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.
Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
14273 results found.
- EP240416a: J-band observations with WINTER
- EP240414a: GMG observation
- GRB 240419A: Swift detection of a burst
- GRB 240418A: TSHAO Zeiss-1000 optical upper limit
- GRB 240418A: NOT optical upper limits
- GRB 240418A: Enhanced Swift-XRT position
- GRB 240418A: AKO Upper Limit
- GRB 240418A: Swift detection of a burst
- EP240417a: EP-WXT detection of a fast X-ray transient
- LIGO/Virgo/KAGRA S240413p: X-ray upper limits from EP-WXT for the candidate AGN counterpart
- LIGO/Virgo/KAGRA S240413p: DECam GW-MMADS candidates
- GRB 240415A: Glowbug gamma-ray detection
- GRB 240414A: Glowbug gamma-ray detection
- LIGO/Virgo/KAGRA S240413p: STEP - T80S Search and Candidate Counterpart Identification
- EP 240416a: Xinglong and NOT decaying optical counterpart
- GRB 240411A: Glowbug gamma-ray detection
- EP240416a: Kinder optical counterpart candidate
- EP240416a: EP-WXT detection of a fast X-ray transient
- GRB 240414A: AbAO optical upprer limit
- GRB 240415A: Swift/UVOT Detection
- GRB 240414A: GAD Observatory, La Spezia, Italy ,upper limit
- GRB 240415A: Earliest optical followup with the Kinder observations
- GRB 240414A: GMG observation
- EP240414a: EP-FXT follow-up observation
- GRB 240415A: Enhanced Swift-XRT position
- GRB 240415A: OHP/T193 optical observations
- GRB 240415A: SAO RAS optical observations
- GRB 240415A: Mondy optical transient detection
- GRB 240414A: Photometric observation from 2.2m CAHA
- GRB 240414A: Swift/UVOT Detection
- GRB 240414A: Mondy optical observations
- GRB 240414A: AKO Optical Upper Limit
- GRB 240415A: Prompt Swift-XRT observations
- EP 240414a: NOT optical counterpart confirmation
- GRB240414A : J-band upper limits from WINTER
- GRB 240414A: Enhanced Swift-XRT position
- GRB 240414A: MarSEC Observatory, Vicenza, Italy, UPPER LIMIT
- LIGO/Virgo/KAGRA S240413p: No Counterparts in DDOTI/OAN Optical Observations
- EP240413A: GOTO optical upper limits
- GRB 240414A: Skynet Optical Afterglow Observations
- EP240414a: Kinder optical counterpart candidate possibly associated with the galaxy SDSS J124601.99-094309.3
- IPN triangulation of GRB 240410A
- EP240413a: possible detection of the X-ray emission with EP-FXT after 14 hours
- EP240414a: EP-WXT detection of a fast X-ray transient
- IPN triangulation of GRB 240411A
- Fermi-LAT gamma-ray observations of IceCube-240412A
- GRB 240414A : MITSuME Akeno optical upper limits
- EP240413a: EP-WXT detection of a fast X-ray transient
- GRB 240414A : OHP/T193 optical counterpart detection
- GRB 240414A: Swift detection of a burst
- EP240408a: GSP optical upper limit
- GRB 240411B: CrAO/ZTSh optical observations
- GRB 240411B: Kinder observations with Lulin observatory
- GRB 240411B: HiPERCAM/GTC observation
- GRB 240411B: 1.3m DFOT Optical observations
- GRB 240411B: OHP/T193 optical observations
- GRB 240405A: Glowbug gamma-ray detection
- GRB 240411B: Enhanced Swift-XRT position
- GRB 240411B: LCO optical afterglow detection
- GRB 240411B: Swift detection of a burst
- EP240408a: BOOTES-6/DPRT optical upper limit
- EP240408a: EP-WXT detection of a fast X-ray transient
- Swift Trigger 1220736: detection of 4U 1543-62.
- Fermi-LAT gamma-ray observations of IceCube-240327A
- GRB 240402C: Glowbug gamma-ray detection
- GRB 240403B: Glowbug gamma-ray detection
- GRB 240403A: Glowbug gamma-ray detection
- LXT 240402A/GRB 240402B: Glowbug gamma-ray detection
- X-ray transient LXT 240402A: WFST optical upper limits
- GRB/FXT 240402B: Kinder optical counterpart candidate
- IceCube-240327B: GRANDMA observations of 4FGL J0555.9+0030
- LXT 240402A: EP-FXT detection of the X-ray afterglow
- X-ray transient LXT 240402A: LEIA detection
- X-ray transient EP240331a: Kinder optical upper limits
- Transient EP240315a: J-band observations of AT2024eju with WIRC
- X-ray transient EP20240331a: MeerLICHT optical upper limits
- GRB 240329A: Glowbug gamma-ray detection
- GRB 240324A: AstroSat CZTI detection of a short burst
- GRB 240331A: AstroSat CZTI detection
- X-ray transient EP240315a: continued ATCA monitoring
- GRB 240328C: Glowbug gamma-ray detection
- X-ray transient EP240315a: Ondrejov D50 optical limit
- Transient EPW20240219aa: REM optical/NIR further observations
- GRB 240320A: Glowbug gamma-ray detection
- X-ray transient EP240315a: ATCA detection of radio counterpart
- IPN triangulation of GRB 240315C (consistent with a fast X-ray transient EP240315a)
- X-ray transient EP240315a: MeerKAT radio detection
- GRB 240318A: Glowbug gamma-ray detection
- GRB 240317C: Glowbug gamma-ray detection
- GRB 240318B: Glowbug gamma-ray detection
- X-ray transient EP240315a: PRIME near infrared detection
- GRB 240317B: Fermi GBM Observation
- X-ray transient EP240315a: 3.6 m TNG NIR detection
- X-ray transient EP240315a/AT2024eju: TShAO (Zeiss-1000) observatory optical upper limit
- X-ray transient EP240315a: EP-FXT detection of the X-ray afterglow
- GRB 240317A: AstroSat CZTI detection
- X-ray transient EP240315a: Kitab observatory optical upper limitns
- X-ray transient EP240315a: Montarrenti Observatory optical upper limit
- X-ray transient EP240315a: orphan FXT?
- X-ray transient EP240315a: Kinder follow-up observations for AT 2024eju with Lulin observatory