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"24368 results found.
- GRB 251205A: Swift-XRT refined Analysis
- Konus-Wind detection of GRB 251118A
- GRB 251205A: NOT optical observations
- Swift GRB 251205A : MASTER OT detection with host galaxy
- Swift GRB251205A: Global MASTER-Net observations report
- GRB 251126B: Fermi GBM Final Localization
- GRB 251203C: SVOM/ECLAIRs refined analysis
- SVOM/sb25120502: SVOM detection of a faint X-ray transient candidate
- GRB 251202A / EP251202a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm and 1-m telescopes at McDonald Observatory
- GRB 251202A: SVOM/GRM observation
- GRB 251203A: SVOM/GRM observation
- EP251130a: JinShan near-infrared observations
- GRB 251203C: SVOM/VT optical counterpart
- GRB 251203C: EP-FXT follow-up observation
- GRB 251129A/EP251129a : SVOM/ECLAIRs refined analysis
- GRB 251203C: LCO optical upper limits
- GRB 251203B: LCO optical upper limits
- GRB 251203C: SVOM detection of a burst
- SVOM GRB251203.77: Global MASTER-Net observations report
- SVOM GRB251203B: Global MASTER-Net observations report
- GRB 251203B: SVOM detection of a burst
- GRB 251129A / EP251129a: SVOM/VT optical color bluer
- GRB 251203A: Fermi GBM Final Real-time Localization
- GRB 251202A / EP251202a: SVOM/VT optical observation
- GRB 251201B: Fermi GBM Observation
- EP251202a/GRB 251202A: KAIT optical observations
- Fermi GRB 251202B: Global MASTER-Net observations report
- GRB 251202B: Fermi GBM Final Real-time Localization
- IPN triangulation of GRB 251129B (short/hard)
- GRB 251202A: Fermi GBM Observation
- GRB 251130B: Glowbug gamma-ray detection
- EP251130a: continued NOT optical observations indicate steep fading phase
- GRB 251122A/EP251122a: CrAO ZTSh optical observations
- Fermi-LAT Gamma-ray Observations of IceCube-251130A
- EP251202a / GRB 251202A: LCO r- and i-band optical detection
- GRB 251126A: SVOM/VT optical observation
- EP251130a: SVOM/VT optical observation
- EP251202a / GRB 251202A: NOT spectroscopic redshift z = 2.785
- Fermi GRB 251202A: Global MASTER-Net observations report
- EP251202a/GRB 251202A: Einstein Probe detection of an X-ray transient
- GRB 251201B: Swift-XRT refined Analysis
- IceCube-251130A: Upper limits from a search for additional neutrino events in IceCube
- GRB 251202A: Fermi GBM Final Real-time Localization
- GRB 251201A: SVOM/GRM observation of a burst
- GRB 251201B: SVOM/VT optical fading
- Swift GRB 251201B : MASTER optical counterpart detection
- Swift GRB 251201B: Global MASTER-Net observations report
- GRB 251201B: Fermi GBM Final Real-time Localization
- SVOM GRB251201.19: Global MASTER-Net observations report
- EP251130a: GTC OSIRIS+ redshift z = 4.035 and rebrightening
- EP251130a: KAIT optical observations
- EP251130A: Optical observation from 1.3m DFOT
- EP251130a: refined analysis of the EP-WXT and EP-FXT observations
- EP251130a: JinShan optical observations
- Fermi GRB 251130B: Global MASTER-Net observations report
- GRB 251127A: SVOM/GRM observation
- IceCube Alert 251130.75: Global MASTER-Net observations report
- IceCube-251130A - IceCube observation of a high-energy neutrino candidate track-like event
- GRB 251130B: Fermi GBM Final Localization Correction
- EP251130a: Global MASTER-Net observations report
- GRB 251130B: Fermi GBM Final Real-time Localization
- EP251129a/GRB 251129A: EP-FXT follow-up observations
- GRB 251130A: Fermi GBM Final Real-time Localization
- GRB 251129A / EP251129a: OSN and CAHA optical follow-up
- GRB 251128A: SVOM/GRM observation of a long burst
- SVOM GRB 251129A : MASTER optical counterpart detection
- GRB 251129A / EP251129a: SVOM/VT optical fading
- EP251129a: Global MASTER-Net observations report
- GRB 251129A: Optical Observations via Virtual Telescope Project, Italy
- GRB 251128A: Fermi GBM Observation
- GRB 251129A: SVOM detection of a burst
- SVOM GRB251129A: Global MASTER-Net observations report
- GRB 251129A: SVOM detection of a burst
- GRB 251126A: Swift-BAT refined analysis
- GRB 251128A: Swift/BAT-GUANO localization skymap of a burst
- Fermi GRB 251128A: Global MASTER-Net observations report
- GRB 251126A: OHP/T193 optical observations and tentative spectroscopic redshift
- GRB 250702B: detection of the compact radio counterpart 139 days after the burst
- GRB 251126A NUTTelA-TAO Early Measurements
- LIGO/Virgo/KAGRA S251112cm: GECKO/KMTNet tiling observations and transient candidates
- GRB 251128A: Fermi GBM Final Real-time Localization
- GRB251126A: Continued optical observation from 1.3m DFOT
- GRB 251126A : MITSuME Akeno optical afterglow candidate detection
- GRB 251126A: 1.3m DFOT optical afterglow detection
- GRB 251125B: GECAM-B detection
- Fermi GRB 251127A: Global MASTER-Net observations report
- GRB 251127A: Fermi GBM Final Real-time Localization
- GRB 251126A: Asiago i-band detection
- Swift GRB 251126A: Global MASTER-Net observations report
- GRB 251121A: Fermi GBM Observation
- GRB 251126A: Swift detection of a burst
- EP251124b follow-up observation by EP-FXT
- Fermi GRB 251125B : MASTER OT J155558.56+581224.1 optical counterpart discovery
- Fermi GRB 251125B: Global MASTER-Net observations report
- GRB 251125B: Fermi GBM Final Real-time Localization
- EP251124b: Global MASTER-Net observations report
- EP251124a: Xinglong GWAC-F60A optical observation
- Fermi GRB 251125A: Global MASTER-Net observations report
- GRB 251125A: Fermi GBM Final Real-time Localization
- EP251124a: Global MASTER-Net observations report