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').
18174 results found.
- 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)
- LIGO/Virgo/KAGRA S241125n: DDOTI Optical Upper Limits
- LIGO/Virgo/KAGRA S241125n: Gaoyazi/GOT optical observations
- LIGO/VIRGO/KAGRA S241125n: GROWTH-India telescope optical observations
- LIGO/Virgo S241125n: Swift XRT observations, 5 X-ray sources
- EP241125a: EP detection of an X-ray transient
- LIGO/Virgo/KAGRA S241125n: COLIBRÍ Upper Limits on a Optical Counterpart at the BAT Position
- LIGO/Virgo/KAGRA S241125n: Upper limits from Fermi-GBM Observations
- LIGO/Virgo/KAGRA S241125n: Updated Coincidence with External Event
- LIGO/Virgo/KAGRA S241125n: Kinder optical upper limit in the BAT error region
- LIGO/Virgo/KAGRA S241125n: Updated Coincidence with External Event
- LIGO/Virgo/KAGRA S241125n: No counterpart candidates in INTEGRAL SPI-ACS prompt observation, comparisong with Swift/BAT counterpart
- LIGO/Virgo/KAGRA S241125n: Updated Sky localization and Coincidence with External Event
- LIGO/Virgo/KAGRA S241125n: Swift/BAT-GUANO candidate counterpart
- Konus-Wind detection of GRB 241117A
- IPN triangulation of GRB 241117A
- GRB 241025A: VIRT Optical Upper Limit
- GRB 241115A: CALET Gamma-Ray Burst Monitor detection
- GRB 241115a: PRIME near-infrared upper limits
- GRB 241117A: Swift/BAT-GUANO localization skymap of a burst
- LIGO/Virgo/KAGRA S241116cq: Upper limits from Swift/BAT-GUANO
- GRB 241115B: Fermi GBM Observation
- GRB 241115B: Swift/BAT-GUANO localization skymap of a long burst
- GRB 241115C: Fermi GBM Observation
- GRB 241115A: Swift-XRT afterglow detection
- EP241115a/GRB 241115D: Optical upper limits with Kinder observations
- EP241115a/GRB 241115D: Swift/XRT follow-up observation
- EP241113a: Swift XRT weak detection
- GRB 241115A: Fermi GBM Observation
- GRB 241115A: LCOGT Optical Upper Limits
- GRB 241115C: Swift/BAT-GUANO localization skymap of a burst
- Swift GRB 241115A: Global MASTER-Net observations report
- GRB 241115A: Swift detection of a burst
- GRB 241113A: Swift-BAT refined analysis
- GRB 241113A: PRIME near-infrared upper limits
- GRB 241113A: J-band observations with WINTER
- GRB 241113B: Swift-XRT observations