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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

2446 results found.

  1. EP260416a: SVOM/VT optical observation
  2. GOTO26djh/AT2026jpw: SVOM/VT optical observation
  3. GRB 260415B: Glowbug gamma-ray detection
  4. GRB 260411B: Glowbug gamma-ray detection
  5. GRB 260415A: Insight-HXMT/HE detection
  6. EP260416a: COLIBRÍ optical counterpart candidate
  7. COLIBRI optical observations of the transient GOTO26djh/AT2026jpw
  8. EP260416a: Global MASTER-Net observations report
  9. EP260416a: Einstein Probe detection of an X-ray transient
  10. GOTO26djh/AT2026jpw : MASTER OT observation
  11. GOTO26djh/AT2026jpw: EP-FXT X-ray counterpart detection
  12. GOTO26djh/AT2026jpw transient: SAO RAS optical observations
  13. NOT r-band observations of the transient GOTO26djh/AT2026jpw
  14. GRB 260415B: NuSTAR detection of long prompt emission
  15. GOTO discovery of fast-fading transient GOTO26djh/AT2026jpw, a candidate orphan afterglow
  16. GRB 260415B: Fermi GBM Final Localization
  17. GRB 260415A: Fermi GBM Final Real-time Localization
  18. Fermi trigger No 797912738: Global MASTER-Net observations report
  19. GRB 260414A: Glowbug gamma-ray detection
  20. EP260409a: Early NIR limits from MIRAGE on the MDM 1.3m telescope
  21. EP260321a: CMO SAI J,K observations
  22. GRB 260412A: Insight-HXMT/HE detection
  23. GRB 260414A: Fermi GBM Final Real-time Localization
  24. The EP-WXT trigger 01709260122 is likely a flaring star
  25. Fermi GRB 260413A: Global MASTER-Net observations report
  26. GRB 260410A: Glowbug gamma-ray detection of a short burst
  27. GRB 260413A: Fermi GBM Final Real-time Localization
  28. GRB 260410B: Insight-HXMT/HE detection
  29. GRB 260410A: Insight-HXMT/HE detection
  30. GRB 260411B: GECAM-B observation of a long burst
  31. EP260321a: SVOM/VT optical observations and color changes around peak
  32. GRB 260410A: CALET Gamma-Ray Burst Monitor detection
  33. The EP-WXT trigger 01709260010 is likely a flaring star
  34. GRB 260412A: GECAM-B observation of a long burst
  35. Fermi GRB 260412A: Global MASTER-Net observations report
  36. GRB 260412A: Fermi GBM Observation
  37. GRB 260310A / AT2026fgk: NuSTAR detection of the rebrightening
  38. GRB 260411B: Fermi-LAT detection
  39. GRB 260412A: SVOM detection of a long burst
  40. GRB 260412A: Fermi GBM Final Real-time Localization
  41. GRB 260411B: COLIBRÍ optical observations
  42. GRB 260410B: Fermi GBM Observation
  43. GRB260411B: 3.6m DOT optical observation
  44. GRB 260411A: SVOM/GRM observation
  45. GRB 260407B: SVOM/GRM detection of a possible magnetar X-ray burst
  46. GRB 260411B: SVOM/GRM observation of a long burst
  47. GRB 260409A: Insight-HXMT/HE detection
  48. GRB 260411B: Fermi GBM Detection
  49. GRB 260411B: GOTO optical counterpart candidate
  50. EP260409a: Gemini/FLAMINGOS2 J-band counterpart
  51. GRB 260411B: BALROG localization (Fermi Trigger 797587480 / GRB 260411337)
  52. GRB 260411B: Fermi GBM Final Real-time Localization
  53. GRB 260411A: Fermi GBM Final Real-time Localization
  54. GRB 260410A: COLIBRÍ optical upper limit
  55. EP-WXT01709259790: Optical Upper limits with kinder observations
  56. GRB 260410A: Fermi GBM Observation
  57. GRB 260410B: SVOM/GRM detection of a short faint burst
  58. The EP-WXT trigger 01709259790 is likely a flaring star
  59. GRB 260410B: Fermi GBM Final Real-time Localization
  60. EP-WXT01709259790: Xinglong optical upper limit
  61. GRB 260410A: Fermi-LAT detection
  62. GRB 260410A: Fermi GBM Final Real-time Localization
  63. EP260409a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  64. EP260321a: Chandra X-ray Non-detection
  65. GRB 260409A: Fermi GBM Final Real-time Localization
  66. The EP-WXT trigger 01709259773 is likely a flaring star
  67. GRB 260407A: GECAM-A detection
  68. GRB 260407A: Insight-HXMT/HE detection
  69. EP260409a: SVOM/VT optical upper limits
  70. EP260409a: COLIBRÍ optical upper limits
  71. GRB 260407A: CALET Gamma-Ray Burst Monitor detection
  72. EP260409a: Global MASTER-Net observations report
  73. EP260409a: Einstein Probe detection of an X-ray transient
  74. GRB 260404A: Fermi GBM Final Localization
  75. GRB 260407A: Glowbug gamma-ray detection
  76. GRB 260402A: SVOM/ECLAIRs refined analysis
  77. GRB 260310A: Continued VLA Multi-frequency Radio Observations
  78. GRB 260310A / AT2026fgk: X-ray rebrightening
  79. EP260402a / GRB 260402A: Mephisto optical upper limits
  80. EP-WXT01709259586: Xinglong optical upper limit
  81. EP260403a: Mephisto optical upper limits
  82. EP260402a/GRB 260402A: Xinglong optical upper limit
  83. EP260321a: Upper limits from VLA radio observations
  84. GRID detection of GRB 260401A
  85. EP260321a: uGMRT observations
  86. GRB 260407A: Fermi GBM Final Real-time Localization
  87. EP260405a: GMOS-N optical upper limits
  88. EP260405a: SVOM/VT optical upper limits
  89. EP260405a: Global MASTER-Net observations report
  90. EP260405a: Einstein Probe detection of a fast X-ray transient
  91. The EP-WXT trigger 01709259621 is likely a flaring star
  92. EP260405a / EP-WXT 11900672904: COLIBRÍ optical upper limits
  93. The EP-WXT trigger 01709259615 is likely a flaring star
  94. Fermi trigger No 797039833: Global MASTER-Net observations report
  95. GRB 260403A: GECAM-B observation of a long burst
  96. EP260324A / AT 2026hir: COLIBRÍ further optical observations
  97. Fermi Gamma-ray Burst Monitor trigger 796972356/260404217 is not a GRB
  98. EP260403a: refined analysis of the EP-WXT and EP-FXT observations
  99. The EP-WXT trigger 01709259586 is likely a flaring star
  100. GRB 260330B: SVOM/VT further optical observation

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