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"26489 results found.
- GRB 260925A: Swift/UVOT Upper Limits
- GRB 260924A: Extreme Isotropic-equivalent Gamma-ray Energy and encouragement for multiwavelength follow-up observations
- GRB 260923A: Glowbug gamma-ray detection
- GRB 260924A: Optical follow-up observations with Kinder
- GRB 260922A: Glowbug gamma-ray detection
- GRB 260925A: Enhanced Swift-XRT position
- GRB 260925A: COLIBRÍ optical upper limits
- GRB 260925A: FRAM-Auger optical limit
- GRB 260924A: Ondrejov D50 optical afterglow detection
- EP260924a: J-band upper limit with WINTER
- GRB 260924A: SVOM/GRM observation
- GRB 260924A: 2.2m CAHA spectroscopic redshift z = 3.51
- GRB 260925A: Swift detection of a burst
- EP260924a: EP-WXT detection of an X-ray transient
- GRB 260924A: J-band observations by the SYSU 80 cm infrared telescope
- GRB 260924A: Swift/UVOT Detection
- GRB 260924A: GROWTH-India Telescope optical observations
- GRB 260924A: Swift-XRT refined Analysis
- Konus-Wind detection of GRB 260922A
- GRB 260921A: SVOM/GRM observation
- GRB 260922A: COLIBRÍ Confirmation of the Optical Counterpart
- GRB 260924A: Fermi GRB Observation
- Konus-Wind detection of GRB 260921A (possible merger-origin)
- GRB 260924A: AstroSat CZTI detection
- GRB 260920A: SVOM/GRM observation
- GRB 260924A: NOT optical counterpart confirmation
- GRB 260924A: Enhanced Swift-XRT position
- The EP-WXT trigger 01709319842 is likely a flaring star
- GRB 260924A: Swift detection of a burst
- EP260806a: e-MERLIN detection at 5 GHz
- GRB 260922A: Ondrejov D50 optical limit
- Fermi-LAT Gamma-ray Observations of IceCube-260919A
- Fermi-LAT Gamma-ray Observations of IceCube-260916A
- EP260920a: VLT/HAWK-I near-infrared counterpart confirmation
- GRB 260922A: J-band upper limit with WINTER
- GRB 260922A: Swift/UVOT Upper Limits
- GRB 260922A: COLIBRÍ Optical Counterpart Candidate (correction to GCN 45698)
- GRB 260922A: COLIBRÍ optical upper limits
- GRB 260922A: Swift-XRT refined Analysis
- GRB 260922A: Enhanced Swift-XRT position
- Fermi-LAT Gamma-ray Observations of IceCube-260805A
- Konus-Wind detection of GRB 260810A
- GRB 260920A: Glowbug gamma-ray detection
- GRB 260918A: SVOM/ECLAIRs refined analysis
- GRB 260922A: SVOM/C-GFT optical upper limit
- GRB 260922A: Swift detection of a burst
- GRB 260917C: AstroSat CZTI detection
- GRB 260921A: AstroSat CZTI detection
- GRB 260921A: Fermi GBM Observation
- GRB 260917B:: SVOM/ECLAIRs refined analysis
- The EP-WXT trigger 01709319528 is likely a flaring star
- EP260920a: VLT/HAWK-I near-infrared candidate
- Swift GRB 260921A: MASTER OT J094129.58+025052.5 possible optical counterpart detection with host galaxy (z=1.3)
- EP260920b: LCO observations
- GRB 260920A: AstroSat CZTI detection
- EP260920b: SVOM/VT optical observation
- EP260920b: refined analysis of the EP-WXT and EP-FXT observations
- EP260920b: COLIBRÍ optical observations
- EP260920b: LCO optical counterpart detection
- The EP-WXT trigger 01709318601 is likely a flaring star
- EP260920b: Einstein Probe detection of an X-ray transient
- IceCube-260919A: Upper limits from a search for additional neutrino events in IceCube
- EP-WXT detected a brightening of HMXB LS V +44 17
- EP260920a: NOT early time optical upper limits
- EP260920a: NOT optical upper limits
- EP260920a: SVOM/VT optical upper limits
- EP260920a: refined analysis of the EP-WXT and autonomous EP-FXT observations
- EP260920a: COLIBRÍ optical upper limits
- EP260917b: EP-FXT non-detection and upper limit
- EP260920a: LCO optical counterpart candidate
- EP260920a: Einstein Probe detection of an X-ray transient
- GRB 260915A: VLT optical and near-infrared upper limits
- EP260917a: refined analysis of the EP-FXT observations
- The EP-WXT trigger 01709318491 is likely a flaring star
- EP260917a: SVOM/VT optical upper limits
- GRB 260918A: SVOM/C-GFT optical upper limits
- Konus-Wind detection of GRB 260916B (short/hard)
- The EP-WXT trigger 01709318279 is likely a flaring star
- GRB 260916B: Glowbug gamma-ray detection of a short burst
- GRB 260918A: EP-FXT follow-up observation
- GRB 260917B: Mondy optical upper limit
- EP260917b: EP-WXT detection of an X-ray transient
- EP260917A: J-band upper limit with WINTER
- GRB 260917B: EP-FXT follow-up observation
- EP260917a: COLIBRÍ optical upper limits
- GRB 260915A: Swift-XRT afterglow detection
- GRB 260918A: LCO optical upper limits
- EP260917a: Einstein Probe detection of an X-ray transient
- GRB 260918A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
- GRB 260918A: SVOM detection of a burst
- GRB 260917B: FRAM-Auger optical limits
- GRB 260916B: Fermi GBM Detection
- IceCube-260916A: Upper limits from a search for additional neutrino events in IceCube
- GRB 260917A: Glowbug gamma-ray detection
- GRB 260915A: SVOM/ECLAIRs refined analysis
- GRB 260917B: WINTER J-band observations
- GRB 260917B: SVOM/VT optical observations
- GRB 260917B: LCO optical observation
- GRB 260917B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
- GRB 260917B: SVOM detection of a faint burst