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"2409 results found.
- GRB 250520A: 10 GHz VLA Afterglow Confirmation
- GRB 250520A: GRBAlpha detection
- GRB 250521B: SVOM/VT optical upper limit
- The EP-WXT trigger 01709176612: SVOM/VT optical observations
- GRB 250521B: EP-FXT follow-up observation and afterglow candidates
- GRB 250521D: SVOM/VT optical observations
- GRB 250521B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
- GRB 250520A: CALET Gamma-Ray Burst Monitor detection
- GRB 250520A: 10 GHz VLA radio source
- GRB 250521B: Swift ToO observations
- GRB 250521B: SVOM detection of a burst through offline search
- Konus-Wind detection of GRB 250520A (short/hard)
- GRB 250520A: VLT/FORS2 Optical Observation
- GRB 250502A: Tautenburg observations
- GRB 250520A: Swift/UVOT Upper Limits
- GRB 250520A: J-band observations with WINTER
- GRB 250520A: Gemini-South optical observations
- GRB 250520A: REM optical/NIR early observations
- GRB 250520A:SVOM/VT optical candidate
- GRB 250520A: COLIBRÍ optical upper limit
- GRB 250520A: DDOTI Optical Upper Limit
- GRB 250520A: AstroSat CZTI detection of a short burst
- GRB 250520A: SVOM/GRM observation
- GRB 250515A:COLIBRÍ optical observations of the GOTO candidate
- GRB 250515A/GOTO25cqo: SVOM/VT optical blue color
- GRB 250512B / EP250512a: SVOM/GRM analysis
- Konus-Wind detection of GRB 250512B / EP250512a
- Konus-Wind detection of GRB 250506A
- EP250512a/GRB 250512B: REM optical/NIR observations
- GRB 250507B: AstroSat CZTI detection
- EP250512a/GRB 250512B refined analysis of the EP-WXT and EP-FXT observations
- GRB 250512B/EP250512a: SVOM/VT optical fading
- GRB 250512B/EP250512a:SVOM/VT bright optical counterpart
- GRB 250506A: GRBAlpha detection
- GRB 250512B: SVOM detection of a burst
- GRB 250507B: SVOM/GRM observation of a burst
- EP250511a: SVOM/VT optical candidate comfirmation
- EP250508a: Gemini NIR upper limits
- GRB 250510A: Swift-XRT observations
- GRB 250510A: follow-up observation with EP-FXT
- GRB 250510A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
- GRB 250510A: SVOM possible detection of a burst
- GRB 250507A: J-band observations with WINTER
- EP250508a: SVOM/VT optical candidate fading
- GRB 250506A: NOT optical upper limits
- EP250508a: SVOM/VT optical candidate
- GRB 250507A: KAIT optical upper limit
- GRB 250505B: SVOM/GRM observation of a short burst
- GRB 250502A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
- GRB 250506A: GECAM detection
- GRB 250506A: Swift-XRT afterglow detection
- GRB 250506A: SVOM/VT optical upper limit
- GRB 250507A: Swift-XRT refined Analysis
- GRB 250506A: Swift/UVOT Upper Limits
- GRB 250427B : SVOM detection of a burst through offline search
- GRB 250507A: follow-up observation with EP-FXT
- GRB 250506A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
- GRB 250507A: refined SVOM/MXT data analysis
- GRB 250507A: REM optical/NIR observations
- GRB 250507A: SVOM/VT optical upper limit
- GRB 250506A: Swift-XRT observations
- GRB 250507A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
- GRB 250507A: SVOM detection of a long burst
- GRB 250506A: Mephisto optical upper limits
- GRB 250506A: Swift ToO observations
- GRB 250502A: Bassano Bresciano Observatory upper limit
- GRB 250506A: Xinglong 2.16m optical upper limit
- SVOM/sb25050601: EP-FXT observations
- GRB 250506A: SVOM improved position and MXT detection of a fading X-ray afterglow
- GRB 250506A: REM optical/NIR upper limits
- GRB 250506A: Fermi GBM Observation
- GRB 250506A: Swift XRT observations and possible counterpart detection
- GRB 250506A: TRT optical observations
- GRB 250506A: SVOM/COLIBRÍ (FM-GFT) Upper Limits on the Optical Counterpart
- GRB 250506A: SVOM detection of a burst
- GRB 250504A: SVOM/VT upper limit
- GRB 250502A: REM optical/NIR observations
- GRB 250502A: Swift/UVOT Follow up
- GRB 250502A: KAIT optical observations
- GRB 250502A: Montarrenti Observatory optical detection
- GRB 250502A: Swift-XRT afterglow detection
- GRB 250502A: NOT optical observations
- GRB 250502a: Liverpool Telescope optical follow-up
- GRB 250502A: AKO Optical Afterglow Detection
- GRB 250502A: LCO optical counterpart detection
- GRB 250502A: Swift ToO observations
- GRB 250502A: Redshift from OSIRIS+/GTC z = 2.163
- GRB 250407A: VZLUSAT-2 detection
- GRB 250502A: Early optical counterpart detection by LCO.
- GRB 250502A: SVOM/VT optical bump
- GRB 250502A: TRT optical afterglow confirmation
- GRB 250502A: SVOM/COLIBRÍ (FM-GFT) Detection of a Bright Optical Counterpart Candidate
- GRB 250502A: SVOM detection of a burst
- GRB 250430A: SVOM/VT optical observations
- SVOM/sb25043004: EP-FXT observations
- GRB 250424A: CALET Gamma-Ray Burst Monitor detection
- SVOM/sb25043004: SVOM detection of a X-ray transient
- EP250428b: GROWTH-India telescope optical upper limit
- EP250428b: SVOM/VT upper limit
- GRB 250424A: SVOM/GRM observation of a long burst