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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"

23573 results found.

  1. GRB 260910B: GOTO tentative optical counterpart candidates
  2. GRB 260909A: KAIT optical upper limit
  3. GRB 260903A: Swift-XRT observations
  4. EP260806a: VLA+ALMA radio detections
  5. GRB 260909A: OHP/T193 z-band upper limit
  6. EP Alert 260909.53: Global MASTER-Net observations report
  7. GRB 260909A: EP-FXT follow-up observation
  8. EP260806a: NOEMA detection
  9. EP260623a: NOEMA detections
  10. The EP-WXT trigger 01709306297 is likely the known LMXB 4U 1745-203
  11. Fermi trigger No 810554827: Global MASTER-Net observations report
  12. EP Alert 260908.60: Global MASTER-Net observations report
  13. GRB 260907A: Glowbug gamma-ray detection of a likely short burst
  14. Fermi GRB 260907B: Global MASTER-Net observations report
  15. Fermi GRB 260907A: Global MASTER-Net observations report
  16. EP260903a: EP-FXT follow-up observation
  17. EP Alert 260905.11: Global MASTER-Net observations report
  18. GRB 260903A: J-band upper limit with WINTER
  19. EP Alert 260903.47: Global MASTER-Net observations report
  20. GRB 260903A: SVOM/ECLAIRs refined analysis
  21. GRB 260903A: SAO RAS optical observations
  22. EP260903a: EP-WXT detection of a fast X-ray transient
  23. EP Alert 260903.62: Global MASTER-Net observations report
  24. GRB 260903A: EP-FXT follow-up observation
  25. NuSTAR Transient 260828: SOAR Optical Upper Limits
  26. SVOM GRB260903A: Global MASTER-Net observations report
  27. GRB 260903A: LCO optical observations
  28. GRB 260903A: SVOM detection of a soft faint burst
  29. Konus-Wind detection of GRB 260829A
  30. EP260901a: Global MASTER-Net observations report
  31. NuSTAR Transient 260828: LCO Optical Upper Limits
  32. GRB 260829A: AstroSat CZTI detection
  33. EP260830a: Global MASTER-Net observations report
  34. IPN triangulation of GRB 260829A
  35. GRB 260827A: Glowbug gamma-ray detection
  36. EP260727a: ATCA 10 GHz detection
  37. GRB 260825A: AstroSat CZTI detection
  38. GRB 260818B: Further EP-FXT observation
  39. GRB 260818B: TNG NIR observations
  40. MAXI GRB260827.40: Global MASTER-Net observations report
  41. GRB 260818B: 6 GHz VLA observations
  42. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  43. EP260822a: Global MASTER-Net observations report
  44. EP Alert 260820.31: Global MASTER-Net observations report
  45. GRB 260809A: SVOM/ECLAIRs refined analysis
  46. IceCube Alert 260825A: Global MASTER-Net observations report
  47. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  48. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  49. GRB 260822A: Retraction of GOTO optical counterpart detection GCN 45431
  50. GRB 260822A: GOTO optical counterpart detection
  51. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  52. GRB 260822A: GOTO optical upper limit
  53. GRB 260818B: VLA radio observations
  54. IceCube Alert 260821A: Global MASTER-Net observations report
  55. The EP-WXT trigger 01709286204 is likely a flaring star
  56. GRB 260818B: SVOM/GRM observation
  57. GRB 260818A: J-band observations with WINTER
  58. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  59. EP260806a: SAO RAS multicolor optical observations
  60. EP260812a: AbAO optical upper limit
  61. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  62. EP260806a: NUTTELA-TAO optical observations
  63. The EP-WXT trigger 01709281429 is likely a flaring star
  64. EP260812a: AZT-22 optical upper limit
  65. EP260812b: GTC/OSIRIS+ tentative spectroscopic redshift z = 2.034
  66. EP260812b: Optical upper limit with Kinder
  67. GRB 260808B: GTC/OSIRIS+ spectroscopic redshift z = 1.295
  68. EP260812b: GOTO detection of the optical counterpart
  69. GRB 260810A: Glowbug gamma-ray detection
  70. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
  71. GRB 260809A: SAO RAS optical observations
  72. GRB 260808B: SAO RAS optical observations
  73. GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
  74. GRB 260806A: CALET Gamma-Ray Burst Monitor detection
  75. GRB 260807A: SVOM/ECLAIRs refined analysis
  76. EP260806a: MAO/AZT-22 optical observations
  77. GRB260808B: MAO/AZT-22 optical observations
  78. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
  79. GRB 260809A: J-band upper limit with WINTER
  80. GRB 260806A: Glowbug gamma-ray detection
  81. GRB 260808A: CALET Gamma-Ray Burst Monitor detection
  82. GRB 260805C: CALET Gamma-Ray Burst Monitor detection
  83. GRB 260804A: CALET Gamma-Ray Burst Monitor detection
  84. GRB 260809A: SVOM/COLIBRÍ (FM-GFT) optical observation
  85. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) optical observation
  86. GRB260809A: MAO/AZT-22 optical observations
  87. EP260809a: J-band upper limit with WINTER
  88. GRB 260808B: J-band upper limit with WINTER
  89. GRB 260808B: SVOM/ECLAIRs refined analysis
  90. GRB 260809A: SVOM detection of a faint burst
  91. GRB 260808B: LCO optical observations
  92. EP260809a: COLIBRÍ optical observations
  93. GRB 260808B: SVOM/VT optical afterglow confirmation
  94. GRB 260808B: SVOM/VT optical candidate from VHF data ( localization correction for GCN 45317 )
  95. GRB 260808B: SVOM/VT optical candidate from VHF data
  96. Fermi GRB 260808A: Global MASTER-Net observations report
  97. IceCube Alert 260807A: Global MASTER-Net observations report
  98. IceCube-260805A: One candidate from the Zwicky Transient Facility
  99. GRB 260807A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  100. EP260806a: COLIBRÍ optical observations

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