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"28047 results found.
- GRB231017A: GROWTH-India upper limits on the optical afterglow
- GRB 231015A: AstroSat CZTI detection
- GRB 231018A: Fermi GBM Detection
- GRB 231017A: Swift-XRT observations
- GRB 231018A: BALROG localization (Fermi Trigger / GRB 231018521)
- GRB 231017A: Swift/BAT-GUANO candidate arcminute localization of a burst
- Fermi-LAT gamma-ray observations of IceCube-231014A
- GRB231017A: Fermi GBM Final Localization
- IceCube-231014A: Upper limits from a search for additional neutrino events in IceCube
- LIGO/Virgo/KAGRA S231014r: Upper limits from Swift/BAT-GUANO
- (correction) Discovery of an optical transient with strong flaring activity: a new blazar candidate in the Messier 31 field
- Discovery of an optical transient with strong flaring activity: a new blazar candidate in the Messier 31 field.
- LIGO/Virgo/KAGRA S231014r: Identification of a GW compact binary merger candidate
- GRB 231004A: Glowbug gamma-ray detection
- LIGO/Virgo/KAGRA S231001aq: Updated Sky localization
- LIGO/Virgo/KAGRA S231005j: Upper limits from Swift/BAT-GUANO
- LIGO/Virgo/KAGRA S231008ap: Updated Sky localization
- LIGO/Virgo/KAGRA S231008ap: Identification of a GW compact binary merger candidate
- IceCube-231004A: Upper limits from a search for additional neutrino events in IceCube
- IceCube-231004A: No significant detection in HAWC
- Fermi-LAT gamma-ray observations of IceCube-231004A
- LIGO/Virgo/KAGRA S231005ah: Updated Sky localization
- LIGO/Virgo/KAGRA S231005ah: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S231005j: Updated Sky localization
- LIGO/Virgo/KAGRA S231005j: Identification of a GW compact binary merger candidate
- transient AT2023sva: radio observations with AMI-LA
- LIGO/Virgo/KAGRA S231001aq: Upper limits from Swift/BAT-GUANO
- LIGO/Virgo/KAGRA S230930al: Upper limits from Swift/BAT-GUANO
- LIGO/Virgo/KAGRA S230928cb: Upper limits from Swift/BAT-GUANO
- GRB 230827B: 10.4m GTC spectroscopic redshift
- LIGO/Virgo/KAGRA S231001aq: Updated Sky localization
- LIGO/Virgo/KAGRA S230930al: Updated Sky localization
- LIGO/Virgo/KAGRA S230928cb: Updated Sky localization
- LIGO/Virgo/KAGRA S231001aq: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S230930al: Identification of a GW compact binary merger candidate
- NuEm-230927A: Swift-XRT follow-up
- LIGO/Virgo/KAGRA S230928cb: Identification of a GW compact binary merger candidate
- AT2023sva / GRB230916B: GIT observations of the afterglow
- transient AT2023sva: A Binary Driven Hypernova with a possible associated supernova
- LIGO/Virgo/KAGRA S230927be: Updated Sky localization
- LIGO/Virgo/KAGRA S230927l: Updated Sky localization
- LIGO/Virgo/KAGRA S230927be: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S230927l: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S230922q: Updated Sky localization
- LIGO/Virgo/KAGRA S230924an: Upper limits from Swift/BAT-GUANO
- LIGO/Virgo/KAGRA S230920al: Upper limits from Swift/BAT-GUANO
- LIGO/Virgo/KAGRA S230919bj: Upper limits from Swift/BAT-GUANO
- LIGO/Virgo/KAGRA S230922g: DECam GW-MMADS candidates
- GRB 230812B: r'-band observations from MISTRAL at Observatoire de Haute-Provence
- LIGO/Virgo/KAGRA S230924an: Updated Sky localization
- LIGO/Virgo/KAGRA S230924an: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S230917af: GRAWITA wide-field observations
- LIGO/Virgo/KAGRA S230922g: Updated Sky localization
- LIGO/Virgo/KAGRA S230922g: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S230922q: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S230917af: Zwicky Transient Facility observations
- IPN triangulation of GRB 230919A (short)
- LIGO/Virgo/KAGRA S230904n: Classification of the candidate AT2023rkw with DBSP
- Fermi GBM Statement for Trigger 716527670/230916144
- GRB 230919A: Swift/BAT-GUANO detection of a possibly short burst outside the coded FOV
- LIGO/Virgo/KAGRA S230920al: Updated Sky localization
- LIGO/Virgo/KAGRA S230919bj: Updated Sky localization
- transient AT2023sva: imaging and spectroscopic observations from MISTRAL at Observatoire de Haute-Provence
- GRB 230812B : optical observations from MISTRAL at Observatoire de Haute-Provence
- GRB 230919A: AstroSat CZTI detection
- LIGO/Virgo/KAGRA S230920al: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S230919bj: Identification of a GW compact binary merger candidate
- GRB 230918B: GOTO detection of a fast-rising transient in the GBM localisation region
- LIGO/Virgo S230917af: Swift XRT observations, 6 X-ray sources
- GRB 230918A (short): Glowbug gamma-ray detection
- GRB 230916B: Glowbug gamma-ray detection
- GRB 230915A: Fermi GBM observation
- GRB 230812B: Radio observations with the uGMRT
- LIGO/Virgo/KAGRA S230917af: MAXI/GSC observations
- GRB 230915B: Glowbug gamma-ray detection
- GRB 230916A: NuSTAR Discovery of Prompt Emission from a Potential GRB
- GRB 230911A: Fermi GBM Observation
- LIGO/Virgo/KAGRA S230904n: Correction of the coordinates of the ZTF candidate counterpart
- Fermi-LAT gamma-ray observations of IceCube-230914A
- GRB 230915A: Swift/BAT-GUANO detection of a burst
- LIGO/Virgo/KAGRA S230914ak: Upper limits from Swift/BAT-GUANO
- Swift Triggers 1192234, 1192235 and 1192236 are not astrophysical events
- IceCube-230914A: Upper limits from a search for additional neutrino events in IceCube
- GRB 230911A: Swift-XRT afterglow detection
- Swift Trigger 1192088 is not an astrophysical event
- GRB 230913A: Glowbug gamma-ray detection
- LIGO/Virgo/KAGRA S230914ak: Updated Sky localization
- LIGO/Virgo/KAGRA S230914ak: Identification of a GW compact binary merger candidate
- GRB 230913A: Fermi GBM Observation
- LIGO/Virgo/KAGRA S230904n: One ZTF candidate counterpart to coincident neutrino event
- Swift Trigger 1191903 is not an astrophysical event
- GRB 230913A: Swift/BAT-GUANO arcminute localization of a burst
- GRB 230911A: GOTO optical counterpart candidate
- GRB 230911D: NuSTAR Detection of Prompt Emission
- GRB 230911C: Swift-XRT refined Analysis
- GRB 230911C: Swift-BAT refined analysis
- LIGO/Virgo/KAGRA S230911ae: Updated Sky localization
- GRB 230911D: Fermi GBM observation
- IPN triangulation of GRB 230911D (long)
- GRB230911C: LCOGT Optical Upper Limits