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"20261 results found.
- GRB 251025A (sb25102501): stellar flare confirmed
- GRB 251025B: SVOM/VT optical observations with VHF data
- GRB 251025B: MASTER OT detection
- GRB 251025B: SVOM/C-GFT optical counterpart detection
- GRB 251025B: SVOM detection of a burst
- GRB 251025A (sb25102501): Likely a stellar flare by SVOM/VT
- GRB 251025A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
- GRB 251025A: SVOM/VT VHF optical upper limit
- GRB 251025A: SVOM detection of a faint burst
- GRB 251003A: VLA Detection
- GRB 251024A: Enhanced Swift-XRT position
- GRB 251024A: LCOGT Optical Afterglow Detection
- GRB 251022A: KAIT optical observations
- GRB 251024A: Swift detection of a burst
- GRB 251023B / EP251023b: COLIBRÍ Confirmation of the Fading Nature of the Optical Candidate
- GRB 251022A: COLIBRÍ Further Multi-frequency Optical Observations
- EP251023a: MAO/AZT-22 optical observations
- EP251023b/GRB 251023B: JinShan optical observation
- GRB 251022A: Swift-XRT detection of GOTO25iym
- EP251023b/GRB 251023B : Einstein Probe detection of a fast X-ray transient
- GRB 251022A: GROWTH-India Telescope optical observations
- GRB 251023C: Swift/BAT-GUANO localization skymap of a burst
- EP251023a: GROWTH-India Telescope optical observations
- GRB 251022A: Fermi GBM Observation
- GRB 251022A: Swift/BAT-GUANO localization skymap of a burst
- EP251023a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm telescope at Teide Observatory
- GRB 251023B / EP#01709247298: COLIBRÍ optical counterpart candidate
- IPN triangulation of GRB 251016B
- EP251023a: COLIBRÍ optical observations
- GRB 251013C: further SAO RAS optical observations
- GRB 251022A: COLIBRÍ optical observations
- GRB 251013C: ISON-Castelgrande observatory optical observations
- GRB 251022A: MASTER OT detection
- GRB 251022A: DDOTI Optical Detection
- EP251021b/GRB 251021A: SVOM/VT optical candidate
- EP251023a: NOT optical counterpart detection
- EP251023a: Einstein Probe detection of an X-ray transient
- EP/WXT 01709247295: GOTO optical afterglow candidate.
- GRB 251022A: GOTO optical counterpart detection
- EP251021b: Einstein Probe detection of a fast X-ray transient
- GRB 251016A: SVOM/ECLAIRs refined analysis
- LIGO/Virgo/KAGRA S251021u: Identification of a GW compact binary merger candidate
- Fermi-LAT gamma-ray observations of IceCube-251018A
- GRB 251017A : RAPAS follow-up observations
- GRB 251017A: COLIBRÍ optical observations of a late plateau
- IceCube-251018A: DDOTI Optical Upper Limit
- GRB 251018A: BOOTES-5 and BOOTES-7 early optical detections
- GRB 251018A: Enhanced Swift-XRT position
- LIGO/Virgo/KAGRA S251018bi: Identification of a GW compact binary merger candidate
- GRB 251016A: Swift-XRT afterglow detection
- GRB 251017A: Swift/UVOT Detection
- GRB 251016A: Swift/UVOT Detection
- GRB 251018A: Swift/UVOT Detection
- GRB 251016A: VLT/FORS2 Optical Observation
- GRB 251017A: COLIBRÍ photometric redshift
- GRB 251018A: MASTER OT detection
- GRB 251018A: TRT optical afterglow detection
- GRB 251018A: Swift detection of a burst with an optical counterpart
- GRB 251017A: J-band detection with WINTER
- GRB 251013C: Liverpool Telescope observations
- GRB 251013C: Leavitt Observatory optical photometry
- GRB 251017A: JinShan observations of the optical afterglow
- GRB 251017A : MITSuME Akeno optical afterglow candidate detection
- GRB 251017A: Enhanced Swift-XRT position
- GRB 251017A: COLIBRÍ Early Afterglow Detection
- GRB 251017A: BOOTES-5/JGT early optical afterglow detection
- GRB 251017A: Swift detection of a burst with an optical counterpart
- GRB 251013C: JinShan observations of the non-thermal rebrightening of the optical counterpart
- GRB 251013C: SVOM/COLIBRÍ (FM-GFT) observations of a strong and late rebrightening of the optical counterpart
- sb25101602: Swift-XRT counterpart detection
- GRB 251016A: SVOM detection of a short burst
- GRB 251014A: Swift-XRT observations
- GRB 251014B: PRIME J-band upper limit
- GRB 251013C: Kilonova-Catcher optical afterglow detection
- GRB 251013D: Swift/UVOT Observations
- GRB 251013C: Swift/UVOT Detection
- Konus-Wind detection of GRB 251007A
- GRB 251013C: detection of a radio counterpart at 15.5GHz
- Swift Trigger 1404295: possible GRB 251015A
- GRB 251014B: Swift/UVOT Upper Limits
- GRB 251014B: VLT/FORS2 Optical Observation
- GRB 251014D: Swift/UVOT Upper Limits
- GRB 251014D: Swift-XRT afterglow detection
- GRB 251013C: MAO/AZT-22 optical observations
- GRB 251011B: SVOM/VT optical upper limit
- GRB 251013C: SVOM/COLIBRÍ (FM-GFT) further multi-band optical observations
- GRB 251013C: Calapai Observatory, Massa S. Giorgio (Messina), optical observation
- GRB 251014D: Swift detection of a burst
- GRB 251014A: PRIME near-infrared upper limits
- GRB 251014A: VLT/FORS2 Optical Observation
- GRB 251013C: MarSEC, optical afterglow photometry
- GRB 251013C: OHP/T193 optical afterglow photometry and spectroscopy
- GRB 251013D: LAST optical upper limit on Swift/BAT-GUANO localization
- GRB 251013C: Bassano Bresciano Observatory optical observations
- GRB 251013C: Early and late-time optical counterpart detection by LCO
- GRB 251013C: Fermi GBM Observation
- GRB 251014A: DDOTI Upper Limit
- GRB 251013C NUTTelA-TAO / BSTI Early Measurements
- LIGO/Virgo/KAGRA S251014cn: Identification of a GW compact binary merger candidate
- GRB 251013C: ULL-ASTRO-MASTER detection of the optical afterglow with the LCO 40-cm telescope at Sutherland Observatory