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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 trigger No 601677816: Global MASTER-Net observations report
  2. Correction to GRB 200125A: Swift-XRT refined analysis
  3. GRB 200125A: Swift-XRT refined Analysis
  4. GRB 200125A: Nanshan-0.6m optical upper limit
  5. GRB 200125A: RATIR Optical Observations
  6. Swift GRB 200125A: Global MASTER-Net observations report
  7. GRB 200125B: BALROG localization (Fermi Trigger 601677816 / GRB 200125864)
  8. GRB 200125B: Fermi GBM Final Real-time Localization
  9. GRB 200125A: Enhanced Swift-XRT position
  10. GRB 200122B: Insight-HXMT/HE detection
  11. GRB 200125A: Swift detection of a burst
  12. LIGO/Virgo S200114f : No significant candidates in TAROT - FRAM - GRANDMA observations
  13. IceCube-200120A: Event likely due to background
  14. GRB 200122A: Optical upper limit: correction to the GCN circ. 26870
  15. GRB 200115A: Assy optical observations
  16. GRB 200122A: AstroSat CZTI detection
  17. GRB 200122A: Optical upper limit
  18. GRB 200122A: Mondy optical upper limit
  19. LIGO/Virgo S191222n: AstroSat CZTI upper limits
  20. LIGO/Virgo S200112r: AstroSat CZTI upper limits
  21. LIGO/Virgo S200114f: AstroSat CZTI upper limits
  22. Konus-Wind observation of GRB 200122A
  23. GRB 200122A: MITSuME Akeno optical upper limits
  24. LIGO/Virgo S200115j: Zwicky Transient Facility search for optical counterparts to Swift X-ray sources
  25. GRB 200122A: RATIR Optical Observations
  26. GRB 200122A: Swift-BAT refined analysis
  27. GRB 200122A: Xinglong-2.16m optical upper limit
  28. GRB 200122A: Swift/UVOT Upper Limits
  29. Fermi trigger No 601363105: Global MASTER-Net observations report
  30. Konus-Wind observation of GRB 200120A
  31. IPN Triangulation of GRB 200120A
  32. LIGO/Virgo S200115j: Further Swift-XRT sources
  33. GRB 200122A: FRAM-ORM optical limit
  34. GRB 200122A: GOTO non-detection of optical afterglow
  35. GRB 200122A: Swift-XRT refined Analysis
  36. GRB 200120A: AstroSat CZTI detection
  37. Fermi-LAT Gamma-ray Observations of IceCube-200120A
  38. LIGO/Virgo S200115j: Upper limits from Konus-Wind observations
  39. LIGO/Virgo S200114f: Upper limits from Konus-Wind observations
  40. LIGO/Virgo S200112r: Upper limits from Konus-Wind observations
  41. GRB 200122A: Enhanced Swift-XRT position
  42. Swift GRB 200122A: Global MASTER-Net observations report
  43. GRB 200122A: Swift detection of a burst
  44. IceCube-200120A: Upper limits from a search for additional neutrino events in IceCube
  45. Fermi trigger No 601254300: Global MASTER-Net observations report
  46. GRB 191031D: XMM-Newton upper limit
  47. GRB 200120A: Insight-HXMT/HE detection
  48. LIGO/VIRGO S200115j: No obvious candidates from Pan-STARRS2 observations
  49. IceCube-200120A: no counterpart candidates in INTEGRAL SPI-ACS and,IBIS prompt observation
  50. LIGO/Virgo S200105ae: Upper limits from Konus-Wind observations
  51. LIGO/Virgo S191222n: Upper limits from Konus-Wind observations
  52. LIGO/Virgo S191216ap: Upper limits from Konus-Wind observations
  53. LIGO/Virgo S191215w: Upper limits from Konus-Wind observations
  54. IceCube-200120A: not observable by Fermi-GBM
  55. IceCube-200120A: IceCube observation of a high-energy neutrino candidate event
  56. GRB 200120A: Fermi GBM Final Real-time Localization
