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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. GRB 240514B: AT2024ixa/GOTO24bph is not consistent with the Fermi localisation
  2. Fermi trigger No 737476171: Global MASTER-Net observations report
  3. GRB 240511A: radio detection of afterglow candidate
  4. GRB 240514B: GOTO candidate optical counterpart
  5. MAXI GRB240514.78: Global MASTER-Net observations report
  6. Fermi Gamma-ray Burst Monitor list of triggers that are not a GRB
  7. GRB 240514E: MAXI/GSC detection of a probable afterglow
  8. GRB 240514B: GRBAlpha detection
  9. LIGO/Virgo/KAGRA S240514x: Updated Sky localization
  10. LIGO/Virgo/KAGRA S240515m: Identification of a GW compact binary merger candidate
  11. GRB 240514B: Fermi GBM Detection
  12. LIGO/Virgo/KAGRA S240422ed: Las Cumbres Observatory Follow-up Observations of the Localization Region
  13. GRB 240513A: Fermi GBM observation
  14. GRB 240513A: Swift-XRT observations
  15. LIGO/Virgo/KAGRA S240513ei: Updated Sky localization
  16. LIGO/Virgo/KAGRA S240514x: Identification of a GW compact binary merger candidate
  17. GRB 240514D: AstroSat CZTI detection
  18. GRB 240514C: Fermi GBM Final Real-time Localization
  19. LIGO/Virgo/KAGRA S240514c: Identification of a GW compact binary merger candidate
  20. Fermi GRB 240514B: Global MASTER-Net observations report
  21. transient: Xinglong Nearby Galaxy Supernova Survey detection of AT2024iss
  22. Fermi Gamma-ray Burst Monitor triggers 737345659/240514093 and GRB240514A are not GRBs
  23. GRB 240514B: Fermi GBM Final Real-time Localization
  24. LIGO/Virgo/KAGRA S240507p: Upper limits from Swift/BAT-GUANO
  25. LIGO/Virgo/KAGRA S240505av: Upper limits from Swift/BAT-GUANO
  26. LIGO/Virgo/KAGRA S240505av: Upper limits from Swift/BAT-GUANO
  27. GRB 240514A: Fermi GBM Final Real-time Localization
  28. GRB 240513A: Tiled Swift observations
  29. LAT GRB240513.31: Global MASTER-Net observations report
  30. GRB 240513A: Fermi-LAT detection
  31. LIGO/Virgo/KAGRA S240513ei: Identification of a GW compact binary merger candidate
  32. GRB 240511A: Fermi GBM Observation
  33. GRB 240511A: Swift-BAT refined analysis
  34. Fermi GRB 240513B: Global MASTER-Net observations report
  35. Fermi trigger No 737277727: Global MASTER-Net observations report
  36. GRB 240513B: Fermi GBM Final Real-time Localization
  37. GRB 240513A: AstroSat CZTI detection
  38. LIGO/Virgo/KAGRA S240513cx: Coverage and upper limits from MAXI/GSC observations
  39. Fermi trigger No 737258655: Global MASTER-Net observations report
  40. GRB 240511A: J-band observations with WINTER
  41. Fermi trigger No 737247400: Global MASTER-Net observations report
  42. Fermi trigger No 737244199: Global MASTER-Net observations report
  43. Fermi trigger No 737218721: Global MASTER-Net observations report
  44. Fermi trigger No 737196587: Global MASTER-Net observations report
  45. Fermi trigger No 737168073: Global MASTER-Net observations report
  46. GRB 240511A: Enhanced Swift-XRT position
  47. GRB 240511A : MITSuME Akeno optical upper limits
  48. LIGO/Virgo/KAGRA S240512r: Updated Sky localization and EM Bright Classification
  49. GRB 240511A: Swift-XRT refined Analysis
  50. GRB 240511A: optical afterglow detection from the NOT
  51. Fermi Gamma-ray Burst Monitor trigger 737102480/240511279 is not a GRB
  52. Fermi Gamma-ray Burst Monitor trigger 737111207/240511380 is not a GRB
