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"
24598 results found.
- GRB 231030B: Fermi GBM Detection
- IPN triangulation of GRB 231020A
- GRB 231030B: BALROG localization (Fermi Trigger 720388704 / GRB 231030832)
- GRB 231028A: Swift-BAT refined analysis
- IceCube-231027A: Upper limits from a search for additional neutrino events in IceCube
- LIGO/Virgo/KAGRA S231029y: Upper limits from Swift/BAT-GUANO
- GRB 231024A: AKO Optical Counterpart Candidate
- LIGO/Virgo/KAGRA S231029y: One counterpart neutrino candidate from IceCube neutrino searches
- LIGO/Virgo/KAGRA S231029ai: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S231029y: Identification of a GW compact binary merger candidate
- GRB 231028A: AstroSat CZTI detection
- GRB 231028A: Glowbug gamma-ray detection
- GRB 231028A: Fermi GBM Detection
- LIGO/Virgo/KAGRA S231028bg: Updated Sky localization
- LIGO/Virgo/KAGRA S231028bg: Identification of a GW compact binary merger candidate
- GRB 231028A: Swift detection of a burst
- GRB 231019A: Glowbug gamma-ray detection
- GRB 231025A: Fermi GBM Observation
- GRB 231024A: Fermi GBM Observation
- GRB 231025A: Swift/BAT-GUANO detection of a likely short burst
- GRB 231020B: AstroSat CZTI detection
- GRB 231024A: GOTO optical counterpart candidate
- LIGO/Virgo/KAGRA S231025a: two counterpart neutrino candidates from IceCube neutrino searches
- The photometry of the transient in Messier 31 field: GMG observation
- GRB 231018A: Swift/BAT-GUANO detection of a long burst outside the coded FOV
- LIGO/Virgo/KAGRA S231020bw: Upper limits from Swift/BAT-GUANO
- LIGO/Virgo/KAGRA S231021az: Coverage and upper limits from MAXI/GSC observations
- LIGO/Virgo/KAGRA S231020bw: Updated Sky localization
- GRB 231020A: Fermi GBM Detection
- GRB 231017A: Mondy optical observations. A possible candidate for an afterglow or host galaxy.
- GRB 231019A: VZLUSAT-2 detection
- GRB 231018A: VZLUSAT-2 detection
- GRB 231020B: BALROG localization (Fermi Trigger 719530557 / GRB 231020900)
- LIGO/Virgo/KAGRA S231020ba: Updated Sky localization and EM Bright Classification
- GRB 231020A: BALROG localization (Fermi Trigger / GRB 231020790)
- LIGO/Virgo/KAGRA S231020ba: Upper limits from Fermi-GBM Observations
- GRB 231015A: NuSTAR Detection of Prompt Emission
- LIGO/Virgo/KAGRA S231020bw: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S231020ba: Coverage and upper limits from MAXI/GSC observations
- GRB 231017A: 1.3m DFOT Optical upper limit
- LIGO/Virgo/KAGRA S231020ba: Identification of a GW compact binary merger candidate
- IceCube-231004A: Upper limits from Fermi-GBM Observations
- GRB 231018A: Glowbug gamma-ray detection
- IPN triangulation of GRB 231018A
- GRB 231017A: Swift/UVOT Upper Limit
- GRB 230911C: ATCA detection of possible radio counterpart
- GRB 231017A: JinShan optical upper limit
- GRB 231018A: GROWTH-India Follow-Up of a Fermi Long GRB
- LIGO/Virgo/KAGRA S231018cb: One counterpart neutrino candidate event from an IceCube neutrino search
- IC231004A: Classification of AT2023uqf/ZTF23abidzvf as a rapidly-evolving supernova with CSM interaction
- GRB 231017A: Las Cumbres optical upper limit
- GRB 231015A: Glowbug gamma-ray detection
- GRB 231017A: LCOGT Optical Upper Limits
- 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
- Title: LIGO/Virgo/KAGRA S230919bj: Upper limits from Swift/BAT-GUANO