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').
18310 results found.
- GRB 241209A: ATCA radio follow-up observations
- GRB 241218A: LCOGT Optical Upper Limit
- GRB 241218A: Enhanced Swift-XRT position
- GRB 241218A: Swift detection of a burst
- GRB 241217A : SVOM/VT optical afterglow detection
- GRB 241217A: Swift-XRT afterglow detection
- EP241217a: Swift-XRT Detection
- GRB 241214A: GRBAlpha detection
- GRB 241213A (EP241213a): GRBAlpha detection
- GRB 241209D: GRBAlpha detection
- GRB 241213A: Swift-BAT refined analysis
- GRB 241214A: Swift/BAT-GUANO localization skymap of a burst
- Konus-Wind detection of GRB 241213A (EP 241213a)
- GRB 241212A: Swift-XRT observations
- GRB 241213B: Swift-XRT observations
- GRB 241209D: CALET Gamma-Ray Burst Monitor detection
- GRB 241213A: SVOM/VT optical candidate
- GRB 241213B: Tiled Swift observations
- GRB 241213A: Swift/UVOT Upper Limits
- GRB 241213A: Swift-XRT refined Analysis
- GRB 241212A: Swift ToO observations
- GRB 241213A: LCOGT Optical Upper Limits
- EP241213a: EP detection of An X-ray Transient
- GRB 241213A: REM optical/NIR upper limits
- GRB 241213A: Enhanced Swift-XRT position
- Swift GRB 241213A: Global MASTER-Net observations report
- GRB 241213A: Swift detection of a burst
- GRB 241209A: Chandra X-ray Detection
- Konus-Wind detection of GRB 241209B
- GRB 241209B: GRBAlpha detection
- GRB 241129A: Fermi GBM Observation
- GRB 241209B: Swift/BAT-GUANO localization skymap of a burst
- GRB 241209D: REM optical/NIR upper limits
- Konus-Wind detection of GRB 241209D
- GRB 241209B: Swift-XRT afterglow detection
- GRB 241209C: Fermi GBM Observation
- GRB 241209A: Swift-XRT refined Analysis
- GRB 241209D: AstroSat CZTI detection
- GRB 241209A: EP-FXT follow-up observations
- GRB 241209B: SVOM/VT afterglow detection
- GRB 241207B: Fermi GBM Observation
- GRB 241209A: BOOTES-7 and 2.2m CAHA early optical upper limits
- GRB 241209D: Swift-XRT refined Analysis
- GRB 241209D: Fermi GBM Observation
- GRB 241209A: VLT/HAWK-I near-IR counterpart candidate
- GRB 241209D: COLIBRÍ detection of the afterglow
- GRB 241209A: COLIBRÍ Optical Upper Limit
- GRB 241209A: Fermi GBM Observation
- GRB 241209C: Swift/BAT-GUANO localization skymap of a burst
- GRB 241209A: GRANDMA/TAROT upper limit
- Swift GRB 241209D: Global MASTER-Net observations report
- GRB 241209B: Swift ToO observations
- GRB 241209A: REM optical/NIR observations
- GRB 241209D: Enhanced Swift-XRT position
- GRB 241209D: Swift detection of a burst
- GRB 241209A: Enhanced Swift-XRT position
- GRB 241209A: GOTO optical upper limits
- GRB 241209A: Prompt enhanced Swift-XRT position
- GRB 241209A: Swift detection of a short burst
- Swift GRB241209.23: Global MASTER-Net observations report
- GRB 241207B: Swift/BAT-GUANO localization skymap of a short burst
- GRB 241206A: DDOTI Upper Limit on the Afterglow
- GRB 241207C: Tiled Swift observations
- GRB 241206A: Fermi GBM observation
- GRB 241206A: Swift/BAT-GUANO localization skymap of a burst
- LIGO/Virgo/KAGRA S241125n: gamma-ray upper limits from joint observations by the LST-1 and MAGIC telescopes
- Fermi-GBM Sub-Threshold Detection of GRB 241128A
- GRB 241128A: Swift/UVOT Upper Limits
- GRB 241129A: Swift/BAT-GUANO localization skymap of a burst
- LIGO/Virgo/KAGRA S241125n: GRANDMA Optical Upper Limits
- SVOM/GRM observation of a short burst from soft gamma repeater Kes 73
- GRB 241128A: Swift-BAT refined analysis
- GRB 241127A: Swift-BAT refined analysis
- GRB 241127A: PRIME near-infrared detection
- GRB 241128A: GRANDMA and Kilonova-Catcher Optical Afterglow Detections and Upperlimits
- Swift-XRT observations of IceCube -241127A
- Swift GRB 241128A: Global MASTER-Net observations report
- GRB 241128A: Swift-XRT refined Analysis
- GRB 241128A: Enhanced Swift-XRT position
- GRB 241128A: 1.5m OSN optical afterglow detection
- GRB 241128A: Swift-XRT afterglow detection
- GRB 241128A: Swift detection of a burst
- GRB 241127A: GRANDMA and Kilonova-Catcher optical afterglow detections
- GRB 241127A: Swift/UVOT Detection
- GRB 241127A: Swift-XRT refined Analysis
- GRB 241127A: SVOM/GRM observation
- GRB 241127A: Enhanced Swift-XRT position
- GRB 241127A: LCOGT (40-cm) optical counterpart detection
- Swift GRB241127.91: Global MASTER-Net OT detection
- LIGO/Virgo/KAGRA S241125n: Update on Coincidence False Alarm Method
- GRB 241127A: Swift detection of a burst with an optical counterpart
- Swift GRB241127.91: Global MASTER-Net observations report
- Swift GRB241127.91: Global MASTER-Net OT detection
- LIGO/Virgo/KAGRA S241125n: Preliminary flux estimate and spectral analysis of the Swift/BAT-GUANO candidate counterpart
- LIGO/Virgo/KAGRA S241125n: Swift-UVOT Upper Limits
- LIGO/Virgo/KAGRA S241125n: EP-FXT follow-up observations
- IPN triangulation of GRB 241114B
- LIGO/Virgo/KAGRA S241125n: COLIBRÍ Upper Limits on Optical Counterparts to Two of the Swift/XRT Sources
- LIGO/Virgo/KAGRA S241125n: SAGUARO follow-up observations with the MMT
- Trigger_18947: Swift ToO observations (retracted)