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"32503 results found.
- GRB251230A: 7DT optical upper limits
- GRB 251230A / EP251230a: NOT observations and spectroscopic redshift upper limit z < 2.2
- EP251229a: BOOTES-2 early optical upper limit
- GRB 251230A: GOTO optical upper limit
- EP251229a: NOT optical upper limits
- GRB 251230A / EP251230a: SVOM/VT optical observation
- EP251229a: refined analysis of the EP-WXT and EP-FXT observations
- GRB 251230A: Early optical counterpart detection by LCO.
- EP-WXT trigger 01709250662 Mephisto and 50cm telescope follow-up
- GRB 251230A: Optical Observations via Virtual Telescope Project, Italy
- EP251230a / GRB 251230A: Einstein Probe detection of an X-ray transient
- GRB 251230A/EP#01709250693 (likely EP251230a): FTW optical and NIR observations
- LIGO/Virgo/KAGRA S251112cm: Candidates from the NSF-DOE Vera C. Rubin Observatory
- Swift GRB 251230A: Global MASTER-Net observations report
- The EP-WXT trigger 01709250693/GRB 251230A: Las Cumbres detection of the optical counterpart
- EP251229a: Global MASTER-Net observations report
- GRB 251226A: Glowbug gamma-ray detection
- GRB 251222A/EP251222b: 1.6m Mephisto optical followup
- GRB 251129A: redshift correction and SN detection at z = 0.505 with GTC
- Fermi GRB 251228A: Global MASTER-Net observations report
- GRB 251226A: SVOM/GRM observation
- IceCube-251225A: Upper limits from a search for additional neutrino events in IceCube
- GRB 251222A: NUTTelA-TAO Early Measurements
- GRB 251222A/EP251222b: Optical detection with Kinder observations
- 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
- Konus-Wind detection of GRB 251222A / EP251222b
- GRB 251222A / EP251222b: LCO detection of the optical counterpart
- 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
- EP251221a: Global MASTER-Net observations report
- GRB 251222A: PRIME near-infrared detection
- EP251221a: NOT optical upper limit
- GRB 251222A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
- GRB 251222A: NOT optical observations
- IceCube-251218A: No Candidate Transients from the Zwicky Transient Facility
- IPN triangulation of GRB 251220B (short)
- GRB 251222A: Swift ToO observations
- GRB 251222A: SVOM/VT optical candidate
- GRB 251222A: SVOM detection of a long burst
- 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/UVOT Upper Limits
- GRB 251221A: Fermi GBM Observation
- 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
- EP251220a: Global MASTER-Net observations report
- GRB 251219A: SVOM/GRM observation of a short burst
- Fermi-LAT Gamma-ray Observations of IceCube-251218A
- IceCube-251218A: Upper limits from a search for additional neutrino events in IceCube
- IceCube-251218A: COLIBRÍ optical upper limits
- GRB 251214B: VIRT Optical Upper Limit
- Fermi GRB 251217A: Global MASTER-Net observations report
- GRB 251215A: Swift/UVOT Upper LImits
- GRB 251215A: Fermi GBM Observation
- Fermi GRB 251216A: Global MASTER-Net observations report
- GRB 251202A/EP251202a: Koshka optical upper limit
- GRB 251214B: Mondy optical upper limit
- GRB 251215A: COLIBRÍ optical upper limit
- 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