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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 190114C: East Asia VLBI Network observations
  2. IPN Triangulation of GRB 190606A (short)
  3. GRB 190606A: Fermi GBM detection
  4. GRB 190530A: Further OAJ/OSN photometry and analysis
  5. GRB 190604B: VLT Afterglow Detection
  6. GRB 190606A: Fermi-LAT detection
  7. GRB 190605B: Insight-HXMT/HE detection
  8. Fermi trigger No 581478912 / GRB 190606A: AGILE/MCAL observations
  9. GRB 190604A: Insight-HXMT/HE detection
  10. Fermi trigger No 581478912 Global MASTER-Net observations report
  11. Fermi trigger No 581469752 Global MASTER-Net observations report
  12. GRB 190605A: Fermi GBM Final Real-time Localization
  13. GRB 190604B: Kitab observatory optical upper limit
  14. GRB 190604A: AstroSat CZTI detection
  15. GRB 190604B: Swift-BAT refined analysis
  16. GRB 190530A: optical follow-up observations at Konkoly
  17. GRB 190604B: BOOTES-3 early optical limits
  18. GRB 190604B: Swift-XRT refined Analysis
  19. GRB190604B: GROWTH-India telescope followup - no optical counterpart found
  20. GRB190604B: Swift/UVOT detection
  21. GRB 190604B: Enhanced Swift-XRT position
  22. GRB190530A: Photometric follow-up with GROWTH-India telescope
  23. LIGO/Virgo S190521r: Gaia Photometric Alerts transient candidate
  24. GRB 190604B: Prompt enhanced Swift-XRT position
  25. GRB 190604B: Swift detection of a burst
  26. Fermi trigger No 581337762 Global MASTER-Net observations report
  27. GRB190604A: BALROG localization (Fermi Trigger 581337762 / GRB 190604446)
  28. GRB 190604A: Fermi GBM Final Real-time Localization
  29. GRB 190531B: CALET Gamma-Ray Burst Monitor detection
  30. S190602aq: MASTER OT detection
  31. LIGO/Virgo S190602aq: AstroSat CZTI upper limits
  32. LIGO/Virgo S190602aq: Upper limits from CALET observations
  33. LIGO/Virgo S190602aq: Upper limits from Insight-HXMT/HE observations
  34. Fermi trigger No 581281470 Global MASTER-Net observations report
  35. GRB 190603A: Fermi GBM Final Real-time Localization
  36. GRB 190531B: Swift/UVOT Upper Limits
  37. Konus-Wind observation of GRB 190531B
  38. GRB 190530A: R-band observation from HCT
  39. LIGO/Virgo S190602aq: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  40. LIGO/Virgo S190602aq: upper limit in INTEGRAL SPI-ACS prompt observations
  41. LIGO/Virgo S190602aq: No counterpart candidates in Fermi-LAT observations
  42. LIGO/Virgo S190602aq: No counterpart candidates in the Swift/BAT Observations
  43. LIGO/Virgo S190602aq: Upper limits from Fermi-GBM Observations
  44. LIGO/Virgo S190602aq: Upper limits from AGILE-GRID observations
  45. LIGO/Virgo S190602aq: No counterpart candidate in AGILE-MCAL observations
  46. LIGO/Virgo S190602aq Global MASTER-Net observations report
  47. LIGO/Virgo S190602aq: Coverage and upper limits from MAXI/GSC observations
  48. LIGO/Virgo S190602aq: No neutrino counterpart candidates in ANTARES search
  49. LIGO/Virgo S190602aq: No counterpart candidates in HAWC observations
  50. LIGO/Virgo S190602aq: Identification of a GW compact binary merger candidate
  51. LIGO/Virgo S190602aq: Upper limits from IceCube neutrino searches
  52. Konus-Wind observation of extremely bright GRB 190530A
  53. GRB 190530A: Insight-HXMT/HE detection
  54. GRB 190531B: Insight-HXMT/HE detection
  55. GRB 190530A: Mondy and AbAO optical observations
  56. GRB 190531B: VLT optical upper limit
  57. Fermi trigger No 581068049 Global MASTER-Net observations report
  58. GRB 190530A: Konkoly optical observations of the afterglow
  59. GRB 190530A: SAO RAS optical observations
  60. GRB 190531B: MASTER optical observation
  61. GRB 190531B: Swift-XRT afterglow detection
  62. GRB 190531B: Fermi GBM observations
  63. Fermi Fermi trigger No 581002688 Global MASTER-Net observations report
  64. GRB 190530A: Swift/UVOT Detection
  65. GRB 190531B: Swift ToO observations
  66. GRB 190531B: Fermi-LAT detection
  67. GRB 190530A: Steep afterglow decay found by OSN
  68. GRB 190531B: name correction re. GCN 24696
  69. GRB 190530A: AbAO optical observations
  70. GRB 190530A: Xinglong 2.16m optical observation
  71. Fermi Trigger 581026217 / GRB 190531840 / GRB190531A: BALROG localization
  72. GRB 190531B: Fermi GBM Final Real-time Localization
  73. GRB 190530A: AstroSat CZTI detection
  74. GRB 190530A: optical afterglow detection by 5 MASTER telescopes
  75. GRB 190530A: Fermi GBM observation
  76. GRB 190531A: Fermi GBM Final Real-time Localization
  77. GRB 190530A: COATLI Optical Detection of the Fading Afterglow
  78. GRB 190530A: Swift-XRT afterglow detection
  79. GRB 190530A: GWAC-F30 optical detection
  80. GRB 190530A: OAJ optical detection
  81. GRB 190530A: NOT photometry and spectroscopy
  82. Fermi GRB190530.43 Global MASTER-Net observations report
  83. GRB 190530A: Bright afterglow confirmed by OSN
  84. GRB 190530A: AGILE/GRID analysis
  85. LIGO/Virgo S190503bf: Gaia Photometric Alerts transient candidate
  86. GRB 190530A: Swift ToO observations
  87. GRB 190530A: MASTER OT detection
  88. GRB 190530A: Fermi-LAT detection
  89. GRB 190530A: AGILE-MCAL detection
  90. Fermi Trigger 580904353 / GRB 190530430 / GRB190530A: BALROG localization
  91. GRB 190530A: Fermi GBM Final Real-time Localization
  92. IceCube-190504A: Kanata optical/NIR follow-up observations
  93. IceCube 41485283_132628.amon retraction
  94. LIGO/Virgo S190425z: No counterpart candidate in Zadko-GRANDMA observations.
  95. LIGO/Virgo S190521r : Gaia Photometric Alerts transient candidate
  96. LIGO/Virgo S190518bb: AstroSat CZTI upper limits
  97. LIGO/Virgo S190521g: AstroSat CZTI upper limits
  98. LIGO/Virgo S190517h: AstroSat CZTI upper limits
  99. LIGO/Virgo S190519bj: AstroSat CZTI upper limits
  100. GRB 190525A: AstroSat CZTI detection

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