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').
18308 results found.
- GRB 250129A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations
- GRB 250129A: COLIBRÍ Continuing Detection of the Afterglow
- GRB 250129A: COLIBRÍ Optical Observations
- GRB 250129A: TNG NIR afterglow detection
- GRB 250129A: GRANDMA/TAROT optical afterglow detection
- GRB 250127A: EP-FXT second observation epoch and confirmation of the x-ray afterglow fading
- GRB 250128B: VLA radio upper limit
- Ep250125A: 1.3m DFOT optical 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: TNG optical upper limit
- GRB 250129A: Swift/UVOT Detection
- GRB 250127A: CrAO and Terskol optical upper limits
- GRB 250129A: Enhanced Swift-XRT position
- GRB 250128B: NOT optical upper limit
- GRB 250129A: REM optical/NIR afterglow detection
- GRB 250129A: Early afterglow detection by LCO.
- Swift GRB 250129A: Global MASTER-Net Slowly evolving LC detection
- GRB 250129A: LCO optical observations
- GRB 250129A: GOTO optical observations show brightening afterglow
- Swift GRB 250129A: Global MASTER-Net observations report
- GRB 250128B: Enhanced Swift-XRT position
- 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 250127A: Swift-XRT observations
- GRB 250127A: EP-FXT afterglow detection
- GRB 250117A: Fermi GBM Observation
- GRB 250127A: SVOM/VT upper limit
- IPN triangulation of GRB 250119C
- GRB 250127A: Swift ToO observations
- GRB 250118A: Fermi GBM Observation
- EP250125a: REM optical counterpart detection
- GRB 250119C: Fermi GBM Observation
- EP250125a: Swift/XRT detection of a fading counterpart
- GRB 250121A: Swift/BAT-GUANO localization skymap of a burst
- IPN triangulation of GRB 250118B
- Konus-Wind detection of GRB 250119B
- IPN triangulation of GRB 250119B
- Improved IPN triangulation of GRB 250107C
- GRB 250114A: Swift-BAT refined analysis
- LIGO/Virgo S250119cv: Swift XRT observations, 5 X-ray sources
- GRB 250119C: Swift/BAT-GUANO localization skymap of a short burst
- GRB 250119B: Swift/BAT-GUANO localization skymap of a long burst
- GRB 250118A: Swift/BAT-GUANO localization skymap of a short burst
- Konus-Wind detection of GRB 250117A
- IPN triangulation of GRB 250117A (short)
- GRB 250117A: SVOM/GRM observation of a short burst
- GRB 250117A: Swift/BAT-GUANO localization skymap of a short burst
- Swift Trigger 1282245 is not a GRB
- GRB 250114B: Swift-XRT afterglow detection
- GRB 250101A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations and rebrightening.
- IPN triangulation of GRB 250113A
- GRB 250114B: Swift-XRT observations
- GRB 250114A: LCO optical counterpart detection.
- GRB 250114A: GRANDMA/TAROT optical afterglow detection
- GRB 250114A: Swift-XRT refined Analysis
- GRB 250114A: LCOGT optical afterglow i-band detection
- GRB 250114B: Swift ToO observations
- EP250111a: SAO RAS optical upper limit
- GRB 250114A: Enhanced Swift-XRT position
- GRB 250114A: REM detection of the optical and NIR counterpart
- Swift GRB250114A: Global MASTER-Net OT detection
- GRB 250114A: LCO optical observations
- GRB 250114A: TRT optical observations
- Swift GRB 250114A: Global MASTER-Net observations report
- GRB 250114A: Swift detection of a burst with an optical counterpart
- GRB 250107A: VZLUSAT-2 detection
- GRB 250109A / EP250109a: GRBAlpha detection
- GRB 250106A: Swift-XRT afterglow detection
- GRB 250109A / EP250109a: Mephisto optical upper limits
- EP250111a: Swift/XRT detection and fading
- EP250108a / AT 2025kg: Swift UVOT detections
- GRB 250109A / EP250109A: Swift/BAT-GUANO localization skymap of a burst
- GRB 250109A / EP250109a: Swift detection of the X-ray afterglow
- GRB 250108A: Swift/XRT afterglow fading
- EP250109a / GRB 250109A: refined EP-WXT analysis and EP-FXT follow-up observation
- EP250109a: Swift/UVOT non-detection
- IPN triangulation of GRB 250107D (short/hard)
- IPN triangulation of GRB 250107C
- GRB 250108B: Swift-BAT refined analysis
- GRB 250108B: 1.3m DFOT upper limit
- GRB 250108B: REM optical/NIR upper limits
- EP250109a: GOTO optical upper limits
- EP250109a: Swift/XRT non-detection
- GRB 250108A: Swift/UVOT Upper Limits
- GRB 250108A: NOT optical upper limit
- GRB 250108B: Swift-XRT refined Analysis
- Swift GRB 250108B: Global MASTER-Net observations report
- GRB 250108A: Swift-XRT afterglow detection
- GRB 250108B: Swift/UVOT Upper Limits
- GRB 250103A: Swift-XRT afterglow detection
- GRB 250108B: Enhanced Swift-XRT position