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').
22278 results found.
- GRB 240519A: BALROG localization (Fermi Trigger 737788024 / GRB 240519213)
- EP240518a: EP-WXT detection of a new X-ray transient
- LIGO/Virgo/KAGRA S240514c: Updated Sky localization
- GRB 240516A: Swift-BAT refined analysis
- IPN triangulation of GRB 240514B (short)
- GRB 240516A: Swift-XRT refined Analysis
- GRB 240516A: Fermi GBM Observation
- GRB 240511A: Observations from GTC/OSIRIS+
- GRB 240516A: Swift detection of a burst
- GRB 240511A: radio detection of afterglow candidate
- MAXI GRB240514.78: Global MASTER-Net observations report
- GRB 240514E: MAXI/GSC detection of a probable afterglow
- LIGO/Virgo/KAGRA S240514x: Updated Sky localization
- LIGO/Virgo/KAGRA S240515m: Identification of a GW compact binary merger candidate
- GRB 240513A: Fermi GBM observation
- GRB 240513A: Swift-XRT observations
- LIGO/Virgo/KAGRA S240513ei: Updated Sky localization
- LIGO/Virgo/KAGRA S240514x: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S240514c: Identification of a GW compact binary merger candidate
- transient: Xinglong Nearby Galaxy Supernova Survey detection of AT2024iss
- LIGO/Virgo/KAGRA S240507p: Upper limits from Swift/BAT-GUANO
- LIGO/Virgo/KAGRA S240505av: Upper limits from Swift/BAT-GUANO
- LIGO/Virgo/KAGRA S240505av: Upper limits from Swift/BAT-GUANO
- LIGO/Virgo/KAGRA S240513ei: Identification of a GW compact binary merger candidate
- GRB 240511A: Fermi GBM Observation
- GRB 240511A: Swift-BAT refined analysis
- LIGO/Virgo/KAGRA S240513cx: Coverage and upper limits from MAXI/GSC observations
- GRB 240511A: J-band observations with WINTER
- Fermi trigger No 737247400: Global MASTER-Net observations report
- Fermi trigger No 737168073: Global MASTER-Net observations report
- GRB 240511A: Enhanced Swift-XRT position
- GRB 240511A : MITSuME Akeno optical upper limits
- LIGO/Virgo/KAGRA S240512r: Updated Sky localization and EM Bright Classification
- GRB 240511A: Swift-XRT refined Analysis
- LIGO/Virgo/KAGRA S240512r: Identification of a GW compact binary merger candidate
- GRB 240511A: Swift detection of a burst
- LIGO/Virgo/KAGRA S240511i: Updated Sky localization
- Fermi trigger No 737111207: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S240511i: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S240422ed: GMOS-S photometry of J-GEM24a
- LIGO/Virgo/KAGRA S240422ed: P200 observations of AT2024hit
- LIGO/Virgo/KAGRA S240422ed: Candidates from the latest GW-MMADS DECam Observations
- EP240506a: Xinglong optical upper limit
- GRB 240504A: Fermi GBM Observation
- EP240506a: Archival radio searching
- EP240506a: TRT optical upper limit
- LIGO/Virgo/KAGRA S240507p: Updated Sky localization and EM Bright Classification
- LIGO/Virgo/KAGRA S240422ed: Upper limits from a two-week IceCube neutrino search
- EP240506a: Optical upper limit with Kinder observations
- IPN triangulation of GRB 240504A
- GRB 240502A: 1.3m DFOT Optical upper limit
- EP240506a: EP-WXT detection of a new fast X-ray transient
- LIGO/Virgo/KAGRA S240507p: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S240422ed: Additional WINTER near-infrared J-band observations
- GRB 240504A: Swift/BAT-GUANO detection of a burst outside the coded FOV
- LIGO/Virgo/KAGRA S240505av: Updated Sky localization and EM Bright Classification
- LIGO/Virgo/KAGRA S240505av: Identification of a GW compact binary merger candidate
- Fermi trigger No 736461232: Global MASTER-Net observations report
- GW170817: VLA observations at ~5.5 yrs since merger
- GRB 240504A: BALROG localization (Fermi Trigger 736492377 / GRB 240504217)
- GRB 240502A: Fermi GBM Observation
- GRB 240415A 1.3m DFOT Optical upper limit
- LIGO/Virgo/KAGRA S240501an: Updated Sky localization and EM Bright Classification
- LIGO/Virgo/KAGRA S240430ca: Updated Sky localization and EM Bright Classification
- GRB 240426A: VZLUSAT-2 detection
- GRB 240425A: VZLUSAT-2 detection
- MeerKAT Discovery of a Probable Radio Counterpart to EP240414a
- GRB 240501B: AstroSat CZTI detection
- GRB 240501A: Fermi GBM Final Real-time Localization
- GRB 240408B: VZLUSAT-2 detection
- GRB 240407A: VZLUSAT-2 detection
- LIGO/Virgo/KAGRA S240501an: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S240430ca: Updated Sky localization and EM Bright Classification
- LIGO/Virgo/KAGRA S240430ca: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S240422ed: GECKO/7DT ToO observations
- Additional DECam GW-MMADS Candidates from three nights of observations
- Fermi-LAT gamma-ray observations of IceCube-240424A
- LIGO/Virgo/KAGRA S240426s: Updated Sky localization
- LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limit for EP240426a
- LIGO/Virgo/KAGRA S240426dl: Updated Sky localization
- LIGO/Virgo/KAGRA S240428dr: Updated Sky localization
- LIGO/Virgo/KAGRA S240422ed: GECKO/KMTNet ToO observations
- LIGO/Virgo/KAGRA S240428dr: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S240422ed: J-band non-detection of J-GEM24a
- LIGO/Virgo/KAGRA S240422ed: DDOTI Optical Upper Limit for J-GEM24a
- EP240426b: AST3-2 optical upper limit
- LIGO/Virgo/KAGRA S240422ed: Observations with 1.6m Mephisto
- LIGO/Virgo S240422ed: Swift XRT observation of EP240426a
- LIGO/Virgo/KAGRA S240422ed: NOT optical observations of EP240426a
- EP240426b: EP-WXT detection of a new fast X-ray transient
- LIGO/Virgo/KAGRA S240422ed: Archival radio detection of EP240426a
- LIGO/Virgo/KAGRA S240422ed: Swope Follow-up of AT2024hfq, AT2024hfr, AT2024hfs, and AT2024hfx
- LIGO/Virgo/KAGRA S240422ed: BOOTES-6/DPRT optical upper limits for EP240426a
- LIGO/VIRGO/KAGRA S240422ed: Historical variability for EP240426a
- GRB 240426A: AstroSat CZTI detection
- XMM-Newton observation of EP240426a
- LIGO/Virgo/KAGRA S240426dl: Identification of a GW compact binary merger candidate
- GRB 240414A: NOEMA detection
- LIGO/Virgo/KAGRA S240422ed: EP240426a possible optical detection
- EP240426a: GMG optical upper limit