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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. EP 241113a: LBT possible optical counterpart
  2. GRB 241113B: KAIT Optical Afterglow Candidate
  3. LIGO/Virgo/KAGRA S241114bi: Upper limits from Fermi-GBM Observations
  4. LIGO/Virgo/KAGRA S241114bi: Coverage and upper limits from MAXI/GSC observations
  5. GRB 241113A: Swift-BAT refined analysis
  6. LIGO/Virgo/KAGRA S241114bi: Identification of a GW compact binary merger candidate
  7. GRB 241113A: PRIME near-infrared upper limits
  8. Fermi GRB 241114A: Global MASTER-Net observations report
  9. EP241113a: Global MASTER-Net observations report
  10. GRB 241114A: Fermi GBM Final Real-time Localization
  11. GRB 241113B: J-band upper limit from WINTER
  12. GRB 241113A: J-band observations with WINTER
  13. EP241113a : J-band observations with WINTER
  14. GRB 241030A: LCO optical observation
  15. GRB 241113B: Swift-XRT observations
  16. IceCube-241113A: Upper limits from a search for additional neutrino events in IceCube
  17. GRB 241113A: 1.6m Mephisto and 50cm array optical upper limits
  18. GRB 241113A: KAIT optical observations
  19. EP241113b: Global MASTER-Net observations report
  20. EP241113b/GRB 241113B: EP detection of GRB 241113B
  21. Fermi-LAT gamma-ray observations of IceCube-241113A
  22. GRB 241113B: SVOM/GRM observation
  23. EP241113a: EP on-board trigger and autonomous follow-up observation
  24. LIGO/Virgo/KAGRA S241114y: Identification of a GW compact binary merger candidate
  25. GRB 241113A: Swift-XRT refined Analysis
  26. EP241107a: SOAR upper limits
  27. GRB 241113A: Swift/UVOT Detection
  28. GRB 241113A: REM detection of the optical/NIR afterglow
  29. Konus-Wind detection of GRB 241107A (short/hard)
  30. LIGO/Virgo/KAGRA S241113p: Identification of a GW compact binary merger candidate
  31. Fermi Gamma-ray Burst Monitor trigger 753166198/241113201 is not a GRB
  32. GRB 241113B: Swift ToO observations
  33. GRB 241113A: LCO optical observations
  34. IceCube-241113A - IceCube observation of a high-energy neutrino candidate track-like event
  35. GRB 241112B: GMG Optical Upper Limit
  36. GRB 241113A: Enhanced Swift-XRT position
  37. GRB241113A: LCOGT (40-cm) optical counterpart detection
  38. GRB 241113B : detection of a long GRB by SVOM/ECLAIRs
  39. GRB 241113A: MASTER010615.66-224018.2 optical counterpart detection
  40. GRB 241113A: Swift detection of a burst with an optical counterpart
  41. Swift GRB241113.33: Global MASTER-Net observations report
  42. SVOM/GRM detection of a short burst from SGR 1E1841-045
  43. Fermi trigger No 753166198: Global MASTER-Net observations report
  44. LIGO/Virgo/KAGRA S241111bn: Updated Sky localization
  45. GRB 241105A: ATCA Radio Upper Limits
  46. GRB 241112B: AbAO optical upper limit
  47. GRB 241107A: GROWTH-India telescope optical upper limit
  48. IceCube Alert 241113.02: Global MASTER-Net observations report
  49. Fermi GRB 241112A: Global MASTER-Net observations report
  50. Fermi-GBM Sub-Threshold Detection of GRB 241112B
  51. GRB 241112B: Optical afterglow detection confirmation in revisiting the Mephisto data
  52. GRB 241112B: Swift-XRT afterglow detection
  53. GRB 241112B: LCO optical detection of the SVOM/VT candidate
  54. GRB 241112B: SVOM/GRM observation
  55. GRB 241112B: SVOM/VT afterglow detection
  56. Fermi Gamma-ray Burst Monitor trigger 752995908/241111230 (GRB 241111A) is not a GRB
  57. GRB 241107A: Swift/BAT candidate arcminute localization of a short burst
  58. GRB 241112B: Mephisto optical upper limits
  59. GRB 241112B: GOTO optical upper limits
  60. GRB 241112B: Swift ToO observations
  61. GRB 241112B : detection of a long GRB by SVOM/ECLAIRs
  62. GRB 241107A: INTEGRAL IBIS localization
  63. EP241107a: EP-FXT follow-up observations
  64. GRB 241112A: Fermi GBM Final Real-time Localization
  65. LIGO/Virgo/KAGRA S241110br: NED Galaxies in the Localization Volume
  66. LIGO/Virgo/KAGRA S241109bn: ATLAS observations and discovery of the potential counterpart AT2024aawt
  67. GRB 241105A: VLT/FORS2 refined spectroscopic redshift z = 2.681
  68. LIGO/Virgo/KAGRA S241111bn: Identification of a GW compact binary merger candidate
  69. IPN triangulation of GRB 241107A (short/hard)
  70. GRB 241107A: INTEGRAL/IBIS/PICsIT detection of a short burst
  71. GRB 241025C: VZLUSAT-2 detection
  72. GRB 241025A: VZLUSAT-2 detection
  73. GRB 241018A: cubesat Avion detection
  74. Fermi trigger No 752990530: Global MASTER-Net observations report
  75. GRB 241111A: Fermi GBM Final Real-time Localization
  76. GRB 241030B: TESS detection of optical counterpart
  77. LIGO/Virgo/KAGRA S241110br: Updated Sky localization
  78. LIGO/Virgo/KAGRA S241110bk: 1 counterpart neutrino candidate event from an IceCube neutrino search
  79. LIGO/Virgo/KAGRA S241110br: Identification of a GW compact binary merger candidate
  80. LIGO/Virgo/KAGRA S241109bn: Upper limits from EP-WXT observations
  81. Fermi trigger No 752878030: Global MASTER-Net observations report
  82. Integral GRB241109.89: Global MASTER-Net observations report
  83. LIGO/Virgo/KAGRA S241109bn: Coverage and upper limits from MAXI/GSC observations
  84. EP241109a: KAIT photometry and 3 m Shane spectroscopy from Lick observatory
  85. LIGO/Virgo/KAGRA S241109bn: Updated Sky localization and EM Bright Classification
  86. INTEGRAL detection of a burst from 1E 1841-045
  87. EP241107a: AbAO optical upper limit
  88. LIGO/Virgo/KAGRA S241109bn: Upper limits from Fermi-GBM Observations
  89. GRB 241108A: Further COLIBRÍ Upper Limits on the Optical Counterpart
  90. LIGO/Virgo/KAGRA S241109p: Updated Sky localization and Source Classification
  91. LIGO/Virgo/KAGRA S241109bn: Global MASTER-Net observations report
  92. LIGO/Virgo/KAGRA S241109bn: Identification of a GW compact binary merger candidate
  93. EP241109a: confirmation of a stellar flare by BOOTES-7
  94. EP241109a: EP on-board trigger and autonomous follow-up observation
  95. GRB 241108A: Swift-XRT observations
  96. LIGO/Virgo/KAGRA S241109p: Identification of a GW compact binary merger candidate
  97. EP241107A: MASTER optical observations of xray transient
  98. EP241107a: KAIT optical observations
  99. GRB 241108A: Swift ToO observations
  100. GRB 241030A: TESS observations

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