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').
32051 results found.
- GRB 250221A: GRANDMA/TAROT Detection
- Fermi Gamma-ray Burst Monitor trigger 761867337/250221909 is not a GRB
- GRB 250221A: Swift-XRT refined Analysis
- GRB 250221A: NOT optical observations
- GRB 250221A: 1.6m Mephisto optical detection
- GRB 250221A: AKO Optical Upper Limit
- GRB 250221A: Swift/UVOT Detection
- GRB 250219A: GRANDMA/Kilonova-Catcher upper limits
- GRB 250221A: REM optical/NIR afterglow detection
- GRB 250221A: Enhanced Swift-XRT position
- GRB 250221A: COLIBRÍ/DDRAGO Confirmation of a Bright Optical Counterpart
- GRB 250221A: Swift detection of a burst with an optical counterpart
- Fermi Gamma-ray Burst Monitor trigger 761788229/250220993 is not a GRB
- GRB 250220B: Fermi GBM Final Real-time Localization
- Fermi Gamma-ray Burst Monitor trigger 761782146/250220923 is not a GRB
- GRB 250220A: Fermi GBM Final Real-time Localization
- Konus-Wind detection of GRB 250217C (short)
- GRB 250219A: Swift/UVOT Upper Limits
- GRB 250219A: OHP/T193 optical upper limit
- GRB 250219A: NOT optical observations
- GRB 250219A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
- GRB 250219A: 1.6m Mephisto optical upper limits
- GRB 250219A: SVOM/VT optical counterpart
- GRB 250219A: Swift-XRT observations
- GRB 250219A: Swift ToO observations
- GRB 250219A: SVOM detection of a burst
- Konus-Wind detection of GRB 250215A / EP250215a
- GRB 250217C: Swift-XRT observations
- GRB 250217C: COLIBRÍ/DDRAGO Upper Limits on the Optical Counterpart
- GRB 250217C: DDOTI Upper Limits on the Optical Afterglow
- GRB 250217C: SVOM/GRM observation
- GRB 250217C: Tiled Swift observations
- GRB 250217C: Fermi GBM Observation
- GRB 250215A / EP250215A: Encouraging Follow-up Observations of a BdHN I with a Rest-Frame Duration 2.3 s at z=4.61
- IPN triangulation of GRB 250217C (short)
- GRB 250213A: Swift-XRT observations
- LIGO/Virgo/KAGRA S250206dm: AZT-33IK Target Optical Observations
- GRB 250216A: AstroSat CZTI detection
- GRB 250217C: AstroSat CZTI detection of a short burst
- Fermi GRB 250217C: Global MASTER-Net observations report
- GRB 250217C: Fermi GBM Final Real-time Localization
- LIGO/Virgo/KAGRA S250206dm: observation in AbAO, optical transient near NED/GLADE+ galaxy WISEA J021210.14+514821.7
- Fermi GRB 250217A: Global MASTER-Net observations report
- GRANDMA/OPD observations of GRB250215A
- GRB 250217B: Fermi GBM Final Real-time Localization
- GRB 250217A: Fermi GBM Final Real-time Localization
- Fermi GRB 250216A: Global MASTER-Net observations report
- GRB 250215A / EP250215a: LCO detection of the afterglow
- GRB 250216A: Fermi GBM Final Real-time Localization
- GRB 250215A: Swift/UVOT Upper Limits
- GRB 250215A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
- EP250215a / GRB 250215A : GTC redshift z = 4.61
- GRB 250215A: Fermi GBM Observation
- EP250215a / GRB 250215A : NOT optical observations
- GRB 250215A/EP250215a: 1.6m Mephisto optical observation report
- GRB 250215A / EP250215a: Gemini-South optical observation of a likely rebrightening
- GRB 250213A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
- GRB 250215A: Swift-XRT refined Analysis
- GRB 250215A: SVOM/GRM observation
- EP250215a / GRB 250215A: AstroSat CZTI detection
- GRB 250215A / EP250215a: SVOM/VT optical candidate comfirmation
- EP250215A/GRB 250215A: INTEGRAL SPI-ACS detection
- EP250215a / GRB 250215A (potentially): NOT likely optical counterpart
- EP250215a: EP-WXT detection and FXT follow-up observation of an X-ray transient
- Fermi GRB 250215A: Global MASTER-Net observations report
- GRB 250215A: Fermi GBM Final Real-time Localization
- GRB 250213A：SVOM/VT optical candidate
- Fermi Gamma-ray Burst Monitor trigger 761206993/250214266 is not a GRB
- Fermi GRB 250214A: Global MASTER-Net observations report
- GRB 250213A: Swift ToO observations
- GRB 250214A: Fermi GBM Final Real-time Localization
- GRB 250213A: SVOM detection of a burst
- GRB 250205A: VIRT Optical Upper Limit
- GRB 250205A: Leavitt Observatory optical upper limit
- GRB 250210A: GRBAlpha detection
- Fermi GRB 250212A: Global MASTER-Net observations report
- GRB 250205A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
- GRB 250211A: SVOM trigger sb25021103 is not a GRB
- GRB 250211B: A long GRB detected by INTEGRAL
- GRB 250211A: Swift ToO observations
- GRB 250212A: Fermi GBM Final Real-time Localization
- GRB 250207A: Fermi GBM Observation
- GRB 250206A: Fermi GBM Observation
- GRB 250205A / EP250205A: radio detection with the VLA
- Konus-Wind detection of GRB 250207A
- Konus-Wind detection of GRB 250206A
- GRB 250210A: SVOM/GRM observation of a long burst
- Fermi Gamma-ray Burst Monitor trigger 760945500/250211240 is not a GRB
- GRB 250207A: Skynet optical afterglow observations
- GRB 241128A: VIRT Optical Upper Limit
- EP250207A: Upper limits from Fermi-GBM Observations
- GRB 250210A: INTEGRAL SPI-ACS detection
- GRB 250210A: AstroSat CZTI detection
- GRB 250209A: MAXI/GSC detection (possible detection of an X-ray flare from 1RXS J145110.3+310648)
- Fermi GRB 250210A: Global MASTER-Net observations report
- GRB 250210A: Fermi GBM Final Real-time Localization
- LIGO/Virgo/KAGRA S250206dm: Upper limits from GECAM Observations
- GRB 250204B: GRBAlpha detection
- GRB 250204A: GRBAlpha detection
- GRB 250207A: 1.3m DFOT Optical observations