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"
2722 results found.
- Swift GRB230818.98: Global MASTER-Net observations report
- IPN triangulation of GRB 230815B
- Fermi GRB 230814A: Global MASTER-Net observations report
- GRB 230812B: continued AbAO optical afterglow observations
- GRB 230812B: Optical observaions from Rozhen Observatory
- GRB 230812B: GRANDMA further observations of ZTF23aaxeacr candidate afterglow
- GRB 230812B: CrAO ZTSh optical observations
- GRB 230812B: Koshka Zeiss-1000 optical observations
- GRB 230812B: Leavitt Observatory optical observations
- GRB 230812B: Osservatorio Astronomico "Nastro Verde" optical observation
- GRB 230812B: AbAO optical observations
- GRB 230812B: Montarrenti Observatory optical observations
- GRB 230812B: Detected Optical Afterglow Candidate
- GRB 230812B: Zwicky Transient Facility Identifies Optical Afterglow Candidate of a Fermi GRB (Trigger 713559497)
- Fermi GRB 230812B: MASTER optical counterpart
- GRB 230812B: KAIT Optical Afterglow Candidate
- GRB 230812B: Improved Swift/XRT localization
- LAT GRB230812.79: Global MASTER-Net observations report
- Fermi GRB 230812B: Global MASTER-Net observations report
- Fermi trigger No 712991593: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S230731an: AstroSat CZTI non-detection and upper limits
- IceCube-230727A: No candidates from the Zwicky Transient Facility
- IceCube-230724A: No counterparts from the Zwicky Transient Facility
- LIGO/Virgo/KAGRA S230726b: one counterpart neutrino candidate from IceCube neutrino searches
- GRB 230725B: Fermi GBM Final Real-time Localization
- GRB 230723B: Osservatorio Astronomico Nastro Verde upper limit
- IceCube Alert 230724.08: Global MASTER-Net observations report
- Fermi trigger No 710741042: Global MASTER-Net observations report
- IceCube-230707A: No candidates from the Zwicky Transient Facility
- IceCube Alert 230708.35: Global MASTER-Net observations report
- Fermi GRB 230707A: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S230627c: GECKO optical follow-up observations of host galaxy candidates and ZTF23aaptsuy/AT2023lxu
- LIGO/Virgo/KAGRA S230627c: GRANDMA observations of galaxies and ZTF counterpart candidates
- LIGO/Virgo/KAGRA S230627c: Upper limits from Swift/BAT-GUANO
- Fermi GRB 230628D: Global MASTER-Net observations report
- GRB 230628E: Swift detection of a burst
- LIGO/Virgo/KAGRA S230627c: Additional observations from the Zwicky Transient Facility
- LIGO/Virgo/KAGRA S230627c: Zwicky Transient Facility observations and candidates
- IceCube-Cascade 230621A: Upper limits from a search for additional neutrino events in IceCube
- Fermi trigger No 709083929: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S230619bg: one counterpart neutrino candidate from IceCube neutrino searches
- LIGO/Virgo/KAGRA S230615az: Wendelstein observations of DESI galaxies and GIT candidates
- ZTF23aaoohpy/AT2023lcr: Liverpool Telescope detection
- LIGO/Virgo S230619x: Global MASTER-Net observations report
- 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 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 S230617aj: Global MASTER-Net observations report
- GRB 230616A: AstroSat CZTI detection
- LIGO/Virgo/KAGRA S230615az: Xinglong-2.16m photometric observations of GIT candidates
- LIGO/Virgo S230616s: Global MASTER-Net observations report
- LIGO/Virgo S230615be: Global MASTER-Net observations report
- LIGO/Virgo S230615t: Global MASTER-Net observations report
- LIGO/Virgo S230611l: Global MASTER-Net observations report
- LIGO/Virgo S230609u: Global MASTER-Net observations report
- LIGO/Virgo S230609a: Global MASTER-Net observations report
- LIGO/Virgo S230608ah: Global MASTER-Net observations report
- Fermi trigger No 707039690: Global MASTER-Net observations report
- GRB 230506B: Chandra localization of the X-ray afterglow
- GRB 230522A: GRBAlpha and VZLUSAT-2 joint detection
- LIGO/Virgo S230601bf: Global MASTER-Net observations report
- LIGO/Virgo S230531f: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S230529ay: Upper limits from CALET observations.
- LIGO/Virgo S230529ay: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S230529ay: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
- LIGO/Virgo S230525a: Global MASTER-Net observations report
- IceCube Alert 230524.47: Global MASTER-Net observations report
- GRB 230524B: AstroSat CZTI detection
- LIGO/Virgo S230522a: Global MASTER-Net observations report
- LIGO/Virgo S230521k: Global MASTER-Net observations report
- LIGO/Virgo S230520ae: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S230518h: GECKO tiling observations with KMTNet
- LIGO/Virgo/KAGRA S230518h: Swope Search and Candidate Counterpart Identification
- LIGO/Virgo S230518h: Global MASTER-Net observations report
- GRB 230513A: Zwicky Transient Facility continuous observations of a Fermi Short GRB (Trigger 705709044)
- Fermi trigger No 705952199: Global MASTER-Net observations report
- GRB 230513A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 705709044)
- GRB 230512A: GRBAlpha detection
- GRB 230510A: OHP/T193 and OHP/T120 optical observations
- GRB 230512A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 705565670)
- GRB 230430A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 704533643)
- GRB 230510A: Nanshan/NEXT optical afterglow detection
- GRB 230506B: Fermi GBM detection
- GRB 230506B: Swift detection of a burst
- GRB 230506B: Swift detection of a burst
- Fermi trigger No 704837952: Global MASTER-Net observations report
- Konus-Wind detection of GRB 230430A
- IPN triangulation of GRB 230430A (short)
- GRB 230430A: Fermi GBM observation
- GRB 230430A: AstroSat CZTI detection
- GRB 230430A: Fermi GBM Final Real-time Localization
- Fermi trigger No 704365743: Global MASTER-Net observations report
- GRB 230427A : OHP/T193 optical upper limit
- GRB 230426A: Fermi GBM Detection
- Fermi GRB 230409C: Global MASTER-Net observations report