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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 240502C: Zeiss-1000 at Koshka observations of GOTO24bao optical counterpart candidate
  2. GRB 240516A: GOTO optical upper limit
  3. LIGO/Virgo/KAGRA S240422ed: GRID non-detection and upper limits
  4. Fermi trigger No 737523389: Global MASTER-Net observations report
  5. GRB 240516A: Swift detection of a burst
  6. Swift GRB240516.15: Global MASTER-Net observations report
  7. GRB 240514B: AT2024ixa/GOTO24bph is not consistent with the Fermi localisation
  8. Fermi trigger No 737476171: Global MASTER-Net observations report
  9. GRB 240511A: radio detection of afterglow candidate
  10. GRB 240514B: GOTO candidate optical counterpart
  11. MAXI GRB240514.78: Global MASTER-Net observations report
  12. Fermi Gamma-ray Burst Monitor list of triggers that are not a GRB
  13. GRB 240514E: MAXI/GSC detection of a probable afterglow
  14. GRB 240514B: GRBAlpha detection
  15. LIGO/Virgo/KAGRA S240514x: Updated Sky localization
  16. LIGO/Virgo/KAGRA S240515m: Identification of a GW compact binary merger candidate
  17. GRB 240514B: Fermi GBM Detection
  18. LIGO/Virgo/KAGRA S240422ed: Las Cumbres Observatory Follow-up Observations of the Localization Region
  19. GRB 240513A: Fermi GBM observation
  20. GRB 240513A: Swift-XRT observations
  21. LIGO/Virgo/KAGRA S240513ei: Updated Sky localization
  22. LIGO/Virgo/KAGRA S240514x: Identification of a GW compact binary merger candidate
  23. GRB 240514D: AstroSat CZTI detection
  24. GRB 240514C: Fermi GBM Final Real-time Localization
  25. LIGO/Virgo/KAGRA S240514c: Identification of a GW compact binary merger candidate
  26. Fermi GRB 240514B: Global MASTER-Net observations report
  27. transient: Xinglong Nearby Galaxy Supernova Survey detection of AT2024iss
  28. Fermi Gamma-ray Burst Monitor triggers 737345659/240514093 and GRB240514A are not GRBs
  29. GRB 240514B: Fermi GBM Final Real-time Localization
  30. LIGO/Virgo/KAGRA S240507p: Upper limits from Swift/BAT-GUANO
  31. LIGO/Virgo/KAGRA S240505av: Upper limits from Swift/BAT-GUANO
  32. LIGO/Virgo/KAGRA S240505av: Upper limits from Swift/BAT-GUANO
  33. GRB 240514A: Fermi GBM Final Real-time Localization
  34. GRB 240513A: Tiled Swift observations
  35. LAT GRB240513.31: Global MASTER-Net observations report
  36. GRB 240513A: Fermi-LAT detection
  37. LIGO/Virgo/KAGRA S240513ei: Identification of a GW compact binary merger candidate
  38. GRB 240511A: Fermi GBM Observation
  39. GRB 240511A: Swift-BAT refined analysis
  40. Fermi GRB 240513B: Global MASTER-Net observations report
  41. Fermi trigger No 737277727: Global MASTER-Net observations report
  42. GRB 240513B: Fermi GBM Final Real-time Localization
  43. GRB 240513A: AstroSat CZTI detection
  44. LIGO/Virgo/KAGRA S240513cx: Coverage and upper limits from MAXI/GSC observations
  45. Fermi trigger No 737258655: Global MASTER-Net observations report
  46. GRB 240511A: J-band observations with WINTER
  47. Fermi trigger No 737247400: Global MASTER-Net observations report
  48. Fermi trigger No 737244199: Global MASTER-Net observations report
  49. Fermi trigger No 737218721: Global MASTER-Net observations report
  50. Fermi trigger No 737196587: Global MASTER-Net observations report
  51. Fermi trigger No 737168073: Global MASTER-Net observations report
