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.
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
23953 results found.
- GRB 250108A: Swift-XRT afterglow detection
- GRB 250108A:SVOM/VT optical candidate
- LIGO/Virgo/KAGRA S250108eo: Identification of a GW compact binary merger candidate
- GRB 250108B: Swift/UVOT Upper Limits
- GRB 250103A: Swift-XRT afterglow detection
- GRB 250108B: Enhanced Swift-XRT position
- GRB 250108B: Swift detection of a burst
- GRB 250107A: Fermi GBM Observation
- GRB 250107A: Swift/BAT-GUANO arcminute localization of a burst
- GRB 250106A: SVOM/VT 2nd optical deep observation
- GRB 250101A: J band upper limit by SYSU 80cm telescope
- EPWXT01709129925: Xinglong optical observations
- GRB 250106A: NOT optical observations
- LIGO/Virgo/KAGRA S250104v: Updated Sky localization
- GRB 250103B: REM optical/NIR upper limits
- GRB 250101A: REM optical/NIR counterpart detection
- GRB 250106A: Swift-XRT observations
- GRB 250106A: SVOM/VT optical candidate
- The EP-WXT trigger 01709129925 is likely a flaring star
- GRB 250103B: Swift-XRT refined Analysis
- GRB 250103B: LCO/1m optical afterglow candidate detection
- GRB 250103A: Bassano Bresciano Observatory upper limit
- GRB 250103A: Swift-XRT observations
- GRB 250101A: 1.3m DFOT optical afterglow detection
- GRB 241229A: 1.3m DFOT upper limit
- GRB 241228B: 1.3m DFOT Optical observations
- GRB 241228A: 1.3m DFOT upper limit
- LIGO/Virgo/KAGRA S250104v: Identification of a GW compact binary merger candidate
- GRB 250103A: Montarrenti Observatory optical detection
- GRB 250101A: further LCOGT optical afterglow observations
- GRB 250103A: TSHAO optical upper limit
- GRB 250103A: Fermi GBM Observation
- GRB 250103B: LCOGT Optical Upper Limit
- IceCube-250102A: Upper limits from a search for additional neutrino events in IceCube
- EP250101a: Liverpool Telescope optical upper limit
- 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