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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"

3039 results found.

  1. GRB 260924A: Ondrejov D50 optical afterglow detection
  2. GRB 260924A: NOT optical counterpart confirmation
  3. Fermi GRB 260923A: Global MASTER-Net observations report
  4. EP Alert 260921.01: Global MASTER-Net observations report
  5. EP260920a: NOT optical upper limits
  6. EP260917a: Global MASTER-Net observations report
  7. EP260920a: COLIBRÍ optical upper limits
  8. EP Alert 260918.24: Global MASTER-Net observations report
  9. SVOM GRB260918.16: Global MASTER-Net observations report
  10. EP Alert 260917.32: Global MASTER-Net observations report
  11. EP Alert 260914.53: Global MASTER-Net observations report
  12. SVOM GRB260914.47: Global MASTER-Net observations report
  13. EP Alert 260909.53: Global MASTER-Net observations report
  14. Fermi GRB 260907B: Global MASTER-Net observations report
  15. Fermi GRB 260907A: Global MASTER-Net observations report
  16. EP Alert 260905.11: Global MASTER-Net observations report
  17. The EP-WXT trigger 01709302592 is likely a flaring star
  18. EP Alert 260903.62: Global MASTER-Net observations report
  19. NuSTAR Transient 260828: SOAR Optical Upper Limits
  20. EP Alert 260820.31: Global MASTER-Net observations report
  21. GRB 260809A: SVOM/ECLAIRs refined analysis
  22. IceCube Alert 260825A: Global MASTER-Net observations report
  23. SVOM trigger sb26081806 is not a GRB
  24. EP260806a: SAO RAS multicolor optical observations
  25. EP260806a: SVOM/ECLAIRs detection through targeted search
  26. Fermi GBM Sub-Threshold Detection of GRB 260809A
  27. GRB 260808B: J-band upper limit with WINTER
  28. EP260809a:refined analysis of the EP-WXT and autonomous EP-FXT observation
  29. GRB 260809A: SVOM detection of a faint burst
  30. EP260806a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  31. Fermi GRB 260805A: Global MASTER-Net observations report
  32. Fermi GRB 260802B: Global MASTER-Net observations report
  33. GRB 260726A: SVOM/ECLAIRs refined analysis
  34. EP260727a: Einstein Probe detection of an X-ray transient
  35. Fermi GRB 260726A: Global MASTER-Net observations report
  36. EP260723a: Liverpool Telescope likely optical counterpart
  37. Fermi GRB 260718A: Global MASTER-Net observations report
  38. EP260703a: SVOM/ECLAIRs Upper Limit
  39. GRB 260714B: Fermi-LAT detection
  40. EP260713a: Einstein Probe detection of an X-ray transient
  41. GRB 260618B: SVOM/VT optical observations indicate shallow decay and reddening
  42. IceCube Alert 260709A: Global MASTER-Net observations report
  43. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  44. EP260703a: EP-WXT detection of a fast X-ray transient
  45. Fermi trigger No 804552016: Global MASTER-Net observations report
  46. EP260628a: EP-FXT follow-up observation
  47. EP260623a: Liverpool Telescope optical observations
  48. EP260623a: REM optical/NIR afterglow detection
  49. Konus-Wind detection of GRB 260616A
  50. GRB 260614A: AstroSat CZTI detection
  51. GRB 260604C: OPD1.6m - GRANDMA observations - detection
  52. GRB 260531B: Glowbug gamma-ray detection
  53. Fermi GRB 260601A: Global MASTER-Net observations report
  54. Fermi trigger No 801900520: Global MASTER-Net observations report
  55. GRB 260531B: Fermi GBM Final Real-time Localization
  56. GRB 260531A: MAXI/GSC detection
  57. GRB 260529A: Fermi GBM Final Real-time Localization
  58. EP260526a: SVOM/VT optical upper limits
  59. EP260527a: SVOM/VT optical observation
  60. Fermi trigger No 801580882: Global MASTER-Net observations report
  61. Fermi trigger No 801135305: Global MASTER-Net observations report
  62. GRB 260516D: GROWTH-India Telescope optical detection
  63. GRB 260515A: CrAO ZTSh BVRI optical observations
  64. SVOM GRB 260515A: Global MASTER-Net observations report
  65. EP260514a: Global MASTER-Net observations report
  66. GRB 260511B: further SAO RAS optical observations
  67. GRB 260511A: NuSTAR detection of prompt emission
  68. GRB 260511A: KAIT optical afterglow observations
  69. GRB 260507B / EP260507a: Fermi-GBM Sub-Threshold Detection
  70. EP260507a: GOTO optical counterpart detection
  71. EP260507a: Einstein Probe detection of an X-ray transient
  72. Fermi GRB 260506A: Global MASTER-Net observations report
  73. SVOM GRB 260504B: MASTER-OAFA optical observations
  74. EP260502a: BOOTES-7 observations of a fading catalogued source close to the X-ray position
  75. EP260430a: Global MASTER-Net observations report
  76. Fermi GRB 260421C: Global MASTER-Net observations report
  77. Fermi GRB 260421B: Global MASTER-Net observations report
  78. Fermi GRB 260417B: Global MASTER-Net observations report
  79. EP260417a: Global MASTER-Net observations report
  80. Fermi GRB 260417A: Global MASTER-Net observations report
  81. EP260416a: Global MASTER-Net observations report
  82. Fermi trigger No 797912738: Global MASTER-Net observations report
  83. GRB 260411B: GOTO optical counterpart candidate
  84. EP260409a: Global MASTER-Net observations report
  85. GRB 260404A: Fermi GBM Final Localization
  86. EP260403a: Mephisto optical upper limits
  87. EP260405a: Global MASTER-Net observations report
  88. Fermi trigger No 797039833: Global MASTER-Net observations report
  89. Fermi Gamma-ray Burst Monitor trigger 796931884/260403749 is not a GRB
  90. GRB 260330B: SVOM/ECLAIRs refined analysis
  91. GRB 260330B: SVOM/VT optical candidate
  92. GRB 260402B: GECAM-B observation
  93. GRB 260402B: Fermi GBM Final Real-time Localization
  94. EP260329b: Mondy and Assy-Turgen optical upper limits
  95. GRB 260310A / AT2026fgk: Luminance-band optical follow-up with a 28cm telescope in Daocheng
  96. EP260321a :Xinglong optical observations
  97. GRB 260321A: SVOM/ECLAIRs refined analysis
  98. Fermi GBM Sub-Threshold Detection of GRB 260330B
  99. GRB 260330B: SVOM detection of a burst
  100. EP260327a: Global MASTER-Net observations report

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