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.
Lucene Examples (click to copy):
subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"
4690 results found.
- EP250427a: LT optical counterpart detection
- GRB 250330B: GRBAlpha detection
- IceCube-250421A: DDOTI Detection of the LAST Candidate
- EP250421A: COLIBRÍ Optical Upper Limit
- GRB 250419A: Mondy Continued Optical Observations
- IceCube Alert 250421.71: Global MASTER-Net observations report
- GRB 250419A: LCO optical afterglow multi-band observations
- GRB 250419A: MASTER optical afterglow observation
- GRB 250407A: GTC/OSIRIS+ spectroscopic redshift z = 1.36
- GRB 250419A: GOTO optical counterpart detection
- GRB 250419A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
- IceCube-250416A: DDOTI Optical Observations
- EP250416a: Gemini South-GMOS optical counterpart
- EP250225a: SVOM/VT optical brightening
- IceCube 250414.324: DDOTI Optical Observations
- EP250404a: Nanshan 0.43m Telescope optical observatios
- Fermi trigger No 766148493: Global MASTER-Net observations report
- Fermi trigger No 766173972: Global MASTER-Net observations report
- GRB 250407A: Continued KAIT/Nickel optical observations
- GRB 250320B: cubesat Avion detection
- IceCube-250406A: Swift-XRT observations
- EP250407a: Global MASTER-Net observations report
- GRB 250407A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
- IceCube-250406A: No candidates from the Zwicky Transient Facility
- Fermi GRB 250407A: Global MASTER-Net observations report
- IceCube 250406A: DDOTI Optical Observations of the Refined Position
- IPN triangulation of GRB 250406B (short/hard)
- IceCube 250406.951: COLIBRÍ/DDRAGO Optical Upper Limit
- IceCube 250406.951: DDOTI Optical Observations
- Fermi GRB 250406A: Global MASTER-Net observations report
- Fermi trigger No 765619921: Global MASTER-Net observations report
- EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
- GRB 250402A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
- EP250402a: Optical upper limit with PD 1.3m observations
- GRB 250403A: AstroSat CZTI detection
- Fermi GRB 250404A: Global MASTER-Net observations report
- EP250404a: Xinglong decaying optical counterpart
- GRB 250403A: Montarrenti Observatory optical detection
- EP250404a: Global MASTER-Net observations report
- GRB 250403A: Fermi GBM observations
- GRB 250327B: VIRT Optical Upper Limit
- EP250404a: Mephisto multi-band optical detection
- GRB 250402A: Mondy optical observations
- GRB 250403A: Swift/UVOT Detection
- GRB 250402A: Swift/UVOT Upper Limits
- 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
- Fermi GRB 250403A: Global MASTER-Net observations report
- GRB 250403A: GOTO optical counterpart follow-up observations
- GRB 250403A: GMG Optical Observation
- GRB 250403A: 1.6m Mephisto multi-band optical detection
- GRB 250403A: GOTO detection of the optical afterglow
- GRB250402A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
- GRB 250402A: REM optical/NIR upper limits
- GRB 250402A: LCO optical counterpart detection
- GRB 250331C: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
- GRB 250331E: SVOM/GRM observation
- GRB250331D: AbAO optical observations
- GRB 250328A: AbAO AS-32 Optical Observations
- GRB 250322B: GRBAlpha detection
- GRB 250331D: Swift-XRT observations
- GRB 250330B: SVOM/GRM observation of a short burst
- Fermi GRB 250331E: Global MASTER-Net observations report
- Fermi GRB 250331D: Global MASTER-Net observations report
- GRB 250330B: EIRSAT-1 GMOD Detection
- GRB 250329A: AbAO, Mondy and SAO RAS optical upper limits
- Fermi trigger No 765078057: Global MASTER-Net observations report
- Swift GRB 250331C: Global MASTER-Net observations report
- Swift GRB 250331B: Global MASTER-Net observations report
- GRB 250331D: Swift/BAT-GUANO arcminute localization of a burst during slew
- GRB 250331C: Enhanced Swift-XRT position
- IceCube-250330A: Upper limits from a search for additional neutrino events in IceCube
- GRB 250320C : SVOM detection of a burst through offline search
- Fermi-LAT gamma-ray observations of IceCube-250330A
- SVOM/sb25033102 is a false trigger
- GRB 250331C: COLIBRÍ/DDRAGO optical upper limit
- GRB 250331B: COLIBRÍ/DDRAGO optical upper limit
- GRB 250331C: Prompt enhanced Swift-XRT position
- GRB 250331C: Swift detection of a burst
- GRB 250330A: SVOM/VT optical upper limit
- GRB 250331A: MAXI/GSC detection
- SVOM/sb25033102: SVOM detection of an X-ray transient
- LIGO/Virgo/KAGRA S250331o: Identification of a GW compact binary merger candidate
- Fermi GRB 250330B: Global MASTER-Net observations report
- Fermi GRB 250330A: Global MASTER-Net observations report
- GRB 250328A: 1.6m Mephisto optical observations
- GRB 250329B: SVOM/COLIBRÍ (F-GFT) optical upper limit
- IceCube-250330A - IceCube observation of a high-energy neutrino candidate track-like event
- IceCube Alert 250330.35: Global MASTER-Net observations report
- Swift GRB250330.26: Global MASTER-Net observations report
- GRB 250329B: SVOM/C-GFT optical upper limit
- GRB 250327B: VLA detection
- GRB 250329B: SVOM/VT optical upper limit
- GRB 250327B: SVOM/COLIBRÍ (F-GFT) Further Observations
- GRB 250329B: 1.6m Mephisto Optical Upper Limits
- LIGO/Virgo/KAGRA S250329fl: 2 counterpart neutrino candidate events from an IceCube neutrino search
- GRB 250329B: GWAC-F50A optical upper limit