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').
18688 results found.
- GRB 241217A / EP241217B: GRANDMA/T1MPicduMidi optical upperlimits
- EP 241217a: NIR detection with P200/WIRC
- EP 241217a: Possible J-band detection with WINTER
- EP241217a: refined EP-WXT analysis and EP-FXT follow-up observations
- GRB 241217A / EP241217b: Nanshan/HMT optical upper limit
- GRB 241217A / EP241217b: NOT optical upper limits
- GRB 241218A: REM optical upper limit
- GRB 241217A/EP241217b: REM optical/NIR upper limits
- EP241217a: REM optical/NIR upper limits
- GRB 241217a: Liverpool Telescope optical follow-up
- EP241217a: Liverpool Telescope optical follow-up
- EP241217a: NOT optical observations
- EP241217a: GROWTH-India Telescope optical observations
- GRB 241218A: NUTTelA-TAO / BSTI Optical Limits
- EP241119a: 7DT Optical upper limits
- EP241217a: Xinglong optical follow-up observations
- EP241217b/GRB 241217A: EP detection of the prompt X-ray emssion
- GRB 241218A: LCOGT Optical Upper Limit
- GRB 241218A: Enhanced Swift-XRT position
- GRB 241217A: GMG Optical Upper Limit
- GRB 241218A: Swift detection of a burst
- GRB 241217A : SVOM/VT optical afterglow detection
- GRB 241217A: Swift-XRT afterglow detection
- GRB 241217A: LCO optical upper limit
- GRB 241217A: GRANDMA/TAROT optical upperlimits
- EP241217a: Swift-XRT Detection
- GRB 241217A : SVOM/ECLAIRs,GRM,MXT detection of a long burst with a bright X-ray afterglow candidate
- EP241217a: Kinder optical follow-up observations
- GRB 241214A: GRBAlpha detection
- GRB 241213A (EP241213a): GRBAlpha detection
- GRB 241209D: GRBAlpha detection
- EP241217A: LCO optical observations
- EP241217a: Gemini-North detection of the likely optical counterpart
- EP241217a: EP detection of an X-ray transient
- EP241107a: VLA Radio Observation
- GRB 241214A: Swift/BAT-GUANO localization skymap of a burst
- Konus-Wind detection of GRB 241213A (EP 241213a)
- GRB 241215A: Mondy AZT-33IK optical observations
- GRB 241212A: Swift-XRT observations
- GRB 241215A: Nanshan/HMT optical upper limit
- GRB 241215A: Montarrenti Observatory optical upper limit
- GRB 241215A: GROWTH-India telescope optical upper limit
- Integral GRB241215.58: Global MASTER-Net observations report
- GRB 241213A: Swift/UVOT Upper Limits
- EP241208a: NOT optical upper limits
- GRB 241213A: LCOGT Optical Upper Limits
- EP241213a: EP detection of An X-ray Transient
- GRB 241213A: REM optical/NIR upper limits
- GRB 241213A: Enhanced Swift-XRT position
- GRB241212A: OHP/T193 optical observations
- GRB 241213A: SAO RAS optical upper limit
- GRB 241213A: Swift detection of a burst
- GRB 241212A : SVOM/C-GFT optical upper limit at early phase
- GRB 241209B: GRANDMA/TRT upper limit
- GRB 241212A: SVOM detection of a bright long burst
- GRB 241209B: GRBAlpha detection
- GRB 241206C: GRBAlpha detection
- LIGO/Virgo/KAGRA S241210d: Updated Sky localization and EM Bright Classification
- GRB 241209B: Swift/BAT-GUANO localization skymap of a burst
- GRB 241209D: REM optical/NIR upper limits
- GRB 241209B: Swift-XRT afterglow detection
- LIGO/Virgo/KAGRA S241210fu: Identification of a GW compact binary merger candidate
- EP241208a: Optical upper limit with Kinder observations
- GRB 241209D: AstroSat CZTI detection
- LIGO/Virgo/KAGRA S241210cw: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S241210d: Identification of a GW compact binary merger candidate
- GRB 241209A: VLT/HAWK-I near-IR counterpart candidate
- GRB 241209D: COLIBRÍ detection of the afterglow
- GRB 241209A: COLIBRÍ Optical Upper Limit
- GRB 241209C: Swift/BAT-GUANO localization skymap of a burst
- GRB 241209A: GRANDMA/TAROT upper limit
- GRB 241209B: BOOTES-5 optical upper limit
- LIGO/Virgo/KAGRA S241102br: continued GRAWITA observations and detection of an optical transient (AT2024adip)
- 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 241114B: cubesat Avion detection
- GRB 241209A: VLT optical observations
- GRB 241209A: GOTO optical upper limits
- GRB 241209B: SVOM/ECLAIRs and GRM detection of a long burst
- EP241208a: EP detection of a fast X-ray transient
- GRB 241209A: Swift detection of a short burst
- GRB 241207B: Swift/BAT-GUANO localization skymap of a short burst
- GRB 241206A: DDOTI Upper Limit on the Afterglow
- EP241206a: BOOTES Global Network optical limits
- EP241206a: EP detection of a fast X-ray transient
- GRB 241206A: Swift/BAT-GUANO localization skymap of a burst
- GRB 241206B: SVOM/ECLAIRs detection of a long soft transient
- EP241201a: 1.6m Mephisto Optical Upper Limits
- GRB 241204A: COLIBRÍ Optical Upper Limit
- EP241202b: KAIT optical upper limit
- GRB 241204A: DDOTI Upper Limits on the Afterglow
- GRB 241201A: GRBAlpha detection
- GRB 241204A: Fermi-LAT detection
- IceCube-241127A: No transient candidates from the Zwicky Transient Facility
- EP241202b: Kinder optical counterpart candidate
- Konus-Wind detection of GRB 241130A
- EP241201a: BOOTES-5 optical upper limit
- EP241202b: EP detection of a fast X-ray transient