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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

36127 results found.

  1. GRB 260730B: CALET Gamma-Ray Burst Monitor detection
  2. GRB 260708A / SN 2026stf: Spectroscopic host redshift z = 0.055 and confirmation of an associated type Ic-BL supernova
  3. GRB 260804A: Fermi GBM Final Real-time Localization
  4. GRB 260708A: LCO further optical observations show supernova features
  5. GRB 260803A: Fermi GBM Final Real-time Localization
  6. Fermi GRB 260802B: Global MASTER-Net observations report
  7. GRB 260802A / EP J223759.5+521421: EP-FXT follow-up observation
  8. GRB 260802A / EP J223759.5+531421: SVOM/VT optical upper limit
  9. GRB 260802A: SVOM/VT optical upper limits from VHF data
  10. GRB 260802A: LCO optical upper limits
  11. GRB 260802B: Fermi GBM Final Localization
  12. GRB 260802A / EP J223759.5+531421: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  13. GRB 260802A/EP J223759.5+531421: SVOM detection of a possible magnetar burst
  14. GRB 260727A: EP-FXT further follow-up observations and candidate afterglow
  15. GRB 260618B: SVOM/VT continued optical observations indicated a steeper and redder decay
  16. GRB 260731A: AstroSat CZTI detection of a long burst
  17. GRB 260730B: AstroSat CZTI detection
  18. GRB 260730B: NuSTAR detection of prompt emission
  19. GRB 260727A: SVOM/ECLAIRs refined analysis
  20. GRB 260726A: SVOM/ECLAIRs refined analysis
  21. GRB260730A: Fermi GBM Final Localization
  22. EP260727a: SAO RAS optical observations
  23. GRB 260727A: AbAO and SAO RAS optical observations
  24. GRB 260726A: EP-FXT follow-up observations
  25. GRB 260727A: SVOM/GRM observation
  26. GRB 260726A: Fermi GBM Observation
  27. Konus-Wind detection of GRB 260727A
  28. GRB 260726A: Liverpool Telescope optical observations
  29. GRB 260727A: Liverpool Telescope optical upper limits
  30. GRB 260728A: Fermi GBM Final Localization
  31. GRB 260727A: EP/FXT follow-up observations
  32. GRB 260727A: Glowbug gamma-ray detection
  33. GRB 260726A: J-band upper limit with WINTER
  34. GRB 260727A: J-band upper limit with WINTER
  35. GRB 260726A: SVOM/VT optical candidate
  36. GRB 260726A: SVOM ECLAIRs improved position and MXT possible detection of a counterpart
  37. GRB 260727A / SVOM sb26072702: RAPAS optical non-detection
  38. GRB 260727A: GOTO early optical upper limit
  39. GRB 260727A: AstroSat CZTI detection
  40. GRB 260727A: Kilonova-Catcher optical upper limit
  41. GRB 260727A: LCO optical upper limits
  42. GRB 260727B: Fermi GBM Final Real-time Localization
  43. Fermi GRB 260726A: Global MASTER-Net observations report
  44. GRB 260727A: SVOM detection of a bright long burst
  45. GRB 260726A: SVOM detection of a burst
  46. GRB 260726A: Fermi GBM Final Real-time Localization
  47. GRB 260616A: cubesat Avion detection
  48. GRB 260602B: cubesat Avion detection
  49. GRB 260601A: cubesat Avion detection
  50. IPN triangulation of GRB 260706B
  51. GRB 260718A: SVOM/ECLAIRs refined analysis
  52. Fermi Gamma-ray Burst Monitor trigger 806592752 / 260724564 is not a GRB
  53. GRB 260723A: Fermi GBM Final Localization
  54. Konus-Wind detection of GRB 260721A
  55. GRB 260722A: Fermi GBM Final Real-time Localization
  56. Fermi GBM trigger 806384210/260722151 is not a GRB
  57. GRB 260721A: NuSTAR detection of prompt emission
  58. Konus-Wind detection of GRB 260714B
  59. GRB 260705A: Retraction of optical counterpart
  60. GRB 260714B: Insight-HXMT/HE detection
  61. GRB 260718A: EP-FXT follow-up observation
  62. Fermi GRB 260718A: Global MASTER-Net observations report
  63. GRB 260718A: LCO optical upper limits
  64. GRB 260711A: SVOM/GRM observation
  65. GRB 260710A: SVOM/GRM observation
  66. GRB 260718A: Fermi GBM Observation
  67. GRB 260718A : GRANDMA and KNC upper limits
  68. GRB 260718A: SVOM/VT optical upper limits
  69. GRB 260718A: SVOM/VT optical upper limits from VHF data
  70. GRB 260718A: SVOM detection of a burst
  71. GRB 260714B: SVOM/GRM observation
  72. GRB 260310A / AT2026fgk: Late-time Chandra Detection
  73. GRB 260714B: GECAM-B observation of a burst
  74. GRB 260618B: EP-FXT follow-up observation upper limit
  75. GRB 260714B: COLIBRÍ optical counterpart candidate
  76. GRB 260715A: Fermi GBM Final Real-time Localization
  77. GRB 260710A: AstroSat CZTI detection
  78. GRB 260709A: AstroSat CZTI detection
  79. GRB 260714B: AstroSat CZTI detection
  80. GRB 260714B: Fermi-LAT detection
  81. GRB 260714B: Fermi GBM Detection
  82. GRB 260714B: BALROG localization (Fermi Trigger 805746211 / GRB 260714766)
  83. GRB 260714B: Fermi GBM Final Real-time Localization
  84. GRB 260706A: ATCA detection of possible radio counterpart
  85. GRB 260705A: ATCA radio observations
  86. GRB 260714A: Fermi GBM Final Real-time Localization
  87. GRB 260619A: SVOM/VT continuous optical observations
  88. GRB 260618B: SVOM/VT optical observations indicate shallow decay and reddening
  89. GRB 260708A: slowly decaying X-ray emission observed by EP/FXT
  90. EP260623a: KAIT optical observations
  91. GRB 260708A: GRANDMA Optical Observations
  92. GRB 260710A: Insight-HXMT/HE detection
  93. GRB 260708A: LCO optical observations
  94. GRB 260710A: Fermi GBM Detection
  95. GRB 260709A: SVOM/GRM detection
  96. GRB 260709A: GECAM-B observation
  97. GRB 260705C: AstroSat CZTI detection
  98. GRB 260710A: Fermi GBM Final Real-time Localization
  99. GRB 260708A: Glowbug gamma-ray detection
  100. GRB 260704A: SVOM/ECLAIRs refined analysis

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