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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"

39156 results found.

  1. Integral GRB250114.55: Global MASTER-Net observations report
  2. GRB 250114A: LCOGT optical afterglow i-band detection
  3. GRB 250114B : GIT optical upper limit
  4. GRB 250114B: Swift ToO observations
  5. EP250111a: SAO RAS optical upper limit
  6. GRB 250114B: a short GRB detected with INTEGRAL
  7. GRB 250114A: Enhanced Swift-XRT position
  8. GRB 250113A: INTEGRAL/SPI-ACS detection
  9. GRB 250114A: VLT/X-shooter spectroscopic redshift z = 4.732
  10. GRB 250114A: REM detection of the optical and NIR counterpart
  11. Swift GRB250114A: Global MASTER-Net OT detection
  12. GRB 250114A: LCO optical observations
  13. GRB 250114A: TRT optical observations
  14. Swift GRB 250114A: Global MASTER-Net observations report
  15. GRB 250114A: Swift detection of a burst with an optical counterpart
  16. GRB 250101A: Terskol Zeiss-2000 optical observations
  17. EP250108a / AT 2025kg: SAO RAS optical observations
  18. GRB 250113A: SVOM/GRM observation of a long burst
  19. GRB 250107A: VZLUSAT-2 detection
  20. GRB 250109A / EP250109a: GRBAlpha detection
  21. GRB 250107D: GRBAlpha detection
  22. GRB 250106A: Swift-XRT afterglow detection
  23. Fermi trigger No 758442826: Global MASTER-Net observations report
  24. EP250111a: KAIT optical observations
  25. GRB 250109A / EP250109a: Mephisto optical upper limits
  26. EP250108a: Mephisto detection
  27. EP250111a: Mondy optical observation
  28. EP250108a / AT 2025kg: LCO optical observations
  29. EP250111a: Global MASTER-Net observations report
  30. EP250109a/GRB 250109A:SVOM/VT optical counterpart
  31. GRB 250101B: Fermi GBM Observation
  32. EP250108a: further NOT optical observations
  33. GRB 250109A / EP250109a: Terskol (INASAN) and SAO RAS observations
  34. GRB 250109A / EP250109A: Swift/BAT-GUANO localization skymap of a burst
  35. GRB 250109A / EP250109a: Swift detection of the X-ray afterglow
  36. GRB 250108A: Swift/XRT afterglow fading
  37. GRB 250107D: CALET Gamma-Ray Burst Monitor detection
  38. GRB 250107C: CALET Gamma-Ray Burst Monitor detection
  39. Konus-Wind detection of GRB 250107C
  40. EP-WXT trigger EP250108a：Xinglong optical follow-up observations
  41. GRB 250101A: CMO RC-500 optical observations
  42. EP250109a / GRB 250109A: refined EP-WXT analysis and EP-FXT follow-up observation
  43. GRB 250109A: Fermi GBM Observation
  44. EP250108a: NOT optical observations
  45. EP-WXT trigger EP250109a：Xinglong optical follow-up observations
  46. GRB 250109a: GMG Optical Upper Limit
  47. Konus-Wind detection of GRB 250107D (short/hard)
  48. IPN triangulation of GRB 250107D (short/hard)
  49. IPN triangulation of GRB 250107C
  50. EP250108a: Liverpool Telescope likely optical counterpart
  51. GRB 250108B: Gemini-North likely redshift z = 2.197
  52. GRB 250108B: Swift-BAT refined analysis
  53. GRB 250108B: 1.3m DFOT upper limit
  54. GRB 250108B: REM optical/NIR upper limits
  55. GRB 250109A /EP250109a: Fermi GBM Final Localization
  56. EP250109a: SVOM/VT optical candidate
  57. EP250109a: Global MASTER-Net observations report
  58. GRB 250107C: SVOM/GRM observation
  59. GRB 250101A: Terskol K-800 optical observations
  60. EP250109a: Swift/XRT non-detection
  61. GRB 250108A: Swift/UVOT Upper Limits
  62. EP250108a: Global MASTER-Net observations report
  63. GRB 250108A: NOT optical upper limit
  64. GRB 250108B: Swift-XRT refined Analysis
  65. Swift GRB 250108B: Global MASTER-Net observations report
  66. Fermi Gamma-ray Burst Monitor trigger 758061038/250108855 is not a GRB
  67. LIGO/Virgo/KAGRA S250108ha: Retraction of GW compact binary merger candidate
  68. GRB 250108B: Gemini-North Candidate Optical Afterglow Detection
  69. GRB 250103A: 1.6m Mephisto optical observations
  70. GRB 250108A: Swift-XRT afterglow detection
  71. GRB 250108A:SVOM/VT optical candidate
  72. GRB 250108B: Swift/UVOT Upper Limits
  73. GRB 250103A: Swift-XRT afterglow detection
  74. GRB 250108B: Enhanced Swift-XRT position
  75. GRB 250108B: Swift detection of a burst
  76. GRB 250108A: Swift ToO observations
  77. GRB 250108A: SVOM detection of a soft long burst
  78. GRB 250107A: Fermi GBM Observation
  79. GRB 241228B: Fermi-LAT detection
  80. Fermi GRB 250107B: Global MASTER-Net observations report
  81. GRB 250107A: Swift ToO observations
  82. GRB 250107A: Swift/BAT-GUANO arcminute localization of a burst
  83. GRB 250107B: Fermi GBM Final Real-time Localization
  84. GRB 250106A: SVOM/VT 2nd optical deep observation
  85. GRB 250101A: J band upper limit by SYSU 80cm telescope
  86. GRB 250107A: Fermi GBM Final Real-time Localization
  87. GRB 250106A: NOT optical observations
  88. GRB 250103B: REM optical/NIR upper limits
  89. GRB 250101A: REM optical/NIR counterpart detection
  90. GRB 250106A: Swift-XRT observations
  91. GRB 250106A: SVOM/VT optical candidate
  92. GRB 250106A: Swift ToO observations
  93. GRB 250106A: SVOM detection of a long burst
  94. Fermi trigger No 757753930: Global MASTER-Net observations report
  95. GRB 241229A: SVOM/VT optical upperlimit
  96. GRB 250103B: Swift-XRT refined Analysis
  97. GRB 250103B: LCO/1m optical afterglow candidate detection
  98. GRB 250103A: Bassano Bresciano Observatory upper limit
  99. GRB 250103B: VLT/X-shooter spectroscopic redshift z = 1.416
  100. GRB 250103A: Swift-XRT observations

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