  57. LIGO/Virgo S200114f: SOAR spectroscopy of AT2020zf, AT2020ace and AT2020ach
  58. IceCube Alert 200120.78: Global MASTER-Net observations report
  59. IceCube 200117A: No significant detection in HAWC
  60. LIGO/Virgo S191213g: Upper limits from Konus-Wind observations
  61. LIGO/Virgo S191205ah: Upper limits from Konus-Wind observations
  62. LIGO/Virgo S191204r: Upper limits from Konus-Wind observations
  63. LIGO/Virgo S191129u: Upper limits from Konus-Wind observations
  64. LIGO/Virgo S200115j: No counterpart detection within possible host galaxies observed by the GRAWITA-Savelli telescope
  65. LIGO/Virgo S200115j: GMOS-N upper limits for ZTF20aafqvyc/AT2020yq from the Gemini Observatory
  66. Fermi-LAT Gamma-ray Observations of IceCube-200117A
  67. LIGO/Virgo S200115j : No significant candidates in TAROT - FRAM - GRANDMA observations
  68. LIGO/Virgo S200115j: Mondy upper limits for ZTF20aafqvyc/AT2020yq
  69. GRB 200115A: Mondy optical observations and correction to GCN 26790
  70. LIGO/Virgo S200115j: LCO upper limits for ZTF20aafqvyc/AT2020yq from the McDonald Observatory 1-m telescope
  71. IceCube-200117A: One Additional Candidate Counterpart from the Zwicky Transient Facility
  72. IceCube-200117A : Upper limits from Insight-HXMT/HE observations
  73. LIGO/Virgo S200115j: NIR upper limits for ZTF20aafqvyc/AT2020yq from the Palomar 200-inch telescope
  74. IceCube-200117A: Candidate Counterpart from the Zwicky Transient Facility
  75. IceCube-200117A: Upper limits from a search for additional neutrino events in IceCube
  76. IceCube-200117A: No Neutrino Counterpart in ANTARES data
  77. LIGO/Virgo S200105ae: More candidates from the Zwicky Transient Facility
  78. GRB 200115A: CALET Gamma-Ray Burst Monitor detection
  79. LIGO/Virgo S200115j: Swift/UVOT observations of Swift/XRT S200115j_X136
  80. LIGO/Virgo S200115j: Updated Sky Localization and source properties
  81. LIGO/Virgo S200114f: More candidates from the Zwicky Transient Facility
  82. IceCube-200117A: Upper limits from Fermi-GBM Observations
  83. IceCube-200117A: no counterpart candidates in INTEGRAL SPI-ACS and,IBIS prompt observation
  84. LIGO/Virgo S200114f: No transients found in J-GEM observations of nearby galaxies
  85. IceCube-200117A: IceCube observation of a high-energy neutrino candidate event
  86. GRB 200115A: AROMA-N Optical Observation
  87. GRB 200117A: Fermi GBM Final Real-time Localization
  88. IceCube Alert 200117.46: Global MASTER-Net observations report
  89. LIGO/Virgo S200115j: Swift-XRT sources
  90. LIGO/Virgo S200115j: Upper limits from CALET observations.
  91. LIGO/Virgo S200114f: ZTF Forced Photometry of the Swift Source S200114f_X2
  92. GRB 200111A: CALET Gamma-Ray Burst Monitor detection
  93. LIGO/Virgo S200115j: No notable candidates in GOTO imaging
  94. LIGO/Virgo S200114f: Upper Limits from Wide-Field Infrared Search with Palomar Gattini-IR
  95. GRB 200115A: DDOTI/OAN optical observations report
  96. LIGO/Virgo S200114f: Possible X-ray transient
  97. GRB 200115A: Mondy optical afterglow candidate
  98. LIGO/Virgo S200112r : No significant candidates in TAROT - FRAM - GRANDMA observations.
  99. LIGO/Virgo S200115j: No neutrino candidates at Pierre Auger Observatory
  100. LIGO/Virgo S200114f: Swift-XRT sources and observations

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