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"22056 results found.
- LIGO/Virgo S230621ad: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S230615az: LBT spectroscopic redshift of the host galaxy of GOTO23hn
- ZTF23aaoohpy/AT2023lcr: SAO RAS observations
- Fermi trigger No 709083929: Global MASTER-Net observations report
- AT2023lcr: VLA radio detection
- ZTF23aaoohpy/AT2023lcr: Montarrenti Observatory optical observations
- ZTF23aaoohpy (AT2023lcr/ATLAS23msn): Upper limits from Konus-Wind observations
- LIGO/Virgo S230620ad: Global MASTER-Net observations report
- ZTF23aaoohpy (AT2023lcr/ATLAS23msn): Swift/UVOT detection
- LIGO/Virgo S230620au: Global MASTER-Net observations report
- ZTF23aaoohpy/AT2023lc: Mondy optical observations
- AT2023lcr: Neil Gehrels Swift Observatory X-ray detection
- AT2023lcr (ATLAS23msn/ZTF23aaoohpy): Kinder observations with Lulin observatory and a probable plateau in the g-band light curve
- AT2023lcr: Pan-STARRS & ATLAS Observations
- ZTF23aaoohpy/AT2023lcr: Keck/LRIS spectroscopy and redshift
- ZTF23aaoohpy/AT2023lcr: Xinglong-2.16m optical observations
- LIGO/Virgo/KAGRA S230615az: Wendelstein observations of DESI galaxies and GIT candidates
- LIGO/Virgo S230620al: Global MASTER-Net observations report
- LIGO/Virgo S230620af: Global MASTER-Net observations report
- LIGO/Virgo S230620z: Global MASTER-Net observations report
- LIGO/Virgo S230620w: Global MASTER-Net observations report
- LIGO/Virgo S230619bg: Global MASTER-Net observations report
- LIGO/Virgo S230620g: Global MASTER-Net observations report
- LIGO/Virgo S230619ay: Global MASTER-Net observations report
- ZTF23aaoohpy/AT2023lcr: Liverpool Telescope detection
- ZTF23aaoohpy/AT2023lcr: OHP/T193 and OHP/T120 optical follow-up observations
- LIGO/Virgo S230619bd: Global MASTER-Net observations report
- LIGO/Virgo S230619bb: Global MASTER-Net observations report
- LIGO/Virgo S230619as: Global MASTER-Net observations report
- LIGO/Virgo S230619ap: Global MASTER-Net observations report
- ZTF23aaoohpy/AT2023lcr: GROWTH-India Telescope follow-up observations
- GRB 230618A: Osservatorio Astronomico Nastro verde upper limit
- ZTF23aaoohpy/AT2023lcr: GOTO early optical observations and constraint
- ZTF23aaoohpy/AT2023lcr: Zwicky Transient Facility discovery of a fast fading red transient
- LIGO/Virgo S230619i: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S230615az: GRANDMA observations of GOTO and GIT candidates
- LIGO/Virgo S230619aa: Global MASTER-Net observations report
- LIGO/Virgo S230619x: Global MASTER-Net observations report
- LIGO/Virgo S230619e: Global MASTER-Net observations report
- LIGO/Virgo S230618at: Global MASTER-Net observations report
- LIGO/Virgo S230618ba: Global MASTER-Net observations report
- LIGO/Virgo S230618az: Global MASTER-Net observations report
- LIGO/Virgo S230618ae: Global MASTER-Net observations report
- LIGO/Virgo S230618aq: Global MASTER-Net observations report
- LIGO/Virgo S230618y: Global MASTER-Net observations report
- LIGO/Virgo S230618s: Global MASTER-Net observations report
- GRB 230618A: Swift/UVOT Upper Limits
- GRB 230616A: Swift-XRT observations
- LIGO/Virgo S230618r: Global MASTER-Net observations report
- LIGO/Virgo S230616aa: Global MASTER-Net observations report
- LIGO/Virgo S230615an: Global MASTER-Net observations report
- LIGO/Virgo S230615ak: Global MASTER-Net observations report
- GRB 230618A: KAIT Optical Observations
- LIGO/Virgo S230617ba: Global MASTER-Net observations report
- LIGO/Virgo S230618k: Global MASTER-Net observations report
- LIGO/Virgo S230618d: Global MASTER-Net observations report
- LIGO/Virgo S230617bc: Global MASTER-Net observations report
- LIGO/Virgo S230617aq: Global MASTER-Net observations report
- LIGO/Virgo S230617ab: Global MASTER-Net observations report
- Swift GRB 230618A: Global MASTER-Net observations report
- LIGO/Virgo S230617aj: Global MASTER-Net observations report
- GRB230618A: LCOGT Optical Observations
- GRB 230616A: Swift ToO observations
- LIGO/Virgo/KAGRA S230615az: T80S Search and Candidate Counterpart Identification
- LIGO/Virgo/KAGRA S230615az: Non-Detections of GROWTH-India Candidates from GECKO Optical Observations
- GRB 230616A: Swift/BAT-GUANO detection of a short burst outside the coded FOV
- LIGO/Virgo/KAGRA S230615az: Xinglong-2.16m photometric observations of GIT candidates
- LIGO/Virgo/KAGRA S230615az: GOTO candidate counterparts
- LIGO/Virgo S230616s: Global MASTER-Net observations report
- LIGO/Virgo S230615be: Global MASTER-Net observations report
- LIGO/Virgo S230615af: Global MASTER-Net observations report
- LIGO/Virgo S230616j: Global MASTER-Net observations report
- LIGO/Virgo S230615av: Global MASTER-Net observations report
- LIGO/Virgo S230615az: Global MASTER-Net observations report
- LIGO/Virgo S230615ax: Global MASTER-Net observations report
- LIGO/Virgo S230615k: Global MASTER-Net observations report
- LIGO/Virgo S230615t: Global MASTER-Net observations report
- LIGO/Virgo S230615i: Global MASTER-Net observations report
- LIGO/Virgo S230613at: Global MASTER-Net observations report
- LIGO/Virgo S230614ac: Global MASTER-Net observations report
- LIGO/Virgo S230614t: Global MASTER-Net observations report
- LIGO/Virgo S230614o: Global MASTER-Net observations report
- GRB 230614B: Swift/BAT-GUANO detection outside the coded FOV
- Fermi trigger No 708426906: Global MASTER-Net observations report
- GRB 230606A: LCOGT Optical Observations
- LIGO/Virgo S230611be: Global MASTER-Net observations report
- LIGO/Virgo S230611l: Global MASTER-Net observations report
- LIGO/Virgo S230609u: Global MASTER-Net observations report
- LIGO/Virgo S230608aw: Global MASTER-Net observations report
- LIGO/Virgo S230608as: Global MASTER-Net observations report
- LIGO/Virgo S230609a: Global MASTER-Net observations report
- LIGO/Virgo S230608ah: Global MASTER-Net observations report
- LIGO/Virgo S230608q: Global MASTER-Net observations report
- ZTF23aamxeqf/AT2023jxk: 1.3m DFOT Optical upper limit
- Fermi GRB 230603A: Global MASTER-Net observations report
- Fermi trigger No 707039690: Global MASTER-Net observations report
- ZTF and GIT Observations of the Candidate Optical Afterglow AT2023jxk
- LIGO/Virgo/KAGRA S230602ap: Zwicky Transient Facility observations
- GRB 230606A: Swift/UVOT Upper Limits
- LIGO/Virgo S230606z: Global MASTER-Net observations report