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').
32069 results found.
- Konus-Wind detection of GRB 250116A
- GRB 250116A: GECAM-B detection of a long burst
- GRB 241217A / EP241217B: radio detection with the VLA
- GRB 250116A: INTEGRAL/SPI-ACS and PICsIT detection
- Swift Trigger 1282245 is not a GRB
- GRB 250116A: Fermi-LAT detection
- GRB 250116A: Fermi GBM Observation of an Extremely Interesting Burst
- GRB 250114B: Swift-XRT afterglow detection
- GRB 250114B: SVOM/VT upper limit
- Fermi Gamma-ray Burst Monitor trigger 758659047/250115776 is not a GRB
- GRB 250101A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations and rebrightening.
- Konus-Wind detection of GRB 250113A
- IPN triangulation of GRB 250113A
- GRB 250114B: Liverpool Telescope optical upper limit
- GRB 250114B : MITSuME Akeno optical afterglow candidate detection
- GRB 250114B: Swift-XRT observations
- GRB 250114A: LCO optical counterpart detection.
- GRB 250114B: OHP/T193 optical upper limit
- GRB 250114A: GRANDMA/TAROT optical afterglow detection
- GRB 250114A: Swift-XRT refined Analysis
- GRB 250114A: LCOGT optical afterglow i-band detection
- GRB 250114B : GIT optical upper limit
- GRB 250114B: Swift ToO observations
- EP250111a: SAO RAS optical upper limit
- GRB 250114B: a short GRB detected with INTEGRAL
- EP250108a: correction to GCN 38908
- GRB 250114A: Enhanced Swift-XRT position
- GRB 250113A: INTEGRAL/SPI-ACS detection
- GRB 250114A: VLT/X-shooter spectroscopic redshift z = 4.732
- GRB 250114A: REM detection of the optical and NIR counterpart
- 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 250101A: Terskol Zeiss-2000 optical observations
- EP250108a / AT 2025kg: SAO RAS optical observations
- GRB 250113A: SVOM/GRM observation of a long burst
- GRB 250107A: VZLUSAT-2 detection
- GRB 250109A / EP250109a: GRBAlpha detection
- GRB 250107D: GRBAlpha detection
- GRB 250106A: Swift-XRT afterglow detection
- EP250111a: KAIT optical observations
- GRB 250109A / EP250109a: Mephisto optical upper limits
- EP250108a: Mephisto detection
- EP250111a: Mondy optical observation
- EP250108a / AT 2025kg (the "kangaroo”): VLT/X-shooter spectroscopic redshift z = 0.176 and LFBOT classification
- EP250109a/GRB 250109A:SVOM/VT optical counterpart
- GRB 250101B: Fermi GBM Observation
- EP250108a: further NOT optical observations
- GRB 250109A / EP250109a: Terskol (INASAN) and SAO RAS observations
- 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
- GRB 250107D: CALET Gamma-Ray Burst Monitor detection
- GRB 250107C: CALET Gamma-Ray Burst Monitor detection
- Konus-Wind detection of GRB 250107C
- GRB 250101A: CMO RC-500 optical observations
- EP250109a / GRB 250109A: refined EP-WXT analysis and EP-FXT follow-up observation
- GRB 250109A: Fermi GBM Observation
- EP250108a: NOT optical observations
- GRB 250109a: GMG Optical Upper Limit
- Konus-Wind detection of GRB 250107D (short/hard)
- IPN triangulation of GRB 250107D (short/hard)
- IPN triangulation of GRB 250107C
- GRB 250108B: Gemini-North likely redshift z = 2.197
- GRB 250108B: Swift-BAT refined analysis
- GRB 250108B: 1.3m DFOT upper limit
- GRB 250108B: REM optical/NIR upper limits
- GRB 250109A /EP250109a: Fermi GBM Final Localization
- GRB 250107C: SVOM/GRM observation
- GRB 250101A: Terskol K-800 optical observations
- 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
- Fermi Gamma-ray Burst Monitor trigger 758061038/250108855 is not a GRB
- LIGO/Virgo/KAGRA S250108ha: Retraction of GW compact binary merger candidate
- GRB 250108B: Gemini-North Candidate Optical Afterglow Detection
- GRB 250103A: 1.6m Mephisto optical observations
- GRB 250108A: Swift-XRT afterglow detection
- GRB 250108A:SVOM/VT optical candidate
- 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 250108A: SVOM detection of a soft long burst
- GRB 250107A: Fermi GBM Observation
- GRB 241228B: Fermi-LAT detection
- Fermi GRB 250107B: Global MASTER-Net observations report
- GRB 250107A: Swift ToO observations
- GRB 250107A: Swift/BAT-GUANO arcminute localization of a burst
- GRB 250107B: Fermi GBM Final Real-time Localization
- GRB 250106A: SVOM/VT 2nd optical deep observation
- GRB 250101A: J band upper limit by SYSU 80cm telescope
- GRB 250107A: Fermi GBM Final Real-time Localization
- GRB 250106A: NOT optical observations
- GRB 250103B: REM optical/NIR upper limits
- GRB 250101A: REM optical/NIR counterpart detection