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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"

3797 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. GRB 260916A: MAXI/GSC detection
  12. MAXI GRB260916.37: Global MASTER-Net observations report
  13. EP Alert 260914.53: Global MASTER-Net observations report
  14. SVOM GRB260914.47: Global MASTER-Net observations report
  15. EP Alert 260909.53: Global MASTER-Net observations report
  16. Fermi GRB 260907B: Global MASTER-Net observations report
  17. Fermi GRB 260907A: Global MASTER-Net observations report
  18. EP Alert 260905.11: Global MASTER-Net observations report
  19. The EP-WXT trigger 01709302592 is likely a flaring star
  20. EP Alert 260903.62: Global MASTER-Net observations report
  21. NuSTAR Transient 260828: SOAR Optical Upper Limits
  22. MAXI GRB260827.40: Global MASTER-Net observations report
  23. EP Alert 260820.31: Global MASTER-Net observations report
  24. GRB 260809A: SVOM/ECLAIRs refined analysis
  25. IceCube Alert 260825A: Global MASTER-Net observations report
  26. SVOM trigger sb26081806 is not a GRB
  27. EP260806a: SAO RAS multicolor optical observations
  28. EP260806a: SVOM/ECLAIRs detection through targeted search
  29. Fermi GBM Sub-Threshold Detection of GRB 260809A
  30. GRB 260808B: J-band upper limit with WINTER
  31. EP260809a:refined analysis of the EP-WXT and autonomous EP-FXT observation
  32. GRB 260809A: SVOM detection of a faint burst
  33. EP260806a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  34. Fermi GRB 260805A: Global MASTER-Net observations report
  35. Fermi GRB 260802B: Global MASTER-Net observations report
  36. GRB 260726A: SVOM/ECLAIRs refined analysis
  37. EP260727a: Einstein Probe detection of an X-ray transient
  38. Fermi GRB 260726A: Global MASTER-Net observations report
  39. EP260723a: Liverpool Telescope likely optical counterpart
  40. Fermi GRB 260718A: Global MASTER-Net observations report
  41. EP260703a: SVOM/ECLAIRs Upper Limit
  42. GRB 260714B: Fermi-LAT detection
  43. EP260713a: Einstein Probe detection of an X-ray transient
  44. GRB 260618B: SVOM/VT optical observations indicate shallow decay and reddening
  45. IceCube Alert 260709A: Global MASTER-Net observations report
  46. GRB260708B: MAXI/GSC detection
  47. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  48. EP260703a: EP-WXT detection of a fast X-ray transient
  49. Fermi trigger No 804552016: Global MASTER-Net observations report
  50. EP260628a: EP-FXT follow-up observation
  51. EP260623a: Liverpool Telescope optical observations
  52. EP260623a: REM optical/NIR afterglow detection
  53. GRB 260616C: GECAM-B observation of a burst
  54. Konus-Wind detection of GRB 260616A
  55. GRB260616C: MAXI/GSC detection
  56. GRB 260614A: AstroSat CZTI detection
  57. GRB 260604C: OPD1.6m - GRANDMA observations - detection
  58. GRB 260531B: Glowbug gamma-ray detection
  59. Fermi GRB 260601A: Global MASTER-Net observations report
  60. Fermi trigger No 801900520: Global MASTER-Net observations report
  61. GRB 260531B: Fermi GBM Final Real-time Localization
  62. GRB 260531A: MAXI/GSC detection
  63. GRB 260529A: Fermi GBM Final Real-time Localization
  64. EP260526a: SVOM/VT optical upper limits
  65. EP260527a: SVOM/VT optical observation
  66. Fermi trigger No 801580882: Global MASTER-Net observations report
  67. Fermi trigger No 801135305: Global MASTER-Net observations report
  68. GRB 260516D: GROWTH-India Telescope optical detection
  69. GRB 260515A: CrAO ZTSh BVRI optical observations
  70. SVOM GRB 260515A: Global MASTER-Net observations report
  71. GRB 260510C: Glowbug gamma-ray detection
  72. GRB 260510C: CALET Gamma-Ray Burst Monitor detection
  73. EP260514a: Global MASTER-Net observations report
  74. GRB 260511B: further SAO RAS optical observations
  75. GRB 260510C: Fermi GBM Observation
  76. GRB 260511A: NuSTAR detection of prompt emission
  77. GRB 260510C: AstroSat CZTI detection
  78. GRB 260510C: EP-FXT follow-up observation
  79. GRB 260511A: KAIT optical afterglow observations
  80. GRB 260510C: SVOM/VT optical upper limits
  81. GRB 260510C: MAXI/GSC detection
  82. GRB 260507B / EP260507a: Fermi-GBM Sub-Threshold Detection
  83. EP260507a: GOTO optical counterpart detection
  84. EP260507a: Einstein Probe detection of an X-ray transient
  85. Fermi GRB 260506A: Global MASTER-Net observations report
  86. SVOM GRB 260504B: MASTER-OAFA optical observations
  87. EP260502a: BOOTES-7 observations of a fading catalogued source close to the X-ray position
  88. EP260430a: Global MASTER-Net observations report
  89. Fermi GRB 260421C: Global MASTER-Net observations report
  90. Fermi GRB 260421B: Global MASTER-Net observations report
  91. Fermi GRB 260417B: Global MASTER-Net observations report
  92. EP260417a: Global MASTER-Net observations report
  93. Fermi GRB 260417A: Global MASTER-Net observations report
  94. EP260416a: Global MASTER-Net observations report
  95. Fermi trigger No 797912738: Global MASTER-Net observations report
  96. GRB 260411B: GOTO optical counterpart candidate
  97. EP260409a: Global MASTER-Net observations report
  98. GRB 260404A: Fermi GBM Final Localization
  99. EP260403a: Mephisto optical upper limits
  100. GRID detection of GRB 260401A

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