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"
28714 results found.
- EP250416a: Global MASTER-Net observations report
- SVOM/sb25041603: SVOM/COLIBRÍ (FM-GFT) Upper Limit on the Optical Counterpart
- GRB 250413A: AstroSat CZTI detection
- EP250304a: ATCA radio observations
- EP250404a: Nanshan 0.43m Telescope optical observatios
- GRB 250411A: DDOTI Optical Observations
- Fermi GRB 250411A: Global MASTER-Net observations report
- GRB 250407A: Continued KAIT/Nickel optical observations
- GRB 250314A: e-MERLIN observations
- GRB 250407A: Mondy and AbAO Optical Observations
- EP250227a: Further NOT optical observations
- GRB 250320B: cubesat Avion detection
- IceCube-250406A: Swift-XRT observations
- IPN triangulation of GRB 250321D (consistent with the fast X-ray transient EP250321a)
- IPN triangulation of GRB 250407A
- EP250407a: Global MASTER-Net observations report
- GRB 250407A: LCO detection of a fading optical counterpart
- Fermi-LAT gamma-ray observations of IceCube-250406A
- EP250407a: Swift-XRT observations
- IceCube-250406A: Upper limits from a search for additional neutrino events in IceCube
- Konus-Wind detection of GRB 250407A
- GRB 250407A: SVOM/GRM observation of a bright long burst
- GRB 250407A: EP-WXT afterglow detection
- EP250407a: EP-WXT detection of a fast X-ray transient
- GRB 250407A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
- GRB 250407A: KAIT Optical Afterglow Candidate
- IceCube-250406A: No candidates from the Zwicky Transient Facility
- GRB 250407A: Fermi GBM Detection
- GRB 250407A: Swift-XRT afterglow detection
- Fermi GRB 250407A: Global MASTER-Net observations report
- GRB 250407A: Swift ToO observations
- GRB 250407A: SRG/ART-XC afterglow detection
- IceCube 250406A: DDOTI Optical Observations of the Refined Position
- Konus-Wind detection of GRB 250406B (short/hard)
- IPN triangulation of GRB 250406B (short/hard)
- IceCube 250406.951: COLIBRÍ/DDRAGO Optical Upper Limit
- GRB 250406A: AstroSat CZTI detection
- EP250404a: Multi-band Optical Observations from UCAS-70 and XL-C14
- Fermi GRB 250406A: Global MASTER-Net observations report
- GRB 250404A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
- EP250404a / GRB 250404A: Montarrenti Observatory optical observations
- GRB 250404A / EP250404a: RC500 INASAN-Kislovodsk optical upper limit
- GRB 250404A / EP250404a: SVOM/GWAC-F60 and F50 observations
- EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
- Konus-Wind detection of GRB 250404A / EP250404a
- GRB 250404A / EP250404a: Mondy optical observations
- EP250404a: refined analysis of the EP-WXT and EP-FXT observations
- GRB 250404A / EP250404a: GMG spectroscopic redshift at z ~ 2.627
- GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
- GRB 250402A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
- EP250402a: Optical upper limit with PD 1.3m observations
- GRB 250404A / EP250404a: NOT optical observations
- GRB 250403A: AstroSat CZTI detection
- EP250404a: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
- EP250404a: REM optical/NIR observations
- EP250404a: Seimei/TriCCS optical counterpart detection
- EP250404A: COLIBRÍ/DDRAGO Optical Observations
- EP250404A / GRB250404A: Ondrejov D50 optical afterglow detection
- EP250404a: LCO optical counterpart detection
- Fermi GRB 250404A: Global MASTER-Net observations report
- GRB 250403A: Montarrenti Observatory optical detection
- EP250404a: Global MASTER-Net observations report
- GRB 250403A: KAIT optical observations
- EP250404a: AKO Optical Afterglow Detection
- EP250404a: LAST detection of optical counterpart
- GRB 250402A: Swift/BAT-GUANO localization skymap of a burst
- EP250404a: Xinglong-2.16m spectroscopic redshift
- GRB 250403A: Fermi GBM observations
- GRB 250327B: VIRT Optical Upper Limit
- EP250404a: Mephisto multi-band optical detection
- GRB 250331C Swift-BAT refined analysis
- GRB 250331B Swift-BAT refined analysis
- GRB 250330A Swift-BAT refined analysis
- EP250321A: J band upper limit by SYSU 80cm telescope
- EP250404a: BOOTES-4/JGT optical afterglow detection
- EP250404a: Nanshan/HMT optical counterpart detection
- EP250404a: Einstein Probe detection of an X-ray transient
- GRB 250402A: Mondy optical observations
- GRB 250403A: Swift/UVOT Detection
- GRB 250402A: Swift/UVOT Upper Limits
- EP250402a: Optical upper limit with Kinder observations
- GRB 250403A: SVOM/VT optical observation
- GRB 250403A: REM NIR afterglow detection
- GRB 250403A: LCO optical counterpart detection
- IceCube-250330A: MASTER detection of PKS 2032+107 blazar flare with Zhirkov effect
- GRB 250403A: JinShan optical observations
- GRB 250402A: EP-FXT afterglow detection
- GRB 250403A: Optical counterpart detection by LCO.
- EP250402a: EP-FXT follow-up observations
- GRB 250403A: Swift-XRT observations
- GRB 250322A: 10 GHz VLA radio upper limits
- Fermi GRB 250403A: Global MASTER-Net observations report
- GRB 250403A: GOTO optical counterpart follow-up observations
- GRB 250402A: NUTTelA-TAO Early Optical Limits
- GRB 250403A: GMG Optical Observation
- GRB 250403A: 1.6m Mephisto multi-band optical detection
- GRB 250402A: Fermi GBM Observation
- GRB 250403A: SVOM/C-GFT optical observations
- GRB 250403A: GOTO detection of the optical afterglow
- GRB 250402A: Swift-XRT observations