  52. GRB 240511A: Enhanced Swift-XRT position
  53. GRB 240511A : MITSuME Akeno optical upper limits
  54. LIGO/Virgo/KAGRA S240512r: Updated Sky localization and EM Bright Classification
  55. GRB 240511A: Swift-XRT refined Analysis
  56. GRB 240511A: optical afterglow detection from the NOT
  57. Fermi Gamma-ray Burst Monitor trigger 737102480/240511279 is not a GRB
  58. Fermi Gamma-ray Burst Monitor trigger 737111207/240511380 is not a GRB
  59. Fermi GBM trigger 737105243/240511311 is not a GRB
  60. Fermi trigger No 737173236: Global MASTER-Net observations report
  61. LIGO/Virgo/KAGRA S240512r: Identification of a GW compact binary merger candidate
  62. Fermi GRB 240511A: Global MASTER-Net observations report
  63. Swift GRB 240511A: Global MASTER-Net observations report
  64. Fermi trigger No 737105243: Global MASTER-Net observations report
  65. Fermi Gamma-ray Burst Monitor trigger 737133200/240511634 is not a GRB
  66. Fermi trigger No 737152719: Global MASTER-Net observations report
  67. GRB 240511A: Prompt enhanced Swift-XRT position
  68. GRB 240511A: Swift detection of a burst
  69. LIGO/Virgo/KAGRA S240511i: Updated Sky localization
  70. GRB 240511A: Fermi GBM Final Real-time Localization
  71. Fermi trigger No 737102480: Global MASTER-Net observations report
  72. Fermi trigger No 737111207: Global MASTER-Net observations report
  73. LIGO/Virgo/KAGRA S240511i: Identification of a GW compact binary merger candidate
  74. Fermi Gamma-ray Burst Monitor trigger 737076431/240510977 is not a GRB
  75. LIGO/Virgo/KAGRA S240422ed: GMOS-S photometry of J-GEM24a
  76. LIGO/Virgo/KAGRA S240422ed: P200 observations of AT2024hit
  77. LIGO/Virgo/KAGRA S240422ed: Candidates from the latest GW-MMADS DECam Observations
  78. Fermi trigger No 736967879: Global MASTER-Net observations report
  79. EP240506a: Xinglong optical upper limit
  80. Fermi Gamma-ray Burst Monitor trigger 230925241/717313591 is not a GRB
  81. EP240506a: CrAO ZTSH optical upper limit
  82. GRB 240504A: Fermi GBM Observation
  83. Fermi Gamma-ray Burst Monitor trigger 736837160/240508208 is not a GRB
  84. EP240506a: Archival radio searching
  85. EP240506a: TRT optical upper limit
  86. EP240506a: BOOTES Network optical upper limit
  87. LIGO/Virgo/KAGRA S240507p: Updated Sky localization and EM Bright Classification
  88. LIGO/Virgo/KAGRA S240422ed: Upper limits from a two-week IceCube neutrino search
  89. Fermi trigger No 736733320: Global MASTER-Net observations report
  90. EP240506a: Optical upper limit with Kinder observations
  91. IPN triangulation of GRB 240504A
  92. GRB 240502A: 1.3m DFOT Optical upper limit
  93. EP240506a: EP-WXT detection of a new fast X-ray transient
  94. LIGO/Virgo/KAGRA S240507p: Identification of a GW compact binary merger candidate
  95. LIGO/Virgo/KAGRA S240422ed: Additional WINTER near-infrared J-band observations
  96. LIGO/Virgo/KAGRA S240422ed: Swope Follow-up of AT2024hfr and AT2024hfs
  97. GRB 240504A: Swift/BAT-GUANO detection of a burst outside the coded FOV
  98. Fermi GBM triggers 736668287/240506253 and 736669277/240506265 are not GRBs
  99. LIGO/Virgo/KAGRA S240505av: Updated Sky localization and EM Bright Classification
  100. Fermi trigger No 736564880: Global MASTER-Net observations report

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