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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"

22912 results found.

  1. EP260306a: Mondy optical upper limit
  2. GRB 260208A: radio detection with the VLA
  3. GRB 260307A: Glowbug gamma-ray detection
  4. GRB 260307B: Mephisto optical upper limits
  5. GRB 260307B: possible NOT optical counterpart
  6. GRB 260307B: SVOM/VT upper limit with X band data analysis
  7. GRB260307B: GROWTH-India Telescope optical upper limit
  8. GRB 260307B: SVOM/VT optical candidate
  9. GRB 260307B: SVOM/C-GFT upper limit
  10. GRB 260307B: SVOM detection of a burst
  11. EP260306a: refined analysis of the EP-WXT and EP-FXT observations
  12. GRB 260207A: TESS Detection and Possible VLA Counterpart
  13. EP260302a: SVOM/VT optical observation
  14. EP260306a: SVOM/VT optical observation
  15. EP260306a: COLIBRÍ optical observations of the fading and red counterpart
  16. EP260306a: Einstein Probe detection of an X-ray transient
  17. GRB 260303A: 1.3m DFOT optical upper limit
  18. EP260214b: ATCA 6 GHz observations
  19. GRB 260303B: AstroSat CZTI detection
  20. GRB 260304A: AstroSat CZTI detection of a long burst
  21. GRB 260303A: SVOM/VT optical observations
  22. GRB 260303A: J-band observations with WINTER
  23. GRB 260303B: Fermi GBM Final Real-time Localization
  24. EP260302a: analysis of the follow-up EP-FXT observation
  25. EP260302a: LCO observations
  26. EP260302a: BOOTES-7 optical counterpart detection at early times
  27. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  28. GRB 260303A: SVOM detection of a burst
  29. EP260302a: Einstein Probe detection of an X-ray transient
  30. GRB 251130B: TERI Gamma-ray detection
  31. GRB 260208A: TERI Gamma-ray detection
  32. EP260227a: Mondy optical observations
  33. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  34. EP260227a: Mephisto optical detection
  35. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  36. EP260227a: SVOM/VT optical observation
  37. GRB 260228A: SVOM/VT optical upper limits
  38. GRB 260225D: SVOM/GRM observation
  39. EP260227A: 3.6m DOT optical afterglow detection
  40. GRB 260225B: SVOM/GRM observation
  41. EP260227a: Liverpool Telescope optical observations
  42. EP260227a: LCOGT Optical Observations
  43. GRB 260226A: Asiago r-band upper limit
  44. EP260227a: Liverpool Telescope observations
  45. EP260227a: COLIBRÍ optical observations
  46. EP260227a: NOT optical observations
  47. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  48. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  49. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  50. EP260214a: VLT/FORS2 optical observations
  51. GRB 260225A: WINTER J-band upper limit
  52. GRB 260226A: COLIBRÍ optical upper limits
  53. GRB 260226A: LCOGT Optical Upper Limit
  54. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  55. GRB 260225D: Glowbug gamma-ray detection of a likely short burst
  56. GRB 260226A: Glowbug gamma-ray detection
  57. GRB 260226A : GROWTH-India Telescope optical observations
  58. GRB 260226A: LAST optical upper limit
  59. The EP-WXT trigger 01709258652 is likely a flaring star
  60. EP260224a: LCO optical upper limits
  61. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  62. GRB 260225A: SVOM/VT optical upper limits
  63. EP260223a: Liverpool Telescope upper limits
  64. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  65. EP260224a: Einstein Probe detection of an X-ray transient
  66. EP 260225.148: COLIBRÍ Confirmation of flaring star
  67. EP260223a: Xinglong optical upper limit
  68. GRB 260223A: Glowbug gamma-ray detection
  69. EP260213a: Mephisto optical upper limits
  70. sb26021801: SVOM/VT optical upper limits
  71. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  72. sb26021801: SVOM/C-GFT upper limit
  73. EP260223a: COLIBRÍ optical upper limits
  74. EP260223a: Einstein Probe detection of an X-ray transient
  75. GRB 260223A: SVOM/GRM observation
  76. GRB 260223A: COLIBRÍ further optical observations and a brightening
  77. EP260221a: Optical upper limit with Kinder observations
  78. GRB 260223A: COLIBRÍ optical observations
  79. GRB 260223A: DDOTI Optical Candidate
  80. EP260221a: Liverpool Telescope detection of COLIBRÍ counterpart candidate
  81. EP260221a: COLIBRÍ optical counterpart candidate
  82. EP260221a: Gemini South z-band upper limit
  83. EP260221a: EP-FXT follow-up observation
  84. EP-WXT01709258519: Xinglong optical upper limit
  85. EP260221a: Xinglong optical upper limit
  86. ZTF26aaglqak/AT2026dbl: COLIBRÍ Optical Observations
  87. EP260221a: GOTO optical upper limit
  88. EP260221a: COLIBRÍ optical upper limit
  89. SVOM alert sb26021801: LCO optical upper limit
  90. EP260221a: Einstein Probe detection of an X-ray transient
  91. SVOM alert sb26021801: LAST optical upper limit
  92. sb26021801: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  93. GRB 260214B/EP260214b: SVOM/ECLAIRs detection through targeted search
  94. EP-WXT 01709258455: NOT optical upper limits
  95. EP260214b: Mondy optical observations
  96. EP260214b: 1.3m DFOT optical upper limit
  97. EP260210a: Mondy optical upper limits
  98. GRB 260208A: AbAO and Terskol optical upper limits
  99. GRB 260208A: continued Mondy optical observations
  100. IPN triangulation of GRB 260212A

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