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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').
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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"

32510 results found.

  1. EP260526a: EP-FXT follow-up observation
  2. EP260527a: SVOM/VT optical observation
  3. EP260527a: COLIBRÍ optical detection
  4. EP260526a: LCO optical upper limits
  5. EP260526a: Einstein Probe detection of a fast X-ray transient
  6. GRB 260525A: AstroSat CZTI detection
  7. The EP-WXT trigger 01709266106 is not a real source
  8. Fermi GRB 260526A: Global MASTER-Net observations report
  9. Fermi GRB 260525A: Global MASTER-Net observations report
  10. GRB 260523B: AstroSat CZTI detection
  11. GRB 260523B: GECAM-B observation
  12. Fermi GRB 260523A: Global MASTER-Net observations report
  13. GRB 260522A: Fermi GBM Observation
  14. GRB 260522B: NuSTAR detection of prompt emission
  15. EP260518a (AT2026ndp): LCO observations and Gemini-South Redshift z = 2.28
  16. GRB 260522A: GOTO optical upper limit
  17. Fermi GRB 260522A: Global MASTER-Net observations report
  18. GRB 260522A: Fermi-LAT detection
  19. GRB 260519C: SVOM/GRM observation
  20. GRB 260511A: iTelescope T-75 optical detection
  21. GRB 260520B: SVOM/GRM observation
  22. GRB 260411B: TERI Gamma-ray detection
  23. GRB 260407A: TERI Gamma-ray detection
  24. GRB 260307A: TERI Gamma-ray detection
  25. GRB 260225D: TERI Gamma-ray detection
  26. GRB 251118A: TERI Gamma-ray detection
  27. GRB 251113A: TERI Gamma-ray detection
  28. GRB 260428A: TERI Gamma-ray detection
  29. Konus-Wind detection of GRB 260519C
  30. GRB 260509A: SVOM/ECLAIRs refined analysis
  31. GRB 260519C: NuSTAR detection of prompt emission
  32. Konus-Wind detection of GRB 260518A
  33. GRB 260516D: SVOM/ECLAIRs refined analysis
  34. GRB 260515A: SVOM/ECLAIRs refined analysis
  35. GRB 260421B: radio detection with the VLA
  36. GRID detection of GRB 260511A
  37. GRB 260509A: CrAO ZTSh optical upper limit (Duplicate Submission)
  38. GRB 260509A: CrAO ZTSh optical upper limit
  39. GRB 260516D: EP-FXT follow-up observation
  40. GRB 260516D: GOTO optical counterpart detection
  41. GRB 260516D: LCO optical observations
  42. GRB 260515A: further Liverpool Telescope observations
  43. GRB 260516D: SVOM/COLIBRÍ (FM-GFT) optical observations
  44. GRB 260516D: GTC/OSIRIS+ spectroscopic redshift z = 1.801
  45. GRB 260516D: GROWTH-India Telescope optical detection
  46. GRB 260516D: SVOM/VT optical bright candidate
  47. GRB 260515A: CrAO ZTSh BVRI optical observations
  48. Fermi GRB 260516C: Global MASTER-Net observations report
  49. Konus-Wind detection of GRB 260515A
  50. GRB 260515A: Liverpool Telescope optical detection
  51. GRB 260515A: LCO optical counterpart detection
  52. GRB 260515A: SVOM/COLIBRÍ (FM-GFT) optical observations
  53. GRB 260515A: EP-FXT follow-up observation
  54. EP260514a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  55. EP260514a: NOT optical counterpart confirmation
  56. EP260514a: TRT optical counterpart candidate
  57. EP260514a: SVOM/VT optical candidate
  58. Fermi GRB 260516B: Global MASTER-Net observations report
  59. GRB 260515A: SVOM/VT optical observations
  60. GRB 260515A: OHP/T193 optical observations
  61. EP260514a: COLIBRÍ optical upper limits
  62. GRID detection of GRB 260507A
  63. GRB 260515A: GTC/OSIRIS+ spectroscopic redshift z = 0.764
  64. GRB 260515A: LCO optical observations
  65. SVOM GRB 260515A: Global MASTER-Net observations report
  66. GRB 260515A: NOT optical observations.
  67. SVOM GRB 260515A: MASTER OT J151044.43+243321.7 optical counterpart detection
  68. GRB 260515A: SVOM/VT optical candidate from VHF data
  69. GRB 260515A: JinShan optical counterpart candidate
  70. GRB 260510C: Glowbug gamma-ray detection
  71. IceCube-260504A: No Candidate Transients from the Zwicky Transient Facility
  72. EP260514a: GROWTH-India Telescope optical upper limit
  73. GRB 260511B: NOT optical observations
  74. Konus-Wind detection of GRB 260512A
  75. GRB 260510C: CALET Gamma-Ray Burst Monitor detection
  76. GRB 260511B: GMG Optical Upper Limit
  77. EP260514a: Global MASTER-Net observations report
  78. EP260512a: LCO optical upper limits
  79. IPN triangulation of GRB 260512A
  80. GRB 260511B: Mephisto multi-band optical followup
  81. Fermi GRB 260514A: Global MASTER-Net observations report
  82. GRB 260512A: AstroSat CZTI detection
  83. EP260512a: EP-FXT follow-up observation
  84. EP260507a: Xinglong Schmidt optical counterpart detection
  85. EP260512a: Global MASTER-Net observations report
  86. Fermi GRB 260513A: Global MASTER-Net observations report
  87. Fermi GRB 260512A: Global MASTER-Net observations report
  88. GRB 260511B: further SAO RAS optical observations
  89. GRB 260509A: SVOM/VT optical observations
  90. Konus-Wind detection of GRB 260511B
  91. EP260512a: COLIBRÍ optical upper limits
  92. GRB 260511B: further J-band observations by the SYSU 80 cm infrared telescope
  93. GRB 260511B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  94. GRB 260512A: NuSTAR detection of prompt emission
  95. GRB 260509A: Infrared J and Hs observations with MDM/MIRAGE
  96. GRB 260510C: Infrared J and Hs detections with MDM/MIRAGE
  97. EP260507a: Infrared J and Hs upper limits with MDM/MIRAGE
  98. GRB 260511A: Glowbug gamma-ray detection
  99. Konus-Wind detection of GRB 260511A
  100. MASS-Cube (GRID 2.0) detection of GRB 260511A

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