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"7444 results found.
- LIGO/Virgo/KAGRA S240421ar: Updated Sky localization
- LIGO/Virgo/KAGRA S240422ed: no candidate counterparts from Pan-STARRS observations of the skymap
- LIGO/Virgo/KAGRA S240422ed: GOTO counterpart search
- LIGO/Virgo/KAGRA S240423br: Retraction of GW compact binary merger candidate
- LIGO/Virgo/KAGRA S240422ed: no candidate counterparts from ATLAS observations
- LIGO/Virgo S240422ed: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
- LIGO/Virgo/KAGRA S240422ed: GW-MMADS DECam observations
- LIGO/Virgo/KAGRA S240422ed: Magellan Observations
- LIGO/Virgo/KAGRA S240422ed: Updated NED Galaxies in the Localization Volume
- LIGO/Virgo/KAGRA S240422ed: AstroSat CZTI non-detection and upper limits
- LIGO/Virgo/KAGRA S240422ed: Upper limits from Fermi-GBM Observations
- LIGO/Virgo/KAGRA S240422ed: Updated Sky localization and EM Bright Classification
- LIGO/Virgo/KAGRA S240421ar: Upper limits from Swift/BAT-GUANO
- LIGO/Virgo/KAGRA S240422ed: Coverage and upper limits from MAXI/GSC observations
- LIGO/Virgo/KAGRA S240422ed: Identification of a GW compact binary merger candidate
- LIGO/Virgo/Kagra S240422ed: NED Galaxies in the Localization Volume
- GRB 240414A: AMI-LA radio observations
- EP240420a: Xinglong decaying optical counterpart
- GRB 240421B: Swift detection of a burst
- EP240420a: Nanshan optical counterpart observations
- EP240420a: GWAC-F50A optical upper limit
- LIGO/Virgo/KAGRA S240421ar: Identification of a GW unmodeled transient candidate
- EP240420a: NOT optical counterpart candidate and potential host
- GRB240418A - Candidate afterglow from NIRES
- IceCube-240419A - IceCube observation of a high-energy neutrino candidate track-like event
- IceCube-240419A - IceCube observation of a high-energy neutrino candidate track-like event
- LIGO/Virgo/KAGRA S240420aw: Retraction of GW compact binary merger candidate
- GRB 240419B: Swift detection of a burst
- GRB 240419A: Swift detection of a burst
- GRB 240418A: AKO Upper Limit
- GRB 240411A: GOTO early optical upper limits
- GRB 240418A: Swift detection of a burst
- LIGO/Virgo/KAGRA S240413p: X-ray upper limits from EP-WXT for the candidate AGN counterpart
- EP240414a: GSP detects optical candidate counterpart AT2024gsa
- LIGO/Virgo/KAGRA S240413p: DECam GW-MMADS candidates
- EP240414a: Pan-STARRS detects re-brightening of the candidate counterpart AT2024gsa
- LIGO/Virgo/KAGRA S240413p: historical ATLAS and ZTF observations of the candidate AGN counterpart
- LIGO/Virgo/KAGRA S240413p: STEP - T80S Search and Candidate Counterpart Identification
- EP 240416a: Xinglong and NOT decaying optical counterpart
- EP240416a: Kinder optical counterpart candidate
- GRB 240414A: GAD Observatory, La Spezia, Italy ,upper limit
- GRB 240415A: Earliest optical followup with the Kinder observations
- GRB 240415B: Swift ToO observations
- GRB 240415A: OHP/T193 optical observations
- X-ray transient EP 240414a - GTC spectroscopic observations
- EP 240414a: NOT optical counterpart confirmation
- GRB 240414A : OHP/T193 second epoch of optical follow-up and afterglow detection
- GRB 240414A: MarSEC Observatory, Vicenza, Italy, UPPER LIMIT
- EP240413A: GOTO optical upper limits
- EP240414a: Kinder optical counterpart candidate possibly associated with the galaxy SDSS J124601.99-094309.3
- LIGO/Virgo/KAGRA S240413p: Updated Sky localization
- LIGO/Virgo/KAGRA S240413p: Zwicky Transient Facility observations
- GRB 240411B: Kinder observations with Lulin observatory
- LIGO/Virgo/Kagra S240413p: NED Galaxies in the Localization Volume
- LIGO/Virgo/KAGRA S240413p: Identification of a GW compact binary merger candidate
- IceCube-240412A - IceCube observation of a high-energy neutrino candidate track-like event
- GRB 240411B: OHP/T193 optical observations
- GRB 240411B: Swift detection of a burst
- EP240408a: GROND detection of a candidate counterpart
- Swift Trigger 1220736: detection of 4U 1543-62.
- IceCube-240327B: GRANDMA/Kilonova-Catcher observations of 4FGL J0555.9+0030 and optical upper limits
- LXT 240402A/GRB 240402B: GECAM-C refined analysis
- GRB/FXT 240402B: Kinder optical counterpart candidate
- IceCube-240327B: GRANDMA observations of 4FGL J0555.9+0030
- GRB/FXT 240402B: VLT/FORS2 optical afterglow candidate
- IceCube-240327B: No candidates from the Zwicky Transient Facility
- IceCube-240327B - IceCube observation of a high-energy neutrino candidate track-like event
- IceCube-240327A - IceCube observation of a high-energy neutrino candidate track-like event
- Transient EPW20240219aa: REM optical/NIR further observations
- X-ray transient EP240315a: Montarrenti Observatory optical upper limit
- X-ray transient EP240315a: Nanshan/HMT optical upper limit
- Einstein Probe detected of a fast X-ray transient EP240315a
- IceCube-240307A - IceCube observation of a high-energy neutrino candidate track-like event
- GRB 231028C: Glowbug gamma-ray confirmation of a prior burst
- Swift detection of Swift J151857.0-572147
- GRB 240303A: Swift detection of a burst
- IceCube-240229A - IceCube observation of a high-energy neutrino candidate track-like event
- GRB 240225B: Swift ToO observations
- GRB 240225B : MITSuME Akeno optical afterglow candidate detection
- GRB 240225B: 3.6m DOT observation
- GRB 240225B: NOT optical observations
- GRB 240225B: Nanshan/HMT optical afterglow detection
- GRB 240225B: GOTO detection of a candidate optical afterglow
- Transient EPW20240219aa: REM optical/NIR upper limits
- GRB 240225B: Tiled Swift observations
- Transient EPW20240219aa: upper limit in gamma-ray range from SPI-ACS/INTEGRAL observations
- GRB 240222A: Swift detection of a burst
- IPN triangulation of GRB 240209A
- GRB 240218A: REM detection of a NIR afterglow candidate
- Gamma-ray flaring activity from the blazar 1ES 1959+650 observed by the Fermi-LAT
- GRB 240218A : r-band upper limit from Observatoire de Haute-Provence
- GRB 240218A: Swift detection of a burst
- GRB 240215A: Tiled Swift observations
- GRB 240209A: Fermi GBM observation
- GRB240209A: OHP/T193 detection of the GOTO afterglow candidate AT2024cew / GOTO24pw
- GRB 240209A: Wendelstein Optical Observations
- GRB 240214A: Tiled Swift observations
- GRB 240209A: NOEMA non-detection of AT2024cew / GOTO24pw counterpart candidate
- GRB 240209A: NOT photometry of the AT2024cew / GOTO24pw counterpart candidate
- GRB 240209A: GOTO optical counterpart candidate