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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"

42209 results found.

  1. EP260223a: Xinglong optical upper limit
  2. The EP-WXT trigger 01709258631 is likely a flaring star
  3. GRB 260223A: Glowbug gamma-ray detection
  4. EP260213a: Mephisto optical upper limits
  5. EP260223a: EP-FXT follow-up observation
  6. sb26021801: SVOM/VT optical upper limits
  7. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  8. sb26021801: SVOM/C-GFT upper limit
  9. EP260223a: COLIBRÍ optical upper limits
  10. EP260223a: Einstein Probe detection of an X-ray transient
  11. GRB 260223A: SVOM/VT optical observation
  12. GRB 260223A: SVOM/GRM observation
  13. GRB 260223A: COLIBRÍ further optical observations and a brightening
  14. EP260221a: Optical upper limit with Kinder observations
  15. GRB 260223A: COLIBRÍ optical observations
  16. GRB 260223A: DDOTI Optical Candidate
  17. GRB 260223A: BALROG localization (Fermi Trigger 793512674 / GRB 260223174)
  18. Fermi GRB 260223A: Global MASTER-Net observations report
  19. GRB 260223A: Fermi GBM Final Real-time Localization
  20. EP260221a: Liverpool Telescope detection of COLIBRÍ counterpart candidate
  21. EP260221a: COLIBRÍ optical counterpart candidate
  22. EP260221a: Gemini South z-band upper limit
  23. GRB 260222A: Fermi GBM Final Real-time Localization
  24. EP260221a: Global MASTER-Net observations report
  25. EP260221a: EP-FXT follow-up observation
  26. Fermi GRB 260221B: Global MASTER-Net observations report
  27. GRB 260221B: Fermi GBM Final Real-time Localization
  28. EP-WXT01709258519: Xinglong optical upper limit
  29. EP260221a: Xinglong optical upper limit
  30. Fermi GRB 260221A: Global MASTER-Net observations report
  31. ZTF26aaglqak/AT2026dbl: COLIBRÍ Optical Observations
  32. GRB 260221A: Fermi GBM Final Real-time Localization
  33. EP260221a: GOTO optical upper limit
  34. EP260221a: COLIBRÍ optical upper limit
  35. SVOM alert sb26021801: LCO optical upper limit
  36. EP260221a: Einstein Probe detection of an X-ray transient
  37. The EP-WXT trigger 01709258519 is likely caused by Mrk 421
  38. GRB 260219A: AstroSat CZTI detection
  39. IceCube-260217A: Upper limits from a search for additional neutrino events in IceCube
  40. GRB 260219A: GECAM-B observation of a long burst
  41. Fermi GRB 260219A: Global MASTER-Net observations report
  42. GRB 260219A: Fermi GBM Final Real-time Localization
  43. SVOM alert sb26021801: LAST optical upper limit
  44. sb26021801: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  45. IceCube Alert 260217A: Global MASTER-Net observations report
  46. Fermi-LAT Gamma-ray Observations of IceCube-260217A
  47. GRB 260217A: Fermi GBM Final Localization
  48. GRB 260214B/EP260214b: SVOM/ECLAIRs detection through targeted search
  49. sb26021801: SVOM detection of a long faint X-ray transient
  50. The EP-WXT trigger 01709258455 is likely a flaring star
  51. EP-WXT 01709258455: NOT optical upper limits
  52. EP260214b: Mondy optical observations
  53. EP260214b: 1.3m DFOT optical upper limit
  54. EP260210a: Mondy optical upper limits
  55. Konus-Wind detection of GRB 260212A
  56. GRB 260208A: AbAO and Terskol optical upper limits
  57. GRB 260208A: continued Mondy optical observations
  58. IceCube-260217A - IceCube observation of a high-energy neutrino candidate track-like event
  59. GRB 260213A: GECAM-B observation of a short burst
  60. GRB 260216A: Fermi GBM Final Real-time Localization
  61. EP260214b: Liverpool Telescope optical observations
  62. GRB 260206A: probable hard X-ray burst from 4U 0513-40
  63. EP260214b: Optical upper limit with Kinder observations
  64. EP260214a: Optical upper limits with Kinder observations
  65. EP260214b: EP-FXT follow-up observation
  66. EP260214a / GRB 260214A: Fermi-GBM Sub-Threshold Detection
  67. EP260214b: DDOTI Optical Detection
  68. EP260214b: GROWTH-India Telescope optical upper limit
  69. EP260214a: VLT near-infrared observation
  70. EP260214b: SVOM/VT optical observation
  71. EP260214a: NOT optical upper limits
  72. EP260214a: COLIBRÍ optical upper limits
  73. EP260214b: OHP/T120 optical observations
  74. EP260214a: refined analysis of the EP-FXT observation
  75. EP260214b: LCO optical counterpart detection
  76. EP260214b: VLT/X-shooter spectroscopic redshift z = 1.208
  77. GRB 260211A: SVOM/VT optical counterpart
  78. EP260214b: COLIBRÍ optical observations
  79. EP260214a: SVOM/VT optical upper limits
  80. EP260214b: NOT optical counterpart detection
  81. EP260214b: Einstein Probe detection of a fast X-ray transient
  82. EP260214a: Global MASTER-Net observations report
  83. EP260214a: Einstein Probe detection of an X-ray transient
  84. GRB 260212A: AstroSat CZTI detection
  85. GRB 260212A: Fermi GBM Observation
  86. EP260213a: Liverpool Telescope optical upper limits
  87. EP260213a: Global MASTER-Net observations report
  88. EP260213a: COLIBRÍ optical upper limits
  89. GRB 260212A: GECAM-B observation
  90. EP260213a: Optical upper limits with Kinder observations
  91. EP260213a: SVOM/VT optical upper limit
  92. EP260213a: Mondy R-band optical upper limit
  93. EP260213a: NUTTelA-TAO Early Optical Limits
  94. EP260213a: SVOM/C-GFT upper limit
  95. EP260213a: refined analysis of the EP-FXT observation
  96. EP260213a: Einstein Probe detection of a fast X-ray transient
  97. EP/WXT 01709258378: NOT optical upper limits
  98. GRB 260212A: SVOM/GRM observation of a long burst
  99. GRB 260213B: Fermi GBM Final Localization
  100. GRB 260213B: BALROG localization (Fermi Trigger 792697214 / GRB 260213736)

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