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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"

39059 results found.

  1. GRB 250114B: OHP/T193 optical upper limit
  2. GRB 250114A: GRANDMA/TAROT optical afterglow detection
  3. GRB 250114A: Swift-XRT refined Analysis
  4. Integral GRB250114.55: Global MASTER-Net observations report
  5. GRB 250114A: LCOGT optical afterglow i-band detection
  6. GRB 250114B : GIT optical upper limit
  7. GRB 250114B: Swift ToO observations
  8. EP250111a: SAO RAS optical upper limit
  9. GRB 250114B: a short GRB detected with INTEGRAL
  10. GRB 250114A: Enhanced Swift-XRT position
  11. GRB 250113A: INTEGRAL/SPI-ACS detection
  12. GRB 250114A: VLT/X-shooter spectroscopic redshift z = 4.732
  13. GRB 250114A: REM detection of the optical and NIR counterpart
  14. Swift GRB250114A: Global MASTER-Net OT detection
  15. GRB 250114A: LCO optical observations
  16. GRB 250114A: TRT optical observations
  17. Swift GRB 250114A: Global MASTER-Net observations report
  18. GRB 250114A: Swift detection of a burst with an optical counterpart
  19. GRB 250101A: Terskol Zeiss-2000 optical observations
  20. EP250108a / AT 2025kg: SAO RAS optical observations
  21. GRB 250113A: SVOM/GRM observation of a long burst
  22. GRB 250107A: VZLUSAT-2 detection
  23. GRB 250109A / EP250109a: GRBAlpha detection
  24. GRB 250107D: GRBAlpha detection
  25. GRB 250106A: Swift-XRT afterglow detection
  26. Fermi trigger No 758442826: Global MASTER-Net observations report
  27. EP250111a: KAIT optical observations
  28. GRB 250109A / EP250109a: Mephisto optical upper limits
  29. EP250108a: Mephisto detection
  30. EP250111a: Mondy optical observation
  31. EP250108a / AT 2025kg: LCO optical observations
  32. EP250111a: Global MASTER-Net observations report
  33. EP250109a/GRB 250109A:SVOM/VT optical counterpart
  34. GRB 250101B: Fermi GBM Observation
  35. EP250108a: further NOT optical observations
  36. GRB 250109A / EP250109a: Terskol (INASAN) and SAO RAS observations
  37. GRB 250109A / EP250109A: Swift/BAT-GUANO localization skymap of a burst
  38. GRB 250109A / EP250109a: Swift detection of the X-ray afterglow
  39. GRB 250108A: Swift/XRT afterglow fading
  40. GRB 250107D: CALET Gamma-Ray Burst Monitor detection
  41. GRB 250107C: CALET Gamma-Ray Burst Monitor detection
  42. Konus-Wind detection of GRB 250107C
  43. EP-WXT trigger EP250108a：Xinglong optical follow-up observations
  44. GRB 250101A: CMO RC-500 optical observations
  45. EP250109a / GRB 250109A: refined EP-WXT analysis and EP-FXT follow-up observation
  46. GRB 250109A: Fermi GBM Observation
  47. EP250108a: NOT optical observations
  48. EP-WXT trigger EP250109a：Xinglong optical follow-up observations
  49. GRB 250109a: GMG Optical Upper Limit
  50. Konus-Wind detection of GRB 250107D (short/hard)
  51. IPN triangulation of GRB 250107D (short/hard)
  52. IPN triangulation of GRB 250107C
  53. EP250108a: Liverpool Telescope likely optical counterpart
  54. GRB 250108B: Gemini-North likely redshift z = 2.197
  55. GRB 250108B: Swift-BAT refined analysis
  56. GRB 250108B: 1.3m DFOT upper limit
  57. GRB 250108B: REM optical/NIR upper limits
  58. GRB 250109A /EP250109a: Fermi GBM Final Localization
  59. EP250109a: SVOM/VT optical candidate
  60. EP250109a: Global MASTER-Net observations report
  61. GRB 250107C: SVOM/GRM observation
  62. GRB 250101A: Terskol K-800 optical observations
  63. EP250109a: Swift/XRT non-detection
  64. GRB 250108A: Swift/UVOT Upper Limits
  65. EP250108a: Global MASTER-Net observations report
  66. GRB 250108A: NOT optical upper limit
  67. GRB 250108B: Swift-XRT refined Analysis
  68. Swift GRB 250108B: Global MASTER-Net observations report
  69. Fermi Gamma-ray Burst Monitor trigger 758061038/250108855 is not a GRB
  70. LIGO/Virgo/KAGRA S250108ha: Retraction of GW compact binary merger candidate
  71. GRB 250108B: Gemini-North Candidate Optical Afterglow Detection
  72. GRB 250103A: 1.6m Mephisto optical observations
  73. GRB 250108A: Swift-XRT afterglow detection
  74. GRB 250108A:SVOM/VT optical candidate
  75. GRB 250108B: Swift/UVOT Upper Limits
  76. GRB 250103A: Swift-XRT afterglow detection
  77. GRB 250108B: Enhanced Swift-XRT position
  78. GRB 250108B: Swift detection of a burst
  79. GRB 250108A: Swift ToO observations
  80. GRB 250108A: SVOM detection of a soft long burst
  81. GRB 250107A: Fermi GBM Observation
  82. GRB 241228B: Fermi-LAT detection
  83. Fermi GRB 250107B: Global MASTER-Net observations report
  84. GRB 250107A: Swift ToO observations
  85. GRB 250107A: Swift/BAT-GUANO arcminute localization of a burst
  86. GRB 250107B: Fermi GBM Final Real-time Localization
  87. GRB 250106A: SVOM/VT 2nd optical deep observation
  88. GRB 250101A: J band upper limit by SYSU 80cm telescope
  89. GRB 250107A: Fermi GBM Final Real-time Localization
  90. GRB 250106A: NOT optical observations
  91. GRB 250103B: REM optical/NIR upper limits
  92. GRB 250101A: REM optical/NIR counterpart detection
  93. GRB 250106A: Swift-XRT observations
  94. GRB 250106A: SVOM/VT optical candidate
  95. GRB 250106A: Swift ToO observations
  96. GRB 250106A: SVOM detection of a long burst
  97. Fermi trigger No 757753930: Global MASTER-Net observations report
  98. GRB 241229A: SVOM/VT optical upperlimit
  99. GRB 250103B: Swift-XRT refined Analysis
  100. GRB 250103B: LCO/1m optical afterglow candidate detection

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