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').
- EP241021a: SAO RAS optical observations
- EP241021a: KAIT optical observations
- EP241021a: EP-FXT follow-up observation update
- IPN triangulation of GRB 241021A (long)
- EP241021a: Optical counterpart observations with the Liverpool Telescope
- EP241021a: 1.3m DFOT Optical observations
- EP241021a: GSP detects optical candidate counterpart
- EP241021a: Optical upper limits with Kinder observations
- EP241021a: TRT optical observations
- GRB 241018A: SVOM/C-GFT optical observations
- EP241021a: NOT likely optical counterpart
- EP EP241021a: Global MASTER-Net observations report
- GRB241017A: 1.3m DFOT optical upper limit
- GRB 241018A: 1.3m DFOT Optical upper limit
- GRB 241018A: EP-FXT afterglow detection
- EP241021a: GOTO optical upper limits
- EP241021a: EP detection of a fast X-ray transient
- IceCube-Cascade 241019A: Upper limits from a search for additional neutrino events in IceCube
- Konus-Wind detection of GRB 241018A
- GRB 241018A: SVOM/GRM observation
- GRB 241018A/sb24101802: Mephisto optical upper limit
- GRB 241017A/sb24101702: Mephisto optical upper limit
- GRB 241018A: BOOTES-4/MET optical upper limit
- GRB 241018A: Mondy optical upper limit
- GRB 241018A: SVOM/VT further analysis and counterpart confirmed
- GRB 241018A: GROWTH-India telescope optical upper limit
- GRB241018A: XingLong Optical Upper Limit
- GRB 241018A: Swift-XRT observations
- GRB 241018A: REM optical/NIR upper limits
- GRB 241018A: NOT optical observations
- GRB 241017A: SVOM/VT follow-up and optical upper limit
- GRB 241018A: SVOM/VT follow-up and optical candidate
- GRB 241018A: LCO/0.4m optical upper limits
- GRB 241018A: Swift ToO observations
- GRB 241006A: VIRT Optical Upper Limit
- GRB 240727A: VIRT Optical Upper Limit
- GRB 241018A: X-ray afterglow candidate observed by MXT
- GRB 241016B: Fermi GBM Observations
- GRB 241018A: Detection of a bright long GRB by SVOM
- GRB 241017A: Swift-XRT observations
- GRB241017a: Liverpool Telescope observations of XRT uncatalogued sources
- GRB 241001A: EP-FXT afterglow detection
- GRB 241017A: GROWTH-India Telescope optical upper limit
- GRB241017A: TOO Observations by SVOM/MXT
- GRB 241016B: Swift/BAT-GUANO localization skymap of a short burst
- GRB 241017A: J-band upper limit from WINTER
- Fermi trigger No 750788395: Global MASTER-Net observations report
- GRB 241016B: SVOM/GRM observation
- GRB241016C: Fermi GBM Final Localization
- Fermi Gamma-ray Burst Monitor trigger 750792698/241016730 is not a GRB
- GRB 241017A: Swift ToO observations
- GRB 241017A : Detection of a weak and soft long duration GRB by SVOM/ECLAIRs
- Fermi GRB 241016B: Global MASTER-Net observations report
- GRB 241016B: Fermi GBM Final Localization
- Fermi GRB 241016A: Global MASTER-Net observations report
- GRB 241016A: Fermi GBM Final Real-time Localization
- IceCube alert 139977_2910365 retraction
- IceCube Alert 241016.04: Global MASTER-Net observations report
- GRB 241010A: Swift-BAT refined analysis
- GRB 241013B: Fermi GBM Observation
- GRB 241013B: Swift/BAT-GUANO localization skymap of a burst
- GRB 241013A: Fermi GBM Observation
- GRB 240916A: radio detection with the VLA
- GRB241013A: REM observations
- GRB 241009A: LCO optical upper limits
- GRB 241013B: SVOM/GRM observation
- Fermi GRB 241013B: Global MASTER-Net observations report
- Integral GRB241013.04: Global MASTER-Net observations report
- GRB 241013B: Fermi GBM Final Real-time Localization
- GRB 241013A: a long GRB detected by INTEGRAL
- GRB 241013A: Fermi GBM Final Real-time Localization
- LIGO/Virgo/KAGRA S241009em: Updated Sky localization
- LIGO/Virgo/KAGRA S241011k: Updated Sky localization
- LIGO/Virgo/KAGRA S241011k: NED Galaxies in the Localization Volume
- LIGO/Virgo/KAGRA S241011k: Identification of a GW compact binary merger candidate
- Fermi Gamma-ray Burst Monitor GRB trigger 750372658/241011869 (GRB 241011A) is not a GRB
- GRB 241011A: Fermi GBM Final Real-time Localization
- GRB 241009A: GRANDMA optical upper limits
- GRB 241009A: Swift-XRT afterglow detection
- GRB 241010A: JinShan optical observations and potential host galaxy
- GRB 241006A: ATCA Radio Upper Limits
- GRB 241010A: Swift-XRT refined Analysis
- LIGO/Virgo/KAGRA S241007bw: Updated Sky localization
- Fermi trigger No 750211959: Global MASTER-Net observations report
- Fermi Gamma-ray Burst Monitor trigger 750303285/241011066 is not a GRB
- Fermi Gamma-ray Burst Monitor trigger 750291012/241010924 is not a GRB
- Swift GRB 241010A: Global MASTER-Net observations report
- Fermi trigger No 750291012: Global MASTER-Net observations report
- GRB 241010A: J-band observations with WINTER
- LIGO/Virgo/KAGRA S241009an: Updated Sky localization
- Fermi GRB 241010B: Global MASTER-Net observations report
- GRB 241010B: Fermi GBM Final Real-time Localization
- IceCube-241006A: Upper limits from a search for additional neutrino events in IceCube
- GRB 241010A: Enhanced Swift-XRT position
- GRB 241010A: LCO optical observations
- GRB 241010A: Swift detection of a burst with an optical counterpart
- Fermi-LAT Gamma-ray Observations of IceCube-241006A
- GRB 241006A: Swift-BAT refined analysis
- GRB 241009A: Swift ToO observations
- LIGO/Virgo/KAGRA S241009l: Updated Sky localization