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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"

26484 results found.

  1. EP260806a: LCO likely optical counterpart
  2. EP260806a: Einstein Probe detection of an X-ray transient
  3. GRB 260715A: cubesat Avion detection
  4. GRB 260709A: cubesat Avion detection
  5. GRB 260708A: cubesat Avion detection
  6. GRB 260730B: Glowbug gamma-ray detection
  7. GRB 260805C: Glowbug gamma-ray detection
  8. GRB 260805B: Glowbug gamma-ray detection
  9. GRB 260804A: Glowbug gamma-ray detection
  10. GRB 260805B: BALROG localization (Fermi Trigger 807622617 / GRB 260805484)
  11. AT 2026wki: EP/FXT follow-up observations
  12. IceCube-Cascade 260801A: Upper limits from a search for additional neutrino events in IceCube
  13. GRB 260802A / EP J223759.5+521421: EP-FXT follow-up observation
  14. GRB 260802A: SVOM/VT optical upper limits from VHF data
  15. GRB 260802A: LCO optical upper limits
  16. GRB 260802A / EP J223759.5+531421: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  17. The EP-WXT trigger 01709277420 is likely a flaring star
  18. GRB 260802A/EP J223759.5+531421: SVOM detection of a possible magnetar burst
  19. GRB 260727A: EP-FXT further follow-up observations and candidate afterglow
  20. GRB 260731A: AstroSat CZTI detection of a long burst
  21. Fermi-LAT Gamma-ray Observations of IceCube-260722A
  22. EP260731a: COLIBRÍ optical upper limit
  23. EP260731a: NOT optical upper limit
  24. EP260731a: Einstein Probe detection of an X-ray transient
  25. GRB 260727A: SVOM/ECLAIRs refined analysis
  26. GRB 260726A: SVOM/ECLAIRs refined analysis
  27. EP260728a: COLIBRÍ optical upper limit
  28. The EP-WXT trigger 01709277130 (EP260729a): refined EP-WXT analysis and association with a flaring star
  29. EP260729a: Einstein Probe detection of an X-ray transient
  30. EP260727a: SAO RAS optical observations
  31. GRB 260727A: AbAO and SAO RAS optical observations
  32. EP260728a: EP-FXT follow-up observation
  33. GRB 260726A: EP-FXT follow-up observations
  34. EP260728a: Einstein Probe detection of a fast X-ray transient
  35. GRB 260727A: SVOM/GRM observation
  36. GRB 260726A: Fermi GBM Observation
  37. EP260727a:refined analysis of the EP-WXT and EP-FXT observation
  38. EP260727a: OHP/T193 optical observations
  39. Konus-Wind detection of GRB 260727A
  40. GRB 260726A: Liverpool Telescope optical observations
  41. GRB 260727A: Liverpool Telescope optical upper limits
  42. EP260727a: Liverpool Telescope confirmation of optical counterpart
  43. GRB 260727A: EP/FXT follow-up observations
  44. EP260727a: Einstein Probe detection of an X-ray transient
  45. The EP-WXT trigger 01709276927 (EP260727a?): NOT likely optical counterpart
  46. GRB 260727A: Glowbug gamma-ray detection
  47. GRB 260726A: J-band upper limit with WINTER
  48. GRB 260727A: J-band upper limit with WINTER
  49. GRB 260727A / SVOM sb26072702: RAPAS optical non-detection
  50. EP260723a: SVOM/ECLAIRs Upper Limit
  51. GRB 260727A: AstroSat CZTI detection
  52. GRB 260727A: Kilonova-Catcher optical upper limit
  53. GRB 260727A: LCO optical upper limits
  54. GRB 260727A: SVOM detection of a bright long burst
  55. GRB 260726A: SVOM detection of a burst
  56. EP260723a: further EP-FXT follow-up observation
  57. EP260725a: EP-FXT follow-up observation and association with a bright flaring star
  58. EP260725a: EP-WXT detection of an X-ray transient
  59. GRB 260616A: cubesat Avion detection
  60. EP260723a: Continued Liverpool Telescope observations suggest hours long optical plateau or rebrightening
  61. GRB 260602B: cubesat Avion detection
  62. GRB 260601A: cubesat Avion detection
  63. GRB 260718A: SVOM/ECLAIRs refined analysis
  64. EP260723a: SVOM/VT optical observation
  65. EP260723a: COLIBRÍ optical observations
  66. EP260723a: NOT optical conterpart confirmation
  67. EP260723a: Liverpool Telescope likely optical counterpart
  68. EP260723a: EP-WXT detection of a fast X-ray transient
  69. IceCube-260722A: Upper limits from a search for additional neutrino events in IceCube
  70. IceCube-260722A: One candidate from the Zwicky Transient Facility (ZTF)
  71. Konus-Wind detection of GRB 260721A
  72. Konus-Wind detection of GRB 260714B
  73. SVOM trigger sb26071506: SVOM/VT confirmation of a stellar flare
  74. GRB 260718A: EP-FXT follow-up observation
  75. GRB 260718A: LCO optical upper limits
  76. GRB 260710A: SVOM/GRM observation
  77. GRB 260718A: Fermi GBM Observation
  78. GRB 260718A : GRANDMA and KNC upper limits
  79. GRB 260718A: SVOM/VT optical upper limits
  80. GRB 260718A: SVOM/VT optical upper limits from VHF data
  81. GRB 260718A: SVOM detection of a burst
  82. GRB 260714B: SVOM/GRM observation
  83. GRB 260310A / AT2026fgk: Late-time Chandra Detection
  84. GRB 260714B: GECAM-B observation of a burst
  85. GRB 260618B: EP-FXT follow-up observation upper limit
  86. GRB 260714B: COLIBRÍ optical counterpart candidate
  87. sb26071506: SVOM detection of a X-ray transient
  88. EP260703a: SVOM/ECLAIRs Upper Limit
  89. GRB 260709A: AstroSat CZTI detection
  90. GRB 260714B: Fermi GBM Detection
  91. IceCube-260712A: Upper limits from a search for additional neutrino events in IceCube
  92. IceCube-260712A: LAST optical follow-up observations of the IceCube neutrino candidate
  93. GRB 260706A: ATCA detection of possible radio counterpart
  94. EP260713a: Einstein Probe detection of an X-ray transient
  95. GRB 260708A: slowly decaying X-ray emission observed by EP/FXT
  96. EP260623a: KAIT optical observations
  97. EP260711a: EP-FXT follow-up observation
  98. GRB 260708A: GRANDMA Optical Observations
  99. Fermi-LAT Gamma-ray Observations of IceCube-260712A
  100. Fermi-LAT Gamma-ray Observations of IceCube-260708A

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