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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"

2409 results found.

  1. EP251122a: refined analysis of the EP-WXT and EP-FXT observations
  2. GRB 251122A / EP251122a: WFST optical observations
  3. GRB 251122A/EP251122a: SVOM/VT optical observations with VHF data
  4. GRB 251122A/EP251122a: Additional, deeper LCO optical r band upper limit
  5. GRB 251122A / EP251122a: LCO optical upper limits
  6. EP251122a / GRB 251122A: optical counterpart candidate with Kinder observations
  7. GRB 251122A/EP251122a: SVOM/C-GFT upper limit
  8. GRB 251122A / EP251122a: SVOM detection of a long burst
  9. LIGO/Virgo/KAGRA S251105aj: SVOM/ECLAIRs detection of a high-energy transient SVOM J2320.0-2901 through targeted search
  10. GRB 251103A: SVOM/ECLAIRs and SVOM/GRM joint refined analysis
  11. EP-WXT trigger 01709248403: confirmation of a stellar flare by SVOM/VT
  12. LIGO/Virgo/KAGRA S251112cm: SVOM/VT optical observations and preliminary results
  13. EP251118a / GRB 251118C: SVOM/VT optical observation
  14. EP251118a / GRB 251118C: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at CTIO
  15. GRB 251116C: NOT optical observations
  16. GRB 251118C: Glowbug gamma-ray detection of the fast X-ray transient EP251118A
  17. GRB 251118C: Swift/BAT rates detection of a burst with a possible association with EP 251118A
  18. GRB 251118C: SVOM/GRM observation of a possible gamma-ray counterpart of EP251118a
  19. GRB 251117A: Insight-HXMT/HE detection
  20. GRB 251119A: SVOM trigger sb25111901 is not a GRB
  21. GRB 251116D: SVOM/GRM observation of a long GRB
  22. GRB 251119A: SVOM detection of a possible burst
  23. GRB 251116C: SVOM/ECLAIRs refined analysis
  24. GRB 251116B: SVOM/ECLAIRs refined analysis
  25. GRB 251117A: AstroSat CZTI detection
  26. GRB 251117A: Fermi GBM observation
  27. GRB 251116D: Insight-HXMT/HE detection
  28. GRB 251117A: Swift/BAT-GUANO localization skymap of a short burst
  29. GRB 251117A: SVOM/GRM observation of a short burst
  30. GRB 251116C: Swift/BAT arcminute localization of a burst
  31. GRB 251116B: SVOM/VT optical upper limit
  32. GRB 251116C: Swift-XRT observations
  33. GRB 251116C: SVOM/VT optical upper limit
  34. GRB 251116B: EP-FXT follow-up observation
  35. GRB 251116B: LCO optical upper limits
  36. GRB 251116C: LCO optical upper limits
  37. SVOM GRB251116C: Global MASTER-Net observations report
  38. GRB 251116C: SVOM detection of a burst
  39. GRB 251116B: SVOM detection of a burst
  40. GRB 251013C: joint SVOM/ECLAIRs-GRM refined analysis
  41. Konus-Wind detection of GRB 251103A
  42. GRB 251111A: SVOM/ECLAIRs refined analysis
  43. GRB 251025B: SVOM/ECLAIRs refined analysis
  44. GRB251111A: 1.3m DFOT optical upper limit
  45. GRB 251106B: Glowbug gamma-ray detection of a likely short burst
  46. GRB 251111A: Swift-XRT afterglow detection
  47. GRB 251111A: SVOM/VT optical observations with X-band data
  48. SVOM GRB251111.42: Global MASTER-Net observations report
  49. GRB 251111A: Swift-XRT observations
  50. SVOM GRB251111.22: Global MASTER-Net observations report
  51. GRB 251111A: EP-FXT counterpart detection
  52. GRB 251111A: SVOM/VT optical observations with VHF data
  53. GRB 251111A: KAIT optical upper limit
  54. GRB 251111A: LCO optical observation
  55. GRB 251111A: SVOM/COLIBRÍ (FM-GFT) optical counterpart detection
  56. GRB 251111A: SVOM detection of a soft burst
  57. GRB 251106A: Swift/UVOT Upper Limits
  58. GRB 251105B: Insight-HXMT/HE detection
  59. GRB 251106B: Insight-HXMT detection
  60. SVOM GRB251108.54: Global MASTER-Net observations report
  61. GRB 251102B: SVOM/GRM observation
  62. SVOM GRB251106.83: Global MASTER-Net observations report
  63. IPN triangulation of GRB 251105B (possible sGRB with EE)
  64. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) fading of the optical counterpart
  65. GRB 251106B: SVOM/GRM observation of a short burst
  66. GRB 251106A: Swift-XRT afterglow detection
  67. GRB 251106A: Kilonova-Catcher optical upper limit
  68. Fermi GBM Sub-Threshold Detection of GRB 251106A
  69. GRB 251106A: Swift/BAT arcminute localization of a burst
  70. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) detection of a likely optical counterpart
  71. GRB 251106A: MASTER optical observations
  72. GRB 251106A: SVOM detection of a burst
  73. GRB 251016A: TERI Gamma-ray detection of a short burst
  74. GRB 250920C: TERI Gamma-ray detection
  75. GRB 251104A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  76. GRB 251105B: AstroSat CZTI detection of a short burst with extended emission
  77. GRB 251023A: SVOM/ECLAIRs detection of a burst through targeted search
  78. Fermi GBM Sub-Threshold Detection of GRB 251105B
  79. GRB 251105B: SVOM/GRM observation of a possible short burst with extended emission
  80. GRB 251104A: SVOM detection of a burst
  81. GRB 251028A: Insight-HXMT/HE detection
  82. GRB 251103A: WFST optical observations
  83. GRB 251103A: Xinglong 2.16m optical detection
  84. GRB 251103A: Insight-HXMT detection
  85. GRB 251013C: 7DT detection and Medium-band SED of Afterglow
  86. GRB 251103A: Swift/BAT-GUANO arcminute localization of a burst
  87. GRB 251103A: Kilonova-Catcher optical afterglow detection
  88. GRB 251103A: Swift/UVOT Detection
  89. GRB 251103A: Fermi GBM Observation
  90. GRB 251103A: SVOM/GRM observation
  91. GRB 251103A: Swift-XRT afterglow detection
  92. GRB 251103A: SVOM/COLIBRÍ (FM-GFT) optical observations
  93. GRB 251103A: LCO optical observation
  94. GRB 251026A: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical counterpart
  95. GRB 251103A: BOOTES-2/TELMA optical afterglow
  96. GRB 251103A: LCO optical afterglow detection
  97. GRB 251103A: SVOM detection of a bright burst
  98. Konus-Wind detection of GRB 251028A
  99. GRB 251025C: SVOM/GRM observation
  100. GRB 251028A: GECAM-B detection

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