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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"
  1. GRB 260515A: SVOM/COLIBRÍ (FM-GFT) optical observations
  2. GRB 260515A: EP-FXT follow-up observation
  3. EP260514a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  4. EP260514a: NOT optical counterpart confirmation
  5. EP260514a: TRT optical counterpart candidate
  6. EP260514a: SVOM/VT optical candidate
  7. Fermi GRB 260516B: Global MASTER-Net observations report
  8. GRB 260516B: Fermi GBM Final Real-time Localization
  9. Fermi Gamma-ray Burst Monitor trigger 800592653/260516119 is not a GRB
  10. GRB 260515A: SVOM/VT optical observations
  11. GRB 260515A: OHP/T193 optical observations
  12. EP260514a: COLIBRÍ optical upper limits
  13. GRB 260516A: Fermi GBM Final Real-time Localization
  14. GRID detection of GRB 260507A
  15. GRB 260515A: GTC/OSIRIS+ spectroscopic redshift z = 0.764
  16. GRB 260515A: LCO optical observations
  17. SVOM GRB 260515A: Global MASTER-Net observations report
  18. GRB 260515A: NOT optical observations.
  19. SVOM GRB 260515A: MASTER OT J151044.43+243321.7 optical counterpart detection
  20. GRB 260515A: SVOM/VT optical candidate from VHF data
  21. GRB 260515A: JinShan optical counterpart candidate
  22. GRB 260515A: SVOM detection of a burst
  23. GRB 260510C: Glowbug gamma-ray detection
  24. IceCube-260504A: No Candidate Transients from the Zwicky Transient Facility
  25. EP260514a: GROWTH-India Telescope optical upper limit
  26. GRB 260511B: NOT optical observations
  27. Konus-Wind detection of GRB 260512A
  28. GRB 260510C: CALET Gamma-Ray Burst Monitor detection
  29. GRB 260511B: GMG Optical Upper Limit
  30. EP260514a: Global MASTER-Net observations report
  31. EP260514a: Einstein Probe detection of a fast X-ray transient
  32. EP260512a: LCO optical upper limits
  33. IPN triangulation of GRB 260512A
  34. GRB 260511B: Mephisto multi-band optical followup
  35. Fermi GRB 260514A: Global MASTER-Net observations report
  36. GRB 260512A: AstroSat CZTI detection
  37. The EP-WXT trigger 01709262077 is likely a flaring star
  38. EP260512a: EP-FXT follow-up observation
  39. EP260507a: Xinglong Schmidt optical counterpart detection
  40. GRB 260514A: Fermi GBM Final Real-time Localization
  41. EP260512a: Global MASTER-Net observations report
  42. Fermi GRB 260513A: Global MASTER-Net observations report
  43. Fermi GRB 260512A: Global MASTER-Net observations report
  44. GRB 260511B: further SAO RAS optical observations
  45. GRB 260513A: Fermi GBM Final Real-time Localization
  46. GRB 260509A: SVOM/VT optical observations
  47. Konus-Wind detection of GRB 260511B
  48. The EP-WXT trigger 01709262036 is likely a flaring star
  49. EP260512a: COLIBRÍ optical upper limits
  50. EP260512a: Einstein Probe detection of an X-ray transient
  51. GRB 260511B: further J-band observations by the SYSU 80 cm infrared telescope
  52. GRB 260511B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  53. GRB 260512A: NuSTAR detection of prompt emission
  54. GRB 260509A: Infrared J and Hs observations with MDM/MIRAGE
  55. GRB 260510C: Infrared J and Hs detections with MDM/MIRAGE
  56. EP260507a: Infrared J and Hs upper limits with MDM/MIRAGE
  57. GRB 260512A: Fermi GBM Final Real-time Localization
  58. GRB 260511A: Glowbug gamma-ray detection
  59. Konus-Wind detection of GRB 260511A
  60. MASS-Cube (GRID 2.0) detection of GRB 260511A
  61. MASS-Cube (GRID 2.0) detection of GRB 260507A
  62. GRB 260511B: SAO RAS optical observations
  63. GRB 260510D: Glowbug gamma-ray detection of a likely short burst
  64. GRB 260511B: FRAM-ORM optical detection
  65. GRB 260511A: EP-FXT follow-up observation
  66. GRB 260511B: EP-FXT follow-up observation
  67. GRB 260511B: LCO optical counterpart detection
  68. GRB260511B: MAO/AZT-22 optical observations
  69. GRB 260511A: SVOM/VT optical observations
  70. GRB 260511B: LCO optical observations
  71. GRB 260511B: OHP/T193 spectroscopic observations
  72. GRB 260511B: GOTO optical counterpart detection
  73. GRB 260511B: Xinglong 2.16m/BEFOSC redshift confirmation
  74. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) further optical observations
  75. GRB 260510A: AstroSat CZTI detection (Erroneous Submission)
  76. GRB 260511B: SVOM/VT optical observations
  77. GRB 260511B: SVOM/COLIBRÍ (FM-GFT) optical observations
  78. GRB 260510B: EP-FXT follow-up observation
  79. GRB 260511B: OSIRIS+/GTC redshift z=2.006
  80. GRB 260510C: Fermi GBM Observation
  81. GRB 260509A: SAO RAS optical observations
  82. GRB 260511A: REM near-infrared detection
  83. GRB 260511B: GROWTH-India Telescope optical observations
  84. GRB 260511B: AstroSat CZTI detection
  85. GRB 260506B: Glowbug gamma-ray detection
  86. GRB 260506A: Glowbug gamma-ray detection of a short burst
  87. GRB 260511B: J-band observations by the SYSU 80 cm infrared telescope
  88. GRB 260511B: NuSTAR detection of prompt emission
  89. GRB 260511A: NuSTAR detection of prompt emission
  90. GRB 260511B: Fermi GBM Detection
  91. GRB 260511C: Fermi GBM Final Real-time Localization
  92. GRB 260511B: SVOM/VT optical observation with VHF data
  93. GRB 260511B: TRT optical observation
  94. GRB 260510B: SVOM/ECLAIRs refined analysis
  95. GRB 260511B : MITSuME Akeno optical afterglow candidate detection
  96. GRB 260511A: Fermi GBM Detection
  97. GRB 260511B SVOM/C-GFT optical counterpart detection
  98. EP260509a: LCO optical upper limits
  99. GRB 260511A: UTGO H50 optical afterglow observation
  100. GRB 260510C: AstroSat CZTI detection

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