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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"

3040 results found.

  1. EP260924a: Global MASTER-Net observations report
  2. GRB 260924A: Ondrejov D50 optical afterglow detection
  3. GRB 260924A: NOT optical counterpart confirmation
  4. Fermi GRB 260923A: Global MASTER-Net observations report
  5. EP Alert 260921.01: Global MASTER-Net observations report
  6. EP260920a: NOT optical upper limits
  7. EP260917a: Global MASTER-Net observations report
  8. EP260920a: COLIBRÍ optical upper limits
  9. EP Alert 260918.24: Global MASTER-Net observations report
  10. SVOM GRB260918.16: Global MASTER-Net observations report
  11. EP Alert 260917.32: Global MASTER-Net observations report
  12. EP Alert 260914.53: Global MASTER-Net observations report
  13. SVOM GRB260914.47: Global MASTER-Net observations report
  14. EP Alert 260909.53: Global MASTER-Net observations report
  15. Fermi GRB 260907B: Global MASTER-Net observations report
  16. Fermi GRB 260907A: Global MASTER-Net observations report
  17. EP Alert 260905.11: Global MASTER-Net observations report
  18. The EP-WXT trigger 01709302592 is likely a flaring star
  19. EP Alert 260903.62: Global MASTER-Net observations report
  20. NuSTAR Transient 260828: SOAR Optical Upper Limits
  21. EP Alert 260820.31: Global MASTER-Net observations report
  22. GRB 260809A: SVOM/ECLAIRs refined analysis
  23. IceCube Alert 260825A: Global MASTER-Net observations report
  24. SVOM trigger sb26081806 is not a GRB
  25. EP260806a: SAO RAS multicolor optical observations
  26. EP260806a: SVOM/ECLAIRs detection through targeted search
  27. Fermi GBM Sub-Threshold Detection of GRB 260809A
  28. GRB 260808B: J-band upper limit with WINTER
  29. EP260809a:refined analysis of the EP-WXT and autonomous EP-FXT observation
  30. GRB 260809A: SVOM detection of a faint burst
  31. EP260806a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  32. Fermi GRB 260805A: Global MASTER-Net observations report
  33. Fermi GRB 260802B: Global MASTER-Net observations report
  34. GRB 260726A: SVOM/ECLAIRs refined analysis
  35. EP260727a: Einstein Probe detection of an X-ray transient
  36. Fermi GRB 260726A: Global MASTER-Net observations report
  37. EP260723a: Liverpool Telescope likely optical counterpart
  38. Fermi GRB 260718A: Global MASTER-Net observations report
  39. EP260703a: SVOM/ECLAIRs Upper Limit
  40. GRB 260714B: Fermi-LAT detection
  41. EP260713a: Einstein Probe detection of an X-ray transient
  42. GRB 260618B: SVOM/VT optical observations indicate shallow decay and reddening
  43. IceCube Alert 260709A: Global MASTER-Net observations report
  44. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  45. EP260703a: EP-WXT detection of a fast X-ray transient
  46. Fermi trigger No 804552016: Global MASTER-Net observations report
  47. EP260628a: EP-FXT follow-up observation
  48. EP260623a: Liverpool Telescope optical observations
  49. EP260623a: REM optical/NIR afterglow detection
  50. Konus-Wind detection of GRB 260616A
  51. GRB 260614A: AstroSat CZTI detection
  52. GRB 260604C: OPD1.6m - GRANDMA observations - detection
  53. GRB 260531B: Glowbug gamma-ray detection
  54. Fermi GRB 260601A: Global MASTER-Net observations report
  55. Fermi trigger No 801900520: Global MASTER-Net observations report
  56. GRB 260531B: Fermi GBM Final Real-time Localization
  57. GRB 260531A: MAXI/GSC detection
  58. GRB 260529A: Fermi GBM Final Real-time Localization
  59. EP260526a: SVOM/VT optical upper limits
  60. EP260527a: SVOM/VT optical observation
  61. Fermi trigger No 801580882: Global MASTER-Net observations report
  62. Fermi trigger No 801135305: Global MASTER-Net observations report
  63. GRB 260516D: GROWTH-India Telescope optical detection
  64. GRB 260515A: CrAO ZTSh BVRI optical observations
  65. SVOM GRB 260515A: Global MASTER-Net observations report
  66. EP260514a: Global MASTER-Net observations report
  67. GRB 260511B: further SAO RAS optical observations
  68. GRB 260511A: NuSTAR detection of prompt emission
  69. GRB 260511A: KAIT optical afterglow observations
  70. GRB 260507B / EP260507a: Fermi-GBM Sub-Threshold Detection
  71. EP260507a: GOTO optical counterpart detection
  72. EP260507a: Einstein Probe detection of an X-ray transient
  73. Fermi GRB 260506A: Global MASTER-Net observations report
  74. SVOM GRB 260504B: MASTER-OAFA optical observations
  75. EP260502a: BOOTES-7 observations of a fading catalogued source close to the X-ray position
  76. EP260430a: Global MASTER-Net observations report
  77. Fermi GRB 260421C: Global MASTER-Net observations report
  78. Fermi GRB 260421B: Global MASTER-Net observations report
  79. Fermi GRB 260417B: Global MASTER-Net observations report
  80. EP260417a: Global MASTER-Net observations report
  81. Fermi GRB 260417A: Global MASTER-Net observations report
  82. EP260416a: Global MASTER-Net observations report
  83. Fermi trigger No 797912738: Global MASTER-Net observations report
  84. GRB 260411B: GOTO optical counterpart candidate
  85. EP260409a: Global MASTER-Net observations report
  86. GRB 260404A: Fermi GBM Final Localization
  87. EP260403a: Mephisto optical upper limits
  88. EP260405a: Global MASTER-Net observations report
  89. Fermi trigger No 797039833: Global MASTER-Net observations report
  90. Fermi Gamma-ray Burst Monitor trigger 796931884/260403749 is not a GRB
  91. GRB 260330B: SVOM/ECLAIRs refined analysis
  92. GRB 260330B: SVOM/VT optical candidate
  93. GRB 260402B: GECAM-B observation
  94. GRB 260402B: Fermi GBM Final Real-time Localization
  95. EP260329b: Mondy and Assy-Turgen optical upper limits
  96. GRB 260310A / AT2026fgk: Luminance-band optical follow-up with a 28cm telescope in Daocheng
  97. EP260321a :Xinglong optical observations
  98. GRB 260321A: SVOM/ECLAIRs refined analysis
  99. Fermi GBM Sub-Threshold Detection of GRB 260330B
  100. GRB 260330B: SVOM detection of a burst

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