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.
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subject:"Swift"body:"GRB"submitter:"Judith Racusin"- GRB 261024D: GECAM-B observation
- The EP-WXT trigger 01709321750 is likely a flaring star
- EP Alert 261026.29: Global MASTER-Net observations report
- GRB 261026A: EP-FXT follow-up observation
- GRB 261024A: SVOM/GRM observation
- GRB 261026A: Upper Limit with 60cm Panzhihua Telescope
- EP 261025a: J-band upper limit with MIRAGE
- GRB 261026A: OHP/T120 optical imaging
- GRB 261024D: Glowbug gamma-ray detection
- GRB 261026B: NuSTAR detection of prompt emission
- GRB 261024D: NuSTAR detection of prompt emission
- GRB 261024C: NuSTAR detection of prompt emission
- GRB 261026A: Ondrejov D50 optical limit
- GRB 261026A: ULL-ASTRO-MASTER optical detection with LCO 40-cm telescope at Haleakalā Observatory
- GRB 261026A: J-band observations by the SYSU 80cm infrared telescope
- GRB 261026A: SVOM/VT optical observations
- IPN triangulation of GRB 260730B
- GRB 261026C: Fermi GBM Final Real-time Localization
- GRB 261020A: Insight-HXMT/HE detection
- SVOM GRB261026.26: Global MASTER-Net observations report
- GRB 261026A: WINTER J-band observations
- GRB 261024D: AstroSat CZTI detection of a long burst
- GRB 261024C: AstroSat CZTI detection of a long burst
- GRB 261019A: GECAM-B observation
- GRB 261019A: SVOM/GRM observation
- Fermi GRB 261026B: Global MASTER-Net observations report
- GRB 261026A: SVOM/VT optical observation from VHF data
- GRB 261026A: KAIT optical observations
- GRB 261026A: SVOM/COLIBRÍ (FM-GFT) optical observations
- GRB 261026B: Fermi GBM Final Real-time Localization
- GRB 261024A: NuSTAR detection of prompt emission
- GRB 261026A: SVOM detection of a burst
- GRB 261025B: Fermi GBM Final Real-time Localization
- EP261025a: J-band upper limit with WINTER
- EP261023a: J-band upper limit with WINTER
- EP 261025a: COLIBRÍ optical upper limit
- EP261025a: Einstein Probe detection of a fast X-ray transient
- GRB 261025A: Fermi GBM Final Localization Correction
- EP261023a: J band upper limit by SYSU 80cm infrared telescope
- GRB 261024B: Fermi GBM Final Real-time Localization
- EP261015a: VST optical observations
- GRB 261024A: BALROG localization (Fermi Trigger 814551785 / GRB 261024683)
- GRB 261024A: Fermi GBM Final Real-time Localization
- EP261023a: Mondy optical upper limit
- EP261015a: MAO/AZT-22 optical observations
- EP261015a: VLA non-detection
- EP261023a: NOT optical counterpart candidate
- EP261023a: Einstein Probe detection of an X-ray transient
- GRB 261019A: Insight-HXMT/HE detection
- The EP-WXT trigger 01709321472 is likely a flaring star
- IceCube-261020A: Upper limits from a search for additional neutrino events in IceCube
- NuSTAR 261020, a 830s hard X-ray transient
- EP261015a: GSP multiband optical follow-up observations
- GRB 261017A: SVOM/GRM observation
- GRB 261021A: Fermi GBM Final Real-time Localization
- EP261015a: Further optical observations with the 1.3m DFOT
- GRB 261020B: AstroSat CZTI detection of a short burst
- Fermi-LAT Gamma-ray Observations of IceCube-261020A
- EP261015a: AZT-20 Assy-Turgen optical observations
- GRB 261020A: Fermi GBM Observation
- GRB 261017A: SAO RAS optical upper limit
- EP261015a: Wendelstein 43 cm optical observations
- GRB 260903A
- EP261015a: Follow-up with the 1.3m DFOT
- EP261015a: Terskol Zeiss-2000 optical upper limit
- EP261007b: Further EP-FXT follow-up observations
- GRB 261017A: COLIBRÍ optical upper limit
- IceCube-261020A - IceCube observation of a high-energy neutrino candidate track-like event
- GRB 261020A: MAXI GSC detection
- GRB 261020A: Fermi GBM Final Real-time Localization
- EP261015a: COLIBRÍ optical observations of a rebrightening
- Konus-Wind detection of GRB 261017A
- GRB 261019A: Fermi GBM Final Localization
- GRB 261017A: Possible Swift/UVOT Detection
- GRB 261017A: Luminance-band upper limit from a 28cm telescope in Chengde
- GRB 261017A: R-band upper limit with the 1.3-m DFOT
- GRB 261017A: Swift-BAT refined analysis
- GRB 261017A: a short minimum variability timescale compatible with a compact object merger origin
- EP261015b: NOT Optical Observations
- GRB 261017A: J band upper limit by the SYSU 80cm infrared telescope
- EP261015c: refined analysis of the EP-FXT observation favors a stellar flare interpretation
- GRB 261017A : MITSuME Akeno optical upper limits
- GRB 261017A: Swift-XRT refined Analysis
- GRB 261017A: Nanshan/NEXT optical upper limit
- GRB 261017A: Enhanced Swift-XRT position
- GRB 261017A: Fermi GBM Observation
- GRB261010A: Retraction of Keck/MOSFIRE near-IR source
- GRB 261017A: Swift detection of a burst
- GRB 261017A: Fermi GBM Final Real-time Localization
- EP261015a: Tentative fading of the candidate optical counterpart from the NOT
- EP261015b: Refined analysis of EP-FXT observations
- EP261015b: J-band upper limit by the SYSU 80cm infrared telescope
- EP261015a: refined analysis of EP-FXT observations
- EP261015c: J-band upper limit with WINTER
- EP261015a: J-band upper limit with WINTER
- EP261006a / AT 2026aetp: Optical follow-up with the 1.3-m DFOT
- GRB 261011A: 1.3m DFOT optical upper limit
- GRB 261010A: Pan-STARRS z-band imaging and upper limit
- EP261015a: SVOM/VT optical observation
- EP241111a and EP250125a: Upper limits from SVOM/GRM Observations