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').
Advanced Search
To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.
Advanced Search Examples (click to copy):
subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"
10364 results found.
- 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
- GRB 241229A: EP-FXT X-ray afterglow confirmation
- EP241217A: J band upper limit by SYSU 80cm telescope
- GRB 241229B: CrAO ZTSh possible optical counterpart of SVOM/VT confirmation
- Konus-Wind detection of GRB 241228A
- EP240702a: 7DT Optical upper limits
- GRB 240606B: 7DT Optical upper limits
- GRB 241228B: Swift-XRT afterglow detection
- GRB 241228B: Swift/BAT-GUANO localization skymap of a burst
- Fermi GRB 241228B: Global MASTER-Net observations report
- GRB 241226A: Swift/BAT-GUANO localization skymap of a burst
- GRB 241228A: Swift-XRT refined Analysis
- GRB 241228A: Swift detection of a burst
- GRB 241217A/EP241217b: continued SOAR observations
- Fermi GRB 241226A: Global MASTER-Net observations report
- Fermi trigger No 756678579: Global MASTER-Net observations report
- IceCube Alert 241224.30: Global MASTER-Net observations report
- EP241223a: Global MASTER-Net observations report
- EP241113a: Non-detection in Radio Follow-up Observations with eMERLIN
- GRB241113A: 7DT Optical upper limits
- Fermi Gamma-ray Burst Monitor trigger 756678579 / 241223854 is not a GRB
- Fermi GRB 241223A: Global MASTER-Net observations report
- GRB 241223A: GOTO optical observations summary
- EP241217a: e-MERLIN radio observations
- GRB 241217A / EP241217b: Non-detection in ATCA Radio Follow-up Observations
- Fermi trigger No 756447119: Global MASTER-Net observations report
- GRB 241217A/EP241217b: SOAR afterglow detection
- EP241217a: Liverpool Telescope optical upper limit
- GRB 241218A: Mondy AZT-33IK optical upper limit
- Konus-Wind detection of GRB 241204A (short/hard)
- EP 241217a: NIR detection with P200/WIRC
- GRB 241217A / EP241217b: NOT optical upper limits
- GRB 241218A: Swift-XRT refined Analysis
- EP241119a: 7DT Optical upper limits
- EP241217b/GRB 241217A: EP detection of the prompt X-ray emssion
- EP241217a: Global MASTER-Net observations report
- GRB 241218A: Swift detection of a burst
- EP241217a: Swift-XRT Detection
- EP241217a: EP detection of an X-ray transient
- GRB 241214A: Swift/BAT-GUANO localization skymap of a burst
- Konus-Wind detection of GRB 241213A (EP 241213a)
- The EP-WXT trigger 01709128948 is likely a flaring star
- GRB 241215A: A long GRB detected by INTEGRAL
- GRB 241213A: Swift-XRT refined Analysis
- EP 241208A : Detection of a long soft transient by SVOM/ECLAIRs
- GRB 241213B: MAXI/GSC detection
- GRB 241213A: Swift detection of a burst
- GRB 241209B: Mondy AZT-33IK and AbAO AS-32 optical observations