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').
19116 results found.
- GRB 241228A: Enhanced Swift-XRT position
- GRB 241228A: Swift detection of a burst
- GRB 241223A: GRBAlpha detection
- GRB 241212A: VZLUSAT-2 detection
- EP241223a: Mondy AZT-33IK optical observations
- GRB 241029A: LCO optical observation
- GRB 241223A: Swift-XRT observations
- LIGO/Virgo/KAGRA S241225v: Identification of a GW compact binary merger candidate
- GRB 241029A: AbAO AS-32 optical observations
- GRB 241223A: Fermi GBM Detection
- LIGO/Virgo/KAGRA S241225c: Identification of a GW compact binary merger candidate
- EP241223a
- EP241223a: EP-WXT detection of a fast X-ray transient
- EP241113a: Non-detection in Radio Follow-up Observations with eMERLIN
- GRB241113A: 7DT Optical upper limits
- GRB 241223A: GOTO optical observations summary
- GRB 241105A: JWST photometric observations of the host galaxy
- EP241217a: e-MERLIN radio observations
- The EP-WXT trigger 01709129287 is likely a flaring star
- EP241217a: Liverpool Telescope optical upper limit
- EP241021a: VLA radio detection
- GRB 241218A: Mondy AZT-33IK optical upper limit
- EP241217a : Leavitt Observatory optical upper limit
- EP241217a: 1.6m Mephisto multi-band optical observations
- GRB 241217a/EP241217B: 1.6m Mephisto optical upper limits
- GRB 241218A: Swift/UVOT Upper Limits
- EP241217a: optical upper limit with the Liverpool Telescope
- GRB 241218A: NOT optical upper limits
- 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