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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').
  1. LIGO/Virgo S240527fv: GRANDMA/FRAM-Auger Optical Observations
  2. GRB 240529A: Swift-XRT refined Analysis
  3. GRB240529A: BOOTES-6/DPRT optical detection
  4. GRB 240529A: Swift/UVOT Detection
  5. GRB 240529A: NOT optical observations
  6. GRB 240529A: AstroSat CZTI detection
  7. GRB 240529A: GOTO optical afterglow detection
  8. GRB 240527B: Swift-XRT afterglow detection
  9. GRB 240529A: Enhanced Swift-XRT position
  10. GRB 240529A: Swift detection of a burst with an optical counterpart
  11. Swift GRB240529.12: Global MASTER-Net observations report
  12. LIGO/Virgo/KAGRA S240527fv: Updated Sky localization
  13. GRB 240527B: Fermi GBM Observation
  14. Fermi GRB 240527A: Global MASTER-Net observations report
  15. LIGO/Virgo/KAGRA S240527fv: Identification of a GW compact binary merger candidate
  16. GRB 240527B: Fermi-LAT detection
  17. LAT GRB240527.59: Global MASTER-Net observations report
  18. LIGO/Virgo/KAGRA S240527en: Identification of a GW compact binary merger candidate
  19. Fermi GRB 240527B: Global MASTER-Net observations report
  20. GRB 240527B: Fermi GBM Final Localization
  21. GRB 240527B: BALROG localization (Fermi Trigger 738511436 / GRB 240527586)
  22. GRB 240527A: Fermi GBM Final Real-time Localization
  23. GRB 240523A: Swift-BAT refined analysis
  24. Fermi trigger No 738348224: Global MASTER-Net observations report
  25. Fermi trigger No 738330463: Global MASTER-Net observations report
  26. LIGO/Virgo/KAGRA S240525p: Updated Sky localization
  27. LIGO/Virgo/KAGRA S240525p: Identification of a GW compact binary merger candidate
  28. GRB 240523A: Swift-XRT refined Analysis
  29. GRB 240523A: Enhanced Swift-XRT position
  30. GRB 240523A: Swift detection of a burst
  31. GRB 240521B: Fermi GBM Observation
  32. Fermi GBM Sub-Threshold Detection of GRB 240516B
  33. GRB 240513A: Swift-XRT afterglow detection
  34. GRB 240521B: Swift/BAT-GUANO arcminute localization of a long burst
  35. Fermi trigger No 737996942: Global MASTER-Net observations report
  36. LIGO/Virgo/KAGRA S240520cv: Updated Sky localization and EM Bright Classification
  37. EP240518a: GSP optical upper limit
  38. GRB 240521A: GECAM-B detection of a long burst
  39. GRB 240516B: AstroSat CZTI detection
  40. LIGO/Virgo/KAGRA S240515m: Upper limits from Swift/BAT-GUANO
  41. LIGO/Virgo/KAGRA S240514x: Upper limits from Swift/BAT-GUANO
  42. LIGO/Virgo/KAGRA S240513ei: Upper limits from Swift/BAT-GUANO
  43. LIGO/Virgo/KAGRA S240520cv: Identification of a GW compact binary merger candidate
  44. IceCube-Cascade 240518A: Upper limits from a search for additional neutrino events in IceCube
  45. GRB 240514B: VZLUSAT-2 detection
  46. GRB 240504A: VZLUSAT-2 detection
  47. GRB 240502A: VZLUSAT-2 detection
  48. GRB 240519A: GRBAlpha detection
  49. GRB 240516A: Swift/UVOT Upper Limits
  50. GRB 240519A: AstroSat CZTI detection
  51. Fermi trigger No 737788024: Global MASTER-Net observations report
  52. EP240518a: possibly identified with a flare star by EP-FXT
  53. GRB 240519A: BALROG localization (Fermi Trigger 737788024 / GRB 240519213)
  54. EP240518a: EP-WXT detection of a new X-ray transient
  55. LIGO/Virgo/KAGRA S240514c: Updated Sky localization
  56. GRB 240516A: Swift-BAT refined analysis
  57. Fermi GRB 240517A: Global MASTER-Net observations report
  58. GRB 240516A ATCA radio observations
  59. IPN triangulation of GRB 240514B (short)
  60. GRB 240513A: Swift ToO observations
  61. GRB 240517A: Fermi GBM Final Real-time Localization
  62. Konus-Wind detection of GRB 240513A
  63. GRB 240516A: AstroSat CZTI detection
  64. GRB 240516A: Swift-XRT refined Analysis
  65. GRB 240514E: A possible candidate BD-21 1074
  66. Fermi trigger No 737559855: Global MASTER-Net observations report
  67. GRB 240516A: Fermi GBM Observation
  68. GRB 240511A: Observations from GTC/OSIRIS+
  69. GRB 240502C: Zeiss-1000 at Koshka observations of GOTO24bao optical counterpart candidate
  70. GRB 240516A: GOTO optical upper limit
  71. LIGO/Virgo/KAGRA S240422ed: GRID non-detection and upper limits
  72. Fermi trigger No 737523389: Global MASTER-Net observations report
  73. GRB 240516A: Swift detection of a burst
  74. Swift GRB240516.15: Global MASTER-Net observations report
  75. GRB 240514B: AT2024ixa/GOTO24bph is not consistent with the Fermi localisation
  76. Fermi trigger No 737476171: Global MASTER-Net observations report
  77. GRB 240511A: radio detection of afterglow candidate
  78. GRB 240514B: GOTO candidate optical counterpart
  79. MAXI GRB240514.78: Global MASTER-Net observations report
  80. Fermi Gamma-ray Burst Monitor list of triggers that are not a GRB
  81. GRB 240514E: MAXI/GSC detection of a probable afterglow
  82. GRB 240514B: GRBAlpha detection
  83. LIGO/Virgo/KAGRA S240514x: Updated Sky localization
  84. LIGO/Virgo/KAGRA S240515m: Identification of a GW compact binary merger candidate
  85. GRB 240514B: Fermi GBM Detection
  86. LIGO/Virgo/KAGRA S240422ed: Las Cumbres Observatory Follow-up Observations of the Localization Region
  87. GRB 240513A: Fermi GBM observation
  88. GRB 240513A: Swift-XRT observations
  89. LIGO/Virgo/KAGRA S240513ei: Updated Sky localization
  90. LIGO/Virgo/KAGRA S240514x: Identification of a GW compact binary merger candidate
  91. GRB 240514D: AstroSat CZTI detection
  92. GRB 240514C: Fermi GBM Final Real-time Localization
  93. LIGO/Virgo/KAGRA S240514c: Identification of a GW compact binary merger candidate
  94. Fermi GRB 240514B: Global MASTER-Net observations report
  95. transient: Xinglong Nearby Galaxy Supernova Survey detection of AT2024iss
  96. Fermi Gamma-ray Burst Monitor triggers 737345659/240514093 and GRB240514A are not GRBs
  97. GRB 240514B: Fermi GBM Final Real-time Localization
  98. LIGO/Virgo/KAGRA S240507p: Upper limits from Swift/BAT-GUANO
  99. LIGO/Virgo/KAGRA S240505av: Upper limits from Swift/BAT-GUANO
  100. LIGO/Virgo/KAGRA S240505av: Upper limits from Swift/BAT-GUANO

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