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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"

23586 results found.

  1. GRB 250128B: TNG optical upper limit
  2. GRB 250129A: Swift/UVOT Detection
  3. GRB 250128B: NOT optical upper limit
  4. GRB 250129A: REM optical/NIR afterglow detection
  5. GRB 250129A: Early afterglow detection by LCO.
  6. GRB 250128B: OHP/T193 optical upper limit
  7. GRB 250129A: LCO optical observations
  8. GRB 250129A: NOT optical observations and redshift confirmation
  9. GRB 250129A: GOTO optical observations show brightening afterglow
  10. The EP-WXT trigger 01709131085 is likely a flaring star
  11. GRB 250128B: Swift-XRT refined Analysis
  12. GRB 250128B: GOTO optical upper limit
  13. GRB 250128B: LCO optical observations
  14. GRB 250128B: Swift detection of a short burst
  15. GRB 250127A: Swift-XRT observations
  16. GRB 250127B: DDOTI Upper Limit on the Afterglow
  17. Fermi-LAT Gamma-ray Observations of IceCube-250102A
  18. GRB 250127A: EP-FXT afterglow detection
  19. Fermi-LAT Gamma-ray Observations of IceCube-250101A
  20. IPN triangulation of GRB 250119C
  21. GRB 250127A: LCO optical upper limit
  22. GRB 241223A: cubesat Avion detection
  23. GRB 250126A: CALET Gamma-Ray Burst Monitor detection
  24. EP250125A: Non-detection from Fermi-GBM Observations
  25. GRB 250126A: MAXI/GSC detection
  26. EP250125a: Optical upper limit with Kinder observations
  27. EP250125a: REM optical counterpart detection
  28. Konus-Wind detection of a bright burst from SGR 1E1841-045 on 2025 January 23
  29. IPN triangulation of a bright burst from SGR 1E1841-045
  30. GRB 250121A: CALET Gamma-Ray Burst Monitor detection
  31. Konus-Wind detection of GRB 250118B
  32. Konus-Wind detection of GRB 250119B
  33. IPN triangulation of GRB 250119B
  34. Improved IPN triangulation of GRB 250107C
  35. GRB 250114A: Swift-BAT refined analysis
  36. GRB 250121A: Fermi-LAT detection
  37. LIGO/Virgo S250119cv: Swift XRT observations, 5 X-ray sources
  38. Fermi-LAT Gamma-ray Observations of IceCube-241224A
  39. Konus-Wind detection of GRB 250117A
  40. IPN triangulation of GRB 250117A (short)
  41. LIGO/Virgo/KAGRA S250119cv: GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  42. EP 250108A: Late-time optical observation by LCO
  43. LIGO/Virgo/KAGRA S250105bn: 1 counterpart neutrino candidate event from an IceCube neutrino search
  44. LIGO/Virgo/KAGRA S250119cv: Updated NED Galaxies in the Localization Volume
  45. LIGO/Virgo/KAGRA S250119cv: NED Galaxies in the Localization Volume
  46. LIGO/Virgo/KAGRA S250119cv: Identification of a GW compact binary merger candidate
  47. EP250108a/AT 2025kg: NOT spectroscopy in agreement with SN Ic-BL
  48. LIGO/Virgo/KAGRA S250119ag: Identification of a GW compact binary merger candidate
  49. LIGO/Virgo/KAGRA S250118dp: Identification of a GW compact binary merger candidate
  50. LIGO/Virgo/KAGRA S250118az: Identification of a GW compact binary merger candidate
  51. EP250108a / AT2025kg: GMG Optical Observations
  52. LIGO/Virgo/KAGRA S250118t: Identification of a GW compact binary merger candidate
  53. Konus-Wind detection of GRB 250116A
  54. GRB 241217A / EP241217B: radio detection with the VLA
  55. GRB 250116A: Fermi GBM Observation of an Extremely Interesting Burst
  56. GRB 250114B: Swift-XRT afterglow detection
  57. GRB 250114B: SVOM/VT upper limit
  58. LIGO/Virgo/KAGRA S250114ax: Updated NED Galaxies in the Localization Volume
  59. GRB 250101A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations and rebrightening.
  60. Konus-Wind detection of GRB 250113A
  61. LIGO/Virgo/KAGRA S250114ax: GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  62. GRB 250114B : MITSuME Akeno optical afterglow candidate detection
  63. GRB 250114B: Swift-XRT observations
  64. GRB 250114A: LCO optical counterpart detection.
  65. GRB 250114A: GRANDMA/TAROT optical afterglow detection
  66. GRB 250114A: LCOGT optical afterglow i-band detection
  67. GRB 250114B : GIT optical upper limit
  68. EP250111a: SAO RAS optical upper limit
  69. LIGO/Virgo/KAGRA S250114ax: NED Galaxies in the Localization Volume
  70. GRB 250114A: REM detection of the optical and NIR counterpart
  71. LIGO/Virgo/KAGRA S250114ax: Identification of a GW compact binary merger candidate
  72. GRB 250114A: LCO optical observations
  73. GRB 250114A: TRT optical observations
  74. GRB 250114A: Swift detection of a burst with an optical counterpart
  75. EP250108a / AT 2025kg: SAO RAS optical observations
  76. GRB 250107A: VZLUSAT-2 detection
  77. GRB 250109A / EP250109a: GRBAlpha detection
  78. GRB 250107D: GRBAlpha detection
  79. GRB 250106A: Swift-XRT afterglow detection
  80. EP250111a: KAIT optical observations
  81. GRB 250109A / EP250109a: Mephisto optical upper limits
  82. EP250108a: Mephisto detection
  83. EP250108a / AT 2025kg: LCO optical observations
  84. EP250109a/GRB 250109A:SVOM/VT optical counterpart
  85. GRB 250109A / EP250109a: Terskol (INASAN) and SAO RAS observations
  86. GRB 250109A / EP250109a: Swift detection of the X-ray afterglow
  87. GRB 250107D: CALET Gamma-Ray Burst Monitor detection
  88. GRB 250107C: CALET Gamma-Ray Burst Monitor detection
  89. Konus-Wind detection of GRB 250107C
  90. EP-WXT trigger EP250108a:Xinglong optical follow-up observations
  91. EP250108a: EP-FXT follow-up observation
  92. EP-WXT trigger EP250109a:Xinglong optical follow-up observations
  93. GRB 250109a: GMG Optical Upper Limit
  94. EP250109a: Swift/UVOT non-detection
  95. Konus-Wind detection of GRB 250107D (short/hard)
  96. IPN triangulation of GRB 250107C
  97. GRB 250108B: Swift-BAT refined analysis
  98. GRB 250108B: REM optical/NIR upper limits
  99. EP250109a: SVOM/VT optical candidate
  100. EP250109a: GOTO optical upper limits

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