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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').
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"
  1. LIGO/Virgo S190408an: GRAWITA optical observations of MASTER OT J231043.63+470956.4
  2. GRB 190404C: MITSuME Akeno and Okayama optical upper limits
  3. LIGO/Virgo S190408an: CALET Observations
  4. LIGO/Virgo S190408an: TMTS Optical Observation
  5. LIGO/Virgo S190408an: DDOTI/OAN Optical Observations
  6. LIGO/Virgo S190408an: HMT optical observations
  7. LIGO/Virgo S190408an: MASTER 3 OT's more detection
  8. Konus-Wind observation of GRB 190404B
  9. LIGO/Virgo ST190408an: Fermi-LAT search for a high-energy gamma-ray counterpart
  10. GRB 190409A: Swift detection of a possible burst
  11. LIGO-Virgo S190408an: further AGILE GRID observations after T0
  12. LIGO/Virgo S190408an: SAGUARO follow-up observations
  13. LIGO/Virgo S190408an: MASTER OT is 27 day old ATLAS SN candidate and unrelated
  14. LIGO/Virgo S190408an: Insight-HXMT/HE observation
  15. LIGO/Virgo S190408an: MASTER OT detection
  16. LIGO/Virgo S190408an: Swift/BAT data search
  17. LIGO/Virgo S190408an: KMTNet observation
  18. CORRECTED TARGET NAME: GRB 190408A: MAXI/GSC detection
  19. GRB 140408A: MAXI/GSC detection
  20. LIGO-Virgo S190408an: AGILE GRID observations
  21. LIGO/Virgo S190408an: MASTER Global Robotic Net optical observations
  22. LIGO/Virgo S190408an: Identification of a GW binary merger candidate
  23. Search for neutrino counterparts to GW candidate S190408an with IceCube
  24. LIGO-Virgo S190408an: HAWC follow-up
  25. INTEGRAL observation of S190408an
  26. LIGO/Virgo S190408an: Fermi GBM Observation
  27. LIGO-Virgo GW S190408an: J-GEM optical/NIR follow-up observations
  28. LIGO-Virgo S190408an: AGILE MCAL observations
  29. GRB 190404C: Swift-XRT afterglow detection
  30. Fermi Gamma-ray Burst Monitor trigger 576420743/190408536 is not a GRB
  31. Fermi TriggNum 576054086 (GRB 1904204.29) / MASTER OT J071404.52+550304.2: CrAO optical observations
  32. Fermi Trigger 576356086 / GRB 190407788 / : BALROG localization
  33. Hard Fermi GRB190404.29/TriggNum576054086: MASTER optical counterpart discovery near PGC020455
  34. Fermi Trigger 576346051 / GRB 190407672 / GRB 190407A: BALROG localization
  35. GRB190404C: Counterpart retraction
  36. GRB 190404B: CALET Gamma-Ray Burst Monitor detection
  37. GRB 190404C: Swift-XRT observations
  38. GRB 190331C: AstroSat CZTI detection
  39. Swift GRB 190331B: Further Swift-XRT observations
  40. GRB190404C: GROWTH-India discovery of optical counterpart
  41. GRB 190404B: Tiled Swift observations
  42. GRB 140404C: MAXI/GSC detection
  43. GRB 140404B: MAXI/GSC detection
  44. GRB 190330A: MITSuME Akeno and Okayama optical upper limits
  45. Trigger 896552: Swift detection of PSR B1055-52
  46. LIGO/Virgo: Announcing the start of Observing Run 3 (O3) and the beginning of the public gravitational-wave alert era
  47. Konus-Wind observation of GRB 190329A
  48. GRB 190331B: BOOTES-3/YA optical observations
  49. GRB 190326B: AstroSat CZTI detection
  50. GRB 190331B: Swift observations of a ground-detected burst
  51. Fermi-LAT Gamma-ray Observations of IceCube-190331A
  52. Search for additional neutrino events from the direction of IceCube-190331A with IceCube
  53. GRB 190401A: Insight-HXMT/HE detection
  54. GRB 190331C: Insight-HXMT/HE detection
  55. GRB 190331A: Insight-HXMT/HE detection
  56. GRB 190330A: Insight-HXMT/HE detection
  57. IceCube-190331A: MASTER optical follow-up observations
  58. GRB 190329A: CALET Gamma-Ray Burst Monitor detection
  59. GRB 190331A: Fermi GBM detection
  60. GRB 190331B: Swift ToO observations
  61. GRB 190331A, Swift-BAT refined analysis
  62. IPN Triangulation of GRB 190329A (long/bright)
  63. IceCube-190331A - IceCube observation of a high-energy neutrino candidate event
  64. GRB 190331A: Swift detection of a burst
  65. Fermi Trigger 575656777 / GRB 190330694 / GRB 190330A: BALROG localization
  66. GRB 190323A: AstroSat CZTI detection
  67. MAGIC follow-up of the X-ray flares of LS I +61�303 dete
  68. GRB 190326A: 2.2m CAHA telescope optical limit
  69. Swift Trigger 895503 is not a GRB
  70. Swift Trigger 895479: Detection of GRO J2058+42
  71. GRB 190326A: Swift-BAT refined analysis - a soft-short GRB or an SGR
  72. GRB 190326B: Insight-HXMT/HE detection
  73. GRB 190326A: Insight-HXMT/HE detection
  74. Swift Trigger 895257: Detection of GRO J2058+42 in outburst
  75. GRB 190326A: MITSuME Okayama optical upper limits
  76. Konus-Wind observation of GRB 190324A
  77. GRB 190324A: Swift/UVOT Observations
  78. GRB 190326B: Fermi GBM detection
  79. GRB 190324B: Insight-HXMT/HE detection
  80. GRB 190324A: Insight-HXMT/HE detection
  81. Fermi Trigger 575278303 / GRB 190326314 / GRB190326B: BALROG localization
  82. GRB 190326A: Swift detection of a short burst
  83. Fermi Trigger 575251142 / GRB 190325999 / GRB 190325A: BALROG localization
  84. GRB 190324A: Swift-BAT refined analysis
  85. GRB 190324A: CALET Gamma-Ray Burst Monitor detection
  86. GRB 190323A: Insight-HXMT/HE detection
  87. GRB 190324A: Swift-XRT refined Analysis
  88. GRB190324A: MASTER OT observations
  89. GRB 190324A: Fermi GBM observation
  90. GRB 190324A: Enhanced Swift-XRT position
  91. Further Chandra observations of GW170817 ~581-583 days since merger
  92. GRB 190324A: VLT/X-shooter redshift
  93. GRB 190321A: Insight-HXMT/HE detection
  94. GRB 190324A: Swift-XRT observations
  95. GRB 190324A: Swift/UVOT afterglow candidate
  96. SWIFT GRB190324.95 Global MASTER-Net observations report
  97. Fermi Trigger 575160247 / GRB 190324947: BALROG localization
  98. GRB 190324A: Swift detection of a burst
  99. Fermi Trigger 575108474 / GRB 190324348: BALROG localization
  100. SWIFT GRB190323.85 Global MASTER-Net observations report

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