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').
23918 results found.
- IceCube-250101A: Upper limits from a search for additional neutrino events in IceCube
- GRB 250101a: Liverpool Telescope optical follow-up
- GRB 250103B: Swift detection of a burst
- GRB 250103A: Xinglong 2.16m Optical Candidate
- GRB 250101B: SVOM/GRM observation
- GRB 250103A: GOTO optical upper limit
- GRB 250103A: SVOM/C-GFT optical upper limit
- GRB 250101A: NUTTelA-TAO / BSTI Optical Limits
- EP241231b: optical upper limit with the Liverpool Telescope
- GRB 250103A: SVOM detection of a long burst (duplicate submission)
- GRB 250103A: SVOM detection of a long burst
- EP250101a: Xinglong optical upper limit
- LIGO/Virgo/KAGRA S241230bd: Upper limits from Swift/BAT-GUANO
- GRB 250101A: Swift-BAT refined analysis
- GRB 250101A: further SAO RAS optical observations
- GRB 250101A: LCO optical counterpart detection
- GRB 250101A NUTTelA-TAO / BSTI Early Measurements
- GRB 250101A: Swift/UVOT Detection
- GRB 250101A: 1.6m Mephisto multi-band optical followup
- GRB 250101A: Swift-XRT refined Analysis
- GRB 250101A: Montarrenti Observatory optical observations and rebrightening
- GRB 250101A: LCOGT optical afterglow detection
- GRB 250101A: OASDG optical observations
- GRB 250101B: Fermi GBM Final Real-time Localization
- GRB 250101A: SAO RAS observations of optical brightening
- GRB 250101A: BOOTES-4/MET optical afterglow detection
- GRB 250101A: AKO Optical Afterglow Detection
- GRB 250101A: SAO RAS optical observations
- GRB 250101A: Enhanced Swift-XRT position
- LIGO/Virgo/KAGRA S250101k: Updated Sky localization and Source Classification
- GRB 250101A: SVOM/C-GFT early optical observations
- LIGO/Virgo/KAGRA S250101k: Upper limits from Fermi-GBM Observations
- GRB 250101A: Nanshan/HMT optical observations
- GRB 250101A : GIT optical detection
- GRB 250101A: GMG Optical Observation
- GRB 250101A: Swift detection of a burst with an optical counterpart
- LIGO/Virgo/KAGRA S241231du: Coverage and upper limit from MAXI/GSC observations
- LIGO/Virgo/KAGRA S250101k: Identification of a GW compact binary merger candidate
- GRB 241229B: Continued CrAO ZTSh observations
- LIGO/Virgo/KAGRA S241231bg: Updated NED Galaxies in the Localization Volume
- LIGO/Virgo/KAGRA S241231bg: Updated Sky localization and EM Bright Classification
- LIGO/Virgo/KAGRA S241230ev: Updated Sky localization
- LIGO/Virgo/KAGRA S241231bg: NED Galaxies in the Localization Volume
- LIGO/Virgo/KAGRA S241230bd: Updated Sky localization
- GRB 241228B: Multiband optical monitoring with 1.6m Mephisto
- GRB 241229B: SVOM/GRM observation
- LIGO/Virgo/KAGRA S241231bg: Identification of a GW compact binary merger candidate
- EP241217A: J band upper limit by SYSU 80cm telescope
- LIGO/Virgo/KAGRA S241230ev: Identification of a GW compact binary merger candidate
- GRB 241229B: SAO RAS optical upper limit
- GRB 241228B: SAO RAS optical observations
- GRB 241229A: SAO RAS optical observations
- IceCube-Cascade 241228A: Upper limits from a search for additional neutrino events in IceCube
- GRB 241229A: Swift-XRT observations
- EP240702a: 7DT Optical upper limits
- GRB 240606B: 7DT Optical upper limits
- LIGO/Virgo/KAGRA S241230bd: Identification of a GW compact binary merger candidate
- GRB 241229B: Swift-BAT refined analysis
- LIGO/Virgo/KAGRA S241225v: Updated Sky localization
- LIGO/Virgo/KAGRA S241225c: Updated Sky localization and EM Bright Classification
- GRB241229B: UVOT upper limits
- GRB 241228B: Fermi GBM Observation
- GRB 241228B: Swift-XRT afterglow detection
- GRB 241229B: Fermi GBM Observation
- GRB 241229B: NUTTelA-TAO / BSTI Optical Limits
- GRB 241228A: Mondy optical afterglow observations
- GRB 241229A: GOTO optical upper limits
- GRB 241228B: VLT/X-shooter redshift of z = 2.674
- GRB 241228A: NOT optical upper limits
- GRB 241228B: LCO optical observation
- GRB 241228A: Swift-BAT refined analysis
- GRB 241228B: Swift/BAT-GUANO localization skymap of a burst
- GRB 241228A: Fermi GBM Observation
- GRB241228B: GROWTH-India Telescope optical observations
- GRB 241228B: LCOGT photometry of the likely optical counterpart GOTO24jmz
- GRB 241226A: Swift/BAT-GUANO localization skymap of a burst
- GRB 241228A: GROWTH-India telescope optical upper limit
- GRB 241228B: TRT optical counterpart confirmation
- GRB 241228A: Swift-XRT refined Analysis
- GRB 241228A: Swift/UVOT Upper Limits
- GRB 241228A: Enhanced Swift-XRT position
- GRB 241228A: Swift detection of a burst
- IceCube-241224A: Upper limits from a search for additional neutrino events in IceCube
- LIGO/Virgo/KAGRA S241225c: Two counterpart neutrino candidates from IceCube neutrino searches
- 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
- Fermi trigger No 756678579: Global MASTER-Net observations report
- 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