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"23610 results found.
- GRB 250920C: GOTO optical counterpart candidate
- Konus-Wind detection of GRB 250919A
- GRB 250920C: Swift detection of a burst
- LIGO/Virgo/KAGRA S250920bq: Coverage and upper limits from MAXI/GSC observations
- GRB 250919A / EP250919a: Insight-HXMT detection
- GRB 250920A: AstroSat CZTI detection
- GRB 250920B: Swift detection of a burst with a bright optical counterpart.
- GRB 250919A: Glowbug gamma-ray detection
- GRB 250919A: Fermi GBM Observation
- GRB 250919A: Swift-XRT afterglow detection
- GRB 250916A: KAIT optical observations
- GRB 250916A: further SAO RAS optical observations
- GRB 250917B: Swift-BAT refined analysis
- LIGO/Virgo/KAGRA S250918aw: 1 counterpart neutrino candidate event from an IceCube neutrino search
- GRB 250917B: Swift/UVOT Upper Limits
- GRB 250916A: OSIRIS+/GTC redshift z = 2.015
- GRB 250916A: Swift-XRT observations
- GRB 250916A: MAO/AZT-22 optical observations
- GRB 250916A: SAO RAS optical observations
- LIGO/Virgo/KAGRA S250917aq: Three counterpart neutrino candidates from IceCube neutrino searches
- GRB 250916A: Glowbug gamma-ray detection
- GRB250917B: WFST optical observations
- GRB 250917B: Swift-XRT observations
- GRB 250916A: GOTO optical counterpart candidate
- GRB 250916A: AstroSat CZTI detection of a bright long burst
- EP250916a: Einstein Probe detection of an X-ray transient
- EP250827b: VLA Observations
- GRB 250912A: SVOM/COLIBRÍ (FM-GFT) optical observations
- GRB 250912A: Swift-XRT observations
- GRB250912A: VLT/HAWK-I follow-up observations
- GRB 250912A: VLT observations
- LIGO/Virgo/KAGRA S250912s: 2 counterpart neutrino candidate events from an IceCube neutrino search
- EP250908c: tentative VLT/FORS2 redshift z = 2.87
- EP250911a: Upper limit from Fermi-GBM Observations
- GRB 250911A: Swift-BAT refined analysis
- EP250911a: SAO RAS optical observations
- EP250911a: Swift-XRT observations
- EP250911a: Optical detection with Kinder observations
- GRB 250911A: Swift/UVOT Detection
- GRB 250910A / EP250910a: Swift-XRT afterglow detection
- GRB 250909B: Insight-HXMT detection
- GRB 250909B: SVOM/GRM observation
- GRB 250910A / EP250910a : VLT/HAWK-I NIR counterpart discovery
- EP250911a: COLIBRÍ optical observations
- EP250911a: LCO optical counterpart discovery
- GRB 250404A / EP250404a: spectroscopic redshift at z = 1.88 (correction to GCN 40084)
- LIGO/Virgo/KAGRA S250911ac: Identification of a GW compact binary merger candidate
- 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 250910A / EP250910a: VLT/HAWK-I near-infrared observations
- GRB 250909B: AstroSat CZTI detection of a long burst
- GRB 250909A: AstroSat CZTI detection
- GRB 250910A: SVOM/MXT possible afterglow detection
- GRB 250702B: Late time Chandra observations
- EP250908b/EP#01709240653: Swift/UVOT Detection
- EP#01709240653: Swift-XRT observations
- The EP-WXT trigger 01709240674 is triggered by the known source SS Cyg
- EP250908c: refined analysis of the EP-WXT and EP-FXT observations
- GRB 250907A: CALET Gamma-Ray Burst Monitor detection
- EP250908c: VLT/FORS2 optical counterpart identification
- EP250908c: Einstein Probe detection of an X-ray transient
- EP250908b: EP-WXT detection of a fast X-ray transient and EP-FXT observation
- GRB 250905A: Swift-BAT refined analysis
- GRB 250903A: Swift-XRT afterglow detection
- LIGO/Virgo/KAGRA S250906ca: Identification of a GW compact binary merger candidate
- SVOM/sb25090605: detection of an X-ray transient from the LMXB 4U 0513-40
- GRB 250905A: Swift-XRT refined Analysis
- GRB 250904A: Swift-BAT refined analysis
- GRB 250905A: KAIT optical upper limit
- GRB 250905A: Swift detection of a burst
- Swift GRB250905.09: Global MASTER-Net observations report
- GRB 250904A: TRT optical counterpart detection
- EP250827a and EP250827b: Upper limit from Fermi-GBM Observations
- GRB 250902B: CALET Gamma-Ray Burst Monitor detection
- GRB 250904A: Swift detection of a burst
- GRB 250902A: CALET Gamma-Ray Burst Monitor detection
- GRB 250902A: VZLUSAT-2 detection
- LIGO/Virgo/KAGRA S250904cv: Identification of a GW compact binary merger candidate
- GRB 250903A: Swift-XRT observations
- EP250903a: Swift-XRT observations
- EP#01709201209: Swift-XRT observations
- GRB 250830C: VZLUSAT-2 detection
- EP250903a: refined analysis of the EP-WXT and EP-FXT observations
- LIGO/Virgo/KAGRA S250904br: Identification of a GW compact binary merger candidate
- The EP-WXT trigger 01709201209 is likely a flaring star
- LIGO/Virgo/KAGRA S250904ae: Identification of a GW compact binary merger candidate
- GRB 250903A: EP-FXT counterpart detection
- GRB 250903A: LCO optical afterglow detection
- EP250901a: Mondy, Assy and SAO RAS optical limits
- Subject GRB 250903A: SVOM/MXT afterglow detection
- EP250903a: LCO candidate counterpart discovery
- GRB 250903A: TRT optical counterpart detection
- GRB 250902B: AstroSat CZTI detection
- EP250903a: TRT optical observations
- EP 250827B: Detection of supernova counterpart by LCO.
- EP/WXT01709201159: GOTO optical follow-up
- EP250827b / AT 2025wkm: TRT optical observations
- EP250827b: NOT spectroscopic observations and AT 2025wkm classification as a broad-lined type-Ic supernova