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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"

28219 results found.

  1. GRB 251126A: Swift-XRT refined Analysis
  2. GRB 251126A : MITSuME Akeno optical afterglow candidate detection
  3. GRB 251126A: NOT optical observations
  4. GRB 251126A: 1.3m DFOT optical afterglow detection
  5. GRB 251126A: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at McDonald Observatory
  6. GRB 251125B: GECAM-B detection
  7. GRB 251127A: Fermi GBM Final Real-time Localization
  8. GRB 251126A: Enhanced Swift-XRT position
  9. GRB 251126A: Kilonova-Catcher optical afterglow detection
  10. GRB 251126A: Asiago i-band detection
  11. GRB 251126A: Nanshan/HMT optical afterglow detection
  12. GRB 251126A: Prompt enhanced Swift-XRT position
  13. GRB 251126A: GIT discovery of the likely optical afterglow
  14. GRB 251126A: Swift detection of a burst
  15. GRB 251125B: COLIBRÍ further observations and photometric redshift upper limit of z < 3
  16. GRB 251125B: COLIBRÍ observations of fading of the MASTER OT candidate
  17. Fermi GRB 251125B : MASTER OT J155558.56+581224.1 optical counterpart discovery
  18. GRB 251125B: Fermi GBM Final Real-time Localization
  19. EP251124b: EP-WXT detection of a fast X-ray transient
  20. EP251124a: Xinglong GWAC-F60A optical observation
  21. GRB 251125A: Fermi GBM Final Real-time Localization
  22. EP251124a: NOT r- and z-band optical upper limits
  23. EP251124a: Swift-XRT observations
  24. GRB 251124A: Fermi GBM Localization by automated pipeline
  25. LIGO/Virgo/KAGRA S251112cm: AT 2025adht Kinder follow-up observations
  26. GRB 251122B: Fermi GBM Final Localization
  27. EP251118A: 6 GHz VLA Detection
  28. GRB 251124a: Fermi GBM Final Localization
  29. LIGO/Virgo/KAGRA S251105aj: SVOM/VT optical observations and preliminary results on SVOM J2320.0-2901
  30. LIGO/Virgo/KAGRA S251105aj: EP-FXT follow-up observations and preliminary results on SVOM J2320.0-2901
  31. EP251124a: Einstein Probe detection of an X-ray transient
  32. GRB 251116C: Swift-XRT confirmation of fading
  33. GRB 251122A/EP251122A: 1.3m DFOT optical detection
  34. EP251118A: 3.6m DOT optical afterglow detection
  35. GRB 251122A / EP251122a: EP-FXT counterpart detection
  36. GRB 251122A / EP251122a: WFST optical observations
  37. GRB 251122A/EP251122a: SVOM/VT optical observations with VHF data
  38. GRB 251122A/EP251122a: Additional, deeper LCO optical r band upper limit
  39. EP251122a / GRB 251122A: optical counterpart candidate with Kinder observations
  40. GRB 251122A / EP251122a: SVOM detection of a long burst
  41. EP251122a: Einstein Probe detection of an X-ray transient
  42. EP251118a: Continued Optical Detection with Kinder observations
  43. LIGO/Virgo/KAGRA S251105aj: SVOM/ECLAIRs detection of a high-energy transient SVOM J2320.0-2901 through targeted search
  44. GRB 251121A: Glowbug gamma-ray detection of a likely short burst
  45. EP251118a: Xinglong-2.16m optical observation
  46. GRB 251121A: Fermi GBM Final Real-time Localization
  47. EP251118A: 1.3m DFOT optical afterglow detection
  48. GRB 251118A: Swift/UVOT Detection
  49. GRB 251118A: Glowbug gamma-ray detection
  50. GRB 251118A: Fermi GBM Observation
  51. GRB 251118A: Swift-XRT afterglow detection
  52. GRB 251103A: SVOM/ECLAIRs and SVOM/GRM joint refined analysis
  53. EP251118a: Optical detection with Kinder observations
  54. GRB 251118A: GECAM-B detection
  55. GRB 251118A: NuSTAR detection of bright prompt emission
  56. EP251118a / GRB 251118C: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at CTIO
  57. GRB 251116C: NOT optical observations
  58. GRB 251118C: Glowbug gamma-ray detection of the fast X-ray transient EP251118A
  59. GRB 251118C: Swift/BAT rates detection of a burst with a possible association with EP 251118A
  60. GRB 251018A: FRAM-Auger optical detection
  61. GRB 251117A: Swift-XRT observations
  62. Konus-Wind detection of GRB 251118C (EP251118a)
  63. GRB 251117A: Insight-HXMT/HE detection
  64. EP251118a: GOTO optical afterglow detection
  65. GRB 251119A: SVOM detection of a possible burst
  66. EP251118a: NOT spectroscopic redshift of z = 1.216
  67. GRB 251118A: Fermi-LAT detection
  68. EP251118a: NOT candidate optical counterpart
  69. GRB 251118A: Swift ToO observations
  70. EP251118a: Einstein Probe detected of a fast X-ray transient
  71. GRB 251118B: Fermi GBM Final Real-time Localization
  72. GRB 251118A: Fermi GBM Final Real-time Localization
  73. GRB 251117A: AstroSat CZTI detection
  74. GRB 251114B: Insight-HXMT/HE detection
  75. GRB 251114B: GECAM-B detection of a short burst
  76. GRB 251013C: Koshka, SAO RAS, Mondy, and CrAO optical observations, possible SN detection
  77. GRB 251116D: Insight-HXMT/HE detection
  78. GRB 251115A: Swift-XRT observations
  79. GRB 251117A: Tiled Swift observations
  80. GRB 251117A: Fermi-LAT detection
  81. GRB 251116C: Swift/BAT arcminute localization of a burst
  82. LIGO/Virgo/KAGRA S251112cm: WFST follow-up observations and preliminary results
  83. GRB 251116C: Swift-XRT observations
  84. GRB 251117A: Fermi GBM Final Localization Correction
  85. GRB 251116D: Glowbug gamma-ray detection
  86. GRB 251116D: AstroSat CZTI detection
  87. GRB 251116C: SVOM/VT optical upper limit
  88. GRB 251116C: SVOM detection of a burst
  89. GRB 251116B: SVOM detection of a burst
  90. GRB 251116A: Fermi GBM Final Real-time Localization
  91. GRB 251115A: Tiled Swift observations
  92. GRB 251115A: Fermi-LAT detection
  93. GRB 251115A: Fermi GBM Final Real-time Localization
  94. GRB 251113A: Glowbug gamma-ray detection
  95. GRB 251113A: AstroSat CZTI detection
  96. GRB 251114B: Fermi GBM Final Real-time Localization
  97. Konus-Wind detection of GRB 251108C
  98. Konus-Wind detection of GRB 251103A
  99. LIGO/Virgo/KAGRA S251112cm: ATLAS targeted observations of the skymap
  100. LIGO/Virgo/KAGRA S251112cm: Swift XRT observations, 20 X-ray sources

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