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').
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"- GRB 180210A: Swift-XRT afterglow detection
- GRB 180210A: Tiled Swift observations
- GRB 180205A: BAO optical observations
- Retraction of Swift trigger 809374
- GRB 180210A: Swift ToO observations
- GRB 180210A: Fermi-LAT detection
- GRB 180210A: Fermi GBM detection
- Trigger 809374: Swift detection of a possible non-burst faint source
- Trigger 809217: Swift trigger on RS CVn Star HD 8357
- GRB180205A: Optical observations with DOAO 1m telescope
- GRB 180205A: AbAO optical observations
- Fermi-GBM Detection of possible burst from AXP CXOU J164710.2-455216/PSR J1647-4552
- GRB 180205A optical observations
- GRB 180202A: Insight-HXMT/HE detection
- GRB 180204A: MITSuME Okayama optical upper limits
- GRB 180205A: confirmation of Swift-BAT trigger time.
- GRB 180205A: Optical observations
- GRB 180205A: Swift/UVOT Detection
- GRB 180205A: Nanshan-1m optical observations
- GRB 180205A: Swift-XRT refined Analysis
- GRB 180205A: Swift-BAT refined analysis
- GRB 180205A: Xinglong TNT optical observation
- GRB 180205A: Further GROND Observations reveal Afterglow is still bright
- GRB 180205A: Nickel telescope optical observations
- Swift Trigger on AXP CXOU J164710.2-455216/PSR J1647-4552
- GRB 180205A: VLT polarimetry
- GRB 180205A: Mondy optical observations
- GRB 180205A: Fermi GBM observation
- Konus-Wind observation of GRB 180204A
- GRB 180205A: VLT/X-shooter redshift
- GRB 180205A: GROND detection of the NIR/optical afterglow
- GRB 180205A: KAIT optical afterglow confirmation
- GRB 180205A: Swift detection of a burst with a bright optical counterpart
- GRB 180204A: Swift-BAT refined analysis
- GRB 180204A: Swift/UVOT Upper Limits
- GRB 180204A: Fermi GBM detection
- GRB 180204A: Enhanced Swift-XRT position
- GRB 180204A: Swift-XRT refined Analysis
- GRB 180204A: Swift detection of a short burst
- GW170817/GRB170817A: Updated results from the full Chandra dataset
- GRB 180126A CALET Gamma-Ray Burst Monitor detection
- GW170817/GRB170817A: Preliminary results of Chandra monitoring
- LIGO/Virgo GW170817: Chandra X-ray Emission Continues to Rise ~156 Days Post-Merger
- GRB 180120A: AstroSat CZTI detection
- Fermi GBM trigger 538030981/180119210 is not a GRB
- LIGO/Virgo G298048 GRAWITA: VST-ESO PARANAL follow up of AT2017gfo
- GRB 180120A: Fermi GBM Detection
- GRB 180120A CALET Gamma-Ray Burst Monitor detection
- Fermi GBM trigger 538316685/180122517 is not a GRB
- GRB 180113B: AstroSat CZTI detection
- GRB 180113A: AstroSat CZTI detection
- GRB 180115A: SEDM Observations
- GRB 180116A CALET Gamma-Ray Burst Monitor detection
- Konus-Wind observation of GRB 171209A
- GRB 180113A CALET Gamma-Ray Burst Monitor detection
- GRB 180112A CALET Gamma-Ray Burst Monitor detection
- GRB 180115A: Swift/UVOT Detection
- GRB 180116A: Fermi GBM Detection
- Konus-Wind observation of GRB 180113B
- IPN Triangulation of GRB 180113B
- GRB 180112A: Insight-HXMT/HE detection/observation
- GRB 180111A AROMA-N optical observation
- Konus-Wind observation of GRB 180113C
- e-MERLIN detection of GRB 171205A
- IPN Triangulation of GRB 180113C
- GRB 180115A: Swift-BAT refined analysis
- GRB 180116A: MAXI/GSC detection
- GRB 180115A: Redshift from OSIRIS/GTC
- GRB 180115A: NOT detection of optical counterpart
- Konus-Wind observation of GRB 180113A
- GRB 180113C: Insight-HXMT/HE observation
- GRB 180113B: Insight-HXMT/HE observation
- GRB 180111A: Insight-HXMT/HE observation
- GRB 180115A: MITSuME Akeno optical upper limits
- GRB 180113A: Swift ToO observations
- GRB 180115A: Swift-XRT refined Analysis
- GRB 180115A: Enhanced Swift-XRT position
- Konus-Wind observation of GRB 180111A
- GRB 180115A: Swift detection of a burst with an optical counterpart.
- GRB 180113C: Fermi GBM detection
- GRB 180111A CALET Gamma-Ray Burst Monitor detection
- GRB 180113A: Swift-BAT refined analysis
- GRB 180111A: AbAO optical observations
- GRB 180113A: KAIT Optical Observations
- GRB 180113B: Fermi GBM detection
- GRB 180113A: Fermi GBM observation
- GRB 180111A: Swift/UVOT Detection
- GRB 180103A: Swift-XRT afterglow detection
- GRB 180113A: Swift detection of a burst
- GRB 180111A: Swift-BAT refined analysis
- GRB 180111A: RATIR Optical and NIR Observations
- GRB 180111A: Swift-XRT refined Analysis
- GRB 180111A: AGILE/MCAL detection
- GRB180111A: Xinglong TNT possible optical detection
- GRB 180111A: Enhanced Swift-XRT position
- GRB 180111A: Swift detection of a burst with an optical counterpart
- Correction to GCN Circular 22316: GRB 171230B: Insight-HXMT detection
- GRB 171230B: Insight-HXMT/HE detection
- GRB 180103A: LCO Sutherland 1-m telescope observations
- Konus-Wind observation of GRB 180103A