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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"

37950 results found.

  1. GRB 260726A: SVOM/VT optical candidate
  2. GRB 260726A: SVOM ECLAIRs improved position and MXT possible detection of a counterpart
  3. GRB 260727A / SVOM sb26072702: RAPAS optical non-detection
  4. GRB 260727A: GOTO early optical upper limit
  5. GRB 260727A: AstroSat CZTI detection
  6. GRB 260727A: Kilonova-Catcher optical upper limit
  7. GRB 260727A: LCO optical upper limits
  8. GRB 260727B: Fermi GBM Final Real-time Localization
  9. Fermi GRB 260726A: Global MASTER-Net observations report
  10. GRB 260727A: SVOM detection of a bright long burst
  11. GRB 260726A: SVOM detection of a burst
  12. GRB 260726A: Fermi GBM Final Real-time Localization
  13. GRB 260616A: cubesat Avion detection
  14. GRB 260602B: cubesat Avion detection
  15. GRB 260601A: cubesat Avion detection
  16. IPN triangulation of GRB 260706B
  17. GRB 260718A: SVOM/ECLAIRs refined analysis
  18. Fermi Gamma-ray Burst Monitor trigger 806592752 / 260724564 is not a GRB
  19. GRB 260723A: Fermi GBM Final Localization
  20. IceCube-260722A: One candidate from the Zwicky Transient Facility (ZTF)
  21. IceCube Alert 260722A: Global MASTER-Net observations report
  22. Konus-Wind detection of GRB 260721A
  23. GRB 260722A: Fermi GBM Final Real-time Localization
  24. Fermi GBM trigger 806384210/260722151 is not a GRB
  25. GRB 260721A: NuSTAR detection of prompt emission
  26. Konus-Wind detection of GRB 260714B
  27. GRB 260705A: Retraction of optical counterpart
  28. GRB 260714B: Insight-HXMT/HE detection
  29. GRB 260718A: EP-FXT follow-up observation
  30. Fermi trigger No 806104130: Global MASTER-Net observations report
  31. Fermi GRB 260718A: Global MASTER-Net observations report
  32. GRB 260718A: LCO optical upper limits
  33. GRB 260711A: SVOM/GRM observation
  34. GRB 260710A: SVOM/GRM observation
  35. GRB 260718A: Fermi GBM Observation
  36. GRB 260718A : GRANDMA and KNC upper limits
  37. GRB 260718A: SVOM/VT optical upper limits
  38. GRB 260718A: SVOM/VT optical upper limits from VHF data
  39. GRB 260718A: SVOM detection of a burst
  40. GRB 260714B: SVOM/GRM observation
  41. GRB 260310A / AT2026fgk: Late-time Chandra Detection
  42. GRB 260714B: GECAM-B observation of a burst
  43. GRB 260618B: EP-FXT follow-up observation upper limit
  44. GRB 260714B: COLIBRÍ optical counterpart candidate
  45. SVOM sb26071506: Global MASTER-Net observations report
  46. IceCube-260712A: No candidates with the Zwicky Transient Facility (ZTF)
  47. GRB 260715A: Fermi GBM Final Real-time Localization
  48. GRB 260710A: AstroSat CZTI detection
  49. GRB 260709A: AstroSat CZTI detection
  50. GRB 260714B: AstroSat CZTI detection
  51. GRB 260714B: Fermi-LAT detection
  52. GRB 260714B: Fermi GBM Detection
  53. GRB 260714B: BALROG localization (Fermi Trigger 805746211 / GRB 260714766)
  54. GRB 260714B: Fermi GBM Final Real-time Localization
  55. GRB 260706A: ATCA detection of possible radio counterpart
  56. GRB 260705A: ATCA radio observations
  57. GRB 260714A: Fermi GBM Final Real-time Localization
  58. GRB 260619A: SVOM/VT continuous optical observations
  59. GRB 260618B: SVOM/VT optical observations indicate shallow decay and reddening
  60. GRB 260708A: slowly decaying X-ray emission observed by EP/FXT
  61. EP260623a: KAIT optical observations
  62. GRB 260708A: GRANDMA Optical Observations
  63. GRB 260710A: Insight-HXMT/HE detection
  64. GRB 260708A: LCO optical observations
  65. GRB 260710A: Fermi GBM Detection
  66. GRB 260709A: SVOM/GRM detection
  67. GRB 260709A: GECAM-B observation
  68. GRB 260705C: AstroSat CZTI detection
  69. GRB 260710A: Fermi GBM Final Real-time Localization
  70. GRB 260708A: Glowbug gamma-ray detection
  71. GRB 260704A: SVOM/ECLAIRs refined analysis
  72. GRB 260706A : GRANDMA Upper limits
  73. GRB 260708A: Kilonova-Catcher optical afterglow detection
  74. GRB 260708A: GECAM-B observation of a burst
  75. IceCube-260708A: One candidate from the Zwicky Transient Facility
  76. GRB 260708A: Fermi-GBM observation
  77. Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
  78. IceCube Alert 260709A: Global MASTER-Net observations report
  79. GRB 260709A: Fermi GBM Final Real-time Localization
  80. LAT GRB260708.42: Global MASTER-Net observations report
  81. GRB 260708A: Fermi-LAT detection
  82. GRB 260705B: SVOM/GRM observation
  83. GRB 260708A: Fermi-GBM detection
  84. GRB 260706A: Further EP-FXT follow-up observation
  85. GRB 260706A: SVOM/VT optical upper limits
  86. Fermi GBM trigger 805087514/260707142 (GRB 260707A) is not a GRB
  87. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  88. GRB 260705C: Glowbug gamma-ray detection of a short burst
  89. GRB 260706A: SVOM/ECLAIRs refined analysis
  90. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  91. GRB 260706A: SVOM/GRM observation
  92. GRB 260706A: REM optical/NIR observations
  93. IceCube-260704A: No candidates from the Zwicky Transient Facility
  94. GRB 260706A: LCO optical upper limit
  95. GRB 260706A: EP-FXT follow-up observation
  96. GRB 260707A: Fermi GBM Final Real-time Localization
  97. GRB 260706A: Fermi GBM Observation
  98. IPN triangulation of GRB 260627A
  99. GRB 260705A: SVOM/ECLAIRs refined analysis
  100. GRB 260706A: SVOM detection of a burst

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