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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. Fermi trigger No 582091643 Global MASTER-Net observations report
  2. Fermi trigger No 582012834 Global MASTER-Net observations report
  3. Fermi trigger No 581986074 Global MASTER-Net observations report
  4. GRB 190611B: Fermi GBM detection
  5. GRB 190611A: Swift-XRT refined Analysis
  6. GRB 190611A: Swift/UVOT Upper Limits
  7. GRB 190611A: Optical observations from VLT/FORS2
  8. GRB 190611A, Swift-BAT refined analysis
  9. GRB 190610B: AstroSat CZTI detection
  10. Fermi trigger No 582004649 Global MASTER-Net observations report
  11. GRB 190612A: Fermi GBM Final Real-time Localization
  12. GRB 190611A: Enhanced Swift-XRT position
  13. GRB 190611A: Swift detection of a burst
  14. Konus-Wind observation of GRB 190606A
  15. GRB 190610A: Swift-BAT refined analysis
  16. GRB 190610A: Insight-HXMT/HE detection
  17. Fermi trigger No 581889628 Global MASTER-Net observations report
  18. GRB 190610C: Fermi GBM Final Real-time Localization
  19. Fermi trigger No 581882394 Global MASTER-Net observations report
  20. GRB190610B: BALROG localization (Fermi Trigger 581882394 / GRB 190610750)
  21. GRB 190610B: Fermi GBM Final Real-time Localization
  22. Fermi trigger No 581841498 Global MASTER-Net observations report
  23. GRB 190610A: Swift detection of a short burst
  24. GRB190609A: BALROG localization (Fermi Trigger 581758450 / GRB 190609315)
  25. GRB 190609A: Fermi GBM Final Real-time Localization
  26. Fermi trigger No 581719018 Global MASTER-Net observations report
  27. GRB 190605A: AstroSat CZTI detection
  28. Fermi trigger No 581645543 Global MASTER-Net observations report
  29. GRB 190608A: Fermi GBM Final Real-time Localization
  30. GRB 190606A: Insight-HXMT/HE detection
  31. LIGO/Virgo S190425z: Swift UVOT - no new sources identified, and a summary of the Swift UVOT processing of GW triggers.
  32. GRB 190114C: East Asia VLBI Network observations
  33. IPN Triangulation of GRB 190606A (short)
  34. GRB 190606A: Fermi GBM detection
  35. GRB 190530A: Further OAJ/OSN photometry and analysis
  36. GRB 190604B: VLT Afterglow Detection
  37. GRB 190606A: Fermi-LAT detection
  38. GRB 190605B: Insight-HXMT/HE detection
  39. Fermi trigger No 581478912 / GRB 190606A: AGILE/MCAL observations
  40. GRB 190604A: Insight-HXMT/HE detection
  41. Fermi trigger No 581478912 Global MASTER-Net observations report
  42. Fermi trigger No 581469752 Global MASTER-Net observations report
  43. GRB 190605A: Fermi GBM Final Real-time Localization
  44. GRB 190604B: Kitab observatory optical upper limit
  45. GRB 190604A: AstroSat CZTI detection
  46. GRB 190604B: Swift-BAT refined analysis
  47. GRB 190530A: optical follow-up observations at Konkoly
  48. GRB 190604B: BOOTES-3 early optical limits
  49. GRB 190604B: Swift-XRT refined Analysis
  50. GRB190604B: GROWTH-India telescope followup - no optical counterpart found
  51. GRB190604B: Swift/UVOT detection
  52. GRB 190604B: Enhanced Swift-XRT position
  53. GRB190530A: Photometric follow-up with GROWTH-India telescope
  54. LIGO/Virgo S190521r: Gaia Photometric Alerts transient candidate
  55. GRB 190604B: Prompt enhanced Swift-XRT position
  56. GRB 190604B: Swift detection of a burst
  57. Fermi trigger No 581337762 Global MASTER-Net observations report
  58. GRB190604A: BALROG localization (Fermi Trigger 581337762 / GRB 190604446)
  59. GRB 190604A: Fermi GBM Final Real-time Localization
  60. GRB 190531B: CALET Gamma-Ray Burst Monitor detection
  61. S190602aq: MASTER OT detection
  62. LIGO/Virgo S190602aq: AstroSat CZTI upper limits
  63. LIGO/Virgo S190602aq: Upper limits from CALET observations
  64. LIGO/Virgo S190602aq: Upper limits from Insight-HXMT/HE observations
  65. Fermi trigger No 581281470 Global MASTER-Net observations report
  66. GRB 190603A: Fermi GBM Final Real-time Localization
  67. GRB 190531B: Swift/UVOT Upper Limits
  68. Konus-Wind observation of GRB 190531B
  69. GRB 190530A: R-band observation from HCT
  70. LIGO/Virgo S190602aq: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  71. LIGO/Virgo S190602aq: upper limit in INTEGRAL SPI-ACS prompt observations
  72. LIGO/Virgo S190602aq: No counterpart candidates in Fermi-LAT observations
  73. LIGO/Virgo S190602aq: No counterpart candidates in the Swift/BAT Observations
  74. LIGO/Virgo S190602aq: Upper limits from Fermi-GBM Observations
  75. LIGO/Virgo S190602aq: Upper limits from AGILE-GRID observations
  76. LIGO/Virgo S190602aq: No counterpart candidate in AGILE-MCAL observations
  77. LIGO/Virgo S190602aq Global MASTER-Net observations report
  78. LIGO/Virgo S190602aq: Coverage and upper limits from MAXI/GSC observations
  79. LIGO/Virgo S190602aq: No neutrino counterpart candidates in ANTARES search
  80. LIGO/Virgo S190602aq: No counterpart candidates in HAWC observations
  81. LIGO/Virgo S190602aq: Identification of a GW compact binary merger candidate
  82. LIGO/Virgo S190602aq: Upper limits from IceCube neutrino searches
  83. Konus-Wind observation of extremely bright GRB 190530A
  84. GRB 190530A: Insight-HXMT/HE detection
  85. GRB 190531B: Insight-HXMT/HE detection
  86. GRB 190530A: Mondy and AbAO optical observations
  87. GRB 190531B: VLT optical upper limit
  88. Fermi trigger No 581068049 Global MASTER-Net observations report
  89. GRB 190530A: Konkoly optical observations of the afterglow
  90. GRB 190530A: SAO RAS optical observations
  91. GRB 190531B: MASTER optical observation
  92. GRB 190531B: Swift-XRT afterglow detection
  93. GRB 190531B: Fermi GBM observations
  94. Fermi Fermi trigger No 581002688 Global MASTER-Net observations report
  95. GRB 190530A: Swift/UVOT Detection
  96. GRB 190531B: Swift ToO observations
  97. GRB 190531B: Fermi-LAT detection
  98. GRB 190530A: Steep afterglow decay found by OSN
  99. GRB 190531B: name correction re. GCN 24696
  100. GRB 190530A: AbAO optical observations

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