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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"

39163 results found.

  1. GRB 250814A: J-band upper limit from WINTER
  2. GRB 250813B: NOT observations of the optical afterglow
  3. GRB 250813B: SVOM/VT optical observations
  4. Subject GRB 250813B: SVOM/MXT refined analysis
  5. GRB 250814A: COLIBRÍ optical upper limit
  6. GRB 250814B: Fermi GBM Final Real-time Localization
  7. GRB 250813A: AstroSat CZTI detection
  8. LIGO/Virgo/KAGRA S250814bg: Identification of a GW compact binary merger candidate possibly associated with GRB 250814A detected by Fermi GBM and Swift BAT
  9. GRB 250813B: VLT X-shooter spectroscopic redshift z = 1.752
  10. GRB 250814A: DDOTI Optical Upper Limit
  11. GRB 250813B: EP-FXT counterpart detection
  12. GRB 250813B: Swift-XRT afterglow detection
  13. GRB 250814A: Swift detection of a burst coincident with a subthreshold GW trigger
  14. GRB 250814A: Fermi GBM Final Real-time Localization
  15. GRB 250813B: SVOM/COLIBRÍ (FM-GFT) optical observations
  16. GRB 250813B: Ondrejov D50 fast decay
  17. GRB 250813B: SVOM detection of a bright long burst (Correction for GCN 41352).
  18. GRB 250813B: Ondrejov D50 optical afterglow detection
  19. GRB 250813B: SVOM detection of a bright long burst
  20. EP250812a: Nickel optical upper limit
  21. GRB 250812A: VLT X-shooter spectroscopic redshift confirmation z = 2.571
  22. GRB 250812A: NTT spectroscopic redshift z = 2.57
  23. GRB 250812A: Swift/UVOT Detection
  24. GRB 250813A: Fermi GBM Final Localization
  25. EP250812a: COLIBRÍ detection of the VT candidate and evidence of flattening
  26. IceCube-250813A - IceCube observation of a high-energy neutrino candidate track-like event
  27. IceCube Alert 250813.14: Global MASTER-Net observations report
  28. GRB 250812A: EP-FXT counterpart detection
  29. GRB 250812A: Swift ToO observations
  30. GRB 250807B: Swift-BAT refined analysis
  31. GRB 250812A: Kilonova-Catcher optical afterglow detection
  32. Fermi Gamma-ray Burst Monitor trigger 776705265/250812644 is not a GRB
  33. GRB 250812A: SVOM/COLIBRÍ (FM-GFT) optical observations
  34. GRB 250812A: SVOM/VT optical afterglow confirmation
  35. GRB 250812A: Swift-XRT afterglow detection
  36. GRB 250812A: TRT likely optical counterpart detection
  37. GRB 250812A: SVOM detection of a faint long burst
  38. GRB 250809A: Swift-BAT refined analysis
  39. Fermi Gamma-ray Burst Monitor trigger 776620220/250811660 is not a GRB
  40. GRB 250807A: Swift-BAT refined analysis
  41. GRB 250809A: Swift/UVOT Detection
  42. Corrected Swift-XRT Refined Analysis of GRB 250809A
  43. GRB 250809A: Swift-XRT refined Analysis
  44. GRB 250807B: SVOM/VT optical observation
  45. GRB 250809A: LCOGT Optical Upper Limits
  46. GRB 250702B: Chandra X-ray Detection
  47. EP250807a: Global MASTER-Net observations report
  48. Fermi GRB 250808A: Global MASTER-Net observations report
  49. Fermi Gamma-ray Burst Monitor trigger 776449964/250809689 is not a GRB
  50. GRB 250808A: VLT X-shooter candidate counterpart
  51. GRB 250809A: Prompt enhanced Swift-XRT position
  52. GRB 250809A: Swift detection of a gamma ray burst
  53. GRB 250808A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  54. GRB 250808A: Fermi GBM Observation
  55. GRB 250808A: Swift-XRT candidate counterpart detection
  56. GRB 250807A: SVOM/VT optical continued observation
  57. EP-WXT trigger 01709195487: KAIT confirmation of the stellar flare
  58. GRB 250808A: SVOM detection of a long burst
  59. GRB 250808A: Fermi GBM Final Real-time Localization
  60. Konus-Wind detection of GRB 250807A
  61. GRB 250807B: Swift/UVOT Detection
  62. GRB 250807B: Kilonova-Catcher optical afterglow detection
  63. GRB 250807A: Swift/UVOT Detection
  64. GRB 250807A: Swift-XRT refined Analysis
  65. GRB 250807B: VLT/X-Shooter spectroscopic redshift z = 1.522
  66. GRB 250806A: SVOM/MXT refined analysis
  67. GRB 250806A: SVOM/ECLAIRs refined analysis
  68. GRB 250806A: Mondy optical observations, and nearby bright galaxy photometry
  69. GRB 250804B: Insight-HXMT detection
  70. GRB 250807A: SVOM/GRM observation
  71. Swift GRB250807.45: Global MASTER-Net observations report
  72. GRB 250807A: AstroSat CZTI detection of bright long burst
  73. GRB 250807B: Swift-XRT refined Analysis
  74. GRB 250806A: NOT z-band upper limit and host galaxy candidate
  75. GRB 250807B: NTT optical observations
  76. EP250807a: COLIBRÍ optical upper limit
  77. GRB 250807A: SVOM/VT optical observation
  78. EP250806a: Upper limit from Fermi-GBM Observations
  79. GRB 250807B: Enhanced Swift-XRT position
  80. Swift GRB250807.65: Global MASTER-Net observations report
  81. GRB 250807A: Enhanced Swift-XRT position
  82. GRB 250807B: Swift detection of a burst with an optical counterpart.
  83. GRB 250805A: Kilonova-Catcher optical upper limits
  84. GRB 250805A: Swift/UVOT Upper Limits
  85. GRB 250806A: Swift/UVOT U-band detection
  86. GRB 250807A: Swift detection of a burst with an optical counterpart
  87. IceCube Alert 250804.84: Global MASTER-Net observations report
  88. GRB 250806A: EP-FXT observation
  89. EP250806a: Global MASTER-Net observations report
  90. EP250806a: Earlier Detection of the VT Candidate by COLIBRÍ and LS
  91. GRB 250806A: J-band upper limit from WINTER
  92. GRB 250805A: Swift-BAT refined analysis
  93. GRB 250806A: KAIT optical upper limit
  94. GRB 250806A: SVOM/VT refined analysis
  95. GRB 250806A: Swift-XRT counterpart detection
  96. EP250806a: COLIBRÍ optical upper limit
  97. GRB 250806A: Kilonova-Catcher optical upper limits
  98. GRB 250806A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  99. GRB 250806A: SVOM/VT optical upper limit
  100. GRB 250806A: SVOM detection of a soft burst

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