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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"

26922 results found.

  1. EP260901a: Global MASTER-Net observations report
  2. GRB 260831B / sb26083106: SVOM/GWAC-F60A/B confirmation of optical variation of nova V* GK Per
  3. GRB 260831B / sb26083106: SVOM/VT optical variability of V* GK Per
  4. EP260901a: EP-WXT detection of a fast X-ray transient
  5. SVOM trigger sb26083106 is not a GRB
  6. GRB 260831B: EP-FXT follow-up observation
  7. GRB 260831B: LCO optical upper limits
  8. EP260830a: Global MASTER-Net observations report
  9. EP260830a: EP-WXT detection of a fast X-ray transient
  10. GRB 260827A: SVOM/GRM observation
  11. GRB 260831B: SVOM detection of a possible burst
  12. IPN triangulation of GRB 260829A
  13. EP260727a: ATCA 10 GHz detection
  14. GRB 260831A: Fermi GBM Final Real-time Localization
  15. GRB 260829A: GECAM-B observation of a long burst
  16. GRB 260825A: SVOM/GRM observation of a long burst
  17. GRB 260825A: GECAM-B observation
  18. GRB 260829A: Fermi GBM Detection
  19. GRB 260829A: BALROG localization (Fermi Trigger 809676494 / GRB 260829256)
  20. GRB 260829A: Fermi GBM Final Real-time Localization
  21. Fermi GBM trigger 809666623/260829141 is not a GRB
  22. GRB 260818B: Further EP-FXT observation
  23. GRB 260818B: VLT optical and nIR observations
  24. GRB 260818B: TNG NIR observations
  25. MAXI GRB260827.40: Global MASTER-Net observations report
  26. The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
  27. GRB 260827A: Fermi GBM Final Real-time Localization
  28. GRB 260818B: 6 GHz VLA observations
  29. GRB 260818B: SVOM/VT optical upper limit and continuous observations
  30. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  31. EP260822a: Global MASTER-Net observations report
  32. EP Alert 260820.31: Global MASTER-Net observations report
  33. GRB 260807A: EP-FXT follow-up observations
  34. GRB 260822A: SVOM/ECLAIRs refined analysis
  35. GRB 260809A: SVOM/ECLAIRs refined analysis
  36. GRB 260822A: SVOM/VT optical upper limits
  37. IceCube Alert 260825A: Global MASTER-Net observations report
  38. GRB 260825A: Fermi GBM Final Real-time Localization
  39. GRB 260822A: EP/FXT follow-up observations
  40. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  41. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  42. EP260822a: EP-FXT non-detection and upper limit
  43. GRB 260822A: SVOM/VT optical detection of COLIBRÍ candidate
  44. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  45. EP260822a: Einstein Probe detection of a fast X-ray transient
  46. GRB 260822A: LCO optical upper limits
  47. The EP-WXT trigger 01709287395 is likely a flaring star
  48. GRB260822B: Fermi GBM Final Localization
  49. GRB 260822A: GROWTH-India Telescope Upper Limits
  50. GRB 260822A: GOTO optical upper limit
  51. GRB 260822A: SVOM detection of a short burst
  52. GRB 260818B: SVOM/C-GFT optical upper limit
  53. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  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. EP detected a brightening of LMXB 1ES 1735-26.9
  58. GRB260820A: Fermi GBM Final Real-Time Localization
  59. GRB 260818B: EP-FXT follow-up observation
  60. GRB 260818A: J-band observations with WINTER
  61. GRB 260818B: SVOM/ECLAIRs refined analysis
  62. GRB 260818A: SVOM/ECLAIRs refined analysis
  63. GRB 260818B: NOT optical upper limits
  64. GRB 260810A: SVOM/GRM observation
  65. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  66. GRB260818A: EP-FXT follow-up observation
  67. GRB 260818B: LCO optical upper limits
  68. GRB 260818B: SVOM detection of a short burst
  69. SVOM trigger sb26081806 is not a GRB
  70. EP260806a: SAO RAS multicolor optical observations
  71. GRB 260818A: LCO optical upper limits
  72. EP260812a: AbAO optical upper limit
  73. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  74. GRB 260818A: SVOM possible detection of a long and faint GRB
  75. EP260806a: SVOM/ECLAIRs detection through targeted search
  76. The EP-WXT trigger 01709281429 is likely a flaring star
  77. EP260812b: GTC/OSIRIS+ tentative spectroscopic redshift z = 2.034
  78. EP260806a: WFST optical observations
  79. The EP-WXT trigger 01709280562 is likely a flaring star
  80. The EP-WXT trigger 01709279838 is likely a flaring star
  81. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  82. GRB 260808B: Liverpool Telescope further optical observations
  83. GRB 260808B: GTC/OSIRIS+ spectroscopic redshift z = 1.295
  84. GRB 260813A: BALROG localization (Fermi Trigger 808341387 / GRB 260813803)
  85. GRB 260813A: Fermi GBM Final Real-time Localization
  86. EP260812a: NOT and Liverpool Telescope upper limits:
  87. EP260812a: refined analysis of the EP-WXT and autonomous EP-FXT observation
  88. EP260812a: SVOM/C-GFT optical upper limit
  89. EP260812b: COLIBRÍ optical observations
  90. EP260812b: SVOM/VT optical observation
  91. GRB 260808A: SVOM/GRM observation
  92. EP260812b: Einstein Probe detection of an X-ray transient
  93. EP trigger #01709278129 (EP260812b?): NOT optical counterpart
  94. Fermi GBM Sub-Threshold Detection of GRB 260809A
  95. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
  96. EP260812a: Einstein Probe detection of an X-ray transient
  97. GRB 260808B: SVOM/VT optical re-brightening at day 3
  98. GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
  99. GRB 260806A: CALET Gamma-Ray Burst Monitor detection
  100. GRB 260808A: GECAM-B observation

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