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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"

1006 results found.

  1. Fermi GRB 260926C: Global MASTER-Net observations report
  2. GRB 260916A: MAXI/GSC detection
  3. MAXI GRB260916.37: Global MASTER-Net observations report
  4. MAXI GRB260827.40: Global MASTER-Net observations report
  5. EP260806a: MAO/AZT-22 optical observations
  6. GRB260708B: MAXI/GSC detection
  7. GRB 260616C: GECAM-B observation of a burst
  8. GRB260616C: MAXI/GSC detection
  9. Fermi GRB 260604C: Global MASTER-Net observations report
  10. Fermi GRB 260604C: Global MASTER-Net observations report
  11. GRB 260531A: MAXI/GSC detection
  12. GRB 260510C: Glowbug gamma-ray detection
  13. GRB 260510C: CALET Gamma-Ray Burst Monitor detection
  14. GRB 260510C: Fermi GBM Observation
  15. GRB 260510C: AstroSat CZTI detection
  16. GRB 260510C: EP-FXT follow-up observation
  17. GRB 260511A: KAIT optical afterglow observations
  18. GRB 260510C: SVOM/VT optical upper limits
  19. GRB 260510C: MAXI/GSC detection
  20. GRID detection of GRB 260401A
  21. GRB 260401A: SVOM/GRM observation
  22. GRB 260401A: GECAM-B observation
  23. GRB 260401A: Fermi GBM Observation
  24. GRB 260401A: NuSTAR detection of prompt emission
  25. GRB 260401A: CALET Gamma-Ray Burst Monitor detection
  26. GRB 260401A: MAXI/GSC detection
  27. EP-WXT trigger 01709259112: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
  28. The EP-WXT trigger 01709259112 is likely a flaring star
  29. GRB 260206A: probable hard X-ray burst from 4U 0513-40
  30. GRB 260206A: Swift-XRT observations
  31. GRB 260206A: Tiled Swift observations
  32. GRB 260206A (or XRB from 4U 0513-40): MAXI/GSC detection
  33. GRID detection of GRB 260131A/B
  34. GRB 260131A/B: EP/FXT X-ray afterglow detection
  35. GRB 260131A: NOT spectroscopic redshift z = 1.434
  36. Konus-Wind detection of GRB 260131A/B
  37. GRB 260131A/B: GOTO candidate optical counterpart consistent with the MAXI localisation
  38. GRB 260131A/B: Fermi GBM Observation
  39. GRB 260131B: MAXI/GSC detection
  40. GRB 260120A: AstroSat CZTI detection
  41. GRB 251220A: MAXI/GSC detection
  42. GRB 251201A: GECAM-B observation of a burst
  43. GRB 251201A: SVOM/GRM observation of a burst
  44. GRB 251201A: MAXI/GSC detection
  45. SVOM GRB 251129A : MASTER optical counterpart detection
  46. LIGO/Virgo/KAGRA S251112cm: ATLAS targeted observations of the skymap
  47. GRB 251112B: MAXI/GSC detection
  48. LIGO/Virgo/KAGRA S251112cm: Coverage and upper limits from MAXI/GSC observations
  49. GRB 251028A: Insight-HXMT/HE detection
  50. Konus-Wind detection of GRB 251028A
  51. GRB 251028A: GECAM-B detection
  52. GRB 251028A: SVOM/GRM observation
  53. GRB 251028A: Fermi GBM Observation
  54. GRB 251028A: Glowbug gamma-ray detection
  55. GRB 251028A: MAXI/GSC detection
  56. GRB 251024A: Swift/UVOT Upper Limits
  57. GRB 251024A: Swift detection of a burst
  58. GRB 251023B: Glowbug gamma-ray detection
  59. GRB 251023B / EP#01709247298: COLIBRÍ optical counterpart candidate
  60. GRB 251023B: CALET Gamma-Ray Burst Monitor detection
  61. EP#01709247298: Swift-XRT counterpart detection
  62. GRB 251023B / MAXI J0451+122: MAXI/GSC detection
  63. GRB 250911A: MAXI/GSC detection
  64. GRB 250925A: SVOM/GWAC-F60A upper limit
  65. LIGO/Virgo/KAGRA S250920bq: Coverage and upper limits from MAXI/GSC observations
  66. Swift GRB 250920B: Global MASTER-Net observations report
  67. GRB 250830B: Swift-XRT afterglow detection
  68. LIGO/Virgo/KAGRA S250831cc: Coverage and upper limits from MAXI/GSC observations
  69. GRB 250830B: Swift-XRT observations
  70. EP250830a/GRB 250830B: Einstein Probe detection of an X-ray transient and Swift/XRT follow-up
  71. LIGO/Virgo/KAGRA S250830bp: Coverage and upper limits from MAXI/GSC observations
  72. GRB 250830B: Swift ToO observations
  73. GRB 250830B: MAXI/GSC detection
  74. GRB 250830A / MAXI J0853+337: MAXI/GSC detection
  75. Fermi trigger No 777883624: Global MASTER-Net observations report
  76. LIGO/Virgo/KAGRA S250818k: Pan-STARRS coverage of the skymap and candidate counterparts
  77. LIGO/Virgo/KAGRA S250818k: Coverage and upper limits from MAXI/GSC observations
  78. GRB 240814A: Fermi GBM Observation
  79. Konus-Wind detection of GRB 250807A
  80. GRB 250721A: Fermi GBM Observation
  81. GRB 250721A: Swift-XRT observations
  82. GRB 250721A: Tiled Swift observations
  83. GRB 250721A: MAXI/GSC detection
  84. EP250702a/GRB 250702B,C,D,E: Archival radio observations from ASKAP VAST
  85. LIGO/Virgo/KAGRA S250704ab: Coverage and upper limits from MAXI/GSC observations
  86. GRBs 250702B,C,D,E / EP250702a: SVOM/GRM observation
  87. EP250702a/GRB 250702B, C, D, E: EP-FXT follow-up observation
  88. GRBs 250702B,C,D,E / EP250702a: Konus-Wind detection of a hard X-ray transient activity
  89. GRB 250702B,C,D,E / EP 250702a: MAXI/GSC detection
  90. GRB 250527B: Swift-XRT observations
  91. GRB 250527B: Tiled Swift observations
  92. GRB 250527B / MAXI J1450-527 : MAXI/GSC detection
  93. MAXI GRB250515.65: Global MASTER-Net observations report
  94. EP#01709175213/IGR J19566+0326: Swift-XRT detection
  95. EP-WXT trigger 01709175213: a new X-ray outburst of LMXB MAXI J1957+032
  96. GRB 250322B: GRBAlpha detection
  97. GRB 250331A: MAXI/GSC detection
  98. EP250311a/GRB 250311A: Correction to EP-WXT detection time
  99. EP250311a/GRB 250311A: EP-FXT follow-up observation
  100. Fermi trigger No 763509110: Global MASTER-Net observations report

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