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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. GRB 190613B: Fermi GBM observation
  2. GRB 190611B: BALROG localization (Fermi Trigger 581986074 / GRB 190611950)
  3. GRB 190613B: Enhanced Swift-XRT position
  4. IPN Triangulation of GRB 190611B
  5. GRB 190613A: Swift-XRT refined Analysis
  6. GRB 190613A: Enhanced Swift-XRT position
  7. GRB 190613B: BALROG localization (Fermi Trigger 582115625 / GRB 190613449)
  8. GRB 190613B: Swift detection of a burst with an optical counterpart
  9. GRB 190613B: Fermi GBM Final Real-time Localization
  10. GRB 190610A: CALET Gamma-Ray Burst Monitor detection
  11. GRB 190609A: AstroSat CZTI detection
  12. GRB 190613A: MASTER OT detection
  13. Swift GRB190613.17 Global MASTER-Net observations report
  14. GRB 190613A: KAIT Optical Afterglow Confirmation
  15. GRB 190613A: BALROG localization (Fermi Trigger 582091643 / GRB 190613172)
  16. GRB 190613A: Fermi GBM Final Real-time Localization
  17. GRB 190613A: Swift detection of a burst with an optical counterpart
  18. Fermi trigger No 582091643 Global MASTER-Net observations report
  19. Fermi trigger No 582012834 Global MASTER-Net observations report
  20. Fermi trigger No 581986074 Global MASTER-Net observations report
  21. GRB 190611B: Fermi GBM detection
  22. GRB 190611A: Swift-XRT refined Analysis
  23. GRB 190611A: Swift/UVOT Upper Limits
  24. GRB 190611A: Optical observations from VLT/FORS2
  25. GRB 190611A, Swift-BAT refined analysis
  26. GRB 190610B: AstroSat CZTI detection
  27. Fermi trigger No 582004649 Global MASTER-Net observations report
  28. GRB 190612A: Fermi GBM Final Real-time Localization
  29. GRB 190611A: Enhanced Swift-XRT position
  30. GRB 190611A: Swift detection of a burst
  31. Konus-Wind observation of GRB 190606A
  32. GRB 190610A: Swift-BAT refined analysis
  33. GRB 190610A: Insight-HXMT/HE detection
  34. Fermi trigger No 581889628 Global MASTER-Net observations report
  35. GRB 190610C: Fermi GBM Final Real-time Localization
  36. Fermi trigger No 581882394 Global MASTER-Net observations report
  37. GRB190610B: BALROG localization (Fermi Trigger 581882394 / GRB 190610750)
  38. GRB 190610B: Fermi GBM Final Real-time Localization
  39. Fermi trigger No 581841498 Global MASTER-Net observations report
  40. GRB 190610A: Swift detection of a short burst
  41. GRB190609A: BALROG localization (Fermi Trigger 581758450 / GRB 190609315)
  42. GRB 190609A: Fermi GBM Final Real-time Localization
  43. Fermi trigger No 581719018 Global MASTER-Net observations report
  44. GRB 190605A: AstroSat CZTI detection
  45. Fermi trigger No 581645543 Global MASTER-Net observations report
  46. GRB 190608A: Fermi GBM Final Real-time Localization
  47. GRB 190606A: Insight-HXMT/HE detection
  48. LIGO/Virgo S190425z: Swift UVOT - no new sources identified, and a summary of the Swift UVOT processing of GW triggers.
  49. GRB 190114C: East Asia VLBI Network observations
  50. IPN Triangulation of GRB 190606A (short)
  51. GRB 190606A: Fermi GBM detection
  52. GRB 190530A: Further OAJ/OSN photometry and analysis
  53. GRB 190604B: VLT Afterglow Detection
  54. GRB 190606A: Fermi-LAT detection
  55. GRB 190605B: Insight-HXMT/HE detection
  56. Fermi trigger No 581478912 / GRB 190606A: AGILE/MCAL observations
  57. GRB 190604A: Insight-HXMT/HE detection
  58. Fermi trigger No 581478912 Global MASTER-Net observations report
  59. Fermi trigger No 581469752 Global MASTER-Net observations report
  60. GRB 190605A: Fermi GBM Final Real-time Localization
  61. GRB 190604B: Kitab observatory optical upper limit
  62. GRB 190604A: AstroSat CZTI detection
  63. GRB 190604B: Swift-BAT refined analysis
  64. GRB 190530A: optical follow-up observations at Konkoly
  65. GRB 190604B: BOOTES-3 early optical limits
  66. GRB 190604B: Swift-XRT refined Analysis
  67. GRB190604B: GROWTH-India telescope followup - no optical counterpart found
  68. GRB190604B: Swift/UVOT detection
  69. GRB 190604B: Enhanced Swift-XRT position
  70. GRB190530A: Photometric follow-up with GROWTH-India telescope
  71. LIGO/Virgo S190521r: Gaia Photometric Alerts transient candidate
  72. GRB 190604B: Prompt enhanced Swift-XRT position
  73. GRB 190604B: Swift detection of a burst
  74. Fermi trigger No 581337762 Global MASTER-Net observations report
  75. GRB190604A: BALROG localization (Fermi Trigger 581337762 / GRB 190604446)
  76. GRB 190604A: Fermi GBM Final Real-time Localization
  77. GRB 190531B: CALET Gamma-Ray Burst Monitor detection
  78. S190602aq: MASTER OT detection
  79. LIGO/Virgo S190602aq: AstroSat CZTI upper limits
  80. LIGO/Virgo S190602aq: Upper limits from CALET observations
  81. LIGO/Virgo S190602aq: Upper limits from Insight-HXMT/HE observations
  82. Fermi trigger No 581281470 Global MASTER-Net observations report
  83. GRB 190603A: Fermi GBM Final Real-time Localization
  84. GRB 190531B: Swift/UVOT Upper Limits
  85. Konus-Wind observation of GRB 190531B
  86. GRB 190530A: R-band observation from HCT
  87. LIGO/Virgo S190602aq: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  88. LIGO/Virgo S190602aq: upper limit in INTEGRAL SPI-ACS prompt observations
  89. LIGO/Virgo S190602aq: No counterpart candidates in Fermi-LAT observations
  90. LIGO/Virgo S190602aq: No counterpart candidates in the Swift/BAT Observations
  91. LIGO/Virgo S190602aq: Upper limits from Fermi-GBM Observations
  92. LIGO/Virgo S190602aq: Upper limits from AGILE-GRID observations
  93. LIGO/Virgo S190602aq: No counterpart candidate in AGILE-MCAL observations
  94. LIGO/Virgo S190602aq Global MASTER-Net observations report
  95. LIGO/Virgo S190602aq: Coverage and upper limits from MAXI/GSC observations
  96. LIGO/Virgo S190602aq: No neutrino counterpart candidates in ANTARES search
  97. LIGO/Virgo S190602aq: No counterpart candidates in HAWC observations
  98. LIGO/Virgo S190602aq: Identification of a GW compact binary merger candidate
  99. LIGO/Virgo S190602aq: Upper limits from IceCube neutrino searches
  100. Konus-Wind observation of extremely bright GRB 190530A

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