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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. SGR 1E 1841-045 / Kes 73: SVOM/GRM observation
  2. GRB 240825A: Swift/UVOT Detection
  3. GRB 240825A: REM detection of the optical/NIR afterglow
  4. GRB 240825A: Swift-XRT refined Analysis
  5. GRB 240825A: VLT/X-shooter redshift
  6. GRB 240825A: SVOM/C-GFT optical observations
  7. GRB 240825A: Montarrenti Observatory optical observations
  8. GRB 240825A: Enhanced Swift-XRT position
  9. GRB 240825A: MASTER optical counterpart observation
  10. GRB 240825A: Fermi-LAT detection
  11. GRB 240825A: LCO optical observations
  12. GRB 240824B: KAIT optical upper limit
  13. SGR 1E 1841-045 / Kes 73 (Trigger 1249878): Osservatorio Atronomico Nastro Verde optical upper limit
  14. GRB 240824B: Fermi GBM Observation
  15. Fermi GRB 240825A: Global MASTER-Net observations report
  16. SGR 1E 1841-045 / Kes 73 (Trigger 1249653) - Osservatorio Astronomico Nastro Verde upper limit
  17. GRB 240824B: NOT optical upper limit
  18. GRB 240825A: GMG Optical Observation
  19. Swift GRB 240825A: Global MASTER-Net observations report
  20. GRB 240825A: 1.6m Mephisto multi-band detection
  21. GRB 240825A: AKO Optical Afterglow Detection
  22. GRB 240825A: Skynet Optical Afterglow observations
  23. GRB 240825A: Nanshan/HMT optical afterglow observations
  24. GRB 240825A: Swift detection of a burst with a bright optical counterpart
  25. GRB 240825A: Fermi GBM Final Real-time Localization
  26. GRB 240824A: Swift-BAT refined analysis
  27. GRB 240824A: SVOM/C-GFT optical upper limit
  28. GRB 240824B: Swift-XRT afterglow detection
  29. GRB 240824A: Swift-XRT observations
  30. LIGO/Virgo/KAGRA S240825ar: Identification of a GW compact binary merger candidate
  31. GRB 240824B: Swift/BAT arcminute localization of a burst
  32. GRB 240824B: Swift ToO observations
  33. Fermi GRB 240824C: Global MASTER-Net observations report
  34. GRB 240824C: Fermi GBM Final Localization
  35. GRB 240824A: Swift/UVOT Upper Limits
  36. GRB 240821A: Swift/UVOT observations of the XRT sources.
  37. GRB 240824B: MAXI/GSC detection
  38. GRB 240824B: Fermi GBM Final Real-time Localization
  39. GRB 240824A: Retraction of GCN 37255
  40. GRB240824A: GRANDMA/TAROT-TCA Upper Limit
  41. SGR 1E 1841-045 / Kes 73: Leavitt Observatory optical upper limit
  42. GRB 240824A: KAIT optical upper limit
  43. GRB 240824A: Skynet Optical Afterglow Discovery
  44. GRB 240824A: Swift detection of a burst
  45. Swift GRB240824.04: Global MASTER-Net observations report
  46. SGR 1E 1841-045 / Kes 73: Montarrenti Observatory optical upper limits
  47. GRB 240821A: Colibri Optical Upper Limit
  48. EP240820a: PRIME J-band Observations
  49. GRB 240821A: Swift-XRT observations
  50. GRB 240822A: AstroSat CZTI detection of a short burst
  51. GRB 240821A: REM optical/NIR upper limits
  52. GRB 240821A: LCO optical observations
  53. GRB 240821A: JinShan optical upper limits
  54. GRB 240809A: Mondy and AbAO Optical Observations
  55. GRB 240821A: SVOM/VT follow-up and optical upper limit
  56. GRB 240821A: GMG Optical Upper Limit
  57. Fermi GRB 240821A: Global MASTER-Net observations report
  58. GECAM-B observation of a short burst from SGR 1E 1841-045 / Kes 73
  59. GRB 240821A: Fermi GBM Observation
  60. Fermi trigger No 745964969: Global MASTER-Net observations report
  61. Fermi trigger No 745925274: Global MASTER-Net observations report
  62. GRB 240821A: Swift ToO observations
  63. Fermi trigger No 746019401: Global MASTER-Net observations report
  64. Fermi-GBM Observations of the reactivation of SGR 1E 1841-045 / Kes 73
  65. Fermi trigger No 745935375: Global MASTER-Net observations report
  66. GRB240821A: EIRSAT-1 GMOD Detection
  67. GRB240821B: First GRB Detected by EIRSAT-1 GMOD
  68. GRB 240821A: EP-FXT follow-up observation and afterglow candidates
  69. Fermi GRB 240821B: Global MASTER-Net observations report
  70. EP240801a: Keck/LRIS spectroscopic redshift confirmation
  71. GRB 240821A: SVOM/GRM observation
  72. GRB 240821A: SVOM/GRM observation
  73. GRB 240821A: GRANDMA/LesMakes-T60 Upper Limit
  74. GRB 240821B: Fermi GBM Final Localization
  75. Fermi trigger No 745866488: Global MASTER-Net observations report
  76. Trigger 1249878: Swift detection of another burst from SGR 1E 1841-045 / Kes 73
  77. GRB 240821A: BALROG localization (Fermi Trigger 745958167 / GRB 240821775)
  78. GRB 240821A : a likely short GRB detected by SVOM/ECLAIRs
  79. GRB 240821A: Fermi GBM Final Real-time Localization
  80. GRB 240819A: Swift-XRT observations
  81. GRB 240819A: JinShan optical upper limits on one Swift/XRT source
  82. GRB 240820B: SVOM/GRM observation
  83. EP240820a: TRT optical upper limit
  84. EP240820a: EP detection of a fast X-ray transient
  85. GRB 240819A: KAIT optical upper limit
  86. EP240816a: PRIME upper limits
  87. Trigger 1249653: Swift detection of SGR 1E 1841-045 / Kes 73
  88. Fermi trigger No 745873283: Global MASTER-Net observations report
  89. Fermi trigger No 745871958: Global MASTER-Net observations report
  90. GRB 240819A : an X-ray transient detected by SVOM/ECLAIRs
  91. GRB 240819A: TRT optical upper limits on the Swift/XRT and EP/FXT sources
  92. GRB 240819A: X-ray follow-up observation with EP-FXT
  93. Fermi Gamma-ray Burst Monitor trigger 745811685 / 240820080 is not a GRB
  94. GRB 240820A: Fermi GBM Final Real-time Localization
  95. GRB 240819A: Swift ToO observations
  96. GRB 240814A: SVOM/GRM observation
  97. EP240816b: Liverpool Telescope optical follow-up observations
  98. GRB 240814C: SVOM/GRM observation
  99. EP240816a: BOOTES-6/DPRT optical upper limit
  100. GRB 240815A: SVOM/GRM observation

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