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').
- GRB 241209B: SVOM/VT optical continuous fading
- EP trigger ID 01709128824 is not a real source
- GRB 241213A: SVOM/VT optical candidate
- GRB 241213B: Tiled Swift observations
- GRB 241213A: Swift/UVOT Upper Limits
- GRB 241213B: CALET Gamma-Ray Burst Monitor detection
- GRB 241213A: Swift-XRT refined Analysis
- GRB 241212A: Fermi GBM detection
- EP241208a: NOT optical upper limits
- GRB 241212A: Swift ToO observations
- GRB 241213A: LCOGT Optical Upper Limits
- EP 241208A : Detection of a long soft transient by SVOM/ECLAIRs
- EP241213a/GRB241213a: Likely joint detection and INTEGRAL/SPI-ACS counterpart
- GRB 241213B: MAXI/GSC detection
- 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
- LIGO/Virgo/KAGRA S241210fu: Updated Sky localization
- Swift GRB 241213A: Global MASTER-Net observations report
- GRB 241213A: Swift detection of a burst
- GRB 241212A : SVOM/C-GFT optical upper limit at early phase
- GRB 241212A : SVOM/VT bright optical afterglow
- GRB 241212A: AstroSat CZTI detection
- GRB 241209B: GRANDMA/TRT upper limit
- GRB 241207A: TSHAO Zeiss-1000 optical observations
- GRB 241212A: SVOM detection of a bright long burst
- GRB 241212A: Fermi GBM Final Real-time Localization
- GRB 241209B: Mondy AZT-33IK and AbAO AS-32 optical observations
- GRB 241209A: Chandra X-ray Detection
- Konus-Wind detection of GRB 241209B
- GRB 241207A: EIRSAT-1 GMOD Detection
- GRB 241209A: Redshift of the likely host galaxy z = 0.784 from OSIRIS+/GTC
- GRB 241209B: GRBAlpha detection
- GRB 241206C: GRBAlpha detection
- LIGO/Virgo/KAGRA S241210cw: Updated Sky localization
- LIGO/Virgo/KAGRA S241210d: Updated Sky localization and EM Bright Classification
- GRB 241211A: Fermi GBM Final Real-time Localization
- GRB 241129A: Fermi GBM Observation
- GRB 241209B: Swift/BAT-GUANO localization skymap of a burst
- GRB 241209D: REM optical/NIR upper limits
- Konus-Wind detection of GRB 241209D
- GRB 241209B: Swift-XRT afterglow detection
- GRB 241209C: Fermi GBM Observation
- GRB 241209A: Swift-XRT refined Analysis
- Fermi Gamma-ray Burst Monitor trigger 755485387 / 241210044 is not a GRB
- LIGO/Virgo/KAGRA S241210fu: Identification of a GW compact binary merger candidate
- EP241208a: Optical upper limit with Kinder observations
- GRB 241128A: CrAO ZTSh and Mondy AZT-33IK optical observations
- GRB 241209D: AstroSat CZTI detection
- GRB 241209A: EP-FXT follow-up observations
- GRB 241209B: SVOM/VT afterglow detection
- LIGO/Virgo/KAGRA S241210cw: Identification of a GW compact binary merger candidate
- EP241208a: Global MASTER-Net observations report
- EP241208a: EP-FXT follow-up observations
- LIGO/Virgo/KAGRA S241210d: Identification of a GW compact binary merger candidate
- Fermi trigger No 755485387: Global MASTER-Net observations report
- GRB 241207B: Fermi GBM Observation
- GRB 241209A: BOOTES-7 and 2.2m CAHA early optical upper limits
- GRB 241209D: Swift-XRT refined Analysis
- GRB 241209D: Fermi GBM Observation
- GRB 241209A: VLT/HAWK-I near-IR counterpart candidate
- GRB 241209D: COLIBRÍ detection of the afterglow
- GRB 241209A: COLIBRÍ Optical Upper Limit
- Fermi GRB 241209D: Global MASTER-Net observations report
- GRB 241209A: Fermi GBM Observation
- GRB 241209C: Swift/BAT-GUANO localization skymap of a burst
- GRB 241209A: GRANDMA/TAROT upper limit
- GRB 241209B: BOOTES-5 optical upper limit
- Swift GRB 241209D: Global MASTER-Net observations report
- Fermi GRB 241209C: Global MASTER-Net observations report
- Fermi GRB 241209E: Global MASTER-Net observations report
- GRB 241209E: Fermi GBM Final Real-time Localization
- GRB 241209B: Swift ToO observations
- 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 241209C: AstroSat CZTI detection
- GRB 241209D: Swift detection of a burst
- GRB 241209D: Fermi GBM Final Real-time Localization
- GRB 241209A: VLT/X-shooter spectroscopy
- GRB 241209A: Enhanced Swift-XRT position
- GRB 241114B: cubesat Avion detection
- GRB 241209A: VLT optical observations
- Fermi GRB 241209A: Global MASTER-Net observations report
- GRB 241209C: Fermi GBM Final Real-time Localization
- GRB 241209A: GOTO optical upper limits
- EP241206a: 1.5m OSN optical limit
- GRB 241209A: Prompt enhanced Swift-XRT position
- 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
- Swift GRB241209.23: Global MASTER-Net observations report
- GRB 241209A: Fermi GBM Final Real-time Localization
- Fermi GRB 241207B: Global MASTER-Net observations report
- GRB 241207B: Swift/BAT-GUANO localization skymap of a short burst
- Fermi Gamma-ray Burst Monitor trigger 755277791/241207641 is not a GRB
- GRB 241201A: AstroSat CZTI detection
- GRB 241206A: DDOTI Upper Limit on the Afterglow