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

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