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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"

3787 results found.

  1. GRB 260916A: MAXI/GSC detection
  2. MAXI GRB260916.37: Global MASTER-Net observations report
  3. EP Alert 260914.53: Global MASTER-Net observations report
  4. SVOM GRB260914.47: Global MASTER-Net observations report
  5. EP Alert 260909.53: Global MASTER-Net observations report
  6. Fermi GRB 260907B: Global MASTER-Net observations report
  7. Fermi GRB 260907A: Global MASTER-Net observations report
  8. EP Alert 260905.11: Global MASTER-Net observations report
  9. The EP-WXT trigger 01709302592 is likely a flaring star
  10. EP Alert 260903.62: Global MASTER-Net observations report
  11. NuSTAR Transient 260828: SOAR Optical Upper Limits
  12. MAXI GRB260827.40: Global MASTER-Net observations report
  13. EP Alert 260820.31: Global MASTER-Net observations report
  14. GRB 260809A: SVOM/ECLAIRs refined analysis
  15. IceCube Alert 260825A: Global MASTER-Net observations report
  16. SVOM trigger sb26081806 is not a GRB
  17. EP260806a: SAO RAS multicolor optical observations
  18. EP260806a: SVOM/ECLAIRs detection through targeted search
  19. Fermi GBM Sub-Threshold Detection of GRB 260809A
  20. GRB 260808B: J-band upper limit with WINTER
  21. EP260809a:refined analysis of the EP-WXT and autonomous EP-FXT observation
  22. GRB 260809A: SVOM detection of a faint burst
  23. EP260806a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  24. Fermi GRB 260805A: Global MASTER-Net observations report
  25. Fermi GRB 260802B: Global MASTER-Net observations report
  26. GRB 260726A: SVOM/ECLAIRs refined analysis
  27. EP260727a: Einstein Probe detection of an X-ray transient
  28. Fermi GRB 260726A: Global MASTER-Net observations report
  29. EP260723a: Liverpool Telescope likely optical counterpart
  30. Fermi GRB 260718A: Global MASTER-Net observations report
  31. EP260703a: SVOM/ECLAIRs Upper Limit
  32. GRB 260714B: Fermi-LAT detection
  33. EP260713a: Einstein Probe detection of an X-ray transient
  34. GRB 260618B: SVOM/VT optical observations indicate shallow decay and reddening
  35. IceCube Alert 260709A: Global MASTER-Net observations report
  36. GRB260708B: MAXI/GSC detection
  37. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  38. EP260703a: EP-WXT detection of a fast X-ray transient
  39. Fermi trigger No 804552016: Global MASTER-Net observations report
  40. EP260628a: EP-FXT follow-up observation
  41. EP260623a: Liverpool Telescope optical observations
  42. EP260623a: REM optical/NIR afterglow detection
  43. GRB 260616C: GECAM-B observation of a burst
  44. Konus-Wind detection of GRB 260616A
  45. GRB260616C: MAXI/GSC detection
  46. GRB 260614A: AstroSat CZTI detection
  47. GRB 260604C: OPD1.6m - GRANDMA observations - detection
  48. GRB 260531B: Glowbug gamma-ray detection
  49. Fermi GRB 260601A: Global MASTER-Net observations report
  50. Fermi trigger No 801900520: Global MASTER-Net observations report
  51. GRB 260531B: Fermi GBM Final Real-time Localization
  52. GRB 260531A: MAXI/GSC detection
  53. GRB 260529A: Fermi GBM Final Real-time Localization
  54. EP260526a: SVOM/VT optical upper limits
  55. EP260527a: SVOM/VT optical observation
  56. Fermi trigger No 801580882: Global MASTER-Net observations report
  57. Fermi trigger No 801135305: Global MASTER-Net observations report
  58. GRB 260516D: GROWTH-India Telescope optical detection
  59. GRB 260515A: CrAO ZTSh BVRI optical observations
  60. SVOM GRB 260515A: Global MASTER-Net observations report
  61. GRB 260510C: Glowbug gamma-ray detection
  62. GRB 260510C: CALET Gamma-Ray Burst Monitor detection
  63. EP260514a: Global MASTER-Net observations report
  64. GRB 260511B: further SAO RAS optical observations
  65. GRB 260510C: Fermi GBM Observation
  66. GRB 260511A: NuSTAR detection of prompt emission
  67. GRB 260510C: AstroSat CZTI detection
  68. GRB 260510C: EP-FXT follow-up observation
  69. GRB 260511A: KAIT optical afterglow observations
  70. GRB 260510C: SVOM/VT optical upper limits
  71. GRB 260510C: MAXI/GSC detection
  72. GRB 260507B / EP260507a: Fermi-GBM Sub-Threshold Detection
  73. EP260507a: GOTO optical counterpart detection
  74. EP260507a: Einstein Probe detection of an X-ray transient
  75. Fermi GRB 260506A: Global MASTER-Net observations report
  76. SVOM GRB 260504B: MASTER-OAFA optical observations
  77. EP260502a: BOOTES-7 observations of a fading catalogued source close to the X-ray position
  78. EP260430a: Global MASTER-Net observations report
  79. Fermi GRB 260421C: Global MASTER-Net observations report
  80. Fermi GRB 260421B: Global MASTER-Net observations report
  81. Fermi GRB 260417B: Global MASTER-Net observations report
  82. EP260417a: Global MASTER-Net observations report
  83. Fermi GRB 260417A: Global MASTER-Net observations report
  84. EP260416a: Global MASTER-Net observations report
  85. Fermi trigger No 797912738: Global MASTER-Net observations report
  86. GRB 260411B: GOTO optical counterpart candidate
  87. EP260409a: Global MASTER-Net observations report
  88. GRB 260404A: Fermi GBM Final Localization
  89. EP260403a: Mephisto optical upper limits
  90. GRID detection of GRB 260401A
  91. EP260405a: Global MASTER-Net observations report
  92. Fermi trigger No 797039833: Global MASTER-Net observations report
  93. Fermi Gamma-ray Burst Monitor trigger 796931884/260403749 is not a GRB
  94. GRB 260330B: SVOM/ECLAIRs refined analysis
  95. GRB 260330B: SVOM/VT optical candidate
  96. GRB 260402B: GECAM-B observation
  97. GRB 260402B: Fermi GBM Final Real-time Localization
  98. GRB 260401A: SVOM/GRM observation
  99. GRB 260401A: GECAM-B observation
  100. GRB 260401A: Fermi GBM Observation

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