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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"

23572 results found.

  1. GRB 260909A: KAIT optical upper limit
  2. GRB 260903A: Swift-XRT observations
  3. EP260806a: VLA+ALMA radio detections
  4. GRB 260909A: OHP/T193 z-band upper limit
  5. EP Alert 260909.53: Global MASTER-Net observations report
  6. GRB 260909A: EP-FXT follow-up observation
  7. EP260806a: NOEMA detection
  8. EP260623a: NOEMA detections
  9. The EP-WXT trigger 01709306297 is likely the known LMXB 4U 1745-203
  10. Fermi trigger No 810554827: Global MASTER-Net observations report
  11. EP Alert 260908.60: Global MASTER-Net observations report
  12. GRB 260907A: Glowbug gamma-ray detection of a likely short burst
  13. Fermi GRB 260907B: Global MASTER-Net observations report
  14. Fermi GRB 260907A: Global MASTER-Net observations report
  15. EP260903a: EP-FXT follow-up observation
  16. EP Alert 260905.11: Global MASTER-Net observations report
  17. GRB 260903A: J-band upper limit with WINTER
  18. EP Alert 260903.47: Global MASTER-Net observations report
  19. GRB 260903A: SVOM/ECLAIRs refined analysis
  20. GRB 260903A: SAO RAS optical observations
  21. EP260903a: EP-WXT detection of a fast X-ray transient
  22. EP Alert 260903.62: Global MASTER-Net observations report
  23. GRB 260903A: EP-FXT follow-up observation
  24. NuSTAR Transient 260828: SOAR Optical Upper Limits
  25. SVOM GRB260903A: Global MASTER-Net observations report
  26. GRB 260903A: LCO optical observations
  27. GRB 260903A: SVOM detection of a soft faint burst
  28. Konus-Wind detection of GRB 260829A
  29. EP260901a: Global MASTER-Net observations report
  30. NuSTAR Transient 260828: LCO Optical Upper Limits
  31. GRB 260829A: AstroSat CZTI detection
  32. EP260830a: Global MASTER-Net observations report
  33. IPN triangulation of GRB 260829A
  34. GRB 260827A: Glowbug gamma-ray detection
  35. EP260727a: ATCA 10 GHz detection
  36. GRB 260825A: AstroSat CZTI detection
  37. GRB 260818B: Further EP-FXT observation
  38. GRB 260818B: TNG NIR observations
  39. MAXI GRB260827.40: Global MASTER-Net observations report
  40. GRB 260818B: 6 GHz VLA observations
  41. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  42. EP260822a: Global MASTER-Net observations report
  43. EP Alert 260820.31: Global MASTER-Net observations report
  44. GRB 260809A: SVOM/ECLAIRs refined analysis
  45. IceCube Alert 260825A: Global MASTER-Net observations report
  46. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  47. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  48. GRB 260822A: Retraction of GOTO optical counterpart detection GCN 45431
  49. GRB 260822A: GOTO optical counterpart detection
  50. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  51. GRB 260822A: GOTO optical upper limit
  52. GRB 260818B: VLA radio observations
  53. IceCube Alert 260821A: Global MASTER-Net observations report
  54. The EP-WXT trigger 01709286204 is likely a flaring star
  55. GRB 260818B: SVOM/GRM observation
  56. GRB 260818A: J-band observations with WINTER
  57. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  58. EP260806a: SAO RAS multicolor optical observations
  59. EP260812a: AbAO optical upper limit
  60. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  61. EP260806a: NUTTELA-TAO optical observations
  62. The EP-WXT trigger 01709281429 is likely a flaring star
  63. EP260812a: AZT-22 optical upper limit
  64. EP260812b: GTC/OSIRIS+ tentative spectroscopic redshift z = 2.034
  65. EP260812b: Optical upper limit with Kinder
  66. GRB 260808B: GTC/OSIRIS+ spectroscopic redshift z = 1.295
  67. EP260812b: GOTO detection of the optical counterpart
  68. GRB 260810A: Glowbug gamma-ray detection
  69. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
  70. GRB 260809A: SAO RAS optical observations
  71. GRB 260808B: SAO RAS optical observations
  72. GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
  73. GRB 260806A: CALET Gamma-Ray Burst Monitor detection
  74. GRB 260807A: SVOM/ECLAIRs refined analysis
  75. EP260806a: MAO/AZT-22 optical observations
  76. GRB260808B: MAO/AZT-22 optical observations
  77. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
  78. GRB 260809A: J-band upper limit with WINTER
  79. GRB 260806A: Glowbug gamma-ray detection
  80. GRB 260808A: CALET Gamma-Ray Burst Monitor detection
  81. GRB 260805C: CALET Gamma-Ray Burst Monitor detection
  82. GRB 260804A: CALET Gamma-Ray Burst Monitor detection
  83. GRB 260809A: SVOM/COLIBRÍ (FM-GFT) optical observation
  84. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) optical observation
  85. GRB260809A: MAO/AZT-22 optical observations
  86. EP260809a: J-band upper limit with WINTER
  87. GRB 260808B: J-band upper limit with WINTER
  88. GRB 260808B: SVOM/ECLAIRs refined analysis
  89. GRB 260809A: SVOM detection of a faint burst
  90. GRB 260808B: LCO optical observations
  91. EP260809a: COLIBRÍ optical observations
  92. GRB 260808B: SVOM/VT optical afterglow confirmation
  93. GRB 260808B: SVOM/VT optical candidate from VHF data ( localization correction for GCN 45317 )
  94. GRB 260808B: SVOM/VT optical candidate from VHF data
  95. Fermi GRB 260808A: Global MASTER-Net observations report
  96. IceCube Alert 260807A: Global MASTER-Net observations report
  97. IceCube-260805A: One candidate from the Zwicky Transient Facility
  98. GRB 260807A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  99. EP260806a: COLIBRÍ optical observations
  100. EP260806a: OSIRIS+/GTC redshift z=0.089

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