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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"

45423 results found.

  1. GRB 240824A: Retraction of GCN 37255
  2. GRB240824A: GRANDMA/TAROT-TCA Upper Limit
  3. SGR 1E 1841-045 / Kes 73: Leavitt Observatory optical upper limit
  4. GRB 240824A: KAIT optical upper limit
  5. GRB 240824A: Skynet Optical Afterglow Discovery
  6. GRB 240824A: Swift detection of a burst
  7. Swift GRB240824.04: Global MASTER-Net observations report
  8. SGR 1E 1841-045 / Kes 73: Montarrenti Observatory optical upper limits
  9. GRB 240821A: Colibri Optical Upper Limit
  10. EP240820a: PRIME J-band Observations
  11. GRB 240821A: Swift-XRT observations
  12. GRB 240822A: AstroSat CZTI detection of a short burst
  13. GRB 240821A: REM optical/NIR upper limits
  14. GRB 240821A: LCO optical observations
  15. GRB 240821A: JinShan optical upper limits
  16. GRB 240809A: Mondy and AbAO Optical Observations
  17. GRB 240821A: SVOM/VT follow-up and optical upper limit
  18. GRB 240821A: GMG Optical Upper Limit
  19. Fermi GRB 240821A: Global MASTER-Net observations report
  20. GECAM-B observation of a short burst from SGR 1E 1841-045 / Kes 73
  21. GRB 240821A: Fermi GBM Observation
  22. Fermi trigger No 745964969: Global MASTER-Net observations report
  23. Fermi trigger No 745925274: Global MASTER-Net observations report
  24. GRB 240821A: Swift ToO observations
  25. Fermi trigger No 746019401: Global MASTER-Net observations report
  26. Fermi-GBM Observations of the reactivation of SGR 1E 1841-045 / Kes 73
  27. Fermi trigger No 745935375: Global MASTER-Net observations report
  28. GRB240821A: EIRSAT-1 GMOD Detection
  29. GRB240821B: First GRB Detected by EIRSAT-1 GMOD
  30. GRB 240821A: EP-FXT follow-up observation and afterglow candidates
  31. Fermi GRB 240821B: Global MASTER-Net observations report
  32. EP240801a: Keck/LRIS spectroscopic redshift confirmation
  33. GRB 240821A: SVOM/GRM observation
  34. GRB 240821A: SVOM/GRM observation
  35. GRB 240821A: GRANDMA/LesMakes-T60 Upper Limit
  36. GRB 240821B: Fermi GBM Final Localization
  37. Fermi trigger No 745866488: Global MASTER-Net observations report
  38. Trigger 1249878: Swift detection of another burst from SGR 1E 1841-045 / Kes 73
  39. GRB 240821A: BALROG localization (Fermi Trigger 745958167 / GRB 240821775)
  40. GRB 240821A : a likely short GRB detected by SVOM/ECLAIRs
  41. GRB 240821A: Fermi GBM Final Real-time Localization
  42. GRB 240819A: Swift-XRT observations
  43. GRB 240819A: JinShan optical upper limits on one Swift/XRT source
  44. GRB 240820B: SVOM/GRM observation
  45. EP240820a: TRT optical upper limit
  46. EP240820a: EP detection of a fast X-ray transient
  47. GRB 240819A: KAIT optical upper limit
  48. Trigger 1249653: Swift detection of SGR 1E 1841-045 / Kes 73
  49. Fermi trigger No 745873283: Global MASTER-Net observations report
  50. Fermi trigger No 745871958: Global MASTER-Net observations report
  51. GRB 240819A : an X-ray transient detected by SVOM/ECLAIRs
  52. GRB 240819A: TRT optical upper limits on the Swift/XRT and EP/FXT sources
  53. GRB 240819A: X-ray follow-up observation with EP-FXT
  54. Fermi Gamma-ray Burst Monitor trigger 745811685 / 240820080 is not a GRB
  55. GRB 240820A: Fermi GBM Final Real-time Localization
  56. GRB 240819A: Swift ToO observations
  57. GRB 240814A: SVOM/GRM observation
  58. EP240816b: Liverpool Telescope optical follow-up observations
  59. GRB 240814C: SVOM/GRM observation
  60. EP240816a: BOOTES-6/DPRT optical upper limit
  61. GRB 240815A: SVOM/GRM observation
  62. GRB 240817A: Fermi GBM Final Real-time Localization
  63. Integral GRB240816.79: Global MASTER-Net observations report
  64. IceCube-240721A: AT2023qqp and AT2024pge likely unrelated
  65. GRB GRB 240809A: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  66. IBAS Alert n.10856: not a GRB
  67. GRB 240805B: Osservatorio Astronomico Nastro Verde upper limit
  68. EP240816b: KAIT optical upper limit
  69. GRB 240814B: GRBAlpha detection
  70. Fermi trigger No 745501396: Global MASTER-Net observations report
  71. EP240816a: EP detection of a fast X-ray transient and follow-up observation
  72. EP EP240816b: Global MASTER-Net observations report
  73. EP240816b: TRT optical upper limit
  74. EP240816b: EP-WXT detection and EP-FXT follow-up observation of a fast X-ray transient
  75. Fermi GRB 240814A: Global MASTER-Net observations report
  76. Fermi GRB 240814C: Global MASTER-Net observations report
  77. Fermi trigger No 745306088: Global MASTER-Net observations report
  78. GRB 240814C: Fermi GBM Final Real-time Localization
  79. Fermi GRB 240814B: Global MASTER-Net observations report
  80. GRB 240812B: SVOM/GRM observation
  81. EP240802a: Kinder optical, SWIFT-UVOT, and SWIFT-XRT upper limits 6 days after the WXT detection
  82. GRB 240814B: Fermi GBM Final Real-time Localization
  83. GRB 240814A: Fermi GBM Final Real-time Localization
  84. LIGO/Virgo/KAGRA S240813d: Updated Sky localization
  85. Fermi trigger No 745220784: Global MASTER-Net observations report
  86. Konus-Wind detection of GRB 240811A
  87. Konus-Wind detection of GRB 240810A
  88. Fermi Gamma-ray Burst Monitor trigger 745220784/240813240 is not a GRB
  89. LIGO/Virgo/KAGRA S240813d: Identification of a GW compact binary merger candidate
  90. LIGO/Virgo/KAGRA S240813c: Updated Sky localization
  91. LIGO/Virgo/KAGRA S240813c: Identification of a GW compact binary merger candidate
  92. GRB 240809A: Correction to the VLA source position in GCN 37158
  93. GRB 240810A: SVOM/GRM observation
  94. Fermi Gamma-ray Burst Monitor trigger 240812940/745194848 is not a GRB
  95. Fermi Gamma-ray Burst Monitor trigger 240812917/745192855 is not a GRB
  96. Fermi Gamma-ray Burst Monitor trigger 240812917/745192855 is not a GRB
  97. GRB 240809A: ATA radio non-detection
  98. GRB 240812D: Fermi GBM Final Real-time Localization
  99. GRB 240812C: Fermi GBM Final Real-time Localization
  100. GRB 240809A : RAPAS follow-up observations

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