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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"

36153 results found.

  1. EP250109a / GRB 250109A: refined EP-WXT analysis and EP-FXT follow-up observation
  2. GRB 250109A: Fermi GBM Observation
  3. EP250108a: NOT optical observations
  4. GRB 250109a: GMG Optical Upper Limit
  5. Konus-Wind detection of GRB 250107D (short/hard)
  6. IPN triangulation of GRB 250107D (short/hard)
  7. IPN triangulation of GRB 250107C
  8. GRB 250108B: Gemini-North likely redshift z = 2.197
  9. GRB 250108B: Swift-BAT refined analysis
  10. GRB 250108B: 1.3m DFOT upper limit
  11. GRB 250108B: REM optical/NIR upper limits
  12. GRB 250109A /EP250109a: Fermi GBM Final Localization
  13. GRB 250107C: SVOM/GRM observation
  14. GRB 250101A: Terskol K-800 optical observations
  15. EP250109a: Swift/XRT non-detection
  16. GRB 250108A: Swift/UVOT Upper Limits
  17. GRB 250108A: NOT optical upper limit
  18. GRB 250108B: Swift-XRT refined Analysis
  19. Swift GRB 250108B: Global MASTER-Net observations report
  20. Fermi Gamma-ray Burst Monitor trigger 758061038/250108855 is not a GRB
  21. LIGO/Virgo/KAGRA S250108ha: Retraction of GW compact binary merger candidate
  22. GRB 250108B: Gemini-North Candidate Optical Afterglow Detection
  23. GRB 250103A: 1.6m Mephisto optical observations
  24. GRB 250108A: Swift-XRT afterglow detection
  25. GRB 250108A:SVOM/VT optical candidate
  26. GRB 250108B: Swift/UVOT Upper Limits
  27. GRB 250103A: Swift-XRT afterglow detection
  28. GRB 250108B: Enhanced Swift-XRT position
  29. GRB 250108B: Swift detection of a burst
  30. GRB 250108A: Swift ToO observations
  31. GRB 250108A: SVOM detection of a soft long burst
  32. GRB 250107A: Fermi GBM Observation
  33. GRB 241228B: Fermi-LAT detection
  34. Fermi GRB 250107B: Global MASTER-Net observations report
  35. GRB 250107A: Swift ToO observations
  36. GRB 250107A: Swift/BAT-GUANO arcminute localization of a burst
  37. GRB 250107B: Fermi GBM Final Real-time Localization
  38. GRB 250106A: SVOM/VT 2nd optical deep observation
  39. GRB 250101A: J band upper limit by SYSU 80cm telescope
  40. GRB 250107A: Fermi GBM Final Real-time Localization
  41. GRB 250106A: NOT optical observations
  42. GRB 250103B: REM optical/NIR upper limits
  43. GRB 250101A: REM optical/NIR counterpart detection
  44. GRB 250106A: Swift-XRT observations
  45. GRB 250106A: SVOM/VT optical candidate
  46. GRB 250106A: Swift ToO observations
  47. GRB 250106A: SVOM detection of a long burst
  48. GRB 241229A: SVOM/VT optical upperlimit
  49. GRB 250103B: Swift-XRT refined Analysis
  50. GRB 250103B: LCO/1m optical afterglow candidate detection
  51. GRB 250103A: Bassano Bresciano Observatory upper limit
  52. GRB 250103B: VLT/X-shooter spectroscopic redshift z = 1.416
  53. GRB 250103A: Swift-XRT observations
  54. GRB 250101A: 1.3m DFOT optical afterglow detection
  55. GRB 241229A: 1.3m DFOT upper limit
  56. GRB 241228B: 1.3m DFOT Optical observations
  57. GRB 241228A: 1.3m DFOT upper limit
  58. GRB 250103A: NOT spectroscopic redshift
  59. GRB 250103B：SVOM/VT optical counterpart
  60. GRB 250103A: Montarrenti Observatory optical detection
  61. GRB 250101A: further LCOGT optical afterglow observations
  62. GRB 250103A: Redshift 4.01 from OSIRIS+/GTC
  63. GRB 250103A: NOT optical observations
  64. GRB 250103A: TSHAO optical upper limit
  65. GRB 250103A: Fermi GBM Observation
  66. GRB 250103B: LCOGT Optical Upper Limit
  67. Swift GRB 250103B: Global MASTER-Net observations report
  68. GRB 250103A: SVOM/VT optical counterpart confirmation
  69. GRB 250103A: Swift ToO observations
  70. GRB 250101a: Liverpool Telescope optical follow-up
  71. GRB 250103B: SVOM detection of a long burst
  72. GRB 250103B: Swift detection of a burst
  73. GRB 250103A: Xinglong 2.16m Optical Candidate
  74. Fermi GRB 250102A: Global MASTER-Net observations report
  75. GRB 250101B: SVOM/GRM observation
  76. GRB 250103A: GOTO optical upper limit
  77. GRB 250103A: SVOM/C-GFT optical upper limit
  78. GRB 250101A: NUTTelA-TAO / BSTI Optical Limits
  79. GRB 250103A: SVOM detection of a long burst (duplicate submission)
  80. GRB 250103A: SVOM detection of a long burst
  81. GRB 250102A: Fermi GBM Final Real-time Localization
  82. LIGO/Virgo/KAGRA S241230bd: Upper limits from Swift/BAT-GUANO
  83. GRB 250101A: Swift-BAT refined analysis
  84. GRB 250101A: further SAO RAS optical observations
  85. GRB 250101A: LCO optical counterpart detection
  86. GRB 250101A NUTTelA-TAO / BSTI Early Measurements
  87. GRB 250101A: GMG spectroscopic redshift at z ~ 2.481
  88. GRB 250101A: Swift/UVOT Detection
  89. GRB 250101A: 1.6m Mephisto multi-band optical followup
  90. GRB 250101A: Swift-XRT refined Analysis
  91. Fermi Gamma-ray Burst Monitor trigger 757464861/250101954 is not a GRB
  92. GRB 250101A: Montarrenti Observatory optical observations and rebrightening
  93. GRB 250101A: LCOGT optical afterglow detection
  94. GRB 250101A: OASDG optical observations
  95. Fermi GRB 250101B: Global MASTER-Net observations report
  96. GRB 250101B: Fermi GBM Final Real-time Localization
  97. GRB 250101A: SAO RAS observations of optical brightening
  98. GRB 250101A: BOOTES-4/MET optical afterglow detection
  99. GRB 250101A: AKO Optical Afterglow Detection
  100. GRB 250101A: SAO RAS optical observations

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