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').
10636 results found.
- GRB 250202C: GRBAlpha detection
- GRB 250129A: 7DT Detection and Medium-band SED of Afterglow
- GRB 250202C: Fermi GBM Final Real-time Localization
- GRB 250202B: AstroSat CZTI detection of a bright long GRB
- Swift GRB250129A: MASTER 4 days observations report
- GRB 250201A: INTEGRAL SPI/ACS detection
- Konus-Wind detection of GRB 250129A
- LIGO/Virgo/KAGRA S250201i: Coverage and upper limits from MAXI/GSC observations
- EP250108A / SN 2025kg: Upper limits from a neutrino search with IceCube
- GRB 250128B: VLA possible radio detection
- GRB 250127A: EP-FXT second observation epoch and confirmation of the x-ray afterglow fading
- GRB 250129A: Skynet optical observations
- GRB 250129A: Swift-XRT refined Analysis
- The EP-WXT trigger 01709131085: KAIT confirmation of the stellar flare
- GRB 250128B: VLT/FORS2 optical observations
- GRB 250128B: Swift-XRT refined Analysis
- Swift GRB 250128B: Global MASTER-Net observations report
- EP250125a: Upper limits from Swift/BAT-GUANO
- GRB 250128B: Swift detection of a short burst
- GRB 250127B: DDOTI Upper Limit on the Afterglow
- Fermi-LAT Gamma-ray Observations of IceCube-250102A
- GRB 250127A: EP-FXT afterglow detection
- GRB 250117A: Fermi GBM Observation
- Fermi GRB 250127B: Global MASTER-Net observations report
- Fermi-LAT Gamma-ray Observations of IceCube-250101A
- GRB 250126A: MAXI/GSC detection
- EP250108a / SN 2025kg: Refined Analysis of EP-WXT Detection
- GECAM-A detection of a bright burst from SGR 1E1841-045
- EP250125a: a new X-ray transient detected by Einstein Probe
- Konus-Wind detection of a bright burst from SGR 1E1841-045 on 2025 January 23
- GRB 250121A: Swift/BAT-GUANO localization skymap of a burst
- IPN triangulation of a bright burst from SGR 1E1841-045
- 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 250121A: Fermi-LAT detection
- 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
- Fermi-LAT Gamma-ray Observations of IceCube-241224A
- GRB 250118A: Swift/BAT-GUANO localization skymap of a short burst
- Konus-Wind detection of GRB 250117A
- IPN triangulation of GRB 250117A (short)
- LIGO/Virgo/KAGRA S250119cv: Updated NED Galaxies in the Localization Volume
- LIGO/Virgo/KAGRA S250119cv: NED Galaxies in the Localization Volume
- GRB 250117A: Swift/BAT-GUANO localization skymap of a short burst
- LIGO/Virgo/KAGRA S250119cv: Identification of a GW compact binary merger candidate
- EP250108a / AT 2025kg: the kangaroo is hopping, evidence for optical rebrightening
- GRB 250117A: GECAM observation of a short burst
- Konus-Wind detection of GRB 250116A
- GRB 250116A: GECAM-B detection of a long burst
- GRB 250116A: Fermi-LAT detection
- LIGO/Virgo/KAGRA S250114ax: Updated NED Galaxies in the Localization Volume
- GRB 250101A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations and rebrightening.
- Konus-Wind detection of GRB 250113A
- IPN triangulation of GRB 250113A
- GRB 250114A: Swift-XRT refined Analysis
- LIGO/Virgo/KAGRA S250114ax: NED Galaxies in the Localization Volume
- GRB 250114A: Swift detection of a burst with an optical counterpart
- GRB 250101A: Terskol Zeiss-2000 optical observations
- GRB 250106A: Swift-XRT afterglow detection
- Fermi trigger No 758442826: Global MASTER-Net observations report
- EP250108a / AT 2025kg: LCO optical observations
- EP250111a: Global MASTER-Net observations report
- EP250108a / AT 2025kg (the "kangaroo”): VLT/X-shooter spectroscopic redshift z = 0.176 and LFBOT classification
- EP250111a: a new X-ray transient detected by Einstein Probe
- GRB 250109A / EP250109A: Swift/BAT-GUANO localization skymap of a burst
- Konus-Wind detection of GRB 250107C
- EP250109a / GRB 250109A: refined EP-WXT analysis and EP-FXT follow-up observation
- Konus-Wind detection of GRB 250107D (short/hard)
- IPN triangulation of GRB 250107D (short/hard)
- EP250109a: EP-WXT detection of an X-ray transient
- EP250108a: EP-WXT detection of an X-ray transient
- GRB 250108B: Swift-XRT refined Analysis
- Swift GRB 250108B: Global MASTER-Net observations report
- Fermi Gamma-ray Burst Monitor trigger 758061038/250108855 is not a GRB
- GRB 250103A: Swift-XRT afterglow detection
- GRB 250108B: Swift detection of a burst
- GRB 241228B: Fermi-LAT detection
- GRB 250101A: J band upper limit by SYSU 80cm telescope
- The EP-WXT trigger 01709129925 is likely a flaring star
- Fermi trigger No 757753930: Global MASTER-Net observations report
- GRB 250103B: Swift-XRT refined Analysis
- GRB 250103A: Bassano Bresciano Observatory upper limit
- IceCube-250101A: Upper limits from a search for additional neutrino events in IceCube
- IceCube Alert 250102.58: Global MASTER-Net observations report
- GRB 250103A: SVOM detection of a long burst (duplicate submission)
- GRB 250103A: SVOM detection of a long burst
- LIGO/Virgo/KAGRA S241230bd: Upper limits from Swift/BAT-GUANO
- GRB 250101A: further SAO RAS optical observations
- GRB 250101A: SAO RAS optical observations
- Swift GRB250101.56: Global MASTER-Net observations report
- GRB 241217a/EP241217b: ATCA Radio Detection
- EP241217a: VLA Radio Detection
- LIGO/Virgo/KAGRA S241231du: Coverage and upper limit from MAXI/GSC observations
- LIGO/Virgo/KAGRA S241231bg: Updated NED Galaxies in the Localization Volume
- LIGO/Virgo/KAGRA S241231bg: NED Galaxies in the Localization Volume