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"26810 results found.
- EP251229a: Einstein Probe detection of an X-ray transient
- GRB 251230A: Swift detection of a burst with a bright optical counterpart
- GRB 251222A/EP251222b: 1.6m Mephisto optical followup
- Fermi GRB 251228A: Global MASTER-Net observations report
- The EP-WXT trigger 01709250662 is likely a flaring star
- GRB 251228A: Fermi GBM Final Real-time Localization
- GRB 251226A: SVOM/GRM observation
- GRB 251226A: GECAM-B detection
- SVOM GRB251227.07: Global MASTER-Net observations report
- The EP-WXT trigger 01709250617 is likely a flaring star
- IceCube Alert 251225.84: Global MASTER-Net observations report
- Fermi Gamma-ray Burst Monitor trigger 788368008/251225630 is not a GRB
- GRB 251222A: NUTTelA-TAO Early Measurements
- EP251222a: Optical upper limit with Kinder observations
- GRB 251221A: Swift-BAT refined analysis
- GRB 251222A/EP251222b: FTW optical and NIR observations
- EP251222a: FTW optical and NIR observations
- GRB 251205A: Kilonova-Catcher optical afterglow detection
- GRB 251222A: AbAO optical observations
- GRB 251222A / EP251222b: Kilonova-Catcher optical afterglow detection
- GRB 251129A / EP251129a: VLA detection of a radio counterpart
- EP251222a: VLT/FORS2 spectroscopic redshift z = 0.505
- GRB 251222A: ZTSH BVRI optical observations
- GRB 251222A: SVOM/COLIBRÍ (FM-GFT) optical observations
- GRB 251222A: Continued 1.3m DFOT optical observation
- EP251220a: 3.6m DOT optical afterglow detection
- GRB 251222A: Fermi GBM Observation
- EP251220a: CrAO ZTSh optical observations
- EP251221a: PRIME upper limit
- EP251222a: Global MASTER-Net observations report
- GRB 251222A / EP251222b: GECAM-B observation
- EP251221a: Liverpool Telescope upper limits
- EP251222a: refined analysis of the EP-WXT and EP-FXT observations
- EP251222b/GRB 251222A: refined analysis of the EP-WXT and EP-FXT observations
- EP251222a: NTT/ULTRACAM optical observations
- EP251222a: GOTO optical upper limit
- GRB 251222A / EP251222b: GOTO optical counterpart detection
- GRB 251222A / EP251222b: LCO optical observations
- GRB 251222A: 1.3m DFOT optical detection
- GRB251221A: 7DT optical upper limits
- EP251222a: GSP Optical Counterpart Detection
- GRB 251222A / EP251222b: VLT/X-shooter spectroscopic redshift z = 3.171
- GRB 251222A / EP251222b: SVOM/VT optical rebrightening
- EP251222b/GRB 251222A: SVOM/GRM observation
- EP251222b/GRB 251222A: Einstein Probe detection of an X-ray transient
- EP251222a: Einstein Probe detection of an X-ray transient
- The EP-WXT trigger 01709250397 is likely a flaring star
- EP251221a: Global MASTER-Net observations report
- EP251221a: NOT optical upper limit
- GRB 251222A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
- GRB 251222A: NOT optical observations
- IPN triangulation of GRB 251220B (short)
- GRB 251222A: BALROG localization (Fermi Trigger / GRB 251222712)
- GRB 251222A: SVOM/VT optical candidate
- GRB 251222A: SVOM detection of a long burst
- SVOM GRB251222A: Global MASTER-Net observations report
- GRB 251222A: Fermi GBM Final Real-time Localization
- EP251220a: PRIME upper limit
- EP251220a: VLT/FORS2 spectroscopic redshift z = 2.375
- GRB 251221A: PRIME near-infrared observation
- EP251220a: NOT optical observations
- EP251220a: FTW optical and NIR observations
- GRB 251221A: UAFO and Mondy optical upper limit
- GRB 251221A: Swift-XRT refined Analysis
- EP251221a: Einstein Probe detection of a fast X-ray transient
- GRB 251221A: Swift/UVOT Upper Limits
- Fermi Gamma-ray Burst Monitor trigger 788028118/251221696 is not a GRB
- GRB 251221A: Fermi GBM Observation
- GRB 251221B: Fermi GBM Final Real-time Localization
- EP251220a: EP-FXT follow-up observation
- GRB 251220B: SVOM/GRM observation of a short burst
- EP251220a: COLIBRÍ confirmation of fading and photometric redshift upper limit of z < 3.4
- EP 251220a: GOTO optical counterpart detection
- GRB 251221A: COLIBRÍ detection of the optical counterpart
- EP 251220a: COLIBRÍ detection of the optical counterpart
- GRB 251221A: Swift detection of a burst
- Swift GRB251221A: Global MASTER-Net observations report
- GRB 251221A: Fermi GBM Final Real-time Localization
- EP251220a: Global MASTER-Net observations report
- EP251220a: EP detection of a fast X-ray transient
- SVOM GRB251220.98: Global MASTER-Net observations report
- GRB 251220B: Fermi GBM Final Real-time Localization
- GRB 251219A: SVOM/GRM observation of a short burst
- GRB 251219A: GECAM-B detection of a possible magnetar X-ray burst from SGR 1830-0645
- IceCube-251218A: COLIBRÍ optical upper limits
- SVOM GRB251219.11: Global MASTER-Net observations report
- IceCube Alert 251218.85: Global MASTER-Net observations report
- Fermi trigger No 787736968: Global MASTER-Net observations report
- Fermi GRB 251217A: Global MASTER-Net observations report
- GRB 251217A: Fermi GBM Final Real-time Localization
- GRB 251215A: Swift/UVOT Upper LImits
- GRB 251215A: Fermi GBM Observation
- Fermi GRB 251216A: Global MASTER-Net observations report
- GRB 251215A: COLIBRÍ optical upper limit
- GRB 251216A: Fermi GBM Final Real-time Localization
- EP251214b: KAIT optical upper limit
- Fermi GRB 251215A: Global MASTER-Net observations report
- EP251214a: Optical upper limit with Kinder observations
- GRB 251214B: 1.6m Mephisto observations with newly installed mosaic cameras
- GRB 251215A: Glowbug gamma-ray detection