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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"

5169 results found.

  1. GRB 261017A: Swift-XRT refined Analysis
  2. GRB 261010A: J-band upper limit by the SYSU 80cm infrared telescope
  3. GRB 261010A: Swift-XRT refined Analysis
  4. GRB 261011A: GOTO optical counterpart detection
  5. EP261006a / AT 2026aetp: Luminance-band optical follow-up with small-aperture telescopes
  6. EP261007b: Refined analysis of the EP-WXT and autonomous EP-FXT observations
  7. EP261006a: Swift/XRT detection of the fading X-ray counterpart
  8. EP261006a: Early Optical Observations by WFST
  9. GRB 261007A / EP261007a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm telescope at McDonald Observatory
  10. GRB 261007A: Autonomous identification and follow-up of the counterpart to GRB 261007A by BTSbot with ZTF and P60/SEDM
  11. SVOM GRB261007.23: Global MASTER-Net observations report
  12. EP261006a: LT and NOT discovery of an optical counterpart
  13. GRB 260924A: Upper limits from a neutrino search with IceCube
  14. Fermi GRB 260926C: Global MASTER-Net observations report
  15. Fermi GRB 260926A: Global MASTER-Net observations report
  16. GRB 260925A: Swift-XRT refined Analysis
  17. EP260924a: EP-FXT follow-up observation
  18. GRB 260924A: J-band observations by the SYSU 80 cm infrared telescope
  19. GRB 260924A: GROWTH-India Telescope optical observations
  20. GRB 260924A: Swift-XRT refined Analysis
  21. GRB 260922A: COLIBRÍ Confirmation of the Optical Counterpart
  22. GRB 260924A: Fermi GRB Observation
  23. GRB 260924A: AstroSat CZTI detection
  24. GRB 260924A: NOT optical counterpart confirmation
  25. GRB 260924A: detection of a bright optical afterglow by the 1.5m OSN telescope
  26. GRB 260924A: Fermi GBM Final Real-time Localization
  27. Fermi GRB 260923A: Global MASTER-Net observations report
  28. GRB 260922A: Ondrejov D50 optical limit
  29. GRB 260922A: Swift-XRT refined Analysis
  30. EP260920b: SVOM/VT optical observation
  31. EP Alert 260921.01: Global MASTER-Net observations report
  32. GRB 260920A: Fermi GBM Final Real-time Localization
  33. EP260917a: Global MASTER-Net observations report
  34. IceCube Alert 260919A: Global MASTER-Net observations report
  35. IPN triangulation of GRB 260810A
  36. EP260917a: COLIBRÍ optical upper limits
  37. GRB 260917A: Glowbug gamma-ray detection
  38. GRB 260915A: SVOM/ECLAIRs refined analysis
  39. GRB 260917B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  40. GRB 260917A: BALROG localization (Fermi Trigger 811304653 / GRB 260917100)
  41. GRB 260917A: Fermi GBM Final Real-time Localization
  42. Fermi trigger No 811304653: Global MASTER-Net observations report
  43. GRB 260909A: NOEMA detection
  44. EP Alert 260914.53: Global MASTER-Net observations report
  45. EP Alert 260909.53: Global MASTER-Net observations report
  46. GRB 260909A: Mondy optical observations and afterglow candidate
  47. The EP-WXT trigger 01709306297 is likely the known LMXB 4U 1745-203
  48. Fermi GRB 260907B: Global MASTER-Net observations report
  49. EP Alert 260903.62: Global MASTER-Net observations report
  50. SVOM GRB260903A: Global MASTER-Net observations report
  51. Konus-Wind detection of GRB 260829A
  52. EP260901a: Global MASTER-Net observations report
  53. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  54. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  55. MAXI GRB260827.40: Global MASTER-Net observations report
  56. The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
  57. EP260822a: Global MASTER-Net observations report
  58. GRB 260809A: SVOM/ECLAIRs refined analysis
  59. IceCube Alert 260825A: Global MASTER-Net observations report
  60. IceCube-Cascade 260824A: Upper limits from a search for additional neutrino events in IceCube
  61. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  62. GRB 260820A: Insight-HXMT/HE detection
  63. GRB260820A: Fermi GBM Final Real-Time Localization
  64. GRB 260818B: NOT optical upper limits
  65. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  66. GRB 260808B: SVOM/VT optical afterglow confirmation
  67. GRB 260808C: Fermi GBM Final Real-time Localization
  68. EP260806a: Liverpool Telescope observations of the counterpart show a blue colour
  69. SN 2026stf / GRB 260708A: ATLAS forced photometry
  70. Fermi GRB 260802B: Global MASTER-Net observations report
  71. EP260731a: Einstein Probe detection of an X-ray transient
  72. GRB260730A: Fermi GBM Final Localization
  73. EP260728a: COLIBRÍ optical upper limit
  74. Fermi GRB 260726A: Global MASTER-Net observations report
  75. IceCube-260722A: Classification of ZTF26abjbxfs/SN 2026vts as a Type Ia Supernova
  76. GRB 260602B: cubesat Avion detection
  77. EP260723a: EP-FXT follow-up observation
  78. IPN triangulation of GRB 260706B
  79. Fermi Gamma-ray Burst Monitor trigger 806592752 / 260724564 is not a GRB
  80. EP260723a: Liverpool Telescope likely optical counterpart
  81. Fermi trigger No 806104130: Global MASTER-Net observations report
  82. IceCube Alert 260709A: Global MASTER-Net observations report
  83. GRB 260705B: SVOM/GRM observation
  84. EP260707a: Einstein Probe detection of an X-ray transient
  85. GRB 260706A: SVOM/ECLAIRs refined analysis
  86. GRB 260704A: SVOM detection of a possible GRB
  87. Fermi GRB 260703A: Global MASTER-Net observations report
  88. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  89. Fermi trigger No 804552016: Global MASTER-Net observations report
  90. GRB 260628A: Fermi GBM Final Real-time Localization
  91. EP260626a: Liverpool Telescope upper limits
  92. EP260623a: Liverpool Telescope optical observations
  93. Fermi GBM trigger 804010507/260624677 is not a GRB
  94. GRB 260624A: Fermi GBM Final Real-time Localization
  95. EP260623a: FRAM-ORM detection of the optical afterglow rise, peak and decay
  96. GRB 260623A: Fermi GBM Final Real-time Localization
  97. The EP-WXT trigger 01709271197 is likely a flaring star
  98. GRB 260604A: 239Alferov CubeSat detection
  99. GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection
  100. GRB 260429A: cubesat Avion detection

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