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"7447 results found.
- LIGO/Virgo S190426c: SAO optical observation
- LIGO/Virgo S190425z: Pierre Auger Observatory follow-up
- LIGO/Virgo S190426c: Identification of a GW compact binary merger candidate
- LIGO/Virgo S190426c: HAWC follow-up
- LIGO/Virgo S190425z: Nearby Galaxies in the Updated Localization Volume
- LIGO/Virgo S190425z: GROND observations of AT2019ebq/PS19qp
- LIGO/Virgo S190425z: Updated localization from LIGO and Virgo data
- LIGO/Virgo S190425z: AMI-LA radio observations of two ZTF afterglow candidates.
- LIGO/Virgo S190425z: GOTO observations
- LIGO/Virgo S190425z: ZTF pre-merger limits on PS1 candidates
- LIGO/Virgo GW190425z: GTC spectroscopic classification of AT2019ebq/PS19qp
- LIGO/Virgo S190425z: CALET Observations
- LIGO/Virgo S190425z: KMTNet Observation
- LIGO/Virgo S190425z - ePESSTO+ NTT spectrum of candidate PS19qo
- LIGO/Virgo S190425z - ePESSTO+ NTT observations
- LIGO/Virgo S190425z: ZTF19aarykkb Imaging from Las Cumbres Observatory
- LIGO/Virgo S190425z: Liverpool Telescope spectroscopy of ZTF19aarykkb
- LIGO/Virgo S190425z - GROWTH-India follow-up of two ZTF candidates
- LIGO/Virgo S190425z - HCT spectroscopy
- LIGO/Virgo S190425z: STARE2 simultaneous L-band radio observations
- LIGO/Virgo S190425z: OVRO-LWA simultaneous low frequency radio observations of localization region
- LIGO/Virgo S190425z: CLU/NED Galaxies in the Localization Volume
- LIGO/Virgo S190425z: ZTF19aarzaod Imaging from Las Cumbres Observatory
- LIGO/Virgo S190425z: Candidates from the Zwicky Transient Facility
- LIGO/Virgo S190425z: Fermi GBM Observations
- LIGO/Virgo S190425z: SQUEAN Observation
- LIGO/Virgo S190421ar: Fermi-LAT search for a high-energy gamma-ray counterpart
- LIGO/VirgoS190425z: HAWC follow-up
- LIGO/Virgo S190425z: INTEGRAL prompt observation
- LIGO/Virgo S190425z: Identification of a GW compact binary merger candidate
- LIGO/Virgo S190421ar/G330308: ANTARES neutrino search
- LIGO/Virgo S190408an: Liverpool Telescope follow-up imaging observations
- GRB 190422A: Swift detection of a burst
- LIGO/Virgo S190421ar: Fermi-GBM Observations
- LIGO/Virgo S190421ar: HAWC follow-up
- LIGO/Virgo S190421ar: Identification of a GW compact binary merger candidate
- LIGO/Virgo S190408an: INTEGRAL follow-up observations
- LIGO/Virgo S190408an: Gaia Photometric Alerts transient candidate
- LIGO/Virgo S190412m: Palomar Gattini-IR Wide-field Infrared Follow-up
- LIGO/Virgo S190412m: GOTO optical coverage - no notable counterparts
- LIGO/Virgo S190412m: Fermi-LAT search for a high-energy gamma-ray counterpart
- LIGO/Virgo S190412m: Fermi-GBM Observations
- LIGO/Virgo S190405ar: Retraction of a GW binary merger candidate
- LIGO/Virgo S190408an: ATLAS observations of the S190412m skymap
- LIGO/Virgo S190408an: Gaia Photometric Alerts transient candidate
- LIGO/Virgo S190412m/G329483: ANTARES neutrino search
- LIGO/Virgo S190412m: HAWC follow-up
- LIGO/Virgo S190412m: Identification of a GW binary merger candidate
- LIGO/Virgo S190408an: GROND Observations of MASTER OT J154209.55-431742.2
- IceCube-190331A: Swift-XRT Follow-up Observations
- LIGO/Virgo S190408an: DDOTI/OAN Optical Observations
- LIGO/Virgo ST190408an: Fermi-LAT search for a high-energy gamma-ray counterpart
- GRB 190409A: Swift detection of a possible burst
- LIGO/Virgo S190408an: MASTER OT is 27 day old ATLAS SN candidate and unrelated
- LIGO/Virgo S190408an: Identification of a GW binary merger candidate
- Search for neutrino counterparts to GW candidate S190408an with IceCube
- LIGO-Virgo S190408an: HAWC follow-up
- GRB 190404C: Swift-XRT observations
- GRB 190404B: Tiled Swift observations
- LIGO/Virgo: Announcing the start of Observing Run 3 (O3) and the beginning of the public gravitational-wave alert era
- GRB 190331B: Swift ToO observations
- IceCube-190331A - IceCube observation of a high-energy neutrino candidate event
- MAGIC follow-up of the X-ray flares of LS I +61�303 dete
- Swift Trigger 895503 is not a GRB
- Swift Trigger 895257: Detection of GRO J2058+42 in outburst
- Further Chandra observations of GW170817 ~581-583 days since merger
- GRB 190324A: Swift/UVOT afterglow candidate
- Correction: Chandra observations of GW170817 ~581 days since merger
- Chandra observations of GW170817 ~581 days since merger
- Swift Trigger 894268: Detection of GRO J2058+42 in outburst
- GRB 190311A: Mondy optical observations
- GRB 190311A: Swift detection of a burst with optical counterpart
- GRB 190306A: Tiled Swift observations
- GRB 190305A: Tiled Swift observations
- INTEGRAL observation of IceCube-190221A
- IceCube-190221A: Swift-XRT Follow-up Observations
- GRB 190219A: CrAO and AbAO optical upper limit
- GRB 190220B: Kitab Observatory optical upper limit
- IceCube-190221A - IceCube observation of a high-energy neutrino candidate event
- GRB 190220B: BOOTES-4 optical observation
- GRB 190219A: NOT optical afterglow candidate
- GRB 190220A: Swift detection of a burst with an optical counterpart
- GRB 190219A: Swift detection of a burst
- GRB 190203A: COATLI Optical Observations
- GRB 190204A: COATLI Optical Detection of the Fading Afterglow
- GRB 190202A: R and I band observation from HCT
- GRB 190204A: Swift detection of a burst with a possible optical counterpart
- Swift Trigger 887541: Swift detection of Swift J1728.9-3613
- GRB 190203A: Koshka Zeiss-1000 optical upper limit
- GRB 190203A: Swift detection of a burst with an optical counterpart
- GRB 190202A: Swift detection of a burst with an optical counterpart
- Improved IPN error box for GRB 190129B
- GRB 190129B: DDOTI Detection of the Possible Afterglow and Suggestion of Fading
- GRB 190129B: Swift/UVOT Upper Limits
- GRB 190129B: ePESSTO NTT optical observations
- GRB 190129B: GROND possible host candidate
- GRB 190129B: Swift-XRT candidate afterglow detection
- GRB 190129B: Tiled Swift observations
- INTEGRAL observation of IceCube-190124A
- Trigger 886266: Another Swift trigger on MAXI J1348-630