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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: Global MASTER-Net observations report
  2. GRB 200127A: Enhanced Swift-XRT position
  3. GRB 200127A: Swift-XRT refined Analysis
  4. Fermi trigger No 601841483: Global MASTER-Net observations report
  5. GRB 200127A: AbAO optical upper limit
  6. GRB 200127B: Fermi GBM Final Real-time Localization
  7. GRB 200125A: Swift-BAT refined analysis
  8. Swift GRB200127.61: Global MASTER-Net observations report
  9. GRB 200127A: Swift detection of a burst
  10. GRB 200125A: Further Swift-XRT observations
  11. GRB 200125B: Fermi GBM observations
  12. GRB 200125A: Swift/UVOT Upper Limits
  13. GRB 200125A: Further RATIR Optical Observations and Confirmation of Fading
  14. Fermi trigger No 601729856: Global MASTER-Net observations report
  15. GRB 200125A: AbAO optical upper limit
  16. GRB 200125B: Insight-HXMT/HE detection
  17. GRB 200125A: TNG detection of a NIR counterpart candidate
  18. Fermi trigger No 601677816: Global MASTER-Net observations report
  19. Correction to GRB 200125A: Swift-XRT refined analysis
  20. GRB 200125A: Swift-XRT refined Analysis
  21. GRB 200125A: Nanshan-0.6m optical upper limit
  22. GRB 200125A: RATIR Optical Observations
  23. Swift GRB 200125A: Global MASTER-Net observations report
  24. GRB 200125B: BALROG localization (Fermi Trigger 601677816 / GRB 200125864)
  25. GRB 200125B: Fermi GBM Final Real-time Localization
  26. GRB 200125A: Enhanced Swift-XRT position
  27. GRB 200122B: Insight-HXMT/HE detection
  28. GRB 200125A: Swift detection of a burst
  29. LIGO/Virgo S200114f : No significant candidates in TAROT - FRAM - GRANDMA observations
  30. IceCube-200120A: Event likely due to background
  31. GRB 200122A: Optical upper limit: correction to the GCN circ. 26870
  32. GRB 200115A: Assy optical observations
  33. GRB 200122A: AstroSat CZTI detection
  34. GRB 200122A: Optical upper limit
  35. GRB 200122A: Mondy optical upper limit
  36. LIGO/Virgo S191222n: AstroSat CZTI upper limits
  37. LIGO/Virgo S200112r: AstroSat CZTI upper limits
  38. LIGO/Virgo S200114f: AstroSat CZTI upper limits
  39. Konus-Wind observation of GRB 200122A
  40. GRB 200122A: MITSuME Akeno optical upper limits
  41. LIGO/Virgo S200115j: Zwicky Transient Facility search for optical counterparts to Swift X-ray sources
  42. GRB 200122A: RATIR Optical Observations
  43. GRB 200122A: Swift-BAT refined analysis
  44. GRB 200122A: Xinglong-2.16m optical upper limit
  45. GRB 200122A: Swift/UVOT Upper Limits
  46. Fermi trigger No 601363105: Global MASTER-Net observations report
  47. Konus-Wind observation of GRB 200120A
  48. IPN Triangulation of GRB 200120A
  49. LIGO/Virgo S200115j: Further Swift-XRT sources
  50. GRB 200122A: FRAM-ORM optical limit
  51. GRB 200122A: GOTO non-detection of optical afterglow
  52. GRB 200122A: Swift-XRT refined Analysis
  53. GRB 200120A: AstroSat CZTI detection
  54. Fermi-LAT Gamma-ray Observations of IceCube-200120A
  55. LIGO/Virgo S200115j: Upper limits from Konus-Wind observations
  56. LIGO/Virgo S200114f: Upper limits from Konus-Wind observations
  57. LIGO/Virgo S200112r: Upper limits from Konus-Wind observations
  58. GRB 200122A: Enhanced Swift-XRT position
  59. Swift GRB 200122A: Global MASTER-Net observations report
  60. GRB 200122A: Swift detection of a burst
  61. IceCube-200120A: Upper limits from a search for additional neutrino events in IceCube
  62. Fermi trigger No 601254300: Global MASTER-Net observations report
  63. GRB 191031D: XMM-Newton upper limit
  64. GRB 200120A: Insight-HXMT/HE detection
  65. LIGO/VIRGO S200115j: No obvious candidates from Pan-STARRS2 observations
  66. IceCube-200120A: no counterpart candidates in INTEGRAL SPI-ACS and,IBIS prompt observation
  67. LIGO/Virgo S200105ae: Upper limits from Konus-Wind observations
  68. LIGO/Virgo S191222n: Upper limits from Konus-Wind observations
  69. LIGO/Virgo S191216ap: Upper limits from Konus-Wind observations
  70. LIGO/Virgo S191215w: Upper limits from Konus-Wind observations
  71. IceCube-200120A: not observable by Fermi-GBM
  72. IceCube-200120A: IceCube observation of a high-energy neutrino candidate event
  73. GRB 200120A: Fermi GBM Final Real-time Localization
  74. LIGO/Virgo S200114f: SOAR spectroscopy of AT2020zf, AT2020ace and AT2020ach
  75. IceCube Alert 200120.78: Global MASTER-Net observations report
  76. IceCube 200117A: No significant detection in HAWC
  77. LIGO/Virgo S191213g: Upper limits from Konus-Wind observations
  78. LIGO/Virgo S191205ah: Upper limits from Konus-Wind observations
  79. LIGO/Virgo S191204r: Upper limits from Konus-Wind observations
  80. LIGO/Virgo S191129u: Upper limits from Konus-Wind observations
  81. LIGO/Virgo S200115j: No counterpart detection within possible host galaxies observed by the GRAWITA-Savelli telescope
  82. LIGO/Virgo S200115j: GMOS-N upper limits for ZTF20aafqvyc/AT2020yq from the Gemini Observatory
  83. Fermi-LAT Gamma-ray Observations of IceCube-200117A
  84. LIGO/Virgo S200115j : No significant candidates in TAROT - FRAM - GRANDMA observations
  85. LIGO/Virgo S200115j: Mondy upper limits for ZTF20aafqvyc/AT2020yq
  86. GRB 200115A: Mondy optical observations and correction to GCN 26790
  87. LIGO/Virgo S200115j: LCO upper limits for ZTF20aafqvyc/AT2020yq from the McDonald Observatory 1-m telescope
  88. IceCube-200117A: One Additional Candidate Counterpart from the Zwicky Transient Facility
  89. IceCube-200117A : Upper limits from Insight-HXMT/HE observations
  90. LIGO/Virgo S200115j: NIR upper limits for ZTF20aafqvyc/AT2020yq from the Palomar 200-inch telescope
  91. IceCube-200117A: Candidate Counterpart from the Zwicky Transient Facility
  92. IceCube-200117A: Upper limits from a search for additional neutrino events in IceCube
  93. IceCube-200117A: No Neutrino Counterpart in ANTARES data
  94. LIGO/Virgo S200105ae: More candidates from the Zwicky Transient Facility
  95. GRB 200115A: CALET Gamma-Ray Burst Monitor detection
  96. LIGO/Virgo S200115j: Swift/UVOT observations of Swift/XRT S200115j_X136
  97. LIGO/Virgo S200115j: Updated Sky Localization and source properties
  98. LIGO/Virgo S200114f: More candidates from the Zwicky Transient Facility
  99. IceCube-200117A: Upper limits from Fermi-GBM Observations
  100. IceCube-200117A: no counterpart candidates in INTEGRAL SPI-ACS and,IBIS prompt observation

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