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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"

3776 results found.

  1. MAXI GRB260827.40: Global MASTER-Net observations report
  2. EP Alert 260820.31: Global MASTER-Net observations report
  3. GRB 260809A: SVOM/ECLAIRs refined analysis
  4. IceCube Alert 260825A: Global MASTER-Net observations report
  5. SVOM trigger sb26081806 is not a GRB
  6. EP260806a: SAO RAS multicolor optical observations
  7. EP260806a: SVOM/ECLAIRs detection through targeted search
  8. Fermi GBM Sub-Threshold Detection of GRB 260809A
  9. GRB 260808B: J-band upper limit with WINTER
  10. EP260809a:refined analysis of the EP-WXT and autonomous EP-FXT observation
  11. GRB 260809A: SVOM detection of a faint burst
  12. EP260806a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  13. Fermi GRB 260805A: Global MASTER-Net observations report
  14. Fermi GRB 260802B: Global MASTER-Net observations report
  15. GRB 260726A: SVOM/ECLAIRs refined analysis
  16. EP260727a: Einstein Probe detection of an X-ray transient
  17. Fermi GRB 260726A: Global MASTER-Net observations report
  18. EP260723a: Liverpool Telescope likely optical counterpart
  19. Fermi GRB 260718A: Global MASTER-Net observations report
  20. EP260703a: SVOM/ECLAIRs Upper Limit
  21. GRB 260714B: Fermi-LAT detection
  22. EP260713a: Einstein Probe detection of an X-ray transient
  23. GRB 260618B: SVOM/VT optical observations indicate shallow decay and reddening
  24. IceCube Alert 260709A: Global MASTER-Net observations report
  25. GRB260708B: MAXI/GSC detection
  26. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  27. EP260703a: EP-WXT detection of a fast X-ray transient
  28. Fermi trigger No 804552016: Global MASTER-Net observations report
  29. EP260628a: EP-FXT follow-up observation
  30. EP260623a: Liverpool Telescope optical observations
  31. EP260623a: REM optical/NIR afterglow detection
  32. GRB 260616C: GECAM-B observation of a burst
  33. Konus-Wind detection of GRB 260616A
  34. GRB260616C: MAXI/GSC detection
  35. GRB 260614A: AstroSat CZTI detection
  36. GRB 260604C: OPD1.6m - GRANDMA observations - detection
  37. GRB 260531B: Glowbug gamma-ray detection
  38. Fermi GRB 260601A: Global MASTER-Net observations report
  39. Fermi trigger No 801900520: Global MASTER-Net observations report
  40. GRB 260531B: Fermi GBM Final Real-time Localization
  41. GRB 260531A: MAXI/GSC detection
  42. GRB 260529A: Fermi GBM Final Real-time Localization
  43. EP260526a: SVOM/VT optical upper limits
  44. EP260527a: SVOM/VT optical observation
  45. Fermi trigger No 801580882: Global MASTER-Net observations report
  46. Fermi trigger No 801135305: Global MASTER-Net observations report
  47. GRB 260516D: GROWTH-India Telescope optical detection
  48. GRB 260515A: CrAO ZTSh BVRI optical observations
  49. SVOM GRB 260515A: Global MASTER-Net observations report
  50. GRB 260510C: Glowbug gamma-ray detection
  51. GRB 260510C: CALET Gamma-Ray Burst Monitor detection
  52. EP260514a: Global MASTER-Net observations report
  53. GRB 260511B: further SAO RAS optical observations
  54. GRB 260510C: Fermi GBM Observation
  55. GRB 260511A: NuSTAR detection of prompt emission
  56. GRB 260510C: AstroSat CZTI detection
  57. GRB 260510C: EP-FXT follow-up observation
  58. GRB 260511A: KAIT optical afterglow observations
  59. GRB 260510C: SVOM/VT optical upper limits
  60. GRB 260510C: MAXI/GSC detection
  61. GRB 260507B / EP260507a: Fermi-GBM Sub-Threshold Detection
  62. EP260507a: GOTO optical counterpart detection
  63. EP260507a: Einstein Probe detection of an X-ray transient
  64. Fermi GRB 260506A: Global MASTER-Net observations report
  65. SVOM GRB 260504B: MASTER-OAFA optical observations
  66. EP260502a: BOOTES-7 observations of a fading catalogued source close to the X-ray position
  67. EP260430a: Global MASTER-Net observations report
  68. Fermi GRB 260421C: Global MASTER-Net observations report
  69. Fermi GRB 260421B: Global MASTER-Net observations report
  70. Fermi GRB 260417B: Global MASTER-Net observations report
  71. EP260417a: Global MASTER-Net observations report
  72. Fermi GRB 260417A: Global MASTER-Net observations report
  73. EP260416a: Global MASTER-Net observations report
  74. Fermi trigger No 797912738: Global MASTER-Net observations report
  75. GRB 260411B: GOTO optical counterpart candidate
  76. EP260409a: Global MASTER-Net observations report
  77. GRB 260404A: Fermi GBM Final Localization
  78. EP260403a: Mephisto optical upper limits
  79. GRID detection of GRB 260401A
  80. EP260405a: Global MASTER-Net observations report
  81. Fermi trigger No 797039833: Global MASTER-Net observations report
  82. Fermi Gamma-ray Burst Monitor trigger 796931884/260403749 is not a GRB
  83. GRB 260330B: SVOM/ECLAIRs refined analysis
  84. GRB 260330B: SVOM/VT optical candidate
  85. GRB 260402B: GECAM-B observation
  86. GRB 260402B: Fermi GBM Final Real-time Localization
  87. GRB 260401A: SVOM/GRM observation
  88. GRB 260401A: GECAM-B observation
  89. GRB 260401A: Fermi GBM Observation
  90. GRB 260401A: NuSTAR detection of prompt emission
  91. GRB 260401A: CALET Gamma-Ray Burst Monitor detection
  92. GRB 260401A: MAXI/GSC detection
  93. EP260329b: Mondy and Assy-Turgen optical upper limits
  94. GRB 260310A / AT2026fgk: Luminance-band optical follow-up with a 28cm telescope in Daocheng
  95. EP260321a :Xinglong optical observations
  96. GRB 260321A: SVOM/ECLAIRs refined analysis
  97. Fermi GBM Sub-Threshold Detection of GRB 260330B
  98. GRB 260330B: SVOM detection of a burst
  99. EP260327a: Global MASTER-Net observations report
  100. GRB 260310A / AT2026fgk: R- and I-band observations with the PKU 60 cm optical telescope

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