  53. Fermi GBM trigger 737105243/240511311 is not a GRB
  54. Fermi trigger No 737173236: Global MASTER-Net observations report
  55. LIGO/Virgo/KAGRA S240512r: Identification of a GW compact binary merger candidate
  56. Fermi GRB 240511A: Global MASTER-Net observations report
  57. Swift GRB 240511A: Global MASTER-Net observations report
  58. Fermi trigger No 737105243: Global MASTER-Net observations report
  59. Fermi Gamma-ray Burst Monitor trigger 737133200/240511634 is not a GRB
  60. Fermi trigger No 737152719: Global MASTER-Net observations report
  61. GRB 240511A: Prompt enhanced Swift-XRT position
  62. GRB 240511A: Swift detection of a burst
  63. LIGO/Virgo/KAGRA S240511i: Updated Sky localization
  64. GRB 240511A: Fermi GBM Final Real-time Localization
  65. Fermi trigger No 737102480: Global MASTER-Net observations report
  66. Fermi trigger No 737111207: Global MASTER-Net observations report
  67. LIGO/Virgo/KAGRA S240511i: Identification of a GW compact binary merger candidate
  68. Fermi Gamma-ray Burst Monitor trigger 737076431/240510977 is not a GRB
  69. LIGO/Virgo/KAGRA S240422ed: GMOS-S photometry of J-GEM24a
  70. LIGO/Virgo/KAGRA S240422ed: P200 observations of AT2024hit
  71. LIGO/Virgo/KAGRA S240422ed: Candidates from the latest GW-MMADS DECam Observations
  72. Fermi trigger No 736967879: Global MASTER-Net observations report
  73. EP240506a: Xinglong optical upper limit
  74. Fermi Gamma-ray Burst Monitor trigger 230925241/717313591 is not a GRB
  75. EP240506a: CrAO ZTSH optical upper limit
  76. GRB 240504A: Fermi GBM Observation
  77. Fermi Gamma-ray Burst Monitor trigger 736837160/240508208 is not a GRB
  78. EP240506a: Archival radio searching
  79. EP240506a: TRT optical upper limit
  80. EP240506a: BOOTES Network optical upper limit
  81. LIGO/Virgo/KAGRA S240507p: Updated Sky localization and EM Bright Classification
  82. LIGO/Virgo/KAGRA S240422ed: Upper limits from a two-week IceCube neutrino search
  83. Fermi trigger No 736733320: Global MASTER-Net observations report
  84. EP240506a: Optical upper limit with Kinder observations
  85. IPN triangulation of GRB 240504A
  86. GRB 240502A: 1.3m DFOT Optical upper limit
  87. EP240506a: EP-WXT detection of a new fast X-ray transient
  88. LIGO/Virgo/KAGRA S240507p: Identification of a GW compact binary merger candidate
  89. LIGO/Virgo/KAGRA S240422ed: Additional WINTER near-infrared J-band observations
  90. LIGO/Virgo/KAGRA S240422ed: Swope Follow-up of AT2024hfr and AT2024hfs
  91. GRB 240504A: Swift/BAT-GUANO detection of a burst outside the coded FOV
  92. Fermi GBM triggers 736668287/240506253 and 736669277/240506265 are not GRBs
  93. LIGO/Virgo/KAGRA S240505av: Updated Sky localization and EM Bright Classification
  94. Fermi trigger No 736564880: Global MASTER-Net observations report
  95. LIGO/Virgo/KAGRA S240505av: Identification of a GW compact binary merger candidate
  96. IceCube-240424A: GRANDMA Optical Upper Limit of Fermi J2151.3+0220
  97. GRB 240502C: Zeiss-1000 at Koshka observatory observations of GOTO optical counterpart candidates
  98. Fermi trigger No 736461232: Global MASTER-Net observations report
  99. IPN triangulation of GRB 240501B and GRB 240501A - possible episodes of ultra long GRB
  100. Fermi GRB 240504A: Global MASTER-Net observations report

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