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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"

26206 results found.

  1. EP260227a: Liverpool Telescope optical observations
  2. EP260227a: LCOGT Optical Observations
  3. GRB 260226A: Asiago r-band upper limit
  4. EP260227a: Thai National Telescope observations
  5. EP260227a: likely GTC/OSIRIS+ redshift z = 2.714
  6. EP260227a: COLIBRÍ optical observations
  7. EP260227a: NOT optical observations
  8. GRB 260225A: SVOM/VT optical continued observations and upper limit
  9. GRID detection of GRB 260223A
  10. EP260227a: Global MASTER-Net observations report
  11. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  12. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  13. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  14. EP260214a: VLT/FORS2 optical observations
  15. GRB 260225A: WINTER J-band upper limit
  16. GRB 260226A: CALET Gamma-Ray Burst Monitor detection
  17. GRB 260226A: COLIBRÍ optical upper limits
  18. GRB 260226A: LCOGT Optical Upper Limit
  19. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  20. GRB 260226A: Glowbug gamma-ray detection
  21. GRB 260226A : GROWTH-India Telescope optical observations
  22. GRB 260226A: Fermi GBM observation
  23. GRB 260226A: Fermi-LAT refined analysis
  24. The EP-WXT trigger 01709258652 is likely a flaring star
  25. LAT GRB260226.44: Global MASTER-Net observations report
  26. Fermi GRB 260226A: Global MASTER-Net observations report
  27. GRB 260226A: AstroSat CZTI detection of bright long burst
  28. EP260214a: VLA 6 GHz detection
  29. GRB 260226A: Fermi-LAT detection of a bright burst
  30. GRB 260226A???: BALROG localization (Fermi Trigger 793795080 / GRB 260226443)
  31. EP260224a: LCO optical upper limits
  32. GRB260225A: SVOM/ECLAIRs refined position
  33. GRB 260226A: Fermi GBM Final Real-time Localization
  34. GRB 260225A: EP-FXT follow-up observation
  35. GRB 260225A: SVOM/VT optical observation
  36. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  37. GRB 260225C: Fermi GBM Final Real-time Localization
  38. GRB 260223A: Fermi GBM Observation
  39. GRB 260225A: SVOM/VT optical upper limits
  40. GRB 260225B: Fermi GBM Final Real-time Localization
  41. EP260126a: VLA 6 GHz detection
  42. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  43. GRB 260225A: SVOM detection of a burst
  44. EP260224a: Einstein Probe detection of an X-ray transient
  45. EP 260225.148: COLIBRÍ Confirmation of flaring star
  46. EP260223a: Xinglong optical upper limit
  47. The EP-WXT trigger 01709258631 is likely a flaring star
  48. EP260213a: Mephisto optical upper limits
  49. EP260223a: EP-FXT follow-up observation
  50. sb26021801: SVOM/VT optical upper limits
  51. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  52. sb26021801: SVOM/C-GFT upper limit
  53. EP260223a: COLIBRÍ optical upper limits
  54. EP260223a: Einstein Probe detection of an X-ray transient
  55. GRB 260223A: SVOM/VT optical observation
  56. GRB 260223A: SVOM/GRM observation
  57. GRB 260223A: COLIBRÍ further optical observations and a brightening
  58. EP260221a: Optical upper limit with Kinder observations
  59. GRB 260223A: COLIBRÍ optical observations
  60. GRB 260223A: DDOTI Optical Candidate
  61. GRB 260223A: BALROG localization (Fermi Trigger 793512674 / GRB 260223174)
  62. Fermi GRB 260223A: Global MASTER-Net observations report
  63. GRB 260223A: Fermi GBM Final Real-time Localization
  64. EP260221a: COLIBRÍ optical counterpart candidate
  65. EP260221a: Gemini South z-band upper limit
  66. GRB 260222A: Fermi GBM Final Real-time Localization
  67. EP260221a: Global MASTER-Net observations report
  68. EP260221a: EP-FXT follow-up observation
  69. Fermi GRB 260221B: Global MASTER-Net observations report
  70. GRB 260221B: Fermi GBM Final Real-time Localization
  71. EP-WXT01709258519: Xinglong optical upper limit
  72. EP260221a: Xinglong optical upper limit
  73. Fermi GRB 260221A: Global MASTER-Net observations report
  74. GRB 260221A: Fermi GBM Final Real-time Localization
  75. EP260221a: GOTO optical upper limit
  76. EP260221a: COLIBRÍ optical upper limit
  77. SVOM alert sb26021801: LCO optical upper limit
  78. EP260221a: Einstein Probe detection of an X-ray transient
  79. The EP-WXT trigger 01709258519 is likely caused by Mrk 421
  80. GRB 260219A: GECAM-B observation of a long burst
  81. Fermi GRB 260219A: Global MASTER-Net observations report
  82. GRB 260219A: Fermi GBM Final Real-time Localization
  83. sb26021801: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  84. IceCube Alert 260217A: Global MASTER-Net observations report
  85. GRB 260217A: Fermi GBM Final Localization
  86. GRB 260214B/EP260214b: SVOM/ECLAIRs detection through targeted search
  87. sb26021801: SVOM detection of a long faint X-ray transient
  88. The EP-WXT trigger 01709258455 is likely a flaring star
  89. EP-WXT 01709258455: NOT optical upper limits
  90. EP260214b: 1.3m DFOT optical upper limit
  91. IPN triangulation of GRB 260212A
  92. GRB 260213A: GECAM-B observation of a short burst
  93. GRB 260216A: Fermi Gamma-ray Burst Monitor trigger 792969362/260216886 is not a GRB
  94. GRB 260216A: Fermi GBM Final Real-time Localization
  95. EP260214b: Liverpool Telescope optical observations
  96. EP260214b: Optical upper limit with Kinder observations
  97. EP260214a: Optical upper limits with Kinder observations
  98. EP260214b: EP-FXT follow-up observation
  99. EP260214a / GRB 260214A: Fermi-GBM Sub-Threshold Detection
  100. EP260214b: DDOTI Optical Detection

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