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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"

43962 results found.

  1. GRB 250114A: REM detection of the optical and NIR counterpart
  2. LIGO/Virgo/KAGRA S250114ax: Identification of a GW compact binary merger candidate
  3. Swift GRB250114A: Global MASTER-Net OT detection
  4. GRB 250114A: LCO optical observations
  5. GRB 250114A: TRT optical observations
  6. Swift GRB 250114A: Global MASTER-Net observations report
  7. GRB 250114A: Swift detection of a burst with an optical counterpart
  8. GRB 250101A: Terskol Zeiss-2000 optical observations
  9. EP250108a / AT 2025kg: SAO RAS optical observations
  10. EP241021a: SMA radio observation
  11. GRB 250113A: SVOM/GRM observation of a long burst
  12. GRB 250107A: VZLUSAT-2 detection
  13. EP250109b: optical upper limits with the Liverpool Telescope
  14. GRB 250109A / EP250109a: GRBAlpha detection
  15. GRB 250107D: GRBAlpha detection
  16. GRB 250106A: Swift-XRT afterglow detection
  17. Fermi trigger No 758442826: Global MASTER-Net observations report
  18. EP250111a: KAIT optical observations
  19. GRB 250109A / EP250109a: Mephisto optical upper limits
  20. EP250108a: Mephisto detection
  21. EP250111a: Mondy optical observation
  22. EP250108a / AT 2025kg: LCO optical observations
  23. EP250111a: Global MASTER-Net observations report
  24. EP250111a: Swift/XRT detection and fading
  25. EP250108a / AT 2025kg: Swift UVOT detections
  26. EP250108a / AT 2025kg (the "kangaroo”): VLT/X-shooter spectroscopic redshift z = 0.176 and LFBOT classification
  27. EP250108a: optical follow-up observations with the Liverpool Telescope
  28. EP250111a: NOT likely optical counterpart
  29. EP250111a: a new X-ray transient detected by Einstein Probe
  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 250107D: CALET Gamma-Ray Burst Monitor detection
  37. GRB 250107C: CALET Gamma-Ray Burst Monitor detection
  38. Konus-Wind detection of GRB 250107C
  39. LIGO/Virgo/KAGRA S250109bi: Updated Sky localization
  40. LIGO/Virgo/KAGRA S250109f: Updated Sky localization
  41. LIGO/Virgo/KAGRA S250108eo: Updated Sky localization
  42. EP-WXT trigger EP250108a：Xinglong optical follow-up observations
  43. GRB 250101A: CMO RC-500 optical observations
  44. EP250109a / GRB 250109A: refined EP-WXT analysis and EP-FXT follow-up observation
  45. EP250108a: EP-FXT follow-up observation
  46. GRB 250109A: Fermi GBM Observation
  47. The EP-WXT trigger 01709130111 is likely a flaring star
  48. EP250108a: NOT optical observations
  49. EP-WXT trigger EP250109a：Xinglong optical follow-up observations
  50. EP250109a: Swift/UVOT non-detection
  51. Konus-Wind detection of GRB 250107D (short/hard)
  52. IPN triangulation of GRB 250107D (short/hard)
  53. IPN triangulation of GRB 250107C
  54. EP250108a: Liverpool Telescope likely optical counterpart
  55. GRB 250108B: Gemini-North likely redshift z = 2.197
  56. GRB 250108B: Swift-BAT refined analysis
  57. GRB 250108B: 1.3m DFOT upper limit
  58. GRB 250108B: REM optical/NIR upper limits
  59. GRB 250109A /EP250109a: Fermi GBM Final Localization
  60. EP250109a: SVOM/VT optical candidate
  61. EP250109a: Global MASTER-Net observations report
  62. GRB 250107C: SVOM/GRM observation
  63. GRB 250101A: Terskol K-800 optical observations
  64. EP250109a: GOTO optical upper limits
  65. EP250109a: Swift/XRT non-detection
  66. GRB 250108A: Swift/UVOT Upper Limits
  67. EP250108a: Global MASTER-Net observations report
  68. EP250109a: EP-WXT detection of an X-ray transient
  69. LIGO/Virgo/KAGRA S250109bi: Identification of a GW compact binary merger candidate
  70. GRB 250108A: NOT optical upper limit
  71. EP250108a: EP-WXT detection of an X-ray transient
  72. LIGO/Virgo/KAGRA S250109f: Identification of a GW compact binary merger candidate
  73. GRB 250108B: Swift-XRT refined Analysis
  74. Swift GRB 250108B: Global MASTER-Net observations report
  75. Fermi Gamma-ray Burst Monitor trigger 758061038/250108855 is not a GRB
  76. LIGO/Virgo/KAGRA S250108ha: Retraction of GW compact binary merger candidate
  77. GRB 250108B: Gemini-North Candidate Optical Afterglow Detection
  78. GRB 250103A: 1.6m Mephisto optical observations
  79. GRB 250108A: Swift-XRT afterglow detection
  80. GRB 250108A:SVOM/VT optical candidate
  81. LIGO/Virgo/KAGRA S250108eo: Identification of a GW compact binary merger candidate
  82. GRB 250108B: Swift/UVOT Upper Limits
  83. GRB 250103A: Swift-XRT afterglow detection
  84. GRB 250108B: Enhanced Swift-XRT position
  85. GRB 250108B: Swift detection of a burst
  86. GRB 250108A: Swift ToO observations
  87. GRB 250108A: SVOM detection of a soft long burst
  88. GRB 250107A: Fermi GBM Observation
  89. GRB 241228B: Fermi-LAT detection
  90. Fermi GRB 250107B: Global MASTER-Net observations report
  91. GRB 250107A: Swift ToO observations
  92. GRB 250107A: Swift/BAT-GUANO arcminute localization of a burst
  93. GRB 250107B: Fermi GBM Final Real-time Localization
  94. GRB 250106A: SVOM/VT 2nd optical deep observation
  95. GRB 250101A: J band upper limit by SYSU 80cm telescope
  96. GRB 250107A: Fermi GBM Final Real-time Localization
  97. EPWXT01709129925: Xinglong optical observations
  98. GRB 250106A: NOT optical observations
  99. LIGO/Virgo/KAGRA S250104v: Updated Sky localization
  100. GRB 250103B: REM optical/NIR upper limits

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