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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"

36397 results found.

  1. EP250812a: Nickel optical upper limit
  2. GRB 250812A: VLT X-shooter spectroscopic redshift confirmation z = 2.571
  3. GRB 250812A: NTT spectroscopic redshift z = 2.57
  4. GRB 250812A: Swift/UVOT Detection
  5. GRB 250813A: Fermi GBM Final Localization
  6. GRB 250812A: EP-FXT counterpart detection
  7. GRB 250812A: Swift ToO observations
  8. GRB 250807B: Swift-BAT refined analysis
  9. GRB 250812A: Kilonova-Catcher optical afterglow detection
  10. Fermi Gamma-ray Burst Monitor trigger 776705265/250812644 is not a GRB
  11. GRB 250812A: SVOM/COLIBRÍ (FM-GFT) optical observations
  12. GRB 250812A: SVOM/VT optical afterglow confirmation
  13. GRB 250812A: Swift-XRT afterglow detection
  14. GRB 250812A: TRT likely optical counterpart detection
  15. GRB 250812A: SVOM detection of a faint long burst
  16. GRB 250809A: Swift-BAT refined analysis
  17. Fermi Gamma-ray Burst Monitor trigger 776620220/250811660 is not a GRB
  18. GRB 250807A: Swift-BAT refined analysis
  19. GRB 250809A: Swift/UVOT Detection
  20. Corrected Swift-XRT Refined Analysis of GRB 250809A
  21. GRB 250809A: Swift-XRT refined Analysis
  22. GRB 250807B: SVOM/VT optical observation
  23. GRB 250809A: LCOGT Optical Upper Limits
  24. GRB 250702B: Chandra X-ray Detection
  25. Fermi GRB 250808A: Global MASTER-Net observations report
  26. Fermi Gamma-ray Burst Monitor trigger 776449964/250809689 is not a GRB
  27. GRB 250808A: VLT X-shooter candidate counterpart
  28. GRB 250809A: Prompt enhanced Swift-XRT position
  29. GRB 250809A: Swift detection of a gamma ray burst
  30. GRB 250808A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  31. GRB 250808A: Fermi GBM Observation
  32. GRB 250808A: Swift-XRT candidate counterpart detection
  33. GRB 250807A: SVOM/VT optical continued observation
  34. EP-WXT trigger 01709195487: KAIT confirmation of the stellar flare
  35. GRB 250808A: SVOM detection of a long burst
  36. GRB 250808A: Fermi GBM Final Real-time Localization
  37. Konus-Wind detection of GRB 250807A
  38. GRB 250807B: Swift/UVOT Detection
  39. GRB 250807B: Kilonova-Catcher optical afterglow detection
  40. IceCube-250804A: Upper limits from a search for additional neutrino events in IceCube
  41. GRB 250807A: Swift/UVOT Detection
  42. GRB 250807A: Swift-XRT refined Analysis
  43. GRB 250807B: VLT/X-Shooter spectroscopic redshift z = 1.522
  44. GRB 250806A: SVOM/MXT refined analysis
  45. GRB 250806A: SVOM/ECLAIRs refined analysis
  46. GRB 250806A: Mondy optical observations, and nearby bright galaxy photometry
  47. GRB 250804B: Insight-HXMT detection
  48. GRB 250807A: SVOM/GRM observation
  49. GRB 250807A: AstroSat CZTI detection of bright long burst
  50. GRB 250807B: Swift-XRT refined Analysis
  51. GRB 250806A: NOT z-band upper limit and host galaxy candidate
  52. GRB 250807B: NTT optical observations
  53. GRB 250807A: SVOM/VT optical observation
  54. EP250806a: Upper limit from Fermi-GBM Observations
  55. GRB 250807B: Enhanced Swift-XRT position
  56. GRB 250807A: Enhanced Swift-XRT position
  57. GRB 250807B: Swift detection of a burst with an optical counterpart.
  58. GRB 250805A: Kilonova-Catcher optical upper limits
  59. GRB 250805A: Swift/UVOT Upper Limits
  60. GRB 250806A: Swift/UVOT U-band detection
  61. GRB 250807A: Swift detection of a burst with an optical counterpart
  62. GRB 250806A: EP-FXT observation
  63. GRB 250806A: J-band upper limit from WINTER
  64. GRB 250805A: Swift-BAT refined analysis
  65. GRB 250806A: KAIT optical upper limit
  66. GRB 250806A: SVOM/VT refined analysis
  67. GRB 250806A: Swift-XRT counterpart detection
  68. GRB 250806A: Kilonova-Catcher optical upper limits
  69. GRB 250806A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  70. GRB 250806A: SVOM/VT optical upper limit
  71. GRB 250806A: SVOM detection of a soft burst
  72. GRB 250805A: SVOM/VT optical counterpart
  73. GRB 250805A: ESO/VLT observations
  74. GRB 250805A: Swift-XRT refined Analysis
  75. GRB 250804B: Swift-XRT observations
  76. GRB 250805A: Enhanced Swift-XRT position
  77. GRB 250804C: AstroSat CZTI detection of a long burst
  78. GRB 250805A: TRT optical upper limits
  79. GRB 250805A: Swift-XRT observations
  80. GRB 250805A: Swift detection of a burst
  81. GRB 250804B: Tiled Swift observations
  82. GRB 250804B: SVOM/GRM observation of a short burst
  83. GRB 250804A: Fermi GBM Final Localization
  84. Fermi Gamma-ray Burst Monitor trigger 775945985/250803856 is not a GRB
  85. GRB 250702B: SMA observations
  86. EP250711a: CrAO and Assy optical observations
  87. GRB 250727A: Swift-XRT afterglow confirmation and refined analysis
  88. LIGO/Virgo/KAGRA S250726ak: Upper limits from Swift/BAT-GUANO
  89. LIGO/Virgo/KAGRA S250725l: Upper limits from Swift/BAT-GUANO
  90. LIGO/Virgo/KAGRA S250727dc: Upper limits from Swift/BAT-GUANO
  91. GRB 250725A: AstroSat CZTI detection
  92. GRB 250727A: EP-FXT follow-up observation
  93. GRB 250725A: PRIME near-infrared observations
  94. GRB: Clarification on Gamma-Ray Burst Naming Convention
  95. GRB 250728A: Swift-XRT observations
  96. GRB 250727A: SVOM/ECLAIRs refined analysis
  97. GRB 250728A: COLIBRÍ optical upper limit
  98. GRB 250728A: Fermi GBM Observation
  99. GRB 250728A: Swift ToO observations
  100. GRB 250728A: Swift/BAT-GUANO arcminute localization of a short burst

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