GCN Circulars
GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"27814 results found.
- GRB 250910A / EP250910a: SVOM/VT afterglow confirmation
- GRB 250909B: Insight-HXMT detection
- GRB 250910A / EP250910a : VLT/HAWK-I NIR counterpart discovery
- EP250911a: LCO optical counterpart discovery
- EP250911a: Einstein Probe detection of an X-ray transient
- GRB 250911A: Enhanced Swift-XRT position
- GRB 250911A: Swift-XRT observations
- GRB 250911A: COLIBRÍ optical counterpart candidate
- GRB 250911A: Swift detection of a burst
- GRB 250910B: Fermi GBM Final Real-time Localization
- EP250910a/GRB 250910A: EP-WXT detection of a fast X-ray transient
- GRB 250909B: AstroSat CZTI detection of a long burst
- GRB 250909A: AstroSat CZTI detection
- GRB 250910A: SVOM/MXT possible afterglow detection
- GRB 250910A: SVOM detection of a faint burst
- LIGO/Virgo/KAGRA S250910b: Retraction of GW compact binary merger candidate
- GRB 250702B: Late time Chandra observations
- EP250908b/EP#01709240653: Swift/UVOT Detection
- EP#01709240653: Swift-XRT observations
- GRB 250907A: CALET Gamma-Ray Burst Monitor detection
- EP250908c: Einstein Probe detection of an X-ray transient
- GRB 250909A: Fermi GBM Final Real-time Localization
- EP250908b: EP-WXT detection of a fast X-ray transient and EP-FXT observation
- GRB 250907A: GECAM-B detection
- GRB 250905A: Swift-BAT refined analysis
- GRB 250903A: Swift-XRT afterglow detection
- SVOM/sb25090605: detection of an X-ray transient from the LMXB 4U 0513-40
- EP250905b: EP-FXT follow-up observation
- EP250905a: Liverpool Telescope observations
- EP250905b: EP-WXT detection of a fast X-ray transient
- GRB 250905A: Swift-XRT refined Analysis
- EP250905a: JinShan likely optical counterpart detection
- IceCube-250905A - IceCube observation of a high-energy neutrino candidate track-like event
- GRB 250904A: Swift-BAT refined analysis
- GRB 250905A: Swift/UVOT Upper Limits
- EP250905a: Einstein Probe detection of an X-ray transient
- GRB 250905B: Fermi GBM Final Localization
- GRB 250905A: Enhanced Swift-XRT position
- GRB 250904A: Swift/UVOT Detection
- GRB 250903A: Swift/UVOT detection
- GRB 250904A: Swift-XRT refined Analysis
- EP detected a brightening of LMXB 1ES 1735-26.9
- GRB 250905A: KAIT optical upper limit
- GRB 250905A: Swift detection of a burst
- Swift GRB250905.09: Global MASTER-Net observations report
- Swift GRB 250904A: Global MASTER-Net observations report
- GRB 250904A: Enhanced Swift-XRT position
- GRB 250904A: TRT optical counterpart detection
- GRB 250902B: CALET Gamma-Ray Burst Monitor detection
- GRB 250904A: Prompt enhanced Swift-XRT position
- GRB 250904A: Swift detection of a burst
- GRB 250902A: CALET Gamma-Ray Burst Monitor detection
- GRB 250902A: VZLUSAT-2 detection
- GRB 250903A: Swift-XRT observations
- EP250903a: Swift-XRT observations
- EP#01709201209: Swift-XRT observations
- EP250903a: retraction of the LCO candidate, and discovery of the likely counterpart
- EP-WXT trigger 01709201209: Liverpool Telescope upper limits
- GRB 250830C: VZLUSAT-2 detection
- GRB 250903A: VLT X-shooter spectroscopic redshift z = 1.590
- GRB 250903A: EP-FXT counterpart detection
- GRB 250902A: GECAM-B detection
- GRB 250903A: LCO optical afterglow detection
- EP250901a: Mondy, Assy and SAO RAS optical limits
- Subject GRB 250903A: SVOM/MXT afterglow detection
- GRB 250903A: TRT optical counterpart detection
- GRB 250902B: AstroSat CZTI detection
- GRB 250903A: SVOM detection of a burst
- EP250903a: Einstein Probe detection of an X-ray transient
- EP 250827B: Detection of supernova counterpart by LCO.
- EP250827b: continued Liverpool Telescope observations
- EP250827b: SVOM/VT observation of AT 2025wkm
- GRB 250902A: Fermi GBM Detection
- GRB 250901A: Swift/UVOT Upper Limit
- GRB 250902B: Fermi GBM Final Real-time Localization
- GRB 250830B: Swift-XRT afterglow detection
- EP250827b: Liverpool Telescope observations
- EP250828a: Early near-infrared follow-up with MIRAGE on the MDM 1.3m telescope
- EP250901a: refined analysis of the EP-WXT and EP-FXT observations
- GRB 250901A: EP-FXT follow-up observation
- GRB 250902A: Fermi GBM Final Real-time Localization
- GRB 250901A: SVOM/VT optical afterglow with VHF data
- GRB 250901A: Swift-XRT afterglow detection
- EP250901a: Swift-XRT observations
- GRB 250901A: LCO optical upper limit
- EP250827b: Swift observations of AT 2025wkm
- EP250831a: NOT optical observations and tentative afterglow candidate
- EP250827b: Contemporaneous detection of EP X-ray flare EP250827b and ZTF transient ZTF25abmpngy/AT2025wkm
- GRB 250901A: SVOM detection of a burst
- GRB 250830C: Insight-HXMT detection
- GRB 250830C: GECAM-B detection
- GRB 250830C: AstroSat CZTI detection of a long burst
- EP250901a: Einstein Probe detection of an X-ray transient
- EP250831a: EP-FXT follow-up observation
- EP250831a: Swift-XRT observations
- IceCube-250831A - IceCube observation of a high-energy neutrino candidate track-like event
- EP250831a: EP-WXT detection of a fast X-ray transient
- GRB 250831A: Swift-XRT counterpart detection
- GRB 250831A: SVOM detection of a soft burst
- GRB 250830B: Swift-XRT observations