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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"

23587 results found.

  1. GRB 241223A: cubesat Avion detection
  2. EP250125a: Optical upper limit with Kinder observations
  3. EP250125a: REM optical counterpart detection
  4. EP250125a: Swift/XRT detection of a fading counterpart
  5. EP250125a: a new X-ray transient detected by Einstein Probe
  6. EP250125a: Gemini-South optical afterglow discovery and redshift z = 2.89
  7. GRB 250121A: Swift/BAT-GUANO localization skymap of a burst
  8. EP250108a: AbAO, CMO and Terskol optical upper limits
  9. Konus-Wind detection of GRB 250118B
  10. IPN triangulation of GRB 250118B
  11. Konus-Wind detection of GRB 250119B
  12. IPN triangulation of GRB 250119B
  13. Improved IPN triangulation of GRB 250107C
  14. LIGO/Virgo S250119cv: Swift XRT observations, 5 X-ray sources
  15. GRB 250119C: Swift/BAT-GUANO localization skymap of a short burst
  16. GRB 250119B: Swift/BAT-GUANO localization skymap of a long burst
  17. Fermi-LAT Gamma-ray Observations of IceCube-241224A
  18. GRB 250118A: Swift/BAT-GUANO localization skymap of a short burst
  19. EP250108a/AT2025kg: 1.3m DFOT Optical observations
  20. Konus-Wind detection of GRB 250117A
  21. IPN triangulation of GRB 250117A (short)
  22. LIGO/Virgo/KAGRA S250119cv: GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  23. EP 250108A: Late-time optical observation by LCO
  24. LIGO/Virgo/KAGRA S250105bn: 1 counterpart neutrino candidate event from an IceCube neutrino search
  25. LIGO/Virgo/KAGRA S250119cv: Updated Sky localization and EM Bright Classification
  26. LIGO/Virgo/KAGRA S250119cv: NED Galaxies in the Localization Volume
  27. GRB 250117A: Swift/BAT-GUANO localization skymap of a short burst
  28. LIGO/Virgo/KAGRA S250119cv: Identification of a GW compact binary merger candidate
  29. LIGO/Virgo/KAGRA S250119ag: Identification of a GW compact binary merger candidate
  30. LIGO/Virgo/KAGRA S250118dp: Identification of a GW compact binary merger candidate
  31. LIGO/Virgo/KAGRA S250118az: Identification of a GW compact binary merger candidate
  32. EP250108a / AT2025kg: GMG Optical Observations
  33. LIGO/Virgo/KAGRA S250118t: Identification of a GW compact binary merger candidate
  34. EP250108a / AT2025kg: VLA radio upper limit
  35. Konus-Wind detection of GRB 250116A
  36. GRB 241217A / EP241217B: radio detection with the VLA
  37. GRB 250114B: Swift-XRT afterglow detection
  38. GRB 250114B: SVOM/VT upper limit
  39. EP250108a: MeerKAT radio upper limit
  40. GRB 250101A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations and rebrightening.
  41. IPN triangulation of GRB 250113A
  42. GRB 250114B: Liverpool Telescope optical upper limit
  43. LIGO/Virgo/KAGRA S250114ax: GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  44. GRB 250114B : MITSuME Akeno optical afterglow candidate detection
  45. GRB 250114B: Swift-XRT observations
  46. GRB 250114A: LCO optical counterpart detection.
  47. GRB 250114B: OHP/T193 optical upper limit
  48. GRB 250114A: GRANDMA/TAROT optical afterglow detection
  49. GRB 250114A: Swift-XRT refined Analysis
  50. GRB 250114A: LCOGT optical afterglow i-band detection
  51. GRB 250114B : GIT optical upper limit
  52. EP250111a: SAO RAS optical upper limit
  53. LIGO/Virgo/KAGRA S250114ax: NED Galaxies in the Localization Volume
  54. GRB 250114A: Enhanced Swift-XRT position
  55. GRB 250113A: INTEGRAL/SPI-ACS detection
  56. GRB 250114A: REM detection of the optical and NIR counterpart
  57. LIGO/Virgo/KAGRA S250114ax: Identification of a GW compact binary merger candidate
  58. GRB 250114A: LCO optical observations
  59. GRB 250114A: TRT optical observations
  60. GRB 250114A: Swift detection of a burst with an optical counterpart
  61. GRB 250101A: Terskol Zeiss-2000 optical observations
  62. EP250108a / AT 2025kg: SAO RAS optical observations
  63. EP241021a: SMA radio observation
  64. GRB 250113A: SVOM/GRM observation of a long burst
  65. EP250109b: optical upper limits with the Liverpool Telescope
  66. GRB 250106A: Swift-XRT afterglow detection
  67. EP250111a: KAIT optical observations
  68. GRB 250109A / EP250109a: Mephisto optical upper limits
  69. EP250108a: Mephisto detection
  70. EP250111a: Mondy optical observation
  71. EP250108a / AT 2025kg: LCO optical observations
  72. EP250108a / AT 2025kg: Swift UVOT detections
  73. EP250111a: NOT likely optical counterpart
  74. GRB 250109A / EP250109a: Terskol (INASAN) and SAO RAS observations
  75. GRB 250109A / EP250109A: Swift/BAT-GUANO localization skymap of a burst
  76. EP-WXT trigger EP250108a：Xinglong optical follow-up observations
  77. GRB 250101A: CMO RC-500 optical observations
  78. EP250109a / GRB 250109A: refined EP-WXT analysis and EP-FXT follow-up observation
  79. EP250108a: EP-FXT follow-up observation
  80. EP250108a: NOT optical observations
  81. EP-WXT trigger EP250109a：Xinglong optical follow-up observations
  82. GRB 250109a: GMG Optical Upper Limit
  83. EP250109a: Swift/UVOT non-detection
  84. Konus-Wind detection of GRB 250107D (short/hard)
  85. IPN triangulation of GRB 250107D (short/hard)
  86. IPN triangulation of GRB 250107C
  87. EP250108a: Liverpool Telescope likely optical counterpart
  88. GRB 250108B: 1.3m DFOT upper limit
  89. GRB 250108B: REM optical/NIR upper limits
  90. EP250109a: SVOM/VT optical candidate
  91. GRB 250101A: Terskol K-800 optical observations
  92. EP250109a: GOTO optical upper limits
  93. EP250109a: Swift/XRT non-detection
  94. GRB 250108A: Swift/UVOT Upper Limits
  95. EP250109a: EP-WXT detection of an X-ray transient
  96. LIGO/Virgo/KAGRA S250109bi: Identification of a GW compact binary merger candidate
  97. GRB 250108A: NOT optical upper limit
  98. EP250108a: EP-WXT detection of an X-ray transient
  99. LIGO/Virgo/KAGRA S250109f: Identification of a GW compact binary merger candidate
  100. GRB 250103A: 1.6m Mephisto optical observations

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