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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"

38258 results found.

  1. GRB 240825A: Enhanced Swift-XRT position
  2. GRB 240825A: MASTER optical counterpart observation
  3. GRB 240825A: Fermi-LAT detection
  4. GRB 240825A: LCO optical observations
  5. GRB 240824B: KAIT optical upper limit
  6. SGR 1E 1841-045 / Kes 73 (Trigger 1249878): Osservatorio Atronomico Nastro Verde optical upper limit
  7. GRB 240824B: Fermi GBM Observation
  8. Fermi GRB 240825A: Global MASTER-Net observations report
  9. SGR 1E 1841-045 / Kes 73 (Trigger 1249653) - Osservatorio Astronomico Nastro Verde upper limit
  10. GRB 240824B: NOT optical upper limit
  11. GRB 240825A: GMG Optical Observation
  12. Swift GRB 240825A: Global MASTER-Net observations report
  13. GRB 240825A: 1.6m Mephisto multi-band detection
  14. GRB 240825A: AKO Optical Afterglow Detection
  15. GRB 240825A: Skynet Optical Afterglow observations
  16. GRB 240825A: Nanshan/HMT optical afterglow observations
  17. GRB 240825A: Swift detection of a burst with a bright optical counterpart
  18. GRB 240825A: Fermi GBM Final Real-time Localization
  19. GRB 240824A: Swift-BAT refined analysis
  20. GRB 240824A: SVOM/C-GFT optical upper limit
  21. GRB 240824B: Swift-XRT afterglow detection
  22. GRB 240824A: Swift-XRT observations
  23. GRB 240824B: Swift/BAT arcminute localization of a burst
  24. GRB 240824B: Swift ToO observations
  25. Fermi GRB 240824C: Global MASTER-Net observations report
  26. GRB 240824C: Fermi GBM Final Localization
  27. GRB 240824A: Swift/UVOT Upper Limits
  28. GRB 240821A: Swift/UVOT observations of the XRT sources.
  29. GRB 240824B: MAXI/GSC detection
  30. GRB 240824B: Fermi GBM Final Real-time Localization
  31. GRB 240824A: Retraction of GCN 37255
  32. GRB240824A: GRANDMA/TAROT-TCA Upper Limit
  33. SGR 1E 1841-045 / Kes 73: Leavitt Observatory optical upper limit
  34. GRB 240824A: KAIT optical upper limit
  35. GRB 240824A: Skynet Optical Afterglow Discovery
  36. GRB 240824A: Swift detection of a burst
  37. Swift GRB240824.04: Global MASTER-Net observations report
  38. SGR 1E 1841-045 / Kes 73: Montarrenti Observatory optical upper limits
  39. GRB 240821A: Colibri Optical Upper Limit
  40. EP240820a: PRIME J-band Observations
  41. GRB 240821A: Swift-XRT observations
  42. GRB 240822A: AstroSat CZTI detection of a short burst
  43. GRB 240821A: REM optical/NIR upper limits
  44. GRB 240821A: LCO optical observations
  45. GRB 240821A: JinShan optical upper limits
  46. GRB 240809A: Mondy and AbAO Optical Observations
  47. GRB 240821A: SVOM/VT follow-up and optical upper limit
  48. GRB 240821A: GMG Optical Upper Limit
  49. Fermi GRB 240821A: Global MASTER-Net observations report
  50. GRB 240821A: Fermi GBM Observation
  51. Fermi trigger No 745964969: Global MASTER-Net observations report
  52. Fermi trigger No 745925274: Global MASTER-Net observations report
  53. GRB 240821A: Swift ToO observations
  54. Fermi trigger No 746019401: Global MASTER-Net observations report
  55. Fermi-GBM Observations of the reactivation of SGR 1E 1841-045 / Kes 73
  56. Fermi trigger No 745935375: Global MASTER-Net observations report
  57. GRB240821B: First GRB Detected by EIRSAT-1 GMOD
  58. GRB 240821A: EP-FXT follow-up observation and afterglow candidates
  59. Fermi GRB 240821B: Global MASTER-Net observations report
  60. EP240801a: Keck/LRIS spectroscopic redshift confirmation
  61. GRB 240821A: SVOM/GRM observation
  62. GRB 240821A: SVOM/GRM observation
  63. GRB 240821A: GRANDMA/LesMakes-T60 Upper Limit
  64. GRB 240821B: Fermi GBM Final Localization
  65. Fermi trigger No 745866488: Global MASTER-Net observations report
  66. Trigger 1249878: Swift detection of another burst from SGR 1E 1841-045 / Kes 73
  67. GRB 240821A: BALROG localization (Fermi Trigger 745958167 / GRB 240821775)
  68. GRB 240821A : a likely short GRB detected by SVOM/ECLAIRs
  69. GRB 240821A: Fermi GBM Final Real-time Localization
  70. GRB 240819A: Swift-XRT observations
  71. GRB 240819A: JinShan optical upper limits on one Swift/XRT source
  72. GRB 240820B: SVOM/GRM observation
  73. EP240820a: TRT optical upper limit
  74. GRB 240819A: KAIT optical upper limit
  75. EP240816a: PRIME upper limits
  76. Fermi trigger No 745873283: Global MASTER-Net observations report
  77. Fermi trigger No 745871958: Global MASTER-Net observations report
  78. GRB 240819A : an X-ray transient detected by SVOM/ECLAIRs
  79. GRB 240819A: TRT optical upper limits on the Swift/XRT and EP/FXT sources
  80. GRB 240819A: X-ray follow-up observation with EP-FXT
  81. Fermi Gamma-ray Burst Monitor trigger 745811685 / 240820080 is not a GRB
  82. GRB 240820A: Fermi GBM Final Real-time Localization
  83. GRB 240819A: Swift ToO observations
  84. GRB 240814A: SVOM/GRM observation
  85. GRB 240814C: SVOM/GRM observation
  86. GRB 240815A: SVOM/GRM observation
  87. GRB 240817A: Fermi GBM Final Real-time Localization
  88. Integral GRB240816.79: Global MASTER-Net observations report
  89. IceCube-240721A: AT2023qqp and AT2024pge likely unrelated
  90. GRB GRB 240809A: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  91. IBAS Alert n.10856: not a GRB
  92. GRB 240805B: Osservatorio Astronomico Nastro Verde upper limit
  93. EP240816b: KAIT optical upper limit
  94. GRB 240814B: GRBAlpha detection
  95. Fermi trigger No 745501396: Global MASTER-Net observations report
  96. EP EP240816b: Global MASTER-Net observations report
  97. EP240816b: TRT optical upper limit
  98. Fermi GRB 240814A: Global MASTER-Net observations report
  99. Fermi GRB 240814C: Global MASTER-Net observations report
  100. Fermi trigger No 745306088: Global MASTER-Net observations report

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