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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"

11749 results found.

  1. Konus-Wind detection of GRB 260601A
  2. EP260610a: Einstein Probe detection of a fast X-ray transient
  3. GRB 260609A: Fermi GBM Final Localization
  4. Konus-Wind detection of GRB 260604C
  5. GRB 260604C: AstroSat CZTI detection
  6. GRB 260604C: SVOM/ECLAIRs refined analysis
  7. Konus-Wind detection of GRB 260607B
  8. GRB 260604C: further SAO RAS optical observations
  9. GRB 260607B: AstroSat CZTI detection
  10. GRB 260607B: Fermi-LAT detection
  11. GRB 260604C: Simeiz Zeiss-1000 optical observations of the afterglow
  12. GRB 260604C: LCO optical upper limit
  13. EP260602d: EP-FXT follow-up observation
  14. EP260602c: EP-FXT follow-up observation
  15. GRB 260601B / EP260601a: AstroSat CZTI detection
  16. GRB 260604C: Fermi GBM Observation
  17. GRB 260604C: LAST detection of optical counterpart candidate
  18. Fermi GRB 260604C: Global MASTER-Net observations report
  19. Fermi GRB 260604C: Global MASTER-Net observations report
  20. SVOM GRB260604.85: Global MASTER-Net observations report
  21. GRB 260604C: SVOM detection of a long burst
  22. GRB 260604C: Fermi GBM Final Real-time Localization
  23. GRB 260603A: Simeiz Zeiss-1000 optical upper limit
  24. EP260602a: EP-FXT follow-up observation
  25. EP260602d: Optical Upper limits with kinder observations
  26. Konus-Wind detection of GRB 260601B/EP260601a
  27. EP260601a/GRB 260601B: EP-FXT follow-up observation
  28. GRB 260601B / EP260601a: Mondy optical upper limit
  29. EP260602d: Einstein Probe detection of a fast X-ray transient
  30. EP260602c: Einstein Probe detection of a fast X-ray transient
  31. EP260602a: COLIBRÍ optical observations
  32. SVOM GRB260603.23: Global MASTER-Net observations report
  33. GRB 260603A: SVOM detection of a burst
  34. Fermi GRB 260602B: Global MASTER-Net observations report
  35. Fermi GRB 260602B: Global MASTER-Net observations report
  36. GRB 260601B/EP260601a: J-band upper limit with WINTER
  37. EP260602a: Optical upper limits with Kinder observations
  38. EP260602a: Einstein Probe detection of a fast X-ray transient
  39. EP-WXT trigger 01709266307 (EP260601a): COLIBRÍ optical observations
  40. GRB 260601A: Fermi GBM Observation
  41. EP260530a/AT 2026nwl: COLIBRÍ optical observations
  42. Fermi GRB 260601A: Global MASTER-Net observations report
  43. GRB 260518B: SVOM/ECLAIRs detection of a soft burst possibly associated with EP 260518a and AT 2026ndp
  44. Fermi trigger No 801900520: Global MASTER-Net observations report
  45. GRB 260531A: MAXI/GSC detection
  46. EP260527a/GRB 260527A: further FTW optical and NIR observations
  47. EP260527a/GRB 260527A: optical upper limit with Kinder observations
  48. EP260527a/GRB 260527A: EP-FXT follow-up observation
  49. Konus-Wind detection of GRB 260527A (short/hard) ~4 min before EP260527a
  50. EP260527a: Einstein Probe detection of a fast X-ray transient
  51. GRB 260524A: SVOM/ECLAIRs detection of a burst through on-ground search
  52. GRB 260525A: AstroSat CZTI detection
  53. Fermi GRB 260526A: Global MASTER-Net observations report
  54. GRB 260523B: AstroSat CZTI detection
  55. Fermi trigger No 801135305: Global MASTER-Net observations report
  56. Fermi GRB 260522A: Global MASTER-Net observations report
  57. GRB 260522A: Fermi-LAT detection
  58. GRB 260511A: iTelescope T-75 optical detection
  59. GRB 260428A: TERI Gamma-ray detection
  60. Konus-Wind detection of GRB 260519C
  61. GRB 260520B: Fermi GBM Final Localization
  62. GRB 260509A: SVOM/ECLAIRs refined analysis
  63. GRB 260520A: Fermi GBM Final Localization
  64. Konus-Wind detection of GRB 260518A
  65. GRB 260518A: AstroSat CZTI detection of a long burst
  66. GRB 260516D: SVOM/ECLAIRs refined analysis
  67. GRB 260516D: EP-FXT follow-up observation
  68. GRB 260516D: SVOM/VT optical bright candidate
  69. GRB 260516D: FRAM-ORM optical limit
  70. GRB 260515A: CrAO ZTSh BVRI optical observations
  71. Fermi GRB 260516C: Global MASTER-Net observations report
  72. GRB 260516D: SVOM possible detection of a burst
  73. Konus-Wind detection of GRB 260515A
  74. GRB 260515A: EP-FXT follow-up observation
  75. EP260514a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  76. Fermi GRB 260516B: Global MASTER-Net observations report
  77. GRID detection of GRB 260507A
  78. GRB 260515A: GTC/OSIRIS+ spectroscopic redshift z = 0.764
  79. SVOM GRB 260515A: Global MASTER-Net observations report
  80. GRB 260515A: SVOM detection of a burst
  81. Konus-Wind detection of GRB 260512A
  82. GRB 260512A: AstroSat CZTI detection
  83. GRB 260511B: further SAO RAS optical observations
  84. Konus-Wind detection of GRB 260511B
  85. Konus-Wind detection of GRB 260511A
  86. MASS-Cube (GRID 2.0) detection of GRB 260507A
  87. GRB 260511B: SAO RAS optical observations
  88. GRB 260510D: Glowbug gamma-ray detection of a likely short burst
  89. GRB 260511A: EP-FXT follow-up observation
  90. GRB 260511B: AstroSat CZTI detection
  91. GRB 260511B: NuSTAR detection of prompt emission
  92. GRB 260510C: AstroSat CZTI detection
  93. Fermi GRB 260511A: Global MASTER-Net observations report
  94. GRB 260510C: MAXI/GSC detection
  95. Fermi GBM Sub-Threshold Detection of GRB 260510B
  96. GRB 260510D: Fermi GBM Final Real-time Localization
  97. GRB 260510B: SVOM detection of a burst
  98. Fermi GRB 260510A: Global MASTER-Net observations report
  99. GRB 260509A: SVOM detection of a burst
  100. GRB 260506B: AstroSat CZTI detection

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