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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"

27099 results found.

  1. Swift GRB250905.09: Global MASTER-Net observations report
  2. Swift GRB 250904A: Global MASTER-Net observations report
  3. GRB 250904A: TRT optical counterpart detection
  4. EP250827a and EP250827b: Upper limit from Fermi-GBM Observations
  5. GRB 250902B: CALET Gamma-Ray Burst Monitor detection
  6. GRB 250904A: Swift detection of a burst
  7. GRB 250902A: CALET Gamma-Ray Burst Monitor detection
  8. GRB 250902A: VZLUSAT-2 detection
  9. GRB 250903A: Swift-XRT observations
  10. EP250903a: Swift-XRT observations
  11. EP#01709201209: Swift-XRT observations
  12. EP250903a: retraction of the LCO candidate, and discovery of the likely counterpart
  13. EP-WXT trigger 01709201209: Liverpool Telescope upper limits
  14. GRB 250830C: VZLUSAT-2 detection
  15. EP250903a: refined analysis of the EP-WXT and EP-FXT observations
  16. GRB 250903A: VLT X-shooter spectroscopic redshift z = 1.590
  17. The EP-WXT trigger 01709201209 is likely a flaring star
  18. GRB 250903A: EP-FXT counterpart detection
  19. GRB 250902A: GECAM-B detection
  20. GRB 250903A: LCO optical observation
  21. GRB 250903A: LCO optical afterglow detection
  22. GRB 250903A: SVOM/VT optical confirmation with VHF data
  23. EP250903a: SVOM/VT optical confirmation
  24. Subject GRB 250903A: SVOM/MXT afterglow detection
  25. EP250903a: LCO candidate counterpart discovery
  26. GRB 250903A: TRT optical counterpart detection
  27. GRB 250903A: SVOM detection of a burst
  28. EP250903a: Global MASTER-Net observations report
  29. EP250903a: TRT optical observations
  30. EP250903a: Einstein Probe detection of an X-ray transient
  31. EP 250827B: Detection of supernova counterpart by LCO.
  32. EP/WXT01709201159: GOTO optical follow-up
  33. EP250827b: NOT spectroscopic observations and AT 2025wkm classification as a broad-lined type-Ic supernova
  34. GRB 250902B: SVOM/GRM observation
  35. EP250827b: SVOM/VT observation of AT 2025wkm
  36. GRB 250831A (SVOM trigger sb25083102): KAIT confirmation of stellar flare
  37. Fermi GRB 250902B: Global MASTER-Net observations report
  38. GRB 250902A: Fermi GBM Detection
  39. GRB 250901A: Swift/UVOT Upper Limit
  40. GRB 250902B: Fermi GBM Final Real-time Localization
  41. LIGO/Virgo/KAGRA S250902av: 1 counterpart neutrino candidate event from an IceCube neutrino search
  42. GRB 250831A (SVOM trigger sb25083102): confirmation of a stellar flare by SVOM/VT
  43. GRB 250902A: SVOM/GRM observation
  44. EP250901a: refined analysis of the EP-WXT and EP-FXT observations
  45. GRB 250901A: EP-FXT follow-up observation
  46. GRB 250901A: NOT optical observations
  47. GRB 250902A: Fermi GBM Final Real-time Localization
  48. GRB 250901A: SVOM/VT optical afterglow with VHF data
  49. EP250901a: Swift-XRT observations
  50. GRB 250901A: LCO optical upper limit
  51. EP250831a: NOT optical observations and tentative afterglow candidate
  52. EP250827b: Contemporaneous detection of EP X-ray flare EP250827b and ZTF transient ZTF25abmpngy/AT2025wkm
  53. GRB 250901A: SVOM detection of a burst
  54. GRB 250831B: SVOM/GRM observation
  55. EP250901a: Mephisto optical upper limits
  56. GRB 250830C: GECAM-B detection
  57. EP250901a: Global MASTER-Net observations report
  58. EP250901a: Einstein Probe detection of an X-ray transient
  59. EP250831a: EP-FXT follow-up observation
  60. EP250831a: Swift-XRT observations
  61. LIGO/Virgo/KAGRA S250831cc: Coverage and upper limits from MAXI/GSC observations
  62. IceCube Alert 250831.75: Global MASTER-Net observations report
  63. EP250831a: Global MASTER-Net observations report
  64. EP250831a: EP-WXT detection of a fast X-ray transient
  65. GRB 250831A (SVOM trigger sb25083102) is likely an outburst from star G 272-61
  66. GRB 250831A: Swift-XRT counterpart detection
  67. GRB 250831A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  68. GRB 250831A: SVOM/VT upper limit with VHF data
  69. GRB 250831A: SVOM detection of a soft burst
  70. EP250830a: Global MASTER-Net observations report
  71. EP250830a/GRB 250830B: Einstein Probe detection of an X-ray transient and Swift/XRT follow-up
  72. LIGO/Virgo/KAGRA S250830bp: Coverage and upper limits from MAXI/GSC observations
  73. EP-WXT trigger 01709200994: Liverpool Telescope upper limits
  74. EP-WXT trigger 01709200994: confirmation of a stellar flare by BOOTES-6
  75. The EP-WXT trigger 01709200994 is likely a flaring star
  76. GRB 250828B: Swift-BAT refined analysis
  77. EP250821a: SOAR observations
  78. EP250827a: very early ATLAS detections, starting 43 sec after the EP trigger
  79. LIGO/Virgo/KAGRA S250818k: MeerKAT detection of an increase in radio flux from AT2025ulz
  80. GRB 250808B: SVOM detection of a burst through offline search
  81. EP250828a: refined analysis of the EP-WXT and EP-FXT observations
  82. EP250828a: Optical counterpart detection with Kinder observations
  83. EP250828a: Liverpool Telescope upper limits
  84. Swift GRB 250828B: Global MASTER-Net observations report
  85. EP250828a: Global MASTER-Net observations report
  86. EP-WXT trigger 01709200800 : KAIT optical observations
  87. EP250827a: Swift/UVOT Detection
  88. EP250828a: NOT optical counterpart confirmation
  89. EP250828a: SVOM/VT optical candidate
  90. GRB 250828B: Swift detection of a burst
  91. EP250827a: STEP/T80S Confirmation of fading optical counterpart
  92. EP250828a: Optical upper limit with Kinder observations
  93. LIGO/Virgo/KAGRA S250818k: uGMRT 1.3 GHz observations of AT2025ulz
  94. EP250827a: LCO observations show fading optical counterpart
  95. GRB 250828A: Fermi GBM Final Localization
  96. EP250828a: Einstein Probe detection of an X-ray transient
  97. EP250827a: Preliminary analysis of the EP-WXT and EP-FXT observations
  98. GRID detection of GRB 250824A
  99. Fermi GRB 250827A: Global MASTER-Net observations report
  100. EP250827a: confirmation of optical rebrightening with LCO

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