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').
32062 results found.
- GRB 250128B: SAO RAS Zeiss-1000 and CrAO ZTSh optical upper limits
- GRB 250128B: VLA radio upper limit
- GRB 250129A: Skynet optical observations
- GRB 250129A: KAIT optical observations of the rebrightening around 5.1 hours
- GRB 250129A: Swift-XRT refined Analysis
- GRB 250128B: Gemini-North optical extended source detection
- The EP-WXT trigger 01709131085: KAIT confirmation of the stellar flare
- GRB 250128B: TNG optical upper limit
- GRB 250129A: Swift/UVOT Detection
- GRB 250128B: VLT/HAWKI near-infrared observations
- GRB 250127A: CrAO and Terskol optical upper limits
- GRB 250129A: Enhanced Swift-XRT position
- GRB 250128B: NOT optical upper limit
- GRB 250128B: VLT/FORS2 optical observations
- GRB 250129A: REM optical/NIR afterglow detection
- GRB 250129A: OHP/T193 optical and spectroscopy observations
- GRB 250129A: Early afterglow detection by LCO.
- GRB 250128B: OHP/T193 optical upper limit
- Swift GRB 250129A: Global MASTER-Net Slowly evolving LC detection
- GRB 250129A: LCO optical observations
- GRB 250129A: NOT optical observations and redshift confirmation
- GRB 250129A: GOTO optical observations show brightening afterglow
- GRB 250129A: VLT/X-shooter redshift of z = 2.151
- Swift GRB 250129A: Global MASTER-Net observations report
- GRB 250128B: Enhanced Swift-XRT position
- Fermi GRB 250128B: Global MASTER-Net observations report
- GRB 250129A: Swift detection of a burst with an optical counterpart
- Swift GRB 250129A: Global MASTER-Net OT detection
- GRB 250128B: Swift-XRT refined Analysis
- GRB 250128B: Fermi GBM Observation
- GRB 250128B: GOTO optical upper limit
- Swift GRB 250128B: Global MASTER-Net observations report
- EP250125a: Upper limits from Swift/BAT-GUANO
- GRB 250128B: LCO optical observations
- GRB 250128B: Swift detection of a short burst
- GRB 250128B: Fermi GBM Final Real-time Localization
- GRB 250127A: Swift-XRT observations
- GRB 250127B: DDOTI Upper Limit on the Afterglow
- GRB 250127A: EP-FXT afterglow detection
- Fermi GRB 250128A: Global MASTER-Net observations report
- GRB 250128A: Fermi GBM Final Real-time Localization
- GRB 250117A: Fermi GBM Observation
- Fermi GRB 250127B: Global MASTER-Net observations report
- GRB 250127A: SVOM/VT upper limit
- GRB 250127B: Fermi GBM Final Real-time Localization
- IPN triangulation of GRB 250119C
- GRB 250127A: Swift ToO observations
- GRB 250127A: LCO optical upper limit
- GRB 241223A: cubesat Avion detection
- GRB 250127A: SVOM detection of a long burst
- GRB 250126A: CALET Gamma-Ray Burst Monitor detection
- EP250125A: Non-detection from Fermi-GBM Observations
- GRB 250126A: MAXI/GSC detection
- GRB 250126A: BALROG localization (Fermi Trigger 759560335 / GRB 250126208)
- GRB 250126A: Fermi GBM Final Real-time Localization
- GRB 250118A: Fermi GBM Observation
- GRB 250119C: Fermi GBM Observation
- GRB 250121A: Swift/BAT-GUANO localization skymap of a burst
- GRB 250121A: CALET Gamma-Ray Burst Monitor detection
- EP250108a: AbAO, CMO and Terskol optical upper limits
- Konus-Wind detection of GRB 250118B
- GRB 250121A: Fermi GBM Observation
- IPN triangulation of GRB 250118B
- Konus-Wind detection of GRB 250119B
- IPN triangulation of GRB 250119B
- GRB 250122A: Fermi GBM Final Real-time Localization
- Improved IPN triangulation of GRB 250107C
- GRB 250114A: Swift-BAT refined analysis
- GRB 250121A: INTEGRAL/SPI-ACS detection
- GRB 250121A: Fermi-LAT detection
- GRB 250119C: Swift/BAT-GUANO localization skymap of a short burst
- GRB 250119B: Swift/BAT-GUANO localization skymap of a long burst
- GRB 250121A: Fermi GBM Final Real-time Localization
- GRB 250118A: Swift/BAT-GUANO localization skymap of a short burst
- GRB 250119B: Fermi GBM Observation
- Konus-Wind detection of GRB 250117A
- IPN triangulation of GRB 250117A (short)
- ATCA detection of possible radio counterpart to GRB 250114A
- GRB 250119B: INTEGRAL/SPI-ACS detection
- EP 250108A: Late-time optical observation by LCO
- GRB 250117A: SVOM/GRM observation of a short burst
- GRB 250119C: Fermi GBM Final Real-time Localization
- GRB 250117A: Swift/BAT-GUANO localization skymap of a short burst
- EP250108a / SN2025kg: Gemini GMOS-S confirmation of an associated broad-lined SN Ic
- EP250108a/AT 2025kg: NOT spectroscopy in agreement with SN Ic-BL
- EP250108a / AT 2025kg: the kangaroo is hopping, evidence for optical rebrightening
- GRB 250117A: GECAM observation of a short burst
- GRB 250119B: BALROG localization (Fermi Trigger 758968026 / GRB 250119352)
- GRB 250119B: Fermi GBM Final Real-time Localization
- GRB 250119A: Fermi GBM Final Real-time Localization
- GRB 250118A: Fermi GBM Final Real-time Localization
- EP250108a / AT2025kg: VLA radio upper limit
- Fermi Gamma-ray Burst Monitor trigger 758829338/250117747 is not a GRB
- Konus-Wind detection of GRB 250116A
- GRB 250116A: GECAM-B detection of a long burst
- GRB 241217A / EP241217B: radio detection with the VLA
- GRB 250116A: INTEGRAL/SPI-ACS and PICsIT detection
- Swift Trigger 1282245 is not a GRB
- GRB 250116A: Fermi-LAT detection
- GRB 250116A: Fermi GBM Observation of an Extremely Interesting Burst