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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"

36804 results found.

  1. GRB 250119B: Fermi GBM Observation
  2. Konus-Wind detection of GRB 250117A
  3. IPN triangulation of GRB 250117A (short)
  4. ATCA detection of possible radio counterpart to GRB 250114A
  5. GRB 250119B: INTEGRAL/SPI-ACS detection
  6. EP 250108A: Late-time optical observation by LCO
  7. GRB 250117A: SVOM/GRM observation of a short burst
  8. GRB 250119C: Fermi GBM Final Real-time Localization
  9. GRB 250117A: Swift/BAT-GUANO localization skymap of a short burst
  10. EP250108a / SN2025kg: Gemini GMOS-S confirmation of an associated broad-lined SN Ic
  11. EP250108a/AT 2025kg: NOT spectroscopy in agreement with SN Ic-BL
  12. EP250108a / AT 2025kg: the kangaroo is hopping, evidence for optical rebrightening
  13. GRB 250117A: GECAM observation of a short burst
  14. GRB 250119B: BALROG localization (Fermi Trigger 758968026 / GRB 250119352)
  15. GRB 250119B: Fermi GBM Final Real-time Localization
  16. GRB 250119A: Fermi GBM Final Real-time Localization
  17. GRB 250118A: Fermi GBM Final Real-time Localization
  18. EP250108a / AT2025kg: VLA radio upper limit
  19. Fermi Gamma-ray Burst Monitor trigger 758829338/250117747 is not a GRB
  20. Konus-Wind detection of GRB 250116A
  21. GRB 250116A: GECAM-B detection of a long burst
  22. GRB 241217A / EP241217B: radio detection with the VLA
  23. GRB 250116A: INTEGRAL/SPI-ACS and PICsIT detection
  24. Swift Trigger 1282245 is not a GRB
  25. GRB 250116A: Fermi-LAT detection
  26. GRB 250116A: Fermi GBM Observation of an Extremely Interesting Burst
  27. GRB 250114B: Swift-XRT afterglow detection
  28. GRB 250114B: SVOM/VT upper limit
  29. Fermi Gamma-ray Burst Monitor trigger 758659047/250115776 is not a GRB
  30. GRB 250101A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations and rebrightening.
  31. Konus-Wind detection of GRB 250113A
  32. IPN triangulation of GRB 250113A
  33. GRB 250114B: Liverpool Telescope optical upper limit
  34. GRB 250114B : MITSuME Akeno optical afterglow candidate detection
  35. GRB 250114B: Swift-XRT observations
  36. GRB 250114A: LCO optical counterpart detection.
  37. GRB 250114B: OHP/T193 optical upper limit
  38. GRB 250114A: GRANDMA/TAROT optical afterglow detection
  39. GRB 250114A: Swift-XRT refined Analysis
  40. GRB 250114A: LCOGT optical afterglow i-band detection
  41. GRB 250114B : GIT optical upper limit
  42. GRB 250114B: Swift ToO observations
  43. EP250111a: SAO RAS optical upper limit
  44. GRB 250114B: a short GRB detected with INTEGRAL
  45. GRB 250114A: Enhanced Swift-XRT position
  46. GRB 250113A: INTEGRAL/SPI-ACS detection
  47. GRB 250114A: VLT/X-shooter spectroscopic redshift z = 4.732
  48. GRB 250114A: REM detection of the optical and NIR counterpart
  49. GRB 250114A: LCO optical observations
  50. GRB 250114A: TRT optical observations
  51. Swift GRB 250114A: Global MASTER-Net observations report
  52. GRB 250114A: Swift detection of a burst with an optical counterpart
  53. GRB 250101A: Terskol Zeiss-2000 optical observations
  54. EP250108a / AT 2025kg: SAO RAS optical observations
  55. GRB 250113A: SVOM/GRM observation of a long burst
  56. GRB 250107A: VZLUSAT-2 detection
  57. GRB 250109A / EP250109a: GRBAlpha detection
  58. GRB 250107D: GRBAlpha detection
  59. GRB 250106A: Swift-XRT afterglow detection
  60. Fermi trigger No 758442826: Global MASTER-Net observations report
  61. EP250111a: KAIT optical observations
  62. GRB 250109A / EP250109a: Mephisto optical upper limits
  63. EP250111a: Mondy optical observation
  64. EP250109a/GRB 250109A:SVOM/VT optical counterpart
  65. GRB 250101B: Fermi GBM Observation
  66. EP250108a: further NOT optical observations
  67. GRB 250109A / EP250109a: Terskol (INASAN) and SAO RAS observations
  68. GRB 250109A / EP250109A: Swift/BAT-GUANO localization skymap of a burst
  69. GRB 250109A / EP250109a: Swift detection of the X-ray afterglow
  70. GRB 250108A: Swift/XRT afterglow fading
  71. GRB 250107D: CALET Gamma-Ray Burst Monitor detection
  72. GRB 250107C: CALET Gamma-Ray Burst Monitor detection
  73. Konus-Wind detection of GRB 250107C
  74. GRB 250101A: CMO RC-500 optical observations
  75. EP250109a / GRB 250109A: refined EP-WXT analysis and EP-FXT follow-up observation
  76. GRB 250109A: Fermi GBM Observation
  77. EP250108a: NOT optical observations
  78. GRB 250109a: GMG Optical Upper Limit
  79. Konus-Wind detection of GRB 250107D (short/hard)
  80. IPN triangulation of GRB 250107D (short/hard)
  81. IPN triangulation of GRB 250107C
  82. GRB 250108B: Gemini-North likely redshift z = 2.197
  83. GRB 250108B: Swift-BAT refined analysis
  84. GRB 250108B: 1.3m DFOT upper limit
  85. GRB 250108B: REM optical/NIR upper limits
  86. GRB 250109A /EP250109a: Fermi GBM Final Localization
  87. GRB 250107C: SVOM/GRM observation
  88. GRB 250101A: Terskol K-800 optical observations
  89. EP250109a: Swift/XRT non-detection
  90. GRB 250108A: Swift/UVOT Upper Limits
  91. GRB 250108A: NOT optical upper limit
  92. GRB 250108B: Swift-XRT refined Analysis
  93. Swift GRB 250108B: Global MASTER-Net observations report
  94. Fermi Gamma-ray Burst Monitor trigger 758061038/250108855 is not a GRB
  95. LIGO/Virgo/KAGRA S250108ha: Retraction of GW compact binary merger candidate
  96. GRB 250108B: Gemini-North Candidate Optical Afterglow Detection
  97. GRB 250103A: 1.6m Mephisto optical observations
  98. GRB 250108A: Swift-XRT afterglow detection
  99. GRB 250108A:SVOM/VT optical candidate
  100. GRB 250108B: Swift/UVOT Upper Limits

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