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"23586 results found.
- GRB 250128B: TNG optical upper limit
- GRB 250129A: Swift/UVOT Detection
- GRB 250128B: NOT optical upper limit
- GRB 250129A: REM optical/NIR afterglow detection
- GRB 250129A: Early afterglow detection by LCO.
- GRB 250128B: OHP/T193 optical upper limit
- GRB 250129A: LCO optical observations
- GRB 250129A: NOT optical observations and redshift confirmation
- GRB 250129A: GOTO optical observations show brightening afterglow
- The EP-WXT trigger 01709131085 is likely a flaring star
- GRB 250128B: Swift-XRT refined Analysis
- GRB 250128B: GOTO optical upper limit
- GRB 250128B: LCO optical observations
- GRB 250128B: Swift detection of a short burst
- GRB 250127A: Swift-XRT observations
- GRB 250127B: DDOTI Upper Limit on the Afterglow
- Fermi-LAT Gamma-ray Observations of IceCube-250102A
- GRB 250127A: EP-FXT afterglow detection
- Fermi-LAT Gamma-ray Observations of IceCube-250101A
- IPN triangulation of GRB 250119C
- GRB 250127A: LCO optical upper limit
- GRB 241223A: cubesat Avion detection
- GRB 250126A: CALET Gamma-Ray Burst Monitor detection
- EP250125A: Non-detection from Fermi-GBM Observations
- GRB 250126A: MAXI/GSC detection
- EP250125a: Optical upper limit with Kinder observations
- EP250125a: REM optical counterpart detection
- Konus-Wind detection of a bright burst from SGR 1E1841-045 on 2025 January 23
- IPN triangulation of a bright burst from SGR 1E1841-045
- GRB 250121A: CALET Gamma-Ray Burst Monitor detection
- Konus-Wind detection of GRB 250118B
- Konus-Wind detection of GRB 250119B
- IPN triangulation of GRB 250119B
- Improved IPN triangulation of GRB 250107C
- GRB 250114A: Swift-BAT refined analysis
- GRB 250121A: Fermi-LAT detection
- LIGO/Virgo S250119cv: Swift XRT observations, 5 X-ray sources
- Fermi-LAT Gamma-ray Observations of IceCube-241224A
- Konus-Wind detection of GRB 250117A
- IPN triangulation of GRB 250117A (short)
- LIGO/Virgo/KAGRA S250119cv: GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
- EP 250108A: Late-time optical observation by LCO
- LIGO/Virgo/KAGRA S250105bn: 1 counterpart neutrino candidate event from an IceCube neutrino search
- LIGO/Virgo/KAGRA S250119cv: Updated NED Galaxies in the Localization Volume
- LIGO/Virgo/KAGRA S250119cv: NED Galaxies in the Localization Volume
- LIGO/Virgo/KAGRA S250119cv: Identification of a GW compact binary merger candidate
- EP250108a/AT 2025kg: NOT spectroscopy in agreement with SN Ic-BL
- LIGO/Virgo/KAGRA S250119ag: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S250118dp: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S250118az: Identification of a GW compact binary merger candidate
- EP250108a / AT2025kg: GMG Optical Observations
- LIGO/Virgo/KAGRA S250118t: Identification of a GW compact binary merger candidate
- Konus-Wind detection of GRB 250116A
- GRB 241217A / EP241217B: radio detection with the VLA
- GRB 250116A: Fermi GBM Observation of an Extremely Interesting Burst
- GRB 250114B: Swift-XRT afterglow detection
- GRB 250114B: SVOM/VT upper limit
- 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
- LIGO/Virgo/KAGRA S250114ax: GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
- GRB 250114B : MITSuME Akeno optical afterglow candidate detection
- GRB 250114B: Swift-XRT observations
- GRB 250114A: LCO optical counterpart detection.
- GRB 250114A: GRANDMA/TAROT optical afterglow detection
- GRB 250114A: LCOGT optical afterglow i-band detection
- GRB 250114B : GIT optical upper limit
- EP250111a: SAO RAS optical upper limit
- LIGO/Virgo/KAGRA S250114ax: NED Galaxies in the Localization Volume
- GRB 250114A: REM detection of the optical and NIR counterpart
- LIGO/Virgo/KAGRA S250114ax: Identification of a GW compact binary merger candidate
- GRB 250114A: LCO optical observations
- GRB 250114A: TRT optical observations
- GRB 250114A: Swift detection of a burst with an optical counterpart
- EP250108a / AT 2025kg: SAO RAS optical observations
- 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
- EP250108a / AT 2025kg: LCO optical observations
- EP250109a/GRB 250109A:SVOM/VT optical counterpart
- GRB 250109A / EP250109a: Terskol (INASAN) and SAO RAS observations
- GRB 250109A / EP250109a: Swift detection of the X-ray afterglow
- GRB 250107D: CALET Gamma-Ray Burst Monitor detection
- GRB 250107C: CALET Gamma-Ray Burst Monitor detection
- Konus-Wind detection of GRB 250107C
- EP-WXT trigger EP250108a:Xinglong optical follow-up observations
- EP250108a: EP-FXT follow-up observation
- EP-WXT trigger EP250109a:Xinglong optical follow-up observations
- GRB 250109a: GMG Optical Upper Limit
- EP250109a: Swift/UVOT non-detection
- Konus-Wind detection of GRB 250107D (short/hard)
- IPN triangulation of GRB 250107C
- GRB 250108B: Swift-BAT refined analysis
- GRB 250108B: REM optical/NIR upper limits
- EP250109a: SVOM/VT optical candidate
- EP250109a: GOTO optical upper limits