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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 200125A: Swift detection of a burst
  2. LIGO/Virgo S200114f : No significant candidates in TAROT - FRAM - GRANDMA observations
  3. IceCube-200120A: Event likely due to background
  4. GRB 200122A: Optical upper limit: correction to the GCN circ. 26870
  5. GRB 200115A: Assy optical observations
  6. GRB 200122A: AstroSat CZTI detection
  7. GRB 200122A: Optical upper limit
  8. GRB 200122A: Mondy optical upper limit
  9. LIGO/Virgo S191222n: AstroSat CZTI upper limits
  10. LIGO/Virgo S200112r: AstroSat CZTI upper limits
  11. LIGO/Virgo S200114f: AstroSat CZTI upper limits
  12. Konus-Wind observation of GRB 200122A
  13. GRB 200122A: MITSuME Akeno optical upper limits
  14. LIGO/Virgo S200115j: Zwicky Transient Facility search for optical counterparts to Swift X-ray sources
  15. GRB 200122A: RATIR Optical Observations
  16. GRB 200122A: Swift-BAT refined analysis
  17. GRB 200122A: Xinglong-2.16m optical upper limit
  18. GRB 200122A: Swift/UVOT Upper Limits
  19. Fermi trigger No 601363105: Global MASTER-Net observations report
  20. Konus-Wind observation of GRB 200120A
  21. IPN Triangulation of GRB 200120A
  22. LIGO/Virgo S200115j: Further Swift-XRT sources
  23. GRB 200122A: FRAM-ORM optical limit
  24. GRB 200122A: GOTO non-detection of optical afterglow
  25. GRB 200122A: Swift-XRT refined Analysis
  26. GRB 200120A: AstroSat CZTI detection
  27. Fermi-LAT Gamma-ray Observations of IceCube-200120A
  28. LIGO/Virgo S200115j: Upper limits from Konus-Wind observations
  29. LIGO/Virgo S200114f: Upper limits from Konus-Wind observations
  30. LIGO/Virgo S200112r: Upper limits from Konus-Wind observations
  31. GRB 200122A: Enhanced Swift-XRT position
  32. Swift GRB 200122A: Global MASTER-Net observations report
  33. GRB 200122A: Swift detection of a burst
  34. IceCube-200120A: Upper limits from a search for additional neutrino events in IceCube
  35. Fermi trigger No 601254300: Global MASTER-Net observations report
  36. GRB 191031D: XMM-Newton upper limit
  37. GRB 200120A: Insight-HXMT/HE detection
  38. LIGO/VIRGO S200115j: No obvious candidates from Pan-STARRS2 observations
  39. IceCube-200120A: no counterpart candidates in INTEGRAL SPI-ACS and,IBIS prompt observation
  40. LIGO/Virgo S200105ae: Upper limits from Konus-Wind observations
  41. LIGO/Virgo S191222n: Upper limits from Konus-Wind observations
  42. LIGO/Virgo S191216ap: Upper limits from Konus-Wind observations
  43. LIGO/Virgo S191215w: Upper limits from Konus-Wind observations
  44. IceCube-200120A: not observable by Fermi-GBM
  45. IceCube-200120A: IceCube observation of a high-energy neutrino candidate event
  46. GRB 200120A: Fermi GBM Final Real-time Localization
  47. LIGO/Virgo S200114f: SOAR spectroscopy of AT2020zf, AT2020ace and AT2020ach
  48. IceCube Alert 200120.78: Global MASTER-Net observations report
  49. IceCube 200117A: No significant detection in HAWC
  50. LIGO/Virgo S191213g: Upper limits from Konus-Wind observations
  51. LIGO/Virgo S191205ah: Upper limits from Konus-Wind observations
  52. LIGO/Virgo S191204r: Upper limits from Konus-Wind observations
  53. LIGO/Virgo S191129u: Upper limits from Konus-Wind observations
  54. LIGO/Virgo S200115j: No counterpart detection within possible host galaxies observed by the GRAWITA-Savelli telescope
