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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"

3316 results found.

  1. EP260116a: COLIBRÍ detection of a fading optical source
  2. EP260119a: Global MASTER-Net observations report
  3. EP260119a: COLIBRÍ optical counterpart candidate
  4. EP260119a: preliminary result from the EP-FXT observation
  5. EP260119a: EP-WXT detection of a fast X-ray transient
  6. GRB 260117A: SVOM/VT optical candidate
  7. GRB 260117A: SVOM/C-GFT upper limit
  8. EP 260116a: COLIBRÍ optical upper limit
  9. EP260116a: Liverpool Telescope upper limits
  10. EP260116A: 1.3m DFOT optical upper limit
  11. EP260116a: Global MASTER-Net observations report
  12. EP260116a: Xinglong optical upper limit
  13. EP260116a: Einstein Probe detection of an X-ray transient
  14. Konus-Wind detection of GRB 260114A
  15. Konus-Wind detection of GRB 251230A / EP251230a
  16. EP-WXT trigger 01709251266: SVOM/C-GFT confirmation of a stellar flare
  17. EP260110a: NOT and GTC Optical and Near-Infrared Observations
  18. EP260110a: TRT optical upper limits
  19. Konus-Wind detection of GRB 260101A
  20. The EP-WXT trigger 01709251266 is likely a flaring star
  21. EP260110a: SVOM/VT optical upper limits
  22. EP260110a: Global MASTER-Net observations report
  23. EP260110a: KAIT optical upper limit
  24. EP260110a: refined analysis of the EP-WXT and EP-FXT observations
  25. EP 260110a: COLIBRÍ optical observations
  26. EP260110a: SVOM/C-GFT upper limit
  27. EP260110a: BOOTES-5/JGU optical upper limit
  28. EP260110a: Einstein Probe detection of an X-ray transient
  29. EP260105b / GRB 260105C : Fermi-GBM Sub-Threshold Detection
  30. EP260105b/EP-WXT trigger 01709251028: Einstein Probe detection of an X-ray transient
  31. The EP-WXT trigger 01709251112 is likely a flaring star
  32. EP260105a: FTW optical observations
  33. The EP-WXT trigger 01709251028 is likely a flaring star
  34. EP260105a: SVOM/VT optical upperlimit
  35. EP260105a: refined analysis of the EP-WXT and EP-FXT observations
  36. EP260105a: LCO Optical Upper limit
  37. EP260104a: Global MASTER-Net observations report
  38. EP260104a: Einstein Probe detection of a fast X-ray transient
  39. EP260105a: Global MASTER-Net observations report
  40. EP260105a: Einstein Probe detection of an X-ray transient
  41. GRB 251230A/EP-WXT trigger 01709250693: Mephisto optical upper limits
  42. GRB 260102A: EP-FXT follow-up observation
  43. EP260101a: Global MASTER-Net observations report
  44. GRB 251230A / EP251230a: GECAM-B detection
  45. GRB 251230A / EP251230a: Insight-HXMT/HE detection
  46. EP260101a: refined analysis of the EP-WXT and EP-FXT observations
  47. EP260101a: Einstein Probe detection of an X-ray transient
  48. GRB 251230A / EP251230a: SVOM/VT optical continued observations and upper limit
  49. EP251229a: Optical upper limit with Kinder observations
  50. EP251230a / GRB 251230A: refined analysis of the EP-WXT and EP-FXT observations
  51. EP251229a: BOOTES-2 early optical upper limit
  52. EP251229a: NOT optical upper limits
  53. GRB 251230A / EP251230a: SVOM/VT optical observation
  54. EP251229a: refined analysis of the EP-WXT and EP-FXT observations
  55. EP-WXT trigger 01709250662 Mephisto and 50cm telescope follow-up
  56. EP251230a / GRB 251230A: Einstein Probe detection of an X-ray transient
  57. GRB 251230A/EP#01709250693 (likely EP251230a): FTW optical and NIR observations
  58. The EP-WXT trigger 01709250693/GRB 251230A: Las Cumbres detection of the optical counterpart
  59. EP251229a: Global MASTER-Net observations report
  60. EP251229a: Einstein Probe detection of an X-ray transient
  61. GRB 251222A/EP251222b: 1.6m Mephisto optical followup
  62. The EP-WXT trigger 01709250662 is likely a flaring star
  63. The EP-WXT trigger 01709250617 is likely a flaring star
  64. EP251222a: Optical upper limit with Kinder observations
  65. EP251220a: 3.6m DOT optical afterglow detection
  66. GRB 251222A: Fermi GBM Observation
  67. EP251220a: CrAO ZTSh optical observations
  68. EP251221a: PRIME upper limit
  69. EP251222a: Global MASTER-Net observations report
  70. EP251221a: Liverpool Telescope upper limits
  71. EP251222a: refined analysis of the EP-WXT and EP-FXT observations
  72. EP251222b/GRB 251222A: refined analysis of the EP-WXT and EP-FXT observations
  73. Konus-Wind detection of GRB 251222A / EP251222b
  74. GRB 251222A / EP251222b: LCO detection of the optical counterpart
  75. EP251222a: NTT/ULTRACAM optical observations
  76. EP251222a: GOTO optical upper limit
  77. GRB 251222A / EP251222b: GOTO optical counterpart detection
  78. EP251222a: GSP Optical Counterpart Detection
  79. GRB 251222A / EP251222b: VLT/X-shooter spectroscopic redshift z = 3.171
  80. EP251222b/GRB 251222A: SVOM/GRM observation
  81. EP251222b/GRB 251222A: Einstein Probe detection of an X-ray transient
  82. EP251222a: Einstein Probe detection of an X-ray transient
  83. The EP-WXT trigger 01709250397 is likely a flaring star
  84. EP251221a: Global MASTER-Net observations report
  85. EP251221a: NOT optical upper limit
  86. EP251220a: VLT/FORS2 spectroscopic redshift z = 2.375
  87. EP251220a: NOT optical observations
  88. EP251221a: Einstein Probe detection of a fast X-ray transient
  89. EP251220a: EP-FXT follow-up observation
  90. EP 251220a: GOTO optical counterpart detection
  91. EP 251220a: COLIBRÍ detection of the optical counterpart
  92. EP251220a: Global MASTER-Net observations report
  93. EP251220a: EP detection of a fast X-ray transient
  94. EP251214b: KAIT optical upper limit
  95. EP251214a: Optical upper limit with Kinder observations
  96. EP251214b: Global MASTER-Net observations report
  97. EP251214b : Einstein Probe detection of a fast X-ray transient
  98. EP251214b : Einstein Probe detection of a fast X-ray transient
  99. EP251214b (EP trigger 01709250023): LCO optical limits
  100. EP251214a: KAIT optical upper limit

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