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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 190611A: Enhanced Swift-XRT position
  2. GRB 190611A: Swift detection of a burst
  3. Konus-Wind observation of GRB 190606A
  4. GRB 190610A: Swift-BAT refined analysis
  5. GRB 190610A: Insight-HXMT/HE detection
  6. Fermi trigger No 581889628 Global MASTER-Net observations report
  7. GRB 190610C: Fermi GBM Final Real-time Localization
  8. Fermi trigger No 581882394 Global MASTER-Net observations report
  9. GRB190610B: BALROG localization (Fermi Trigger 581882394 / GRB 190610750)
  10. GRB 190610B: Fermi GBM Final Real-time Localization
  11. Fermi trigger No 581841498 Global MASTER-Net observations report
  12. GRB 190610A: Swift detection of a short burst
  13. GRB190609A: BALROG localization (Fermi Trigger 581758450 / GRB 190609315)
  14. GRB 190609A: Fermi GBM Final Real-time Localization
  15. Fermi trigger No 581719018 Global MASTER-Net observations report
  16. GRB 190605A: AstroSat CZTI detection
  17. Fermi trigger No 581645543 Global MASTER-Net observations report
  18. GRB 190608A: Fermi GBM Final Real-time Localization
  19. GRB 190606A: Insight-HXMT/HE detection
  20. LIGO/Virgo S190425z: Swift UVOT - no new sources identified, and a summary of the Swift UVOT processing of GW triggers.
  21. GRB 190114C: East Asia VLBI Network observations
  22. IPN Triangulation of GRB 190606A (short)
  23. GRB 190606A: Fermi GBM detection
  24. GRB 190530A: Further OAJ/OSN photometry and analysis
  25. GRB 190604B: VLT Afterglow Detection
  26. GRB 190606A: Fermi-LAT detection
  27. GRB 190605B: Insight-HXMT/HE detection
  28. Fermi trigger No 581478912 / GRB 190606A: AGILE/MCAL observations
  29. GRB 190604A: Insight-HXMT/HE detection
  30. Fermi trigger No 581478912 Global MASTER-Net observations report
  31. Fermi trigger No 581469752 Global MASTER-Net observations report
  32. GRB 190605A: Fermi GBM Final Real-time Localization
  33. GRB 190604B: Kitab observatory optical upper limit
  34. GRB 190604A: AstroSat CZTI detection
  35. GRB 190604B: Swift-BAT refined analysis
  36. GRB 190530A: optical follow-up observations at Konkoly
  37. GRB 190604B: BOOTES-3 early optical limits
  38. GRB 190604B: Swift-XRT refined Analysis
  39. GRB190604B: GROWTH-India telescope followup - no optical counterpart found
  40. GRB190604B: Swift/UVOT detection
  41. GRB 190604B: Enhanced Swift-XRT position
  42. GRB190530A: Photometric follow-up with GROWTH-India telescope
  43. LIGO/Virgo S190521r: Gaia Photometric Alerts transient candidate
  44. GRB 190604B: Prompt enhanced Swift-XRT position
  45. GRB 190604B: Swift detection of a burst
  46. Fermi trigger No 581337762 Global MASTER-Net observations report
  47. GRB190604A: BALROG localization (Fermi Trigger 581337762 / GRB 190604446)
  48. GRB 190604A: Fermi GBM Final Real-time Localization
  49. GRB 190531B: CALET Gamma-Ray Burst Monitor detection
  50. S190602aq: MASTER OT detection
  51. LIGO/Virgo S190602aq: AstroSat CZTI upper limits
  52. LIGO/Virgo S190602aq: Upper limits from CALET observations
  53. LIGO/Virgo S190602aq: Upper limits from Insight-HXMT/HE observations
  54. Fermi trigger No 581281470 Global MASTER-Net observations report
  55. GRB 190603A: Fermi GBM Final Real-time Localization
  56. GRB 190531B: Swift/UVOT Upper Limits
  57. Konus-Wind observation of GRB 190531B
  58. GRB 190530A: R-band observation from HCT
  59. LIGO/Virgo S190602aq: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  60. LIGO/Virgo S190602aq: upper limit in INTEGRAL SPI-ACS prompt observations
  61. LIGO/Virgo S190602aq: No counterpart candidates in Fermi-LAT observations
  62. LIGO/Virgo S190602aq: No counterpart candidates in the Swift/BAT Observations
  63. LIGO/Virgo S190602aq: Upper limits from Fermi-GBM Observations
  64. LIGO/Virgo S190602aq: Upper limits from AGILE-GRID observations
  65. LIGO/Virgo S190602aq: No counterpart candidate in AGILE-MCAL observations
  66. LIGO/Virgo S190602aq Global MASTER-Net observations report
  67. LIGO/Virgo S190602aq: Coverage and upper limits from MAXI/GSC observations
  68. LIGO/Virgo S190602aq: No neutrino counterpart candidates in ANTARES search
  69. LIGO/Virgo S190602aq: No counterpart candidates in HAWC observations
  70. LIGO/Virgo S190602aq: Identification of a GW compact binary merger candidate
  71. LIGO/Virgo S190602aq: Upper limits from IceCube neutrino searches
  72. Konus-Wind observation of extremely bright GRB 190530A
  73. GRB 190530A: Insight-HXMT/HE detection
  74. GRB 190531B: Insight-HXMT/HE detection
  75. GRB 190530A: Mondy and AbAO optical observations
  76. GRB 190531B: VLT optical upper limit
  77. Fermi trigger No 581068049 Global MASTER-Net observations report
  78. GRB 190530A: Konkoly optical observations of the afterglow
  79. GRB 190530A: SAO RAS optical observations
  80. GRB 190531B: MASTER optical observation
  81. GRB 190531B: Swift-XRT afterglow detection
  82. GRB 190531B: Fermi GBM observations
  83. Fermi Fermi trigger No 581002688 Global MASTER-Net observations report
  84. GRB 190530A: Swift/UVOT Detection
  85. GRB 190531B: Swift ToO observations
  86. GRB 190531B: Fermi-LAT detection
  87. GRB 190530A: Steep afterglow decay found by OSN
  88. GRB 190531B: name correction re. GCN 24696
  89. GRB 190530A: AbAO optical observations
  90. GRB 190530A: Xinglong 2.16m optical observation
  91. Fermi Trigger 581026217 / GRB 190531840 / GRB190531A: BALROG localization
  92. GRB 190531B: Fermi GBM Final Real-time Localization
  93. GRB 190530A: AstroSat CZTI detection
  94. GRB 190530A: optical afterglow detection by 5 MASTER telescopes
  95. GRB 190530A: Fermi GBM observation
  96. GRB 190531A: Fermi GBM Final Real-time Localization
  97. GRB 190530A: COATLI Optical Detection of the Fading Afterglow
  98. GRB 190530A: Swift-XRT afterglow detection
  99. GRB 190530A: GWAC-F30 optical detection
  100. GRB 190530A: OAJ optical detection

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