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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"

19538 results found.

  1. GRB 240912A: Enhanced Swift-XRT position
  2. GRB 240912A: Swift detection of a burst with an optical counterpart
  3. GRB 240910A: Fermi GBM Observation
  4. GRB 240910A: Swift-XRT detection of GOTO24fvl/AT2024vfp
  5. GRB 240910A: JinShan optical observations
  6. GRB 240910A: GOTO candidate optical counterpart
  7. GRB 240910A: Swift ToO observations
  8. IPN triangulation of GRB 240905B (short)
  9. GRB 240905E: SVOM/VT optical observations
  10. LIGO/Virgo/KAGRA S240908bs: Upper limits from Swift/BAT-GUANO
  11. LIGO/Virgo/KAGRA S240907cg: Upper limits from Swift/BAT-GUANO
  12. GRB 240905B: GOTO optical upper limits
  13. GRB 240905E: GIT optical upper limit
  14. GRB 240905B: Swift-XRT observations
  15. GRB 240905E: Gaoyazi/GOT optical upper limits
  16. GRB 240905B: Fermi-LAT detection
  17. GRB 240905B: Swift ToO observations
  18. GRB 240905E: J-band observations with WINTER
  19. GRB 240905E: CrAO Optical Afterglow observations, possible OT candidate
  20. GRB 240905E: AKO Optical Upper Limit
  21. GRB 240905E: SVOM/C-GFT optical upper limit
  22. GRB 240905E: NOT optical upper limits
  23. GRB 240905E: REM optical/NIR upper limits
  24. GRB 240905E: Swift-XRT refined Analysis
  25. GRB 240905E: SVOM/GRM observation
  26. GRB 240905E: LCOGT Optical Upper Limit
  27. GRB 240905E: Swift/UVOT Upper Limits
  28. GRB 240905E: SAO RAS optical upper limit
  29. GRB 240905E: Nanshan/HMT optical upper limit
  30. Swift GRB 240905E: Global MASTER-Net observations report
  31. GRB 240905E: Swift detection of a burst
  32. GRB 240819A: Optical upper limits from TESS
  33. Swift GRB 240904A: Global MASTER-Net observations report
  34. GRB 240904A: Swift detection of a burst
  35. LIGO/Virgo/KAGRA S240825ar: Upper limits from Swift/BAT-GUANO
  36. LIGO/Virgo/KAGRA S240807h: Upper limits from Swift/BAT-GUANO
  37. GRB 240828A: GECAM detection
  38. GRB 240825A: MeerLICHT afterglow detection
  39. GRB240828B: REM optical/NIR upper limits
  40. GRB 240828B: AbAO optical upper limit
  41. GRB 240828B: Mephisto optical upper limit
  42. GRB 240828B: GRANDMA Optical Upper Limit
  43. GRB 240829A: Swift-BAT refined analysis
  44. GRB 240825A: Swift-BAT refined analysis
  45. GRB 240828B: J-band upper limit from WINTER
  46. GRB 240828B: GMG Optical Upper Limit
  47. GRB 240828B: KAIT optical upper limit
  48. GRB 240828A: Fermi GBM Observation
  49. GRB 240828A: Swift-XRT afterglow detection
  50. GRB 240828B: Swift-XRT afterglow detection
  51. GRB 240829A: Swift detection of a burst
  52. Swift GRB240829.16: Global MASTER-Net observations report
  53. GRB 240828A: Fermi-LAT detection
  54. GRB 240828A: Tiled Swift observations
  55. GRB 240825A: Upper limits from a neutrino search with IceCube
  56. GRB 240819A as a likely X-Ray Flash
  57. GRB 240828B: Swift ToO observations
  58. GRB 240821A: the second and third EP-FXT follow-up observations and afterglow candidates
  59. GRB 240825A: GECAM detection
  60. GRB 240824A: GIT optical upper limit
  61. GRB 240819A: Swift afterglow confirmation
  62. GRB 240824B: Ondrejov D50 optical limit
  63. GRB 240825A: PRIME near-infrared detection
  64. Konus-Wind detection of GRB 240825A (bright/long)
  65. GRB 240825A: Fermi GBM Observation
  66. GRB 240825A: AKO Optical Follow-Up Observations
  67. GRB 240825A: AstroSat CZTI detection of the long bright burst
  68. SGR 1E 1841-045 / Kes 73: SVOM/GRM observation
  69. GRB 240825A: Swift/UVOT Detection
  70. GRB 240825A: REM detection of the optical/NIR afterglow
  71. GRB 240825A: Swift-XRT refined Analysis
  72. GRB 240825A: VLT/X-shooter redshift
  73. GRB 240825A: SVOM/C-GFT optical observations
  74. GRB 240825A: Montarrenti Observatory optical observations
  75. GRB 240825A: Enhanced Swift-XRT position
  76. GRB 240825A: MASTER optical counterpart observation
  77. GRB 240825A: Fermi-LAT detection
  78. GRB 240825A: LCO optical observations
  79. GRB 240824B: KAIT optical upper limit
  80. GRB 240824B: Fermi GBM Observation
  81. GRB 240825A: GMG Optical Observation
  82. Swift GRB 240825A: Global MASTER-Net observations report
  83. GRB 240825A: 1.6m Mephisto multi-band detection
  84. GRB 240825A: AKO Optical Afterglow Detection
  85. GRB 240825A: Skynet Optical Afterglow observations
  86. GRB 240825A: Nanshan/HMT optical afterglow observations
  87. GRB 240825A: Swift detection of a burst with a bright optical counterpart
  88. GRB 240824A: Swift-BAT refined analysis
  89. GRB 240824A: SVOM/C-GFT optical upper limit
  90. GRB 240824B: Swift-XRT afterglow detection
  91. GRB 240824A: Swift-XRT observations
  92. GRB 240824B: Swift/BAT arcminute localization of a burst
  93. GRB 240824B: Swift ToO observations
  94. GRB 240824A: Swift/UVOT Upper Limits
  95. GRB 240821A: Swift/UVOT observations of the XRT sources.
  96. GRB240824A: GRANDMA/TAROT-TCA Upper Limit
  97. SGR 1E 1841-045 / Kes 73: Leavitt Observatory optical upper limit
  98. GRB 240824A: KAIT optical upper limit
  99. GRB 240824A: Skynet Optical Afterglow Discovery
  100. GRB 240824A: Swift detection of a burst

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