  55. LIGO/Virgo S200115j: GMOS-N upper limits for ZTF20aafqvyc/AT2020yq from the Gemini Observatory
  56. Fermi-LAT Gamma-ray Observations of IceCube-200117A
  57. LIGO/Virgo S200115j : No significant candidates in TAROT - FRAM - GRANDMA observations
  58. LIGO/Virgo S200115j: Mondy upper limits for ZTF20aafqvyc/AT2020yq
  59. GRB 200115A: Mondy optical observations and correction to GCN 26790
  60. LIGO/Virgo S200115j: LCO upper limits for ZTF20aafqvyc/AT2020yq from the McDonald Observatory 1-m telescope
  61. IceCube-200117A: One Additional Candidate Counterpart from the Zwicky Transient Facility
  62. IceCube-200117A : Upper limits from Insight-HXMT/HE observations
  63. LIGO/Virgo S200115j: NIR upper limits for ZTF20aafqvyc/AT2020yq from the Palomar 200-inch telescope
  64. IceCube-200117A: Candidate Counterpart from the Zwicky Transient Facility
  65. IceCube-200117A: Upper limits from a search for additional neutrino events in IceCube
  66. IceCube-200117A: No Neutrino Counterpart in ANTARES data
  67. LIGO/Virgo S200105ae: More candidates from the Zwicky Transient Facility
  68. GRB 200115A: CALET Gamma-Ray Burst Monitor detection
  69. LIGO/Virgo S200115j: Swift/UVOT observations of Swift/XRT S200115j_X136
  70. LIGO/Virgo S200115j: Updated Sky Localization and source properties
  71. LIGO/Virgo S200114f: More candidates from the Zwicky Transient Facility
  72. IceCube-200117A: Upper limits from Fermi-GBM Observations
  73. IceCube-200117A: no counterpart candidates in INTEGRAL SPI-ACS and,IBIS prompt observation
  74. LIGO/Virgo S200114f: No transients found in J-GEM observations of nearby galaxies
  75. IceCube-200117A: IceCube observation of a high-energy neutrino candidate event
  76. GRB 200115A: AROMA-N Optical Observation
  77. GRB 200117A: Fermi GBM Final Real-time Localization
  78. IceCube Alert 200117.46: Global MASTER-Net observations report
  79. LIGO/Virgo S200115j: Swift-XRT sources
  80. LIGO/Virgo S200115j: Upper limits from CALET observations.
  81. LIGO/Virgo S200114f: ZTF Forced Photometry of the Swift Source S200114f_X2
  82. GRB 200111A: CALET Gamma-Ray Burst Monitor detection
  83. LIGO/Virgo S200115j: No notable candidates in GOTO imaging
  84. LIGO/Virgo S200114f: Upper Limits from Wide-Field Infrared Search with Palomar Gattini-IR
  85. GRB 200115A: DDOTI/OAN optical observations report
  86. LIGO/Virgo S200114f: Possible X-ray transient
  87. GRB 200115A: Mondy optical afterglow candidate
  88. LIGO/Virgo S200112r : No significant candidates in TAROT - FRAM - GRANDMA observations.
  89. LIGO/Virgo S200115j: No neutrino candidates at Pierre Auger Observatory
  90. LIGO/Virgo S200114f: Swift-XRT sources and observations
  91. LIGO/Virgo S200115j: no counterpart candidate in SVOM/GWAC observations
  92. LIGO/Virgo S200116ah: Retraction of GW compact binary merger candidate
  93. LIGO/Virgo S200116ah: Global MASTER-Net observations report
  94. GRB 200111A: AstroSat CZTI detection
  95. Baksan Neutrino Observatory Alert 200116.22: Global MASTER-Net observations report
  96. Baksan Neutrino Observatory Alert 200116.21: Global MASTER-Net observations report
  97. GRB 200115A: Swift-BAT refined analysis
  98. LIGO/Virgo S200115j: no counterpart candidates in the Swift/BAT observations
  99. IPN triangulation of GRB 200111A
  100. LIGO/Virgo S200115j High Rank XRT sources are spurious

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