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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 581719018 Global MASTER-Net observations report
  2. GRB 190605A: AstroSat CZTI detection
  3. Fermi trigger No 581645543 Global MASTER-Net observations report
  4. GRB 190608A: Fermi GBM Final Real-time Localization
  5. GRB 190606A: Insight-HXMT/HE detection
  6. LIGO/Virgo S190425z: Swift UVOT - no new sources identified, and a summary of the Swift UVOT processing of GW triggers.
  7. GRB 190114C: East Asia VLBI Network observations
  8. IPN Triangulation of GRB 190606A (short)
  9. GRB 190606A: Fermi GBM detection
  10. GRB 190530A: Further OAJ/OSN photometry and analysis
  11. GRB 190604B: VLT Afterglow Detection
  12. GRB 190606A: Fermi-LAT detection
  13. GRB 190605B: Insight-HXMT/HE detection
  14. Fermi trigger No 581478912 / GRB 190606A: AGILE/MCAL observations
  15. GRB 190604A: Insight-HXMT/HE detection
  16. Fermi trigger No 581478912 Global MASTER-Net observations report
  17. Fermi trigger No 581469752 Global MASTER-Net observations report
  18. GRB 190605A: Fermi GBM Final Real-time Localization
  19. GRB 190604B: Kitab observatory optical upper limit
  20. GRB 190604A: AstroSat CZTI detection
  21. GRB 190604B: Swift-BAT refined analysis
  22. GRB 190530A: optical follow-up observations at Konkoly
  23. GRB 190604B: BOOTES-3 early optical limits
  24. GRB 190604B: Swift-XRT refined Analysis
  25. GRB190604B: GROWTH-India telescope followup - no optical counterpart found
  26. GRB190604B: Swift/UVOT detection
  27. GRB 190604B: Enhanced Swift-XRT position
  28. GRB190530A: Photometric follow-up with GROWTH-India telescope
  29. LIGO/Virgo S190521r: Gaia Photometric Alerts transient candidate
  30. GRB 190604B: Prompt enhanced Swift-XRT position
  31. GRB 190604B: Swift detection of a burst
  32. Fermi trigger No 581337762 Global MASTER-Net observations report
  33. GRB190604A: BALROG localization (Fermi Trigger 581337762 / GRB 190604446)
  34. GRB 190604A: Fermi GBM Final Real-time Localization
  35. GRB 190531B: CALET Gamma-Ray Burst Monitor detection
  36. S190602aq: MASTER OT detection
  37. LIGO/Virgo S190602aq: AstroSat CZTI upper limits
  38. LIGO/Virgo S190602aq: Upper limits from CALET observations
  39. LIGO/Virgo S190602aq: Upper limits from Insight-HXMT/HE observations
  40. Fermi trigger No 581281470 Global MASTER-Net observations report
  41. GRB 190603A: Fermi GBM Final Real-time Localization
  42. GRB 190531B: Swift/UVOT Upper Limits
  43. Konus-Wind observation of GRB 190531B
  44. GRB 190530A: R-band observation from HCT
  45. LIGO/Virgo S190602aq: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  46. LIGO/Virgo S190602aq: upper limit in INTEGRAL SPI-ACS prompt observations
  47. LIGO/Virgo S190602aq: No counterpart candidates in Fermi-LAT observations
  48. LIGO/Virgo S190602aq: No counterpart candidates in the Swift/BAT Observations
  49. LIGO/Virgo S190602aq: Upper limits from Fermi-GBM Observations
  50. LIGO/Virgo S190602aq: Upper limits from AGILE-GRID observations
  51. LIGO/Virgo S190602aq: No counterpart candidate in AGILE-MCAL observations
  52. LIGO/Virgo S190602aq Global MASTER-Net observations report
  53. LIGO/Virgo S190602aq: Coverage and upper limits from MAXI/GSC observations
  54. LIGO/Virgo S190602aq: No neutrino counterpart candidates in ANTARES search
  55. LIGO/Virgo S190602aq: No counterpart candidates in HAWC observations
  56. LIGO/Virgo S190602aq: Identification of a GW compact binary merger candidate
  57. LIGO/Virgo S190602aq: Upper limits from IceCube neutrino searches
  58. Konus-Wind observation of extremely bright GRB 190530A
  59. GRB 190530A: Insight-HXMT/HE detection
  60. GRB 190531B: Insight-HXMT/HE detection
  61. GRB 190530A: Mondy and AbAO optical observations
  62. GRB 190531B: VLT optical upper limit
  63. Fermi trigger No 581068049 Global MASTER-Net observations report
  64. GRB 190530A: Konkoly optical observations of the afterglow
  65. GRB 190530A: SAO RAS optical observations
  66. GRB 190531B: MASTER optical observation
  67. GRB 190531B: Swift-XRT afterglow detection
  68. GRB 190531B: Fermi GBM observations
  69. Fermi Fermi trigger No 581002688 Global MASTER-Net observations report
  70. GRB 190530A: Swift/UVOT Detection
  71. GRB 190531B: Swift ToO observations
  72. GRB 190531B: Fermi-LAT detection
  73. GRB 190530A: Steep afterglow decay found by OSN
  74. GRB 190531B: name correction re. GCN 24696
  75. GRB 190530A: AbAO optical observations
  76. GRB 190530A: Xinglong 2.16m optical observation
  77. Fermi Trigger 581026217 / GRB 190531840 / GRB190531A: BALROG localization
  78. GRB 190531B: Fermi GBM Final Real-time Localization
  79. GRB 190530A: AstroSat CZTI detection
  80. GRB 190530A: optical afterglow detection by 5 MASTER telescopes
  81. GRB 190530A: Fermi GBM observation
  82. GRB 190531A: Fermi GBM Final Real-time Localization
  83. GRB 190530A: COATLI Optical Detection of the Fading Afterglow
  84. GRB 190530A: Swift-XRT afterglow detection
  85. GRB 190530A: GWAC-F30 optical detection
  86. GRB 190530A: OAJ optical detection
  87. GRB 190530A: NOT photometry and spectroscopy
  88. Fermi GRB190530.43 Global MASTER-Net observations report
  89. GRB 190530A: Bright afterglow confirmed by OSN
  90. GRB 190530A: AGILE/GRID analysis
  91. LIGO/Virgo S190503bf: Gaia Photometric Alerts transient candidate
  92. GRB 190530A: Swift ToO observations
  93. GRB 190530A: MASTER OT detection
  94. GRB 190530A: Fermi-LAT detection
  95. GRB 190530A: AGILE-MCAL detection
  96. Fermi Trigger 580904353 / GRB 190530430 / GRB190530A: BALROG localization
  97. GRB 190530A: Fermi GBM Final Real-time Localization
  98. IceCube-190504A: Kanata optical/NIR follow-up observations
  99. IceCube 41485283_132628.amon retraction
  100. LIGO/Virgo S190425z: No counterpart candidate in Zadko-GRANDMA observations.

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