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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"

27447 results found.

  1. Fermi trigger No 801580882: Global MASTER-Net observations report
  2. GRB 260524A: SVOM/ECLAIRs detection of a burst through on-ground search
  3. EP260526a: Einstein Probe detection of a fast X-ray transient
  4. EP260526.405: COLIBRÍ optical upper limits
  5. The EP-WXT trigger 01709266106 is not a real source
  6. Fermi GRB 260526A: Global MASTER-Net observations report
  7. GRB 260526A: Fermi GBM Final Real-time Localization
  8. EP01709266106 (EP260526a?): Liverpool Telescope upper limits
  9. EP-WXT 01709266106: NOT optical upper limits
  10. Fermi GRB 260525A: Global MASTER-Net observations report
  11. GRB 260525A: Fermi GBM Final Real-time Localization
  12. Fermi GRB 260523A: Global MASTER-Net observations report
  13. GRB 260523B: Fermi GBM Final Real-time Localization
  14. GRB 260523A: Fermi GBM Final Real-time Localization
  15. GRB 260522A: Fermi GBM Observation
  16. EP260518a (AT2026ndp): LCO observations and Gemini-South Redshift z = 2.28
  17. GRB 260522B: Fermi GBM Final Real-time Localization
  18. GRB 260522A: GOTO optical upper limit
  19. Fermi trigger No 801135305: Global MASTER-Net observations report
  20. Fermi GRB 260522A: Global MASTER-Net observations report
  21. GRB 260522A: Fermi-LAT detection
  22. GRB 260519C: SVOM/GRM observation
  23. GRB 260522A: Fermi GBM Final Real-time Localization
  24. GRB 260511A: iTelescope T-75 optical detection
  25. GRB 260520B: Fermi GBM Final Localization
  26. GRB 260520A: Fermi GBM Final Localization
  27. GRB 260519D: Fermi GBM Final Localization Correction
  28. GRB 260519B: Fermi GBM Final Localization
  29. GRB 260519A: Fermi GBM Final Localization
  30. GRB 260516D: SVOM/ECLAIRs refined analysis
  31. GRB 260515A: SVOM/ECLAIRs refined analysis
  32. GRB 260509A: CrAO ZTSh optical upper limit
  33. GRB 260516D: EP-FXT follow-up observation
  34. GRB 260516D: LCO optical observations
  35. GRB 260515A: further Liverpool Telescope observations
  36. GRB 260516D: SVOM/COLIBRÍ (FM-GFT) optical observations
  37. GRB 260516D: GTC/OSIRIS+ spectroscopic redshift z = 1.801
  38. GRB 260516D: GROWTH-India Telescope optical detection
  39. GRB 260516D: SVOM/VT optical bright candidate
  40. GRB 260516D: FRAM-ORM optical limit
  41. GRB 260515A: CrAO ZTSh BVRI optical observations
  42. Fermi GRB 260516C: Global MASTER-Net observations report
  43. SVOM GRB260516D: Global MASTER-Net observations report
  44. GRB 260516D: SVOM possible detection of a burst
  45. GRB 260516C: Fermi GBM Final Real-time Localization
  46. GRB 260515A: LCO optical counterpart detection
  47. Fermi Gamma-ray Burst Monitor trigger 800627191/260516518 is not a GRB
  48. GRB 260515A: SVOM/COLIBRÍ (FM-GFT) optical observations
  49. GRB 260515A: EP-FXT follow-up observation
  50. EP260514a: NOT optical counterpart confirmation
  51. EP260514a: TRT optical counterpart candidate
  52. EP260514a: SVOM/VT optical candidate
  53. Fermi GRB 260516B: Global MASTER-Net observations report
  54. GRB 260516B: Fermi GBM Final Real-time Localization
  55. Fermi Gamma-ray Burst Monitor trigger 800592653/260516119 is not a GRB
  56. GRB 260515A: SVOM/VT optical observations
  57. GRB 260515A: OHP/T193 optical observations
  58. EP260514a: COLIBRÍ optical upper limits
  59. GRB 260516A: Fermi GBM Final Real-time Localization
  60. GRB 260515A: GTC/OSIRIS+ spectroscopic redshift z = 0.764
  61. GRB 260515A: LCO optical observations
  62. SVOM GRB 260515A: Global MASTER-Net observations report
  63. GRB 260515A: NOT optical observations.
  64. GRB 260515A: SVOM/VT optical candidate from VHF data
  65. GRB 260515A: JinShan optical counterpart candidate
  66. GRB 260515A: SVOM detection of a burst
  67. EP260514a: GROWTH-India Telescope optical upper limit
  68. GRB 260511B: NOT optical observations
  69. GRB 260510C: CALET Gamma-Ray Burst Monitor detection
  70. GRB 260511B: GMG Optical Upper Limit
  71. EP260514a: Global MASTER-Net observations report
  72. IPN triangulation of GRB 260512A
  73. GRB 260511B: Mephisto multi-band optical followup
  74. Fermi GRB 260514A: Global MASTER-Net observations report
  75. The EP-WXT trigger 01709262077 is likely a flaring star
  76. EP260507a: Xinglong Schmidt optical counterpart detection
  77. GRB 260514A: Fermi GBM Final Real-time Localization
  78. EP260512a: Global MASTER-Net observations report
  79. Fermi GRB 260513A: Global MASTER-Net observations report
  80. Fermi GRB 260512A: Global MASTER-Net observations report
  81. GRB 260513A: Fermi GBM Final Real-time Localization
  82. GRB 260509A: SVOM/VT optical observations
  83. The EP-WXT trigger 01709262036 is likely a flaring star
  84. EP260512a: COLIBRÍ optical upper limits
  85. EP260512a: Einstein Probe detection of an X-ray transient
  86. GRB 260509A: Infrared J and Hs observations with MDM/MIRAGE
  87. GRB 260510C: Infrared J and Hs detections with MDM/MIRAGE
  88. EP260507a: Infrared J and Hs upper limits with MDM/MIRAGE
  89. GRB 260512A: Fermi GBM Final Real-time Localization
  90. GRB 260511B: SAO RAS optical observations
  91. GRB 260511A: EP-FXT follow-up observation
  92. GRB 260511B: EP-FXT follow-up observation
  93. GRB 260511B: LCO optical counterpart detection
  94. GRB260511B: MAO/AZT-22 optical observations
  95. GRB 260511A: SVOM/VT optical observations
  96. GRB 260511B: LCO optical observations
  97. GRB 260511B: GOTO optical counterpart detection
  98. GRB 260511B: Xinglong 2.16m/BEFOSC redshift confirmation
  99. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) further optical observations
  100. GRB 260511B: SVOM/VT optical observations

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