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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 241113A: MASTER010615.66-224018.2 optical counterpart detection
  2. GRB 241113A: Swift detection of a burst with an optical counterpart
  3. Swift GRB241113.33: Global MASTER-Net observations report
  4. SVOM/GRM detection of a short burst from SGR 1E1841-045
  5. Fermi trigger No 753166198: Global MASTER-Net observations report
  6. LIGO/Virgo/KAGRA S241111bn: Updated Sky localization
  7. GRB 241105A: ATCA Radio Upper Limits
  8. GRB 241112B: AbAO optical upper limit
  9. GRB 241107A: GROWTH-India telescope optical upper limit
  10. IceCube Alert 241113.02: Global MASTER-Net observations report
  11. Fermi GRB 241112A: Global MASTER-Net observations report
  12. Fermi-GBM Sub-Threshold Detection of GRB 241112B
  13. GRB 241112B: Optical afterglow detection confirmation in revisiting the Mephisto data
  14. GRB 241112B: Swift-XRT afterglow detection
  15. GRB 241112B: LCO optical detection of the SVOM/VT candidate
  16. GRB 241112B: SVOM/GRM observation
  17. GRB 241112B: SVOM/VT afterglow detection
  18. Fermi Gamma-ray Burst Monitor trigger 752995908/241111230 (GRB 241111A) is not a GRB
  19. GRB 241107A: Swift/BAT candidate arcminute localization of a short burst
  20. GRB 241112B: Mephisto optical upper limits
  21. GRB 241112B: GOTO optical upper limits
  22. GRB 241112B: Swift ToO observations
  23. GRB 241112B : detection of a long GRB by SVOM/ECLAIRs
  24. GRB 241107A: INTEGRAL IBIS localization
  25. EP241107a: EP-FXT follow-up observations
  26. GRB 241112A: Fermi GBM Final Real-time Localization
  27. LIGO/Virgo/KAGRA S241110br: NED Galaxies in the Localization Volume
  28. LIGO/Virgo/KAGRA S241109bn: ATLAS observations and discovery of the potential counterpart AT2024aawt
  29. GRB 241105A: VLT/FORS2 refined spectroscopic redshift z = 2.681
  30. LIGO/Virgo/KAGRA S241111bn: Identification of a GW compact binary merger candidate
  31. IPN triangulation of GRB 241107A (short/hard)
  32. GRB 241107A: INTEGRAL/IBIS/PICsIT detection of a short burst
  33. GRB 241025C: VZLUSAT-2 detection
  34. GRB 241025A: VZLUSAT-2 detection
  35. GRB 241018A: cubesat Avion detection
  36. Fermi trigger No 752990530: Global MASTER-Net observations report
  37. GRB 241111A: Fermi GBM Final Real-time Localization
  38. GRB 241030B: TESS detection of optical counterpart
  39. LIGO/Virgo/KAGRA S241110br: Updated Sky localization
  40. LIGO/Virgo/KAGRA S241110bk: 1 counterpart neutrino candidate event from an IceCube neutrino search
  41. LIGO/Virgo/KAGRA S241110br: Identification of a GW compact binary merger candidate
  42. LIGO/Virgo/KAGRA S241109bn: Upper limits from EP-WXT observations
  43. Fermi trigger No 752878030: Global MASTER-Net observations report
  44. Integral GRB241109.89: Global MASTER-Net observations report
  45. LIGO/Virgo/KAGRA S241109bn: Coverage and upper limits from MAXI/GSC observations
  46. EP241109a: KAIT photometry and 3 m Shane spectroscopy from Lick observatory
  47. LIGO/Virgo/KAGRA S241109bn: Updated Sky localization and EM Bright Classification
  48. INTEGRAL detection of a burst from 1E 1841-045
  49. EP241107a: AbAO optical upper limit
  50. LIGO/Virgo/KAGRA S241109bn: Upper limits from Fermi-GBM Observations
  51. GRB 241108A: Further COLIBRÍ Upper Limits on the Optical Counterpart
  52. LIGO/Virgo/KAGRA S241109p: Updated Sky localization and Source Classification
  53. LIGO/Virgo/KAGRA S241109bn: Global MASTER-Net observations report
  54. LIGO/Virgo/KAGRA S241109bn: Identification of a GW compact binary merger candidate
  55. EP241109a: confirmation of a stellar flare by BOOTES-7
  56. EP241109a: EP on-board trigger and autonomous follow-up observation
  57. GRB 241108A: Swift-XRT observations
  58. LIGO/Virgo/KAGRA S241109p: Identification of a GW compact binary merger candidate
  59. EP241107A: MASTER optical observations of xray transient
  60. EP241107a: KAIT optical observations
  61. GRB 241108A: Swift ToO observations
  62. GRB 241030A: TESS observations
  63. GRB 241108A: COLIBRÍ Upper Limits on the Optical Counterpart
  64. GRB 241108A : a likely weak long GRB detected by SVOM/ECLAIRs
  65. EP241107a: Kinder optical follow-up observations
  66. GRB 241025A: radio detection with the VLA
  67. GRB 241104A: CALET Gamma-Ray Burst Monitor detection
  68. EP241107a: AKO Optical Afterglow Follow-Up Observations
  69. EP241107a: GSP detects optical counterpart
  70. EP241107a: Gemini-South spectroscopic confirmation (z = 0.456)
  71. GRB 241107A: SVOM/GRM detection of a short burst
  72. GRB 241105A: EP-FXT follow-up observations
  73. GRB 241105A: SVOM/GRM observation
  74. EP241107a: OHP/T193 photometric and spectroscopic observations
  75. GRB 241105a: PRIME near-infrared upper limits
  76. EP241107a: FTW Optical and NIR observations of the optical counterpart
  77. GRB 241105A: ePESSTO+ NTT optical afterglow detection
  78. EP241107a: GIT optical observations
  79. EP241107a: Global MASTER-Net observations report
  80. EP241107a: SVOM/C-GFT optical observations
  81. EP241107a: AKO Optical Afterglow Detection
  82. GRB 241025A: LBT optical observations
  83. GRB241105A: Gemini-South Optical Afterglow Detection
  84. EP241107a: EP on-board trigger and autonomous follow-up observation
  85. GRB 241105A: VLT/FORS2 optical afterglow rapid fading
  86. GRB 241105A: Swift/UVOT Detection
  87. EP241101a: CrAO ZTSH optical observations
  88. GRB 241105A: Swift/BAT-GUANO refined analysis of short burst with extended emission
  89. GRB 241030A: optical afterglow detection from the INAF Asiago Observatory
  90. GRB 241105A: BOOTES-7 optical detection
  91. GRB 241030A: Mondy optical observations
  92. GRB241105A: Fermi GBM Observation of a Short Burst with Extended Emission
  93. Konus-Wind detection of GRB 241105A (short with extended emission)
  94. LIGO/Virgo/KAGRA S241106ba: 1 counterpart neutrino candidate event from an IceCube neutrino search
  95. LIGO/Virgo/KAGRA S241102o: 1 counterpart neutrino candidate event from an IceCube neutrino search
  96. Konus-Wind detection of GRB 241021A
  97. GRB 241105A: SVOM/VT optical afterglow observations
  98. GRB 241105A: Swift-XRT afterglow detection
  99. GRB 241105A: VLT/FORS2 spectroscopic redshift z = 2.681
  100. GRB 241104A: Swift-XRT observations

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