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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"

38582 results found.

  1. GRB 260421B: LCO optical afterglow confirmation
  2. GRB 260421B: SVOM/COLIBRÍ (FM-GFT) optical detection of a candidate counterpart
  3. GRB 260421B: TRT optical counterpart detection
  4. GRB 260421B: SVOM detection of a long burst
  5. GRB 260421B: BALROG localization (Fermi Trigger 798437606 / GRB 260421176)
  6. GRB 260421B: Fermi GBM Final Real-time Localization
  7. GRB 260421A: Fermi GBM Final Real-time Localization
  8. GRB 260412A: LCOGT Optical Upper Limits
  9. The EP-WXT trigger 01709260314 is likely a flaring star
  10. EP260416a: Optical follow-up observations with Kinder
  11. GOTO26djh/AT2026jpw: CrAO and Mondy optical observations of the transient
  12. EP-WXT trigger 01709260303: KAIT optical observations
  13. EP260416a: 1.5m OSN and 2.2m CAHA optical monitoring
  14. The EP-WXT trigger 01709260303 is likely a flaring star
  15. GRB 260417A: SVOM/GRM observation
  16. EP260321A/AT2026gzf: Optical observation from 1.3m DFOT
  17. GRB 260419B: Fermi GBM Final Real-time Localization
  18. GRB 260419A: Fermi GBM Final Real-time Localization
  19. EP260417a: GROWTH-India Telescope optical upper limit
  20. EP260417b: GROWTH-India Telescope optical upper limit
  21. EP260416a: Ondrejov D50 optical detection
  22. GRB 260418B: Fermi GBM Final Real-time Localization
  23. EP260416a: VLT/FORS2 spectroscopic redshift confirmation
  24. EP260417a/GRB 260417A: refined analysis of the EP-WXT and follow-up EP-FXT observations
  25. EP260416a: NOT tentative spectroscopic redshift of z =1.909
  26. GRB 260418A: Fermi GBM Final Real-time Localization
  27. EP260416a: GMG Optical Observation
  28. Konus-Wind detection of GRB 260411B
  29. GRB 260417B: Fermi GBM Final Real-time Localization
  30. GRB 260417A: AstroSat CZTI detection
  31. IPN triangulation of GRB 260411B
  32. EP260416a: LCO observations confirm end of flaring phase
  33. EP260324a / AT2026hir: Further multiband optical follow-up with the PKU 60cm Telescope
  34. EP260417a: Einstein Probe detection of an X-ray transient
  35. EP260416a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  36. EP260417b: Einstein Probe detection of a fast X-ray transient
  37. EP-WXT trigger 01709259586: KAIT optical observations
  38. EP260416a: KAIT optical upper limit
  39. GRB 260414A: Insight-HXMT/HE detection
  40. EP260416a: COLIBRÍ confirmation of the optical rebrightening
  41. EP260416a: WFST optical observations and rebrightening
  42. GRB 260417A: Fermi GBM Final Real-time Localization
  43. GOTO26djh/AT2026jpw: ZTSh R,I bands observations of the transient
  44. EP260416a: SVOM/VT optical observation
  45. GOTO26djh/AT2026jpw: SVOM/VT optical observation
  46. GRB 260415B: Glowbug gamma-ray detection
  47. GRB 260411B: Glowbug gamma-ray detection
  48. GRB 260415A: Insight-HXMT/HE detection
  49. EP260416a: COLIBRÍ optical counterpart candidate
  50. COLIBRI optical observations of the transient GOTO26djh/AT2026jpw
  51. EP260416a: Einstein Probe detection of an X-ray transient
  52. GOTO26djh/AT2026jpw : MASTER OT observation
  53. GOTO26djh/AT2026jpw: EP-FXT X-ray counterpart detection
  54. GOTO26djh/AT2026jpw transient: SAO RAS optical observations
  55. NOT r-band observations of the transient GOTO26djh/AT2026jpw
  56. GRB 260415B: NuSTAR detection of long prompt emission
  57. GOTO discovery of fast-fading transient GOTO26djh/AT2026jpw, a candidate orphan afterglow
  58. GRB 260415B: Fermi GBM Final Localization
  59. GRB 260415A: Fermi GBM Final Real-time Localization
  60. GRB 260414A: Glowbug gamma-ray detection
  61. EP260409a: Early NIR limits from MIRAGE on the MDM 1.3m telescope
  62. EP260321a: CMO SAI J,K observations
  63. GRB 260412A: Insight-HXMT/HE detection
  64. GRB 260414A: Fermi GBM Final Real-time Localization
  65. The EP-WXT trigger 01709260122 is likely a flaring star
  66. GRB 260410A: Glowbug gamma-ray detection of a short burst
  67. GRB 260413A: Fermi GBM Final Real-time Localization
  68. GRB 260410B: Insight-HXMT/HE detection
  69. GRB 260410A: Insight-HXMT/HE detection
  70. Konus-Wind detection of GRB 260410A (short/hard)
  71. GRB 260411B: GECAM-B observation of a long burst
  72. EP260321a: SVOM/VT optical observations and color changes around peak
  73. GRB 260410A: CALET Gamma-Ray Burst Monitor detection
  74. The EP-WXT trigger 01709260010 is likely a flaring star
  75. GRB 260412A: GECAM-B observation of a long burst
  76. GRB 260412A: Fermi GBM Observation
  77. GRB 260411B: Fermi-LAT detection
  78. GRB 260412A: SVOM detection of a long burst
  79. GRB 260412A: Fermi GBM Final Real-time Localization
  80. GRB 260411B: COLIBRÍ optical observations
  81. GRB 260410B: Fermi GBM Observation
  82. GRB260411B: 3.6m DOT optical observation
  83. GRB 260411A: SVOM/GRM observation
  84. GRB 260407B: SVOM/GRM detection of a possible magnetar X-ray burst
  85. GRB 260411B: SVOM/GRM observation of a long burst
  86. GRB 260409A: Insight-HXMT/HE detection
  87. GRB 260411B: Fermi GBM Detection
  88. GRB 260411B: GOTO optical counterpart candidate
  89. EP260409a: Gemini/FLAMINGOS2 J-band counterpart
  90. GRB 260411B: BALROG localization (Fermi Trigger 797587480 / GRB 260411337)
  91. GRB 260411B: Fermi GBM Final Real-time Localization
  92. GRB 260411A: Fermi GBM Final Real-time Localization
  93. GRB 260410A: COLIBRÍ optical upper limit
  94. EP-WXT01709259790: Optical Upper limits with kinder observations
  95. GRB 260410A: Fermi GBM Observation
  96. GRB 260410B: SVOM/GRM detection of a short faint burst
  97. The EP-WXT trigger 01709259790 is likely a flaring star
  98. GRB 260410B: Fermi GBM Final Real-time Localization
  99. EP-WXT01709259790: Xinglong optical upper limit
  100. GRB 260410A: Fermi-LAT detection

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