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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"

27216 results found.

  1. GRB 250506A: NOT optical upper limits
  2. EP250508a: follow-up observation with EP-FXT
  3. EP250508a: SVOM/VT optical candidate
  4. EP250508a: refined analysis of the EP-WXT and EP-FXT observations
  5. GRB 250505B: SVOM/GRM observation of a short burst
  6. GRB 250506A: GECAM detection
  7. EP250508a: REM optical/NIR observations
  8. EP250508a: Global MASTER-Net observations report
  9. GRB 250506A: SVOM/VT optical upper limit
  10. EP250508a: COLIBRÍ Optical Limit
  11. EP250508a: Einstein Probe detection of an X-ray transient
  12. GRB 250507A: Swift-XRT refined Analysis
  13. GRB 250427B : SVOM detection of a burst through offline search
  14. GRB 250507A: follow-up observation with EP-FXT
  15. EP#01709175213/IGR J19566+0326: Swift-XRT detection
  16. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  17. GRB 250507A: refined SVOM/MXT data analysis
  18. GRB 250507A: REM optical/NIR observations
  19. GRB 250507A: SVOM/VT optical upper limit
  20. GRB 250507A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  21. EP-WXT trigger 01709175213: a new X-ray outburst of LMXB MAXI J1957+032
  22. GRB 250507A: SVOM detection of a long burst
  23. GRB 250506A: Mephisto optical upper limits
  24. GRB 250502A: Bassano Bresciano Observatory upper limit
  25. IceCube Alert 250506.59: Global MASTER-Net observations report
  26. GRB 250506A: Xinglong 2.16m optical upper limit
  27. SVOM/sb25050601: EP-FXT observations
  28. GRB 250506A: SVOM improved position and MXT detection of a fading X-ray afterglow
  29. GRB 250506A: REM optical/NIR upper limits
  30. GRB 250506A: Fermi GBM Observation
  31. GRB 250506A: Swift XRT observations and possible counterpart detection
  32. GRB 250506A: TRT optical observations
  33. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) Upper Limits on the Optical Counterpart
  34. GRB 250506A: SVOM detection of a burst
  35. GRB 250504A: Swift-BAT refined analysis
  36. GRB 250430A: Swift-BAT refined analysis
  37. GRB 250506A: Fermi GBM Final Real-time Localization
  38. GRB 250504A: Swift-XRT refined Analysis
  39. Fermi GRB 250505A: Global MASTER-Net observations report
  40. GRB 250504A: SVOM/VT upper limit
  41. GRB 250504A: REM optical/NIR observations
  42. GRB 250502A: REM optical/NIR observations
  43. GRB 250505A: Fermi GBM Final Real-time Localization
  44. GRB 250504A: MeerLICHT optical afterglow detection
  45. GRB 250504A: Fermi GBM Observation
  46. Fermi GRB 250504A: Global MASTER-Net observations report
  47. GRB 250504A: Swift detection of a burst
  48. GRB 250504A: Fermi GBM Final Real-time Localization
  49. Swift GRB250504.98: Global MASTER-Net observations report
  50. GRB 250502A: Swift/UVOT Follow up
  51. Fermi trigger No 767975731: Global MASTER-Net observations report
  52. GRB 250502A: NOT optical observations
  53. GRB 250502a: Liverpool Telescope optical follow-up
  54. GRB 250502A: AKO Optical Afterglow Detection
  55. GRB 250502A: LCO optical counterpart detection
  56. GRB 250502C: Fermi GBM Final Localization
  57. GRB 250502B: DDOTI Optical Observations
  58. GRB 250430A: Swift-XRT refined Analysis
  59. GRB 250502A: Early optical counterpart detection by LCO.
  60. GRB 250430A: Swift/UVOT Detection
  61. GRB 250502A: SVOM/VT optical bump
  62. GRB 250502A: TRT optical afterglow confirmation
  63. Fermi GRB 250502B: Global MASTER-Net observations report
  64. GRB 250502A: SVOM/COLIBRÍ (FM-GFT) Detection of a Bright Optical Counterpart Candidate
  65. GRB 250502B: Fermi GBM Final Real-time Localization
  66. GRB 250502A: SVOM detection of a burst
  67. GRB 250430A: SVOM/VT optical observations
  68. GRB 250430A: KAIT optical observations
  69. GRB 250430A: NUTTelA-TAO Early Measurements
  70. EP250427a / GRB 250427A: OHP/T193 photometric observations: third visit
  71. GRB 250430A: DDOTI Optical Observations
  72. GRB 250430A: Leavitt Observatory optical upper limit
  73. GRB 250430A: Bassano Bresciano Observatory upper limit
  74. GRB 250430A : MITSuME Akeno optical upper limits
  75. GRB 250430A / EP250430a: VLT/X-shooter spectroscopic redshift z = 0.767
  76. SVOM/sb25043004: EP-FXT observations
  77. EP250430a/GRB 250430A: Einstein Probe WXT detection of the X-ray prompt emission
  78. GRB 250424A: CALET Gamma-Ray Burst Monitor detection
  79. GRB 250430A: AKO Optical Afterglow Detection
  80. GRB 250430A: Kanata optical upper limit
  81. EP 250427A: Optical counterpart detection by LCO.
  82. GRB 250430A: Swift detection of a burst with optical counterpart
  83. Swift GRB250430.73: Global MASTER-Net observations report
  84. EP250428b: FTW optical and NIR observations
  85. EP250427a/GRB250427A: HCT optical follow-up
  86. EP250427a / GRB 250427A: OHP/T193 continued photometric observations
  87. SVOM/sb25043004: SVOM detection of a X-ray transient
  88. Fermi trigger No 767623859: Global MASTER-Net observations report
  89. EP250428b: refined analysis of the EP-FXT follow-up observation
  90. EP250428b: GROWTH-India telescope optical upper limit
  91. EP250428b: SVOM/VT upper limit
  92. EP250428b: Global MASTER-Net observations report
  93. EP250428b: Einstein Probe detection of a fast X-ray transient
  94. EP250427a / GRB 250427A: OHP/T193 photometric observations
  95. EP250427a: EP-FXT follow-up observations
  96. EP250427a/GRB 250427A: FTW optical and NIR observations of the counterpart
  97. EP250427a: Lesedi optical counterpart detection
  98. EP250427A: COLIBRÍ Continuing Optical Observations
  99. GRB250427A/EP250427a GIT optical afterglow detection:
  100. GRB 250427A: Swift-XRT refined Analysis

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