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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"
  1. EP241113a: Swift XRT weak detection
  2. GRB 241115A: Fermi GBM Observation
  3. GRB 241115A: LCOGT Optical Upper Limits
  4. GRB 241115C: Swift/BAT-GUANO localization skymap of a burst
  5. Fermi GRB 241115B: Global MASTER-Net observations report
  6. LIGO/Virgo/KAGRA S241114bi: Updated Sky localization and EM Bright Classification
  7. EP241115a: Global MASTER-Net observations report
  8. GRB 241115B: Fermi GBM Final Real-time Localization
  9. LIGO/Virgo/KAGRA S241113p: Updated Sky localization
  10. EP241115a: EP detection of a fast X-ray transient
  11. EP241113a: No Detection in Fermi-GBM Observations
  12. Swift GRB 241115A: Global MASTER-Net observations report
  13. Fermi GRB 241115A: Global MASTER-Net observations report
  14. GRB 241115A: Swift detection of a burst
  15. GRB 241115A: Fermi GBM Final Real-time Localization
  16. EP 241113a: LBT possible optical counterpart
  17. GRB 241113B: KAIT Optical Afterglow Candidate
  18. LIGO/Virgo/KAGRA S241114bi: Upper limits from Fermi-GBM Observations
  19. LIGO/Virgo/KAGRA S241114bi: Coverage and upper limits from MAXI/GSC observations
  20. GRB 241113A: Swift-BAT refined analysis
  21. LIGO/Virgo/KAGRA S241114bi: Identification of a GW compact binary merger candidate
  22. GRB 241113A: PRIME near-infrared upper limits
  23. Fermi GRB 241114A: Global MASTER-Net observations report
  24. EP241113a: Global MASTER-Net observations report
  25. GRB 241114A: Fermi GBM Final Real-time Localization
  26. GRB 241113B: J-band upper limit from WINTER
  27. GRB 241113A: J-band observations with WINTER
  28. EP241113a : J-band observations with WINTER
  29. GRB 241030A: LCO optical observation
  30. GRB 241113B: Swift-XRT observations
  31. IceCube-241113A: Upper limits from a search for additional neutrino events in IceCube
  32. GRB 241113A: 1.6m Mephisto and 50cm array optical upper limits
  33. GRB 241113A: KAIT optical observations
  34. EP241113b: Global MASTER-Net observations report
  35. EP241113b/GRB 241113B: EP detection of GRB 241113B
  36. Fermi-LAT gamma-ray observations of IceCube-241113A
  37. GRB 241113B: SVOM/GRM observation
  38. EP241113a: EP on-board trigger and autonomous follow-up observation
  39. LIGO/Virgo/KAGRA S241114y: Identification of a GW compact binary merger candidate
  40. GRB 241113A: Swift-XRT refined Analysis
  41. EP241107a: SOAR upper limits
  42. GRB 241113A: Swift/UVOT Detection
  43. GRB 241113A: REM detection of the optical/NIR afterglow
  44. Konus-Wind detection of GRB 241107A (short/hard)
  45. LIGO/Virgo/KAGRA S241113p: Identification of a GW compact binary merger candidate
  46. Fermi Gamma-ray Burst Monitor trigger 753166198/241113201 is not a GRB
  47. GRB 241113B: Swift ToO observations
  48. GRB 241113A: LCO optical observations
  49. IceCube-241113A - IceCube observation of a high-energy neutrino candidate track-like event
  50. GRB 241112B: GMG Optical Upper Limit
  51. GRB 241113A: Enhanced Swift-XRT position
  52. GRB241113A: LCOGT (40-cm) optical counterpart detection
  53. GRB 241113B : detection of a long GRB by SVOM/ECLAIRs
  54. GRB 241113A: MASTER010615.66-224018.2 optical counterpart detection
  55. GRB 241113A: Swift detection of a burst with an optical counterpart
  56. Swift GRB241113.33: Global MASTER-Net observations report
  57. SVOM/GRM detection of a short burst from SGR 1E1841-045
  58. Fermi trigger No 753166198: Global MASTER-Net observations report
  59. LIGO/Virgo/KAGRA S241111bn: Updated Sky localization
  60. GRB 241105A: ATCA Radio Upper Limits
  61. GRB 241112B: AbAO optical upper limit
  62. GRB 241107A: GROWTH-India telescope optical upper limit
  63. IceCube Alert 241113.02: Global MASTER-Net observations report
  64. Fermi GRB 241112A: Global MASTER-Net observations report
  65. Fermi-GBM Sub-Threshold Detection of GRB 241112B
  66. GRB 241112B: Optical afterglow detection confirmation in revisiting the Mephisto data
  67. GRB 241112B: Swift-XRT afterglow detection
  68. GRB 241112B: LCO optical detection of the SVOM/VT candidate
  69. GRB 241112B: SVOM/GRM observation
  70. GRB 241112B: SVOM/VT afterglow detection
  71. Fermi Gamma-ray Burst Monitor trigger 752995908/241111230 (GRB 241111A) is not a GRB
  72. GRB 241107A: Swift/BAT candidate arcminute localization of a short burst
  73. GRB 241112B: Mephisto optical upper limits
  74. GRB 241112B: GOTO optical upper limits
  75. GRB 241112B: Swift ToO observations
  76. GRB 241112B : detection of a long GRB by SVOM/ECLAIRs
  77. GRB 241107A: INTEGRAL IBIS localization
  78. EP241107a: EP-FXT follow-up observations
  79. GRB 241112A: Fermi GBM Final Real-time Localization
  80. LIGO/Virgo/KAGRA S241110br: NED Galaxies in the Localization Volume
  81. LIGO/Virgo/KAGRA S241109bn: ATLAS observations and discovery of the potential counterpart AT2024aawt
  82. GRB 241105A: VLT/FORS2 refined spectroscopic redshift z = 2.681
  83. LIGO/Virgo/KAGRA S241111bn: Identification of a GW compact binary merger candidate
  84. IPN triangulation of GRB 241107A (short/hard)
  85. GRB 241107A: INTEGRAL/IBIS/PICsIT detection of a short burst
  86. GRB 241025C: VZLUSAT-2 detection
  87. GRB 241025A: VZLUSAT-2 detection
  88. GRB 241018A: cubesat Avion detection
  89. Fermi trigger No 752990530: Global MASTER-Net observations report
  90. GRB 241111A: Fermi GBM Final Real-time Localization
  91. GRB 241030B: TESS detection of optical counterpart
  92. LIGO/Virgo/KAGRA S241110br: Updated Sky localization
  93. LIGO/Virgo/KAGRA S241110bk: 1 counterpart neutrino candidate event from an IceCube neutrino search
  94. LIGO/Virgo/KAGRA S241110br: Identification of a GW compact binary merger candidate
  95. LIGO/Virgo/KAGRA S241109bn: Upper limits from EP-WXT observations
  96. Fermi trigger No 752878030: Global MASTER-Net observations report
  97. Integral GRB241109.89: Global MASTER-Net observations report
  98. LIGO/Virgo/KAGRA S241109bn: Coverage and upper limits from MAXI/GSC observations
  99. EP241109a: KAIT photometry and 3 m Shane spectroscopy from Lick observatory
  100. LIGO/Virgo/KAGRA S241109bn: Updated Sky localization and EM Bright Classification

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