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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"

5173 results found.

  1. EP261015a: AZT-20 Assy-Turgen optical observations
  2. EP261015a: Terskol Zeiss-2000 optical upper limit
  3. GRB 261020A: MAXI GSC detection
  4. GRB 261019A: Fermi GBM Final Localization
  5. GRB 261017A: Swift-XRT refined Analysis
  6. GRB 261010A: J-band upper limit by the SYSU 80cm infrared telescope
  7. GRB 261010A: Swift-XRT refined Analysis
  8. GRB 261011A: GOTO optical counterpart detection
  9. EP261006a / AT 2026aetp: Luminance-band optical follow-up with small-aperture telescopes
  10. EP261007b: Refined analysis of the EP-WXT and autonomous EP-FXT observations
  11. EP261006a: Swift/XRT detection of the fading X-ray counterpart
  12. EP261006a: Early Optical Observations by WFST
  13. GRB 261007A / EP261007a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm telescope at McDonald Observatory
  14. GRB 261007A: Autonomous identification and follow-up of the counterpart to GRB 261007A by BTSbot with ZTF and P60/SEDM
  15. SVOM GRB261007.23: Global MASTER-Net observations report
  16. EP261006a: LT and NOT discovery of an optical counterpart
  17. GRB 260924A: Upper limits from a neutrino search with IceCube
  18. Fermi GRB 260926C: Global MASTER-Net observations report
  19. Fermi GRB 260926A: Global MASTER-Net observations report
  20. GRB 260925A: Swift-XRT refined Analysis
  21. EP260924a: EP-FXT follow-up observation
  22. GRB 260924A: J-band observations by the SYSU 80 cm infrared telescope
  23. GRB 260924A: GROWTH-India Telescope optical observations
  24. GRB 260924A: Swift-XRT refined Analysis
  25. GRB 260922A: COLIBRÍ Confirmation of the Optical Counterpart
  26. GRB 260924A: Fermi GRB Observation
  27. GRB 260924A: AstroSat CZTI detection
  28. GRB 260924A: NOT optical counterpart confirmation
  29. GRB 260924A: detection of a bright optical afterglow by the 1.5m OSN telescope
  30. GRB 260924A: Fermi GBM Final Real-time Localization
  31. Fermi GRB 260923A: Global MASTER-Net observations report
  32. GRB 260922A: Ondrejov D50 optical limit
  33. GRB 260922A: Swift-XRT refined Analysis
  34. EP260920b: SVOM/VT optical observation
  35. EP Alert 260921.01: Global MASTER-Net observations report
  36. GRB 260920A: Fermi GBM Final Real-time Localization
  37. EP260917a: Global MASTER-Net observations report
  38. IceCube Alert 260919A: Global MASTER-Net observations report
  39. IPN triangulation of GRB 260810A
  40. EP260917a: COLIBRÍ optical upper limits
  41. GRB 260917A: Glowbug gamma-ray detection
  42. GRB 260915A: SVOM/ECLAIRs refined analysis
  43. GRB 260917B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  44. GRB 260917A: BALROG localization (Fermi Trigger 811304653 / GRB 260917100)
  45. GRB 260917A: Fermi GBM Final Real-time Localization
  46. Fermi trigger No 811304653: Global MASTER-Net observations report
  47. GRB 260909A: NOEMA detection
  48. EP Alert 260914.53: Global MASTER-Net observations report
  49. EP Alert 260909.53: Global MASTER-Net observations report
  50. GRB 260909A: Mondy optical observations and afterglow candidate
  51. The EP-WXT trigger 01709306297 is likely the known LMXB 4U 1745-203
  52. Fermi GRB 260907B: Global MASTER-Net observations report
  53. EP Alert 260903.62: Global MASTER-Net observations report
  54. SVOM GRB260903A: Global MASTER-Net observations report
  55. Konus-Wind detection of GRB 260829A
  56. EP260901a: Global MASTER-Net observations report
  57. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  58. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  59. MAXI GRB260827.40: Global MASTER-Net observations report
  60. The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
  61. EP260822a: Global MASTER-Net observations report
  62. GRB 260809A: SVOM/ECLAIRs refined analysis
  63. IceCube Alert 260825A: Global MASTER-Net observations report
  64. IceCube-Cascade 260824A: Upper limits from a search for additional neutrino events in IceCube
  65. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  66. GRB 260820A: Insight-HXMT/HE detection
  67. GRB260820A: Fermi GBM Final Real-Time Localization
  68. GRB 260818B: NOT optical upper limits
  69. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  70. GRB 260808B: SVOM/VT optical afterglow confirmation
  71. GRB 260808C: Fermi GBM Final Real-time Localization
  72. EP260806a: Liverpool Telescope observations of the counterpart show a blue colour
  73. SN 2026stf / GRB 260708A: ATLAS forced photometry
  74. Fermi GRB 260802B: Global MASTER-Net observations report
  75. EP260731a: Einstein Probe detection of an X-ray transient
  76. GRB260730A: Fermi GBM Final Localization
  77. EP260728a: COLIBRÍ optical upper limit
  78. Fermi GRB 260726A: Global MASTER-Net observations report
  79. IceCube-260722A: Classification of ZTF26abjbxfs/SN 2026vts as a Type Ia Supernova
  80. GRB 260602B: cubesat Avion detection
  81. EP260723a: EP-FXT follow-up observation
  82. IPN triangulation of GRB 260706B
  83. Fermi Gamma-ray Burst Monitor trigger 806592752 / 260724564 is not a GRB
  84. EP260723a: Liverpool Telescope likely optical counterpart
  85. Fermi trigger No 806104130: Global MASTER-Net observations report
  86. IceCube Alert 260709A: Global MASTER-Net observations report
  87. GRB 260705B: SVOM/GRM observation
  88. EP260707a: Einstein Probe detection of an X-ray transient
  89. GRB 260706A: SVOM/ECLAIRs refined analysis
  90. GRB 260704A: SVOM detection of a possible GRB
  91. Fermi GRB 260703A: Global MASTER-Net observations report
  92. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  93. Fermi trigger No 804552016: Global MASTER-Net observations report
  94. GRB 260628A: Fermi GBM Final Real-time Localization
  95. EP260626a: Liverpool Telescope upper limits
  96. EP260623a: Liverpool Telescope optical observations
  97. Fermi GBM trigger 804010507/260624677 is not a GRB
  98. GRB 260624A: Fermi GBM Final Real-time Localization
  99. EP260623a: FRAM-ORM detection of the optical afterglow rise, peak and decay
  100. GRB 260623A: Fermi GBM Final Real-time Localization

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