- GRB 260727A: AbAO and SAO RAS optical observations
- EP260728a: EP-FXT follow-up observation
- GRB 260726A: EP-FXT follow-up observations
- EP260728a: Einstein Probe detection of a fast X-ray transient
- GRB 260727A: SVOM/GRM observation
- GRB 260726A: Fermi GBM Observation
- EP260727a: 1.5m OSN optical counterpart detection
- EP260727a:refined analysis of the EP-WXT and EP-FXT observation
- EP260727a: OHP/T193 optical observations
- GRB 260726A: Liverpool Telescope optical observations
- GRB 260727A: Liverpool Telescope optical upper limits
- EP260727a: NUTTELA-TAO Early Optical Limits
- GRB 260728A: Fermi GBM Final Localization
- GRB 260727A: EP/FXT follow-up observations
- EP260727a: Einstein Probe detection of an X-ray transient
- The EP-WXT trigger 01709276927 (EP260727a?): NOT likely optical counterpart
- GRB 260726A: J-band upper limit with WINTER
- GRB 260727A: J-band upper limit with WINTER