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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"

11750 results found.

  1. EP260610b: Einstein Probe detection of an X-ray transient
  2. Konus-Wind detection of GRB 260601A
  3. EP260610a: Einstein Probe detection of a fast X-ray transient
  4. GRB 260609A: Fermi GBM Final Localization
  5. Konus-Wind detection of GRB 260604C
  6. GRB 260604C: AstroSat CZTI detection
  7. GRB 260604C: SVOM/ECLAIRs refined analysis
  8. Konus-Wind detection of GRB 260607B
  9. GRB 260604C: further SAO RAS optical observations
  10. GRB 260607B: AstroSat CZTI detection
  11. GRB 260607B: Fermi-LAT detection
  12. GRB 260604C: Simeiz Zeiss-1000 optical observations of the afterglow
  13. GRB 260604C: LCO optical upper limit
  14. EP260602d: EP-FXT follow-up observation
  15. EP260602c: EP-FXT follow-up observation
  16. GRB 260601B / EP260601a: AstroSat CZTI detection
  17. GRB 260604C: Fermi GBM Observation
  18. GRB 260604C: LAST detection of optical counterpart candidate
  19. Fermi GRB 260604C: Global MASTER-Net observations report
  20. Fermi GRB 260604C: Global MASTER-Net observations report
  21. SVOM GRB260604.85: Global MASTER-Net observations report
  22. GRB 260604C: SVOM detection of a long burst
  23. GRB 260604C: Fermi GBM Final Real-time Localization
  24. GRB 260603A: Simeiz Zeiss-1000 optical upper limit
  25. EP260602a: EP-FXT follow-up observation
  26. EP260602d: Optical Upper limits with kinder observations
  27. Konus-Wind detection of GRB 260601B/EP260601a
  28. EP260601a/GRB 260601B: EP-FXT follow-up observation
  29. GRB 260601B / EP260601a: Mondy optical upper limit
  30. EP260602d: Einstein Probe detection of a fast X-ray transient
  31. EP260602c: Einstein Probe detection of a fast X-ray transient
  32. EP260602a: COLIBRÍ optical observations
  33. SVOM GRB260603.23: Global MASTER-Net observations report
  34. GRB 260603A: SVOM detection of a burst
  35. Fermi GRB 260602B: Global MASTER-Net observations report
  36. Fermi GRB 260602B: Global MASTER-Net observations report
  37. GRB 260601B/EP260601a: J-band upper limit with WINTER
  38. EP260602a: Optical upper limits with Kinder observations
  39. EP260602a: Einstein Probe detection of a fast X-ray transient
  40. EP-WXT trigger 01709266307 (EP260601a): COLIBRÍ optical observations
  41. GRB 260601A: Fermi GBM Observation
  42. EP260530a/AT 2026nwl: COLIBRÍ optical observations
  43. Fermi GRB 260601A: Global MASTER-Net observations report
  44. GRB 260518B: SVOM/ECLAIRs detection of a soft burst possibly associated with EP 260518a and AT 2026ndp
  45. Fermi trigger No 801900520: Global MASTER-Net observations report
  46. GRB 260531A: MAXI/GSC detection
  47. EP260527a/GRB 260527A: further FTW optical and NIR observations
  48. EP260527a/GRB 260527A: optical upper limit with Kinder observations
  49. EP260527a/GRB 260527A: EP-FXT follow-up observation
  50. Konus-Wind detection of GRB 260527A (short/hard) ~4 min before EP260527a
  51. EP260527a: Einstein Probe detection of a fast X-ray transient
  52. GRB 260524A: SVOM/ECLAIRs detection of a burst through on-ground search
  53. GRB 260525A: AstroSat CZTI detection
  54. Fermi GRB 260526A: Global MASTER-Net observations report
  55. GRB 260523B: AstroSat CZTI detection
  56. Fermi trigger No 801135305: Global MASTER-Net observations report
  57. Fermi GRB 260522A: Global MASTER-Net observations report
  58. GRB 260522A: Fermi-LAT detection
  59. GRB 260511A: iTelescope T-75 optical detection
  60. GRB 260428A: TERI Gamma-ray detection
  61. Konus-Wind detection of GRB 260519C
  62. GRB 260520B: Fermi GBM Final Localization
  63. GRB 260509A: SVOM/ECLAIRs refined analysis
  64. GRB 260520A: Fermi GBM Final Localization
  65. Konus-Wind detection of GRB 260518A
  66. GRB 260518A: AstroSat CZTI detection of a long burst
  67. GRB 260516D: SVOM/ECLAIRs refined analysis
  68. GRB 260516D: EP-FXT follow-up observation
  69. GRB 260516D: SVOM/VT optical bright candidate
  70. GRB 260516D: FRAM-ORM optical limit
  71. GRB 260515A: CrAO ZTSh BVRI optical observations
  72. Fermi GRB 260516C: Global MASTER-Net observations report
  73. GRB 260516D: SVOM possible detection of a burst
  74. Konus-Wind detection of GRB 260515A
  75. GRB 260515A: EP-FXT follow-up observation
  76. EP260514a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  77. Fermi GRB 260516B: Global MASTER-Net observations report
  78. GRID detection of GRB 260507A
  79. GRB 260515A: GTC/OSIRIS+ spectroscopic redshift z = 0.764
  80. SVOM GRB 260515A: Global MASTER-Net observations report
  81. GRB 260515A: SVOM detection of a burst
  82. Konus-Wind detection of GRB 260512A
  83. GRB 260512A: AstroSat CZTI detection
  84. GRB 260511B: further SAO RAS optical observations
  85. Konus-Wind detection of GRB 260511B
  86. Konus-Wind detection of GRB 260511A
  87. MASS-Cube (GRID 2.0) detection of GRB 260507A
  88. GRB 260511B: SAO RAS optical observations
  89. GRB 260510D: Glowbug gamma-ray detection of a likely short burst
  90. GRB 260511A: EP-FXT follow-up observation
  91. GRB 260511B: AstroSat CZTI detection
  92. GRB 260511B: NuSTAR detection of prompt emission
  93. GRB 260510C: AstroSat CZTI detection
  94. Fermi GRB 260511A: Global MASTER-Net observations report
  95. GRB 260510C: MAXI/GSC detection
  96. Fermi GBM Sub-Threshold Detection of GRB 260510B
  97. GRB 260510D: Fermi GBM Final Real-time Localization
  98. GRB 260510B: SVOM detection of a burst
  99. Fermi GRB 260510A: Global MASTER-Net observations report
  100. GRB 260509A: SVOM detection of a burst

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