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"24373 results found.
- GRB 250407A: EP-WXT afterglow detection
- IceCube-250406A: No candidates from the Zwicky Transient Facility
- GRB 250407A: Fermi GBM Detection
- Fermi GRB 250407A: Global MASTER-Net observations report
- GRB 250407A: SRG/ART-XC afterglow detection
- LIGO/Virgo/KAGRA S250331o: Upper limits from Swift/BAT-GUANO
- Konus-Wind detection of GRB 250406B (short/hard)
- IPN triangulation of GRB 250406B (short/hard)
- GRB 250407A: BALROG localization (Fermi Trigger 765733706 / GRB 250407659)
- GRB 250407A: Fermi GBM Final Real-time Localization
- IceCube-250406A - IceCube observation of a high-energy neutrino candidate track-like event
- IceCube Alert 250406.95: Global MASTER-Net observations report
- Fermi trigger No 765663719: Global MASTER-Net observations report
- 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.
- GRB 250406A: Fermi GBM Final Real-time Localization
- EP250404a / GRB 250404A: Montarrenti Observatory optical observations
- Fermi trigger No 765619921: Global MASTER-Net observations report
- EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
- Konus-Wind detection of GRB 250404A / EP250404a
- 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 250331D: Swift-XRT afterglow detection
- EP250404a: REM optical/NIR observations
- EP250404a: LCO optical counterpart detection
- Fermi GRB 250404A: Global MASTER-Net observations report
- EP250404a: Xinglong decaying optical counterpart
- GRB 250403A: Montarrenti Observatory optical detection
- GRB 250404A: Fermi GBM Detection
- EP250404a: Global MASTER-Net observations report
- GRB 250403A: KAIT optical observations
- GRB 250402A: Swift/BAT-GUANO localization skymap of a burst
- GRB 250403A: Fermi GBM observations
- EP250404a: Mephisto multi-band optical detection
- GRB 250331C Swift-BAT refined analysis
- GRB 250331B Swift-BAT refined analysis
- GRB 250330A Swift-BAT refined analysis
- EP250404a: Nanshan/HMT optical counterpart detection
- GRB 250404A: Fermi GBM Final Real-time Localization
- 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
- EP250402a: EP-FXT follow-up 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: 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 250403A : SVOM detection of a burst
- GRB 250403A: Fermi GBM Final Real-time Localization
- GRB 250402A: REM optical/NIR upper limits
- GRB 250402A: LCO optical counterpart detection
- GRB 250402A: refined SVOM/MXT data analysis
- The EP-WXT trigger 01709133862 is a flaring star
- GRB 250402A: SVOM/VT optical counterpart
- GRB 250402A: SVOM detection of a burst
- GRB 250331D: Fermi GBM observation
- GRB 250322B: GRBAlpha detection
- GRB 250331D: Swift-XRT observations
- GRB 250322B possible detection by the AstroSat Satellite
- LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Epoch 2)
- Fermi GRB 250331E: Global MASTER-Net observations report
- Fermi GRB 250331D: Global MASTER-Net observations report
- GRB 250330B: EIRSAT-1 GMOD Detection
- GRB 250331E: Fermi GBM Final Real-time Localization
- GRB 250327A Swift-BAT refined analysis
- LIGO/Virgo/KAGRA S250331o: Updated Sky localization
- 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
- Konus-Wind detection of GRB 250327B
- IceCube-250330A: Upper limits from a search for additional neutrino events in IceCube
- LIGO/Virgo/KAGRA S250331o: NED Galaxies in the 3-Initial Localization Volume
- GRB 250320C : SVOM detection of a burst through offline search
- GRB20250327B: 45th Parallel Observatory upper limit
- Fermi-LAT gamma-ray observations of IceCube-250330A
- SVOM/sb25033102 is a false trigger
- GRB 250330A: Fermi GBM Observation
- GRB 250331C: COLIBRÍ/DDRAGO optical upper limit
- GRB 250331B: COLIBRÍ/DDRAGO optical upper limit
- GRB 250331D: Fermi GBM Final Real-time Localization
- GRB 250331B: Swift detection of a burst
- GRB 250330A: SVOM/VT optical upper limit
- 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
- GRB 250330B: Fermi GBM Final Real-time Localization
- Fermi GRB 250330A: Global MASTER-Net observations report
- GRB 250330A: BOOTES-7 early optical upper limit
- GRB 250328A: 1.6m Mephisto optical observations
- GRB 250329B: SVOM/COLIBRÍ (F-GFT) optical upper limit
- GRB 250330A: Fermi GBM Final Localization