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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. LIGO/Virgo S200128d: Upper limits from CALET observations
  2. LIGO/Virgo S200128d: No counterpart candidates in KAIT observations
  3. Fermi-LAT ANTARES coincidence: IceCube neutrino search
  4. LIGO/Virgo S200128d: no counterpart candidates in the Swift/BAT observations
  5. Fermi-LAT ANTARES 200127.79 coincidence: MASTER alert observation and presence of young pulsar close to error-box
  6. GRB 200127A: Swift/UVOT Upper Limits
  7. IPN triangulation of GRB 200125B
  8. GRB 200128B: AGILE/MCAL detection of a burst
  9. LIGO/Virgo S200128d: Upper limits from Fermi-GBM Observations
  10. Fermi-LAT-ANTARES coincidence
  11. GRB 200127A: Mondy optical upper limit
  12. GRB200127A: Nordic Optical telecope optical upper limit
  13. LIGO/Virgo S200128d : no neutrino counterpart candidate in ANTARES search
  14. GRB 200125B: DDOTI/OAN optical observations report
  15. LIGO/Virgo S200128d: Coverage and upper limits from MAXI/GSC observations
  16. GRB 200128A: Fermi GBM Final Real-time Localization
  17. LIGO/Virgo S200128d: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  18. LIGO/Virgo S200128d: No counterpart candidates in HAWC observations
  19. LIGO/Virgo S200128d: Identification of a GW compact binary merger candidate
  20. LIGO/Virgo S200128d: Upper limits from IceCube neutrino searches
  21. GRB 200127A: Nanshan-0.6m optical upper limit
  22. LIGO/Virgo S200128d: Global MASTER-Net observations report
  23. GRB 200127A: Enhanced Swift-XRT position
  24. GRB 200127A: Swift-XRT refined Analysis
  25. Fermi trigger No 601841483: Global MASTER-Net observations report
  26. GRB 200127A: AbAO optical upper limit
  27. GRB 200127B: Fermi GBM Final Real-time Localization
  28. GRB 200125A: Swift-BAT refined analysis
  29. Swift GRB200127.61: Global MASTER-Net observations report
  30. GRB 200127A: Swift detection of a burst
  31. GRB 200125A: Further Swift-XRT observations
  32. GRB 200125B: Fermi GBM observations
  33. GRB 200125A: Swift/UVOT Upper Limits
  34. GRB 200125A: Further RATIR Optical Observations and Confirmation of Fading
  35. Fermi trigger No 601729856: Global MASTER-Net observations report
  36. GRB 200125A: AbAO optical upper limit
  37. GRB 200125B: Insight-HXMT/HE detection
  38. GRB 200125A: TNG detection of a NIR counterpart candidate
  39. Fermi trigger No 601677816: Global MASTER-Net observations report
  40. Correction to GRB 200125A: Swift-XRT refined analysis
  41. GRB 200125A: Swift-XRT refined Analysis
  42. GRB 200125A: Nanshan-0.6m optical upper limit
  43. GRB 200125A: RATIR Optical Observations
  44. Swift GRB 200125A: Global MASTER-Net observations report
  45. GRB 200125B: BALROG localization (Fermi Trigger 601677816 / GRB 200125864)
  46. GRB 200125B: Fermi GBM Final Real-time Localization
  47. GRB 200125A: Enhanced Swift-XRT position
  48. GRB 200122B: Insight-HXMT/HE detection
  49. GRB 200125A: Swift detection of a burst
  50. LIGO/Virgo S200114f : No significant candidates in TAROT - FRAM - GRANDMA observations
  51. IceCube-200120A: Event likely due to background
  52. GRB 200122A: Optical upper limit: correction to the GCN circ. 26870
  53. GRB 200115A: Assy optical observations
  54. GRB 200122A: AstroSat CZTI detection
  55. GRB 200122A: Optical upper limit
  56. GRB 200122A: Mondy optical upper limit
  57. LIGO/Virgo S191222n: AstroSat CZTI upper limits
  58. LIGO/Virgo S200112r: AstroSat CZTI upper limits
  59. LIGO/Virgo S200114f: AstroSat CZTI upper limits
  60. Konus-Wind observation of GRB 200122A
  61. GRB 200122A: MITSuME Akeno optical upper limits
  62. LIGO/Virgo S200115j: Zwicky Transient Facility search for optical counterparts to Swift X-ray sources
  63. GRB 200122A: RATIR Optical Observations
  64. GRB 200122A: Swift-BAT refined analysis
  65. GRB 200122A: Xinglong-2.16m optical upper limit
  66. GRB 200122A: Swift/UVOT Upper Limits
  67. Fermi trigger No 601363105: Global MASTER-Net observations report
  68. Konus-Wind observation of GRB 200120A
  69. IPN Triangulation of GRB 200120A
  70. LIGO/Virgo S200115j: Further Swift-XRT sources
  71. GRB 200122A: FRAM-ORM optical limit
  72. GRB 200122A: GOTO non-detection of optical afterglow
  73. GRB 200122A: Swift-XRT refined Analysis
  74. GRB 200120A: AstroSat CZTI detection
  75. Fermi-LAT Gamma-ray Observations of IceCube-200120A
  76. LIGO/Virgo S200115j: Upper limits from Konus-Wind observations
  77. LIGO/Virgo S200114f: Upper limits from Konus-Wind observations
  78. LIGO/Virgo S200112r: Upper limits from Konus-Wind observations
  79. GRB 200122A: Enhanced Swift-XRT position
  80. Swift GRB 200122A: Global MASTER-Net observations report
  81. GRB 200122A: Swift detection of a burst
  82. IceCube-200120A: Upper limits from a search for additional neutrino events in IceCube
  83. Fermi trigger No 601254300: Global MASTER-Net observations report
  84. GRB 191031D: XMM-Newton upper limit
  85. GRB 200120A: Insight-HXMT/HE detection
  86. LIGO/VIRGO S200115j: No obvious candidates from Pan-STARRS2 observations
  87. IceCube-200120A: no counterpart candidates in INTEGRAL SPI-ACS and,IBIS prompt observation
  88. LIGO/Virgo S200105ae: Upper limits from Konus-Wind observations
  89. LIGO/Virgo S191222n: Upper limits from Konus-Wind observations
  90. LIGO/Virgo S191216ap: Upper limits from Konus-Wind observations
  91. LIGO/Virgo S191215w: Upper limits from Konus-Wind observations
  92. IceCube-200120A: not observable by Fermi-GBM
  93. IceCube-200120A: IceCube observation of a high-energy neutrino candidate event
  94. GRB 200120A: Fermi GBM Final Real-time Localization
  95. LIGO/Virgo S200114f: SOAR spectroscopy of AT2020zf, AT2020ace and AT2020ach
  96. IceCube Alert 200120.78: Global MASTER-Net observations report
  97. IceCube 200117A: No significant detection in HAWC
  98. LIGO/Virgo S191213g: Upper limits from Konus-Wind observations
  99. LIGO/Virgo S191205ah: Upper limits from Konus-Wind observations
  100. LIGO/Virgo S191204r: Upper limits from Konus-Wind observations

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