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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-LAT ANTARES 200127.79 coincidence: MASTER alert observation and presence of young pulsar close to error-box
  2. GRB 200127A: Swift/UVOT Upper Limits
  3. IPN triangulation of GRB 200125B
  4. GRB 200128B: AGILE/MCAL detection of a burst
  5. LIGO/Virgo S200128d: Upper limits from Fermi-GBM Observations
  6. Fermi-LAT-ANTARES coincidence
  7. GRB 200127A: Mondy optical upper limit
  8. GRB200127A: Nordic Optical telecope optical upper limit
  9. LIGO/Virgo S200128d : no neutrino counterpart candidate in ANTARES search
  10. GRB 200125B: DDOTI/OAN optical observations report
  11. LIGO/Virgo S200128d: Coverage and upper limits from MAXI/GSC observations
  12. GRB 200128A: Fermi GBM Final Real-time Localization
  13. LIGO/Virgo S200128d: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  14. LIGO/Virgo S200128d: No counterpart candidates in HAWC observations
  15. LIGO/Virgo S200128d: Identification of a GW compact binary merger candidate
  16. LIGO/Virgo S200128d: Upper limits from IceCube neutrino searches
  17. GRB 200127A: Nanshan-0.6m optical upper limit
  18. LIGO/Virgo S200128d: Global MASTER-Net observations report
  19. GRB 200127A: Enhanced Swift-XRT position
  20. GRB 200127A: Swift-XRT refined Analysis
  21. Fermi trigger No 601841483: Global MASTER-Net observations report
  22. GRB 200127A: AbAO optical upper limit
  23. GRB 200127B: Fermi GBM Final Real-time Localization
  24. GRB 200125A: Swift-BAT refined analysis
  25. Swift GRB200127.61: Global MASTER-Net observations report
  26. GRB 200127A: Swift detection of a burst
  27. GRB 200125A: Further Swift-XRT observations
  28. GRB 200125B: Fermi GBM observations
  29. GRB 200125A: Swift/UVOT Upper Limits
  30. GRB 200125A: Further RATIR Optical Observations and Confirmation of Fading
  31. Fermi trigger No 601729856: Global MASTER-Net observations report
  32. GRB 200125A: AbAO optical upper limit
  33. GRB 200125B: Insight-HXMT/HE detection
  34. GRB 200125A: TNG detection of a NIR counterpart candidate
  35. Fermi trigger No 601677816: Global MASTER-Net observations report
  36. Correction to GRB 200125A: Swift-XRT refined analysis
  37. GRB 200125A: Swift-XRT refined Analysis
  38. GRB 200125A: Nanshan-0.6m optical upper limit
  39. GRB 200125A: RATIR Optical Observations
  40. Swift GRB 200125A: Global MASTER-Net observations report
  41. GRB 200125B: BALROG localization (Fermi Trigger 601677816 / GRB 200125864)
  42. GRB 200125B: Fermi GBM Final Real-time Localization
  43. GRB 200125A: Enhanced Swift-XRT position
  44. GRB 200122B: Insight-HXMT/HE detection
  45. GRB 200125A: Swift detection of a burst
  46. LIGO/Virgo S200114f : No significant candidates in TAROT - FRAM - GRANDMA observations
  47. IceCube-200120A: Event likely due to background
  48. GRB 200122A: Optical upper limit: correction to the GCN circ. 26870
  49. GRB 200115A: Assy optical observations
  50. GRB 200122A: AstroSat CZTI detection
  51. GRB 200122A: Optical upper limit
  52. GRB 200122A: Mondy optical upper limit
  53. LIGO/Virgo S191222n: AstroSat CZTI upper limits
  54. LIGO/Virgo S200112r: AstroSat CZTI upper limits
  55. LIGO/Virgo S200114f: AstroSat CZTI upper limits
  56. Konus-Wind observation of GRB 200122A
  57. GRB 200122A: MITSuME Akeno optical upper limits
  58. LIGO/Virgo S200115j: Zwicky Transient Facility search for optical counterparts to Swift X-ray sources
  59. GRB 200122A: RATIR Optical Observations
  60. GRB 200122A: Swift-BAT refined analysis
  61. GRB 200122A: Xinglong-2.16m optical upper limit
  62. GRB 200122A: Swift/UVOT Upper Limits
  63. Fermi trigger No 601363105: Global MASTER-Net observations report
  64. Konus-Wind observation of GRB 200120A
  65. IPN Triangulation of GRB 200120A
  66. LIGO/Virgo S200115j: Further Swift-XRT sources
  67. GRB 200122A: FRAM-ORM optical limit
  68. GRB 200122A: GOTO non-detection of optical afterglow
  69. GRB 200122A: Swift-XRT refined Analysis
  70. GRB 200120A: AstroSat CZTI detection
  71. Fermi-LAT Gamma-ray Observations of IceCube-200120A
  72. LIGO/Virgo S200115j: Upper limits from Konus-Wind observations
  73. LIGO/Virgo S200114f: Upper limits from Konus-Wind observations
  74. LIGO/Virgo S200112r: Upper limits from Konus-Wind observations
  75. GRB 200122A: Enhanced Swift-XRT position
  76. Swift GRB 200122A: Global MASTER-Net observations report
  77. GRB 200122A: Swift detection of a burst
  78. IceCube-200120A: Upper limits from a search for additional neutrino events in IceCube
  79. Fermi trigger No 601254300: Global MASTER-Net observations report
  80. GRB 191031D: XMM-Newton upper limit
  81. GRB 200120A: Insight-HXMT/HE detection
  82. LIGO/VIRGO S200115j: No obvious candidates from Pan-STARRS2 observations
  83. IceCube-200120A: no counterpart candidates in INTEGRAL SPI-ACS and,IBIS prompt observation
  84. LIGO/Virgo S200105ae: Upper limits from Konus-Wind observations
  85. LIGO/Virgo S191222n: Upper limits from Konus-Wind observations
  86. LIGO/Virgo S191216ap: Upper limits from Konus-Wind observations
  87. LIGO/Virgo S191215w: Upper limits from Konus-Wind observations
  88. IceCube-200120A: not observable by Fermi-GBM
  89. IceCube-200120A: IceCube observation of a high-energy neutrino candidate event
  90. GRB 200120A: Fermi GBM Final Real-time Localization
  91. LIGO/Virgo S200114f: SOAR spectroscopy of AT2020zf, AT2020ace and AT2020ach
  92. IceCube Alert 200120.78: Global MASTER-Net observations report
  93. IceCube 200117A: No significant detection in HAWC
  94. LIGO/Virgo S191213g: Upper limits from Konus-Wind observations
  95. LIGO/Virgo S191205ah: Upper limits from Konus-Wind observations
  96. LIGO/Virgo S191204r: Upper limits from Konus-Wind observations
  97. LIGO/Virgo S191129u: Upper limits from Konus-Wind observations
  98. LIGO/Virgo S200115j: No counterpart detection within possible host galaxies observed by the GRAWITA-Savelli telescope
  99. LIGO/Virgo S200115j: GMOS-N upper limits for ZTF20aafqvyc/AT2020yq from the Gemini Observatory
  100. Fermi-LAT Gamma-ray Observations of IceCube-200117A

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