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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"

26207 results found.

  1. EP260214b: DDOTI Optical Detection
  2. EP260214b: GROWTH-India Telescope optical upper limit
  3. EP260214a: VLT near-infrared observation
  4. EP260214b: SVOM/VT optical observation
  5. EP260214a: NOT optical upper limits
  6. EP260214a: COLIBRÍ optical upper limits
  7. EP260214b: OHP/T120 optical observations
  8. EP260214a: refined analysis of the EP-FXT observation
  9. EP260214b: LCO optical counterpart detection
  10. EP260214b: VLT/X-shooter spectroscopic redshift z = 1.208
  11. GRB 260211A: SVOM/VT optical counterpart
  12. EP260214b: COLIBRÍ optical observations
  13. EP260214a: SVOM/VT optical upper limits
  14. EP260214b: NOT optical counterpart detection
  15. EP260214b: Einstein Probe detection of a fast X-ray transient
  16. EP260214a: Global MASTER-Net observations report
  17. EP260214a: Einstein Probe detection of an X-ray transient
  18. GRB 260212A: Fermi GBM Observation
  19. EP260213a: Global MASTER-Net observations report
  20. EP260213a: COLIBRÍ optical upper limits
  21. GRB 260212A: GECAM-B observation
  22. EP260213a: Optical upper limits with Kinder observations
  23. EP260213a: SVOM/VT optical upper limit
  24. EP260213a: NUTTelA-TAO Early Optical Limits
  25. EP260213a: SVOM/C-GFT upper limit
  26. EP260213a: refined analysis of the EP-FXT observation
  27. EP260213a: Einstein Probe detection of a fast X-ray transient
  28. EP/WXT 01709258378: NOT optical upper limits
  29. GRB 260212A: SVOM/GRM observation of a long burst
  30. GRB 260213B: Fermi GBM Final Localization
  31. GRB 260213B: BALROG localization (Fermi Trigger 792697214 / GRB 260213736)
  32. GRB 260211A - SVOM/ECLAIRs refined analysis
  33. GRB 260204A: SVOM/ECLAIRs refined analysis
  34. GRB 260213A: Fermi GBM Final Localization
  35. GRB 260211A: EP-FXT follow-up observation
  36. GRB 260211A: SVOM/VT optical observation
  37. GRB 260211A: GOTO optical upper limit
  38. Fermi GRB 260212A: Global MASTER-Net observations report
  39. GRB 260212A: Fermi GBM Final Real-time Localization
  40. GRB 260210A: SVOM/GRM observation
  41. Fermi GBM Sub-Threshold Detection of GRB 260211A
  42. GRB 260128B: SVOM/ECLAIRs refined analysis
  43. GRID detection of GRB 260207B
  44. GRB 260211A: LCO optical upper limits
  45. GRB260131A/B: 3.6m DOT Optical Observations
  46. GRB 260211A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  47. Fermi trigger No 792537871: Global MASTER-Net observations report
  48. GRB 260211A: SVOM detection of a burst
  49. GRB 260208A: Swift UVOT detection
  50. EP260209a: COLIBRÍ optical upper limit
  51. Fermi GRB 260210C: Global MASTER-Net observations report
  52. EP260209a: LCO optical upper limits
  53. EP260210a: Global MASTER-Net observations report
  54. EP260210a: refined analysis of the EP-FXT observation
  55. EP260209a: Global MASTER-Net observations report
  56. GRB 260208A: LCO detection of the optical counterpart
  57. EP260209a: Einstein Probe detection of a fast X-ray transient
  58. EP260210a: Optical upper limits with Kinder observations
  59. IPN triangulation of GRB 260207B (short/hard with EE)
  60. GRB 260210C: Fermi GBM Final Real-time Localization
  61. GRB 260210B: Fermi GBM Final Real-time Localization
  62. EP260210a: SVOM/VT optical upper limit
  63. EP260210a: COLIBRÍ optical upper limit
  64. EP260210a: SVOM/C-GFT upper limit
  65. GRB 260208B: refined analysis of the EP-FXT observation
  66. EP260210a: Einstein Probe detection of an X-ray transient
  67. GRB 260208C: SVOM/GRM observation
  68. GRB260208A: Liverpool Telescope optical follow-up observations
  69. GRB 260208A: Fermi GBM Observation
  70. Fermi GRB 260209A: Global MASTER-Net observations report
  71. GRB 260208B: Swift-XRT observations
  72. GRB 260204A: Swift/UVOT Upper Limits
  73. GRB 260208B: COLIBRÍ optical observations
  74. GRB 260208A: 1.3m DFOT optical detection
  75. GRB 260208A: COLIBRÍ optical observations
  76. GRB 260208B: EP-FXT observation
  77. GRB 260208A: Liverpool Telescope optical detection
  78. Fermi GRB 260208C: Global MASTER-Net observations report
  79. GRB 260208B: SVOM/VT optical candidate
  80. GRB 260208A: GECAM-B observation of a bright burst
  81. GRB 260208A: Zwicky Transient Facility Follow-Up of a Fermi GRB (Trigger 792220053)
  82. GRB 260209A: Fermi GBM Final Real-time Localization
  83. GRB 260208A: SVOM/VT optical observation
  84. Fermi GRB 260208D: Global MASTER-Net observations report
  85. GRB 260208D: Fermi GBM Final Real-time Localization
  86. GRB 260208B: SVOM/GRM observation of a bright burst
  87. GRB 260208B: Fermi GBM Detection
  88. LAT GRB 260208B: Global MASTER-Net observations report
  89. GRB 260208B: Fermi-LAT detection
  90. GRB 260208C: Fermi GBM Final Real-time Localization
  91. GRB 260208A: Fermi-LAT detection
  92. GRB 260207B: GECAM-B observation
  93. GRB 260208A: Fermi GBM Classification Correction
  94. GRB 260208A: GOTO detection of a potential optical counterpart (GOTO26aob)
  95. GRB 260208A : MASTER bright optical transient inside retracted Fermi error-box
  96. GRB 260208B: BALROG localization (Fermi Trigger 792237169 / GRB 260208412)
  97. GRB 260208B: Fermi GBM Final Real-time Localization
  98. Fermi GRB 260208A: Global MASTER-Net observations report
  99. Fermi Gamma-ray Burst Monitor trigger 792220053/260208214 is not a GRB
  100. GRB 260208A: Fermi GBM Final Real-time Localization

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