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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').
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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"
  1. Updates to IceCube realtime alert system for muon tracks
  2. GRB 241117A: SVOM/GRM observation of a short burst with extended emission
  3. GRB 241117A: Fermi GBM Detection
  4. Fermi GRB 241117B: Global MASTER-Net observations report
  5. GRB 241117B: Fermi GBM Final Real-time Localization
  6. IceCube-Cascade 241116A: Upper limits from a search for additional neutrino events in IceCube
  7. LIGO/Virgo/KAGRA S241116cq: Updated Sky localization
  8. GRB 241115B: Swift/BAT-GUANO localization skymap of a long burst
  9. Fermi GRB 241117A: Global MASTER-Net observations report
  10. GRB 241117A: Fermi GBM Final Real-time Localization
  11. GRB 241115C: Fermi GBM Observation
  12. GRB 241115A: Swift-XRT afterglow detection
  13. LIGO/Virgo/KAGRA S241116cq: Identification of a GW compact binary merger candidate
  14. EP241115a/GRB 241115D: Optical upper limits with Kinder observations
  15. GRB 241115A: Mephisto upper limits
  16. GRB 241113B: Mephisto upper limits
  17. EP241115a/GRB 241115D: Swift/XRT follow-up observation
  18. GRB 241115D / EP 241115a: SVOM/GRM observation
  19. The EP-WXT trigger 01709120856 is likely a flaring star
  20. EP241113a: Swift XRT weak detection
  21. GRB 241115A: Fermi GBM Observation
  22. GRB 241115A: LCOGT Optical Upper Limits
  23. GRB 241115C: Swift/BAT-GUANO localization skymap of a burst
  24. Fermi GRB 241115B: Global MASTER-Net observations report
  25. LIGO/Virgo/KAGRA S241114bi: Updated Sky localization and EM Bright Classification
  26. EP241115a: Global MASTER-Net observations report
  27. GRB 241115B: Fermi GBM Final Real-time Localization
  28. LIGO/Virgo/KAGRA S241113p: Updated Sky localization
  29. EP241115a: EP detection of a fast X-ray transient
  30. EP241113a: No Detection in Fermi-GBM Observations
  31. Swift GRB 241115A: Global MASTER-Net observations report
  32. Fermi GRB 241115A: Global MASTER-Net observations report
  33. GRB 241115A: Swift detection of a burst
  34. GRB 241115A: Fermi GBM Final Real-time Localization
  35. EP 241113a: LBT possible optical counterpart
  36. GRB 241113B: KAIT Optical Afterglow Candidate
  37. LIGO/Virgo/KAGRA S241114bi: Upper limits from Fermi-GBM Observations
  38. LIGO/Virgo/KAGRA S241114bi: Coverage and upper limits from MAXI/GSC observations
  39. GRB 241113A: Swift-BAT refined analysis
  40. LIGO/Virgo/KAGRA S241114bi: Identification of a GW compact binary merger candidate
  41. GRB 241113A: PRIME near-infrared upper limits
  42. Fermi GRB 241114A: Global MASTER-Net observations report
  43. EP241113a: Global MASTER-Net observations report
  44. GRB 241114A: Fermi GBM Final Real-time Localization
  45. GRB 241113B: J-band upper limit from WINTER
  46. GRB 241113A: J-band observations with WINTER
  47. EP241113a : J-band observations with WINTER
  48. GRB 241030A: LCO optical observation
  49. GRB 241113B: Swift-XRT observations
  50. IceCube-241113A: Upper limits from a search for additional neutrino events in IceCube
  51. GRB 241113A: 1.6m Mephisto and 50cm array optical upper limits
  52. GRB 241113A: KAIT optical observations
  53. EP241113b: Global MASTER-Net observations report
  54. EP241113b/GRB 241113B: EP detection of GRB 241113B
  55. Fermi-LAT gamma-ray observations of IceCube-241113A
  56. GRB 241113B: SVOM/GRM observation
  57. EP241113a: EP on-board trigger and autonomous follow-up observation
  58. LIGO/Virgo/KAGRA S241114y: Identification of a GW compact binary merger candidate
  59. GRB 241113A: Swift-XRT refined Analysis
  60. EP241107a: SOAR upper limits
  61. GRB 241113A: Swift/UVOT Detection
  62. GRB 241113A: REM detection of the optical/NIR afterglow
  63. Konus-Wind detection of GRB 241107A (short/hard)
  64. LIGO/Virgo/KAGRA S241113p: Identification of a GW compact binary merger candidate
  65. Fermi Gamma-ray Burst Monitor trigger 753166198/241113201 is not a GRB
  66. GRB 241113B: Swift ToO observations
  67. GRB 241113A: LCO optical observations
  68. IceCube-241113A - IceCube observation of a high-energy neutrino candidate track-like event
  69. GRB 241112B: GMG Optical Upper Limit
  70. GRB 241113A: Enhanced Swift-XRT position
  71. GRB241113A: LCOGT (40-cm) optical counterpart detection
  72. GRB 241113B : detection of a long GRB by SVOM/ECLAIRs
  73. GRB 241113A: MASTER010615.66-224018.2 optical counterpart detection
  74. GRB 241113A: Swift detection of a burst with an optical counterpart
  75. Swift GRB241113.33: Global MASTER-Net observations report
  76. SVOM/GRM detection of a short burst from SGR 1E1841-045
  77. Fermi trigger No 753166198: Global MASTER-Net observations report
  78. LIGO/Virgo/KAGRA S241111bn: Updated Sky localization
  79. GRB 241105A: ATCA Radio Upper Limits
  80. GRB 241112B: AbAO optical upper limit
  81. GRB 241107A: GROWTH-India telescope optical upper limit
  82. IceCube Alert 241113.02: Global MASTER-Net observations report
  83. Fermi GRB 241112A: Global MASTER-Net observations report
  84. Fermi-GBM Sub-Threshold Detection of GRB 241112B
  85. GRB 241112B: Optical afterglow detection confirmation in revisiting the Mephisto data
  86. GRB 241112B: Swift-XRT afterglow detection
  87. GRB 241112B: LCO optical detection of the SVOM/VT candidate
  88. GRB 241112B: SVOM/GRM observation
  89. GRB 241112B: SVOM/VT afterglow detection
  90. Fermi Gamma-ray Burst Monitor trigger 752995908/241111230 (GRB 241111A) is not a GRB
  91. GRB 241107A: Swift/BAT candidate arcminute localization of a short burst
  92. GRB 241112B: Mephisto optical upper limits
  93. GRB 241112B: GOTO optical upper limits
  94. GRB 241112B: Swift ToO observations
  95. GRB 241112B : detection of a long GRB by SVOM/ECLAIRs
  96. GRB 241107A: INTEGRAL IBIS localization
  97. EP241107a: EP-FXT follow-up observations
  98. GRB 241112A: Fermi GBM Final Real-time Localization
  99. LIGO/Virgo/KAGRA S241110br: NED Galaxies in the Localization Volume
  100. LIGO/Virgo/KAGRA S241109bn: ATLAS observations and discovery of the potential counterpart AT2024aawt

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