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').
18174 results found.
- 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
- GRB 250108B: Swift detection of a burst
- GRB 250108A: Swift ToO observations
- GRB 250107A: Fermi GBM Observation
- GRB 241228B: Fermi-LAT detection
- GRB 250107A: Swift ToO observations
- GRB 250107A: Swift/BAT-GUANO arcminute localization of a burst
- GRB 250106A: NOT optical observations
- GRB 250103B: REM optical/NIR upper limits
- GRB 250101A: REM optical/NIR counterpart detection
- GRB 250106A: Swift-XRT observations
- GRB 250106A: Swift ToO observations
- GRB 241229A: SVOM/VT optical upperlimit
- GRB 250103B: Swift-XRT refined Analysis
- GRB 250103B: LCO/1m optical afterglow candidate detection
- GRB 250103A: Swift-XRT observations
- GRB 250101A: 1.3m DFOT optical afterglow detection
- GRB 241229A: 1.3m DFOT upper limit
- GRB 241228A: 1.3m DFOT upper limit
- GRB 250103B:SVOM/VT optical counterpart
- GRB 250101A: further LCOGT optical afterglow observations
- GRB 250103B: LCOGT Optical Upper Limit
- Swift GRB 250103B: Global MASTER-Net observations report
- GRB 250103A: Swift ToO observations
- GRB 250101a: Liverpool Telescope optical follow-up
- GRB 250103B: SVOM detection of a long burst
- GRB 250103B: Swift detection of a burst
- LIGO/Virgo/KAGRA S241230bd: Upper limits from Swift/BAT-GUANO
- GRB 250101A: Swift-BAT refined analysis
- GRB 250101A: further SAO RAS optical observations
- GRB 250101A: LCO optical counterpart detection
- GRB 250101A: GMG spectroscopic redshift at z ~ 2.481
- GRB 250101A: Swift/UVOT Detection
- GRB 250101A: 1.6m Mephisto multi-band optical followup
- GRB 250101A: Swift-XRT refined Analysis