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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"

43960 results found.

  1. Swift GRB250114A: Global MASTER-Net OT detection
  2. GRB 250114A: LCO optical observations
  3. GRB 250114A: TRT optical observations
  4. Swift GRB 250114A: Global MASTER-Net observations report
  5. GRB 250114A: Swift detection of a burst with an optical counterpart
  6. GRB 250101A: Terskol Zeiss-2000 optical observations
  7. EP250108a / AT 2025kg: SAO RAS optical observations
  8. EP241021a: SMA radio observation
  9. GRB 250113A: SVOM/GRM observation of a long burst
  10. GRB 250107A: VZLUSAT-2 detection
  11. EP250109b: optical upper limits with the Liverpool Telescope
  12. GRB 250109A / EP250109a: GRBAlpha detection
  13. GRB 250107D: GRBAlpha detection
  14. GRB 250106A: Swift-XRT afterglow detection
  15. Fermi trigger No 758442826: Global MASTER-Net observations report
  16. EP250111a: KAIT optical observations
  17. GRB 250109A / EP250109a: Mephisto optical upper limits
  18. EP250108a: Mephisto detection
  19. EP250111a: Mondy optical observation
  20. EP250108a / AT 2025kg: LCO optical observations
  21. EP250111a: Global MASTER-Net observations report
  22. EP250111a: Swift/XRT detection and fading
  23. EP250108a / AT 2025kg: Swift UVOT detections
  24. EP250108a / AT 2025kg (the "kangaroo”): VLT/X-shooter spectroscopic redshift z = 0.176 and LFBOT classification
  25. EP250108a: optical follow-up observations with the Liverpool Telescope
  26. EP250111a: NOT likely optical counterpart
  27. EP250111a: a new X-ray transient detected by Einstein Probe
  28. EP250109a/GRB 250109A:SVOM/VT optical counterpart
  29. GRB 250101B: Fermi GBM Observation
  30. EP250108a: further NOT optical observations
  31. GRB 250109A / EP250109a: Terskol (INASAN) and SAO RAS observations
  32. GRB 250109A / EP250109A: Swift/BAT-GUANO localization skymap of a burst
  33. GRB 250109A / EP250109a: Swift detection of the X-ray afterglow
  34. GRB 250107D: CALET Gamma-Ray Burst Monitor detection
  35. GRB 250107C: CALET Gamma-Ray Burst Monitor detection
  36. Konus-Wind detection of GRB 250107C
  37. LIGO/Virgo/KAGRA S250109bi: Updated Sky localization
  38. LIGO/Virgo/KAGRA S250109f: Updated Sky localization
  39. LIGO/Virgo/KAGRA S250108eo: Updated Sky localization
  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. EP250108a: EP-FXT follow-up observation
  44. GRB 250109A: Fermi GBM Observation
  45. The EP-WXT trigger 01709130111 is likely a flaring star
  46. EP250108a: NOT optical observations
  47. EP-WXT trigger EP250109a：Xinglong optical follow-up observations
  48. EP250109a: Swift/UVOT non-detection
  49. Konus-Wind detection of GRB 250107D (short/hard)
  50. IPN triangulation of GRB 250107D (short/hard)
  51. IPN triangulation of GRB 250107C
  52. EP250108a: Liverpool Telescope likely optical counterpart
  53. GRB 250108B: Gemini-North likely redshift z = 2.197
  54. GRB 250108B: Swift-BAT refined analysis
  55. GRB 250108B: 1.3m DFOT upper limit
  56. GRB 250108B: REM optical/NIR upper limits
  57. GRB 250109A /EP250109a: Fermi GBM Final Localization
  58. EP250109a: SVOM/VT optical candidate
  59. EP250109a: Global MASTER-Net observations report
  60. GRB 250107C: SVOM/GRM observation
  61. GRB 250101A: Terskol K-800 optical observations
  62. EP250109a: GOTO optical upper limits
  63. EP250109a: Swift/XRT non-detection
  64. GRB 250108A: Swift/UVOT Upper Limits
  65. EP250108a: Global MASTER-Net observations report
  66. EP250109a: EP-WXT detection of an X-ray transient
  67. LIGO/Virgo/KAGRA S250109bi: Identification of a GW compact binary merger candidate
  68. GRB 250108A: NOT optical upper limit
  69. EP250108a: EP-WXT detection of an X-ray transient
  70. LIGO/Virgo/KAGRA S250109f: Identification of a GW compact binary merger candidate
  71. GRB 250108B: Swift-XRT refined Analysis
  72. Swift GRB 250108B: Global MASTER-Net observations report
  73. Fermi Gamma-ray Burst Monitor trigger 758061038/250108855 is not a GRB
  74. LIGO/Virgo/KAGRA S250108ha: Retraction of GW compact binary merger candidate
  75. GRB 250108B: Gemini-North Candidate Optical Afterglow Detection
  76. GRB 250103A: 1.6m Mephisto optical observations
  77. GRB 250108A: Swift-XRT afterglow detection
  78. GRB 250108A:SVOM/VT optical candidate
  79. LIGO/Virgo/KAGRA S250108eo: Identification of a GW compact binary merger candidate
  80. GRB 250108B: Swift/UVOT Upper Limits
  81. GRB 250103A: Swift-XRT afterglow detection
  82. GRB 250108B: Enhanced Swift-XRT position
  83. GRB 250108B: Swift detection of a burst
  84. GRB 250108A: Swift ToO observations
  85. GRB 250108A: SVOM detection of a soft long burst
  86. GRB 250107A: Fermi GBM Observation
  87. GRB 241228B: Fermi-LAT detection
  88. Fermi GRB 250107B: Global MASTER-Net observations report
  89. GRB 250107A: Swift ToO observations
  90. GRB 250107A: Swift/BAT-GUANO arcminute localization of a burst
  91. GRB 250107B: Fermi GBM Final Real-time Localization
  92. GRB 250106A: SVOM/VT 2nd optical deep observation
  93. GRB 250101A: J band upper limit by SYSU 80cm telescope
  94. GRB 250107A: Fermi GBM Final Real-time Localization
  95. EPWXT01709129925: Xinglong optical observations
  96. GRB 250106A: NOT optical observations
  97. LIGO/Virgo/KAGRA S250104v: Updated Sky localization
  98. GRB 250103B: REM optical/NIR upper limits
  99. GRB 250101A: REM optical/NIR counterpart detection
  100. GRB 250106A: Swift-XRT observations

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