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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"

34170 results found.

  1. GRB 251129A: SVOM/VT optical counterpart confirmation with VHF data
  2. GRB 251128A: Fermi GBM Observation
  3. GRB 251129A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  4. GRB 251129A: SVOM detection of a burst
  5. GRB 251129A: SVOM detection of a burst
  6. GRB 251126A: Swift-BAT refined analysis
  7. GRB 251126A: TShAO, Mondy, and AbAO optical observations
  8. GRB 251128A: Swift/BAT-GUANO localization skymap of a burst
  9. Fermi GRB 251128A: Global MASTER-Net observations report
  10. GRB 251127A: Glowbug gamma-ray detection
  11. GRB 251126A: OHP/T193 optical observations and tentative spectroscopic redshift
  12. GRB 251126A: further SAO RAS optical observations
  13. GRB 250702B: detection of the compact radio counterpart 139 days after the burst
  14. GRB 251126A NUTTelA-TAO Early Measurements
  15. GRB251126A: MAO/AZT-22 optical observations
  16. GRB 251128A: Fermi GBM Final Real-time Localization
  17. GRB251126A: Continued optical observation from 1.3m DFOT
  18. GRB 251126A: Swift/UVOT Detection
  19. GRB 251126A: Mondy and SAO RAS optical observations
  20. GRB 251126A: Swift-XRT refined Analysis
  21. GRB 251126A : MITSuME Akeno optical afterglow candidate detection
  22. GRB 251126A: NOT optical observations
  23. GRB 251126A: 1.3m DFOT optical afterglow detection
  24. GRB 251126A: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at McDonald Observatory
  25. GRB 251126A: COLIBRÍ photometric redshift z = 3.5
  26. GRB 251125B: GECAM-B detection
  27. Fermi GRB 251127A: Global MASTER-Net observations report
  28. GRB 251127A: Fermi GBM Final Real-time Localization
  29. GRB 251126A: Enhanced Swift-XRT position
  30. GRB 251126A: Kilonova-Catcher optical afterglow detection
  31. GRB 251126A: Asiago i-band detection
  32. GRB 251126A: Nanshan/HMT optical afterglow detection
  33. Swift GRB 251126A: Global MASTER-Net observations report
  34. GRB 251121A: Fermi GBM Observation
  35. GRB 251126A: Prompt enhanced Swift-XRT position
  36. GRB 251126A: GIT discovery of the likely optical afterglow
  37. GRB 251126A: Swift detection of a burst
  38. GRB 251125B: COLIBRÍ further observations and photometric redshift upper limit of z < 3
  39. GRB 251125B: COLIBRÍ observations of fading of the MASTER OT candidate
  40. Fermi GRB 251125B : MASTER OT J155558.56+581224.1 optical counterpart discovery
  41. Fermi GRB 251125B: Global MASTER-Net observations report
  42. GRB 251125B: Fermi GBM Final Real-time Localization
  43. Fermi GRB 251125A: Global MASTER-Net observations report
  44. GRB 251125A: Fermi GBM Final Real-time Localization
  45. GRB 251124A: Fermi GBM Localization by automated pipeline
  46. GRB 251122B: Fermi GBM Final Localization
  47. Fermi GRB 251124a: Global MASTER-Net observations report
  48. GRB 251124a: Fermi GBM Final Localization
  49. GRB 251116C: Swift-XRT confirmation of fading
  50. GRB 251122A/EP251122a: FTW optical and NIR observations
  51. GRB 251122A/EP251122A: 1.3m DFOT optical detection
  52. GRB 251122A / EP251122a: Xinglong 2.16m optical observation
  53. GRB 251122A / EP251122a: EP-FXT counterpart detection
  54. EP251122a: refined analysis of the EP-WXT and EP-FXT observations
  55. GRB 251122A / EP251122a: WFST optical observations
  56. GRB 251122A/EP251122a: SVOM/VT optical observations with VHF data
  57. GRB 251122A/EP251122a: Additional, deeper LCO optical r band upper limit
  58. GRB 251122A / EP251122a: LCO optical upper limits
  59. EP251122a / GRB 251122A: optical counterpart candidate with Kinder observations
  60. GRB 251122A/EP251122a: SVOM/C-GFT upper limit
  61. GRB 251122A / EP251122a: SVOM detection of a long burst
  62. GRB 251121A: Swift/BAT-GUANO localization skymap of a short burst
  63. GRB 251121A: Glowbug gamma-ray detection of a likely short burst
  64. EP251118a: Xinglong-2.16m optical observation
  65. GRB 251115A: Fermi GBM Observation
  66. GRB 251121A: Fermi GBM Final Real-time Localization
  67. Fermi Gamma-ray Burst Monitor trigger 785388351 / 251121143 is not a GRB
  68. GRB 251118A: Swift/UVOT Detection
  69. EP251118a / GRB 251118C: SAO RAS optical observations
  70. GRB 251118A: Glowbug gamma-ray detection
  71. GRB 251118A: Fermi GBM Observation
  72. GRB 251118A: Swift-XRT afterglow detection
  73. GRB 251103A: SVOM/ECLAIRs and SVOM/GRM joint refined analysis
  74. GRB 251118A: GECAM-B detection
  75. EP251118a / GRB 251118C: SVOM/VT optical observation
  76. GRB 251118A: NuSTAR detection of bright prompt emission
  77. EP251118a / GRB 251118C: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at CTIO
  78. GRB 251116C: NOT optical observations
  79. GRB 251118C: Glowbug gamma-ray detection of the fast X-ray transient EP251118A
  80. GRB 251118C: Swift/BAT rates detection of a burst with a possible association with EP 251118A
  81. GRB 251018A: FRAM-Auger optical detection
  82. GRB 251117A: Swift-XRT observations
  83. EP251118A / GRB 251118C : MASTER optical counterpart observations
  84. GRB 251118C: SVOM/GRM observation of a possible gamma-ray counterpart of EP251118a
  85. Konus-Wind detection of GRB 251118C (EP251118a)
  86. GRB 251117A: Insight-HXMT/HE detection
  87. GRB 251119A: SVOM trigger sb25111901 is not a GRB
  88. GRB 251116D: SVOM/GRM observation of a long GRB
  89. GRB 251119A: SVOM detection of a possible burst
  90. EP251118a: NOT spectroscopic redshift of z = 1.216
  91. GRB 251118A: Fermi-LAT detection
  92. GRB 251118A: Swift ToO observations
  93. Fermi GRB 251118B: Global MASTER-Net observations report
  94. GRB 251118B: Fermi GBM Final Real-time Localization
  95. LIGO/Virgo/KAGRA S251112cm: Upper limits from Glowbug gamma-ray observations
  96. GRB 251118A: BALROG localization (Fermi Trigger 785190695 / GRB 251118855)
  97. GRB 251117A: FTW Observations of Swift candidate X-ray sources
  98. GRB 251118A: Fermi GBM Final Real-time Localization
  99. GRB 251116C: SVOM/ECLAIRs refined analysis
  100. GRB 251116B: SVOM/ECLAIRs refined analysis

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