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 180305A: RATIR Optical Observations
- GRB 180305A: Swift/UVOT Upper Limits
- GRB 180305A: Mondy optical observations
- GRB 180305A: Swift-XRT afterglow detection
- Konus-Wind observation of GRB 180305A
- GRB 180305A: RATIR Optical Afterglow Candidate
- GRB 180305A: Swift ToO observations
- GRB 180305A: Fermi GBM detection
- GRB 180305A: Fermi-LAT detection
- GRB 180221B: Insight-HXMT/HE observation
- Fermi GBM trigger 541402602/180227234 is not a GRB
- GRB 180224A: Swift/UVOT Detection
- Konus-Wind observation of GRB 180223A
- GRB 180224A: OASDG optical observations
- IPN Triangulation of GRB 180223A (long)
- GRB 180210A: Insight-HXMT/HE observation
- Swift Trigger 811686 is probably not an astrophysical source.
- GRB 180224A: AbAO optical observations
- GRB 180224A: Swift-BAT refined analysis
- GRB 180224A: RATIR Optical Observations
- GRB 180224A: Swift-XRT refined Analysis
- GRB180224A: Global MASTER-Net bright OT detection
- GRB 180224A: Enhanced Swift-XRT position
- GRB 180224A: Swift detection of a burst with an optical counterpart
- GRB 180218A: AstroSat CZTI detection
- MAXI J1813-095 source: AbAO optical observations
- GRB 180222A: Swift/UVOT Upper Limits
- GRB 180221B CALET Gamma-Ray Burst Monitor detection
- GRB 180222A: Swift-XRT refined Analysis
- GRB 180222A: Swift-BAT refined analysis
- GRB 180222A: Enhanced Swift-XRT position
- GRB 180222A: A long GRB detected by INTEGRAL
- GRB 180222A: Swift detection of a burst
- Swift trigger 811074 (possible GRB 180221A): Swift refined analysis
- Swift Trigger 811167: Detection of MAXI J1813-095
- GRB 180205A: Mondy optical observations
- GRB 180219A CALET Gamma-Ray Burst Monitor detection
- GRB180221A: MASTER-OAFA optical observations
- Swift Trigger 811074: possible GRB 180221A
- Konus-Wind observation of GRB 180218A
- GRB 180218A CALET Gamma-Ray Burst Monitor detection
- GRB 180218A: Fermi GBM Detection
- IPN Triangulation of GRB 180218A (long/bright)
- GRB 180204A: 15 GHz upper limits from AMI
- GRB 180112A: AstroSat CZTI detection
- Fermi GBM triggers 540405116/180215689 and 540476225/180216512 are not a GRBs
- Swift J1658.2-4242: Swift BAT and XRT refined analysis
- Swift trigger 810300: MASTER-OAFA robotic report
- Swift J1658.2-4242 (trigger 810300): Swift-XRT position
- Swift Trigger 810300 is a probable new Galactic source: Swift J1658.2-4242
- Konus-Wind observation of GRB 180210A
- GRB 180205A: SEDM Observations
- 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