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').
Advanced Search
To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.
Advanced Search Examples (click to copy):
subject:"Swift"body:"GRB"submitter:"Judith Racusin"32485 results found.
- GRB 250103B:SVOM/VT optical counterpart
- 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: Redshift 4.01 from OSIRIS+/GTC
- GRB 250103A: NOT optical 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
- Swift GRB 250103B: Global MASTER-Net observations report
- GRB 250103A: SVOM/VT optical counterpart confirmation
- EP250101a: Liverpool Telescope optical upper limit
- GRB 250103A: Swift ToO observations
- IceCube-250101A: Upper limits from a search for additional neutrino events in IceCube
- GRB 250101a: Liverpool Telescope optical follow-up
- GRB 250103B: SVOM detection of a long burst
- GRB 250103A: Xinglong 2.16m Optical Candidate
- Fermi GRB 250102A: Global MASTER-Net observations report
- 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
- EP250101a: Xinglong optical upper limit
- 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: GMG spectroscopic redshift at z ~ 2.481
- GRB 250101A: Swift/UVOT Detection
- GRB 250101A: 1.6m Mephisto multi-band optical followup
- GRB 250101A: Montarrenti Observatory optical observations and rebrightening
- GRB 250101A: LCOGT optical afterglow detection
- GRB 250101A: OASDG optical observations
- Fermi GRB 250101B: Global MASTER-Net observations report
- GRB 250101A: SAO RAS observations of optical brightening
- GRB 250101A: AKO Optical Afterglow Detection
- GRB 250101A: SAO RAS optical observations
- LIGO/Virgo/KAGRA S250101k: Updated Sky localization and Source Classification
- GRB 250101A: Xinglong-2.16m spectroscopic redshift
- GRB 250101A: SVOM/C-GFT early optical observations
- LIGO/Virgo/KAGRA S250101k: Upper limits from Fermi-GBM Observations
- GRB 250101A: MASTER earlier OT observations with SOSS emission features
- GRB 250101A: Nanshan/HMT optical observations
- GRB 250101A : GIT optical detection
- GRB 250101A: GMG Optical Observation
- GRB 241217a/EP241217b: ATCA Radio Detection
- EP241217a: VLA Radio Detection
- LIGO/Virgo/KAGRA S250101k: Identification of a GW compact binary merger candidate
- GRB 241229B: Continued CrAO ZTSh observations
- LIGO/Virgo/KAGRA S241231bg: Updated Sky localization and EM Bright Classification
- LIGO/Virgo/KAGRA S241230ev: Updated Sky localization
- LIGO/Virgo/KAGRA S241230bd: Updated Sky localization
- GRB 241229A: EP-FXT X-ray afterglow confirmation
- 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 241229B: CrAO ZTSh possible optical counterpart of SVOM/VT confirmation
- GRB 241229A: SAO RAS optical observations
- GRB 241229B: SVOM/VT optical candidate
- GRB 241229A: Swift-XRT observations
- Konus-Wind detection of GRB 241228A
- GRB 241229A: EP-FXT afterglow candidates
- 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: D50 optical detection
- GRB 241228B: Fermi GBM Observation
- GRB 241229B: Fermi GBM Observation
- GRB 241229A: Swift ToO observations
- GRB 241229B: NUTTelA-TAO / BSTI Optical Limits
- GRB 241228A: Mondy optical afterglow observations
- IceCube-241224A: No transient candidates from the Zwicky Transient Facility
- Swift GRB 241229B: Global MASTER-Net observations report
- 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
- Fermi GRB 241228B: Global MASTER-Net observations report
- GRB 241228A: Fermi GBM Observation
- GRB241228B: GROWTH-India Telescope optical observations
- Swift GRB 241228A: Global MASTER-Net observations report
- GRB 241228B: LCOGT photometry of the likely optical counterpart GOTO24jmz
- GRB 241228B: GOTO24jmz optical follow-up observations
- GRB 241226A: Swift/BAT-GUANO localization skymap of a burst
- GRB 241228A: GROWTH-India telescope optical upper limit
- GRB 241228B: Swift ToO observations
- GRB 241228B: TRT optical counterpart confirmation
- GRB 241228A: Swift/UVOT Upper Limits