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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"

26496 results found.

  1. GRB 260808B / EPF_J230056.0+082842: EP-FXT follow-up observation
  2. EP260809a: Einstein Probe detection of an X-ray transient
  3. GRB 260808B: SVOM/VT optical candidate from VHF data ( localization correction for GCN 45317 )
  4. GRB 260808B: SVOM/VT optical candidate from VHF data
  5. GRB 260808B: SVOM detection of a faint burst
  6. GRB 260807A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  7. GRB 260807A: SVOM possible detection of a faint burst
  8. EP260806a: COLIBRÍ optical observations
  9. EP260806a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  10. EP260806a: SVOM/VT optical observation
  11. EP260806a: Liverpool Telescope observations of the counterpart show a blue colour
  12. EP260731a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  13. EP260806a: LCO likely optical counterpart
  14. EP260806a: Einstein Probe detection of an X-ray transient
  15. GRB 260715A: cubesat Avion detection
  16. GRB 260709A: cubesat Avion detection
  17. GRB 260708A: cubesat Avion detection
  18. GRB 260730B: Glowbug gamma-ray detection
  19. GRB 260805C: Glowbug gamma-ray detection
  20. GRB 260805B: Glowbug gamma-ray detection
  21. GRB 260804A: Glowbug gamma-ray detection
  22. GRB 260805B: BALROG localization (Fermi Trigger 807622617 / GRB 260805484)
  23. AT 2026wki: EP/FXT follow-up observations
  24. IceCube-Cascade 260801A: Upper limits from a search for additional neutrino events in IceCube
  25. GRB 260802A / EP J223759.5+521421: EP-FXT follow-up observation
  26. GRB 260802A: SVOM/VT optical upper limits from VHF data
  27. GRB 260802A: LCO optical upper limits
  28. GRB 260802A / EP J223759.5+531421: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  29. The EP-WXT trigger 01709277420 is likely a flaring star
  30. GRB 260802A/EP J223759.5+531421: SVOM detection of a possible magnetar burst
  31. GRB 260727A: EP-FXT further follow-up observations and candidate afterglow
  32. GRB 260731A: AstroSat CZTI detection of a long burst
  33. Fermi-LAT Gamma-ray Observations of IceCube-260722A
  34. EP260731a: COLIBRÍ optical upper limit
  35. EP260731a: NOT optical upper limit
  36. EP260731a: Einstein Probe detection of an X-ray transient
  37. GRB 260727A: SVOM/ECLAIRs refined analysis
  38. GRB 260726A: SVOM/ECLAIRs refined analysis
  39. EP260728a: COLIBRÍ optical upper limit
  40. The EP-WXT trigger 01709277130 (EP260729a): refined EP-WXT analysis and association with a flaring star
  41. EP260729a: Einstein Probe detection of an X-ray transient
  42. EP260727a: SAO RAS optical observations
  43. GRB 260727A: AbAO and SAO RAS optical observations
  44. EP260728a: EP-FXT follow-up observation
  45. GRB 260726A: EP-FXT follow-up observations
  46. EP260728a: Einstein Probe detection of a fast X-ray transient
  47. GRB 260727A: SVOM/GRM observation
  48. GRB 260726A: Fermi GBM Observation
  49. EP260727a:refined analysis of the EP-WXT and EP-FXT observation
  50. EP260727a: OHP/T193 optical observations
  51. Konus-Wind detection of GRB 260727A
  52. GRB 260726A: Liverpool Telescope optical observations
  53. GRB 260727A: Liverpool Telescope optical upper limits
  54. EP260727a: Liverpool Telescope confirmation of optical counterpart
  55. GRB 260727A: EP/FXT follow-up observations
  56. EP260727a: Einstein Probe detection of an X-ray transient
  57. The EP-WXT trigger 01709276927 (EP260727a?): NOT likely optical counterpart
  58. GRB 260727A: Glowbug gamma-ray detection
  59. GRB 260726A: J-band upper limit with WINTER
  60. GRB 260727A: J-band upper limit with WINTER
  61. GRB 260727A / SVOM sb26072702: RAPAS optical non-detection
  62. EP260723a: SVOM/ECLAIRs Upper Limit
  63. GRB 260727A: AstroSat CZTI detection
  64. GRB 260727A: Kilonova-Catcher optical upper limit
  65. GRB 260727A: LCO optical upper limits
  66. GRB 260727A: SVOM detection of a bright long burst
  67. GRB 260726A: SVOM detection of a burst
  68. EP260723a: further EP-FXT follow-up observation
  69. EP260725a: EP-FXT follow-up observation and association with a bright flaring star
  70. EP260725a: EP-WXT detection of an X-ray transient
  71. GRB 260616A: cubesat Avion detection
  72. EP260723a: Continued Liverpool Telescope observations suggest hours long optical plateau or rebrightening
  73. GRB 260602B: cubesat Avion detection
  74. GRB 260601A: cubesat Avion detection
  75. GRB 260718A: SVOM/ECLAIRs refined analysis
  76. EP260723a: SVOM/VT optical observation
  77. EP260723a: COLIBRÍ optical observations
  78. EP260723a: NOT optical conterpart confirmation
  79. EP260723a: Liverpool Telescope likely optical counterpart
  80. EP260723a: EP-WXT detection of a fast X-ray transient
  81. IceCube-260722A: Upper limits from a search for additional neutrino events in IceCube
  82. IceCube-260722A: One candidate from the Zwicky Transient Facility (ZTF)
  83. Konus-Wind detection of GRB 260721A
  84. Konus-Wind detection of GRB 260714B
  85. SVOM trigger sb26071506: SVOM/VT confirmation of a stellar flare
  86. GRB 260718A: EP-FXT follow-up observation
  87. GRB 260718A: LCO optical upper limits
  88. GRB 260710A: SVOM/GRM observation
  89. GRB 260718A: Fermi GBM Observation
  90. GRB 260718A : GRANDMA and KNC upper limits
  91. GRB 260718A: SVOM/VT optical upper limits
  92. GRB 260718A: SVOM/VT optical upper limits from VHF data
  93. GRB 260718A: SVOM detection of a burst
  94. GRB 260714B: SVOM/GRM observation
  95. GRB 260310A / AT2026fgk: Late-time Chandra Detection
  96. GRB 260714B: GECAM-B observation of a burst
  97. GRB 260618B: EP-FXT follow-up observation upper limit
  98. GRB 260714B: COLIBRÍ optical counterpart candidate
  99. sb26071506: SVOM detection of a X-ray transient
  100. EP260703a: SVOM/ECLAIRs Upper Limit

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