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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').
  1. Fermi GRB 241115B: Global MASTER-Net observations report
  2. LIGO/Virgo/KAGRA S241114bi: Updated Sky localization and EM Bright Classification
  3. EP241115a: Global MASTER-Net observations report
  4. GRB 241115B: Fermi GBM Final Real-time Localization
  5. LIGO/Virgo/KAGRA S241113p: Updated Sky localization
  6. EP241115a: EP detection of a fast X-ray transient
  7. EP241113a: No Detection in Fermi-GBM Observations
  8. Swift GRB 241115A: Global MASTER-Net observations report
  9. Fermi GRB 241115A: Global MASTER-Net observations report
  10. GRB 241115A: Swift detection of a burst
  11. GRB 241115A: Fermi GBM Final Real-time Localization
  12. EP 241113a: LBT possible optical counterpart
  13. GRB 241113B: KAIT Optical Afterglow Candidate
  14. LIGO/Virgo/KAGRA S241114bi: Upper limits from Fermi-GBM Observations
  15. LIGO/Virgo/KAGRA S241114bi: Coverage and upper limits from MAXI/GSC observations
  16. GRB 241113A: Swift-BAT refined analysis
  17. LIGO/Virgo/KAGRA S241114bi: Identification of a GW compact binary merger candidate
  18. GRB 241113A: PRIME near-infrared upper limits
  19. Fermi GRB 241114A: Global MASTER-Net observations report
  20. EP241113a: Global MASTER-Net observations report
  21. GRB 241114A: Fermi GBM Final Real-time Localization
  22. GRB 241113B: J-band upper limit from WINTER
  23. GRB 241113A: J-band observations with WINTER
  24. EP241113a : J-band observations with WINTER
  25. GRB 241030A: LCO optical observation
  26. GRB 241113B: Swift-XRT observations
  27. IceCube-241113A: Upper limits from a search for additional neutrino events in IceCube
  28. GRB 241113A: 1.6m Mephisto and 50cm array optical upper limits
  29. GRB 241113A: KAIT optical observations
  30. EP241113b: Global MASTER-Net observations report
  31. EP241113b/GRB 241113B: EP detection of GRB 241113B
  32. Fermi-LAT gamma-ray observations of IceCube-241113A
  33. GRB 241113B: SVOM/GRM observation
  34. EP241113a: EP on-board trigger and autonomous follow-up observation
  35. LIGO/Virgo/KAGRA S241114y: Identification of a GW compact binary merger candidate
  36. GRB 241113A: Swift-XRT refined Analysis
  37. EP241107a: SOAR upper limits
  38. GRB 241113A: Swift/UVOT Detection
  39. GRB 241113A: REM detection of the optical/NIR afterglow
  40. Konus-Wind detection of GRB 241107A (short/hard)
  41. LIGO/Virgo/KAGRA S241113p: Identification of a GW compact binary merger candidate
  42. Fermi Gamma-ray Burst Monitor trigger 753166198/241113201 is not a GRB
  43. GRB 241113B: Swift ToO observations
  44. GRB 241113A: LCO optical observations
  45. IceCube-241113A - IceCube observation of a high-energy neutrino candidate track-like event
  46. GRB 241112B: GMG Optical Upper Limit
  47. GRB 241113A: Enhanced Swift-XRT position
  48. GRB241113A: LCOGT (40-cm) optical counterpart detection
  49. GRB 241113B : detection of a long GRB by SVOM/ECLAIRs
  50. GRB 241113A: MASTER010615.66-224018.2 optical counterpart detection
  51. GRB 241113A: Swift detection of a burst with an optical counterpart
  52. Swift GRB241113.33: Global MASTER-Net observations report
  53. SVOM/GRM detection of a short burst from SGR 1E1841-045
  54. Fermi trigger No 753166198: Global MASTER-Net observations report
  55. LIGO/Virgo/KAGRA S241111bn: Updated Sky localization
  56. GRB 241105A: ATCA Radio Upper Limits
  57. GRB 241112B: AbAO optical upper limit
  58. GRB 241107A: GROWTH-India telescope optical upper limit
  59. IceCube Alert 241113.02: Global MASTER-Net observations report
  60. Fermi GRB 241112A: Global MASTER-Net observations report
  61. Fermi-GBM Sub-Threshold Detection of GRB 241112B
  62. GRB 241112B: Optical afterglow detection confirmation in revisiting the Mephisto data
  63. GRB 241112B: Swift-XRT afterglow detection
  64. GRB 241112B: LCO optical detection of the SVOM/VT candidate
  65. GRB 241112B: SVOM/GRM observation
  66. GRB 241112B: SVOM/VT afterglow detection
  67. Fermi Gamma-ray Burst Monitor trigger 752995908/241111230 (GRB 241111A) is not a GRB
  68. GRB 241107A: Swift/BAT candidate arcminute localization of a short burst
  69. GRB 241112B: Mephisto optical upper limits
  70. GRB 241112B: GOTO optical upper limits
  71. GRB 241112B: Swift ToO observations
  72. GRB 241112B : detection of a long GRB by SVOM/ECLAIRs
  73. GRB 241107A: INTEGRAL IBIS localization
  74. EP241107a: EP-FXT follow-up observations
  75. GRB 241112A: Fermi GBM Final Real-time Localization
  76. LIGO/Virgo/KAGRA S241110br: NED Galaxies in the Localization Volume
  77. LIGO/Virgo/KAGRA S241109bn: ATLAS observations and discovery of the potential counterpart AT2024aawt
  78. GRB 241105A: VLT/FORS2 refined spectroscopic redshift z = 2.681
  79. LIGO/Virgo/KAGRA S241111bn: Identification of a GW compact binary merger candidate
  80. IPN triangulation of GRB 241107A (short/hard)
  81. GRB 241107A: INTEGRAL/IBIS/PICsIT detection of a short burst
  82. GRB 241025C: VZLUSAT-2 detection
  83. GRB 241025A: VZLUSAT-2 detection
  84. GRB 241018A: cubesat Avion detection
  85. Fermi trigger No 752990530: Global MASTER-Net observations report
  86. GRB 241111A: Fermi GBM Final Real-time Localization
  87. GRB 241030B: TESS detection of optical counterpart
  88. LIGO/Virgo/KAGRA S241110br: Updated Sky localization
  89. LIGO/Virgo/KAGRA S241110bk: 1 counterpart neutrino candidate event from an IceCube neutrino search
  90. LIGO/Virgo/KAGRA S241110br: Identification of a GW compact binary merger candidate
  91. LIGO/Virgo/KAGRA S241109bn: Upper limits from EP-WXT observations
  92. Fermi trigger No 752878030: Global MASTER-Net observations report
  93. Integral GRB241109.89: Global MASTER-Net observations report
  94. LIGO/Virgo/KAGRA S241109bn: Coverage and upper limits from MAXI/GSC observations
  95. EP241109a: KAIT photometry and 3 m Shane spectroscopy from Lick observatory
  96. LIGO/Virgo/KAGRA S241109bn: Updated Sky localization and EM Bright Classification
  97. INTEGRAL detection of a burst from 1E 1841-045
  98. EP241107a: AbAO optical upper limit
  99. LIGO/Virgo/KAGRA S241109bn: Upper limits from Fermi-GBM Observations
  100. GRB 241108A: Further COLIBRÍ Upper Limits on the Optical Counterpart

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