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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. Fermi GRB 241117A: Global MASTER-Net observations report
  2. GRB 241117A: Fermi GBM Final Real-time Localization
  3. GRB 241115C: Fermi GBM Observation
  4. GRB 241115A: Swift-XRT afterglow detection
  5. LIGO/Virgo/KAGRA S241116cq: Identification of a GW compact binary merger candidate
  6. EP241115a/GRB 241115D: Optical upper limits with Kinder observations
  7. GRB 241115A: Mephisto upper limits
  8. GRB 241113B: Mephisto upper limits
  9. EP241115a/GRB 241115D: Swift/XRT follow-up observation
  10. GRB 241115D / EP 241115a: SVOM/GRM observation
  11. The EP-WXT trigger 01709120856 is likely a flaring star
  12. EP241113a: Swift XRT weak detection
  13. GRB 241115A: Fermi GBM Observation
  14. GRB 241115A: LCOGT Optical Upper Limits
  15. GRB 241115C: Swift/BAT-GUANO localization skymap of a burst
  16. Fermi GRB 241115B: Global MASTER-Net observations report
  17. LIGO/Virgo/KAGRA S241114bi: Updated Sky localization and EM Bright Classification
  18. EP241115a: Global MASTER-Net observations report
  19. GRB 241115B: Fermi GBM Final Real-time Localization
  20. LIGO/Virgo/KAGRA S241113p: Updated Sky localization
  21. EP241115a: EP detection of a fast X-ray transient
  22. EP241113a: No Detection in Fermi-GBM Observations
  23. Swift GRB 241115A: Global MASTER-Net observations report
  24. Fermi GRB 241115A: Global MASTER-Net observations report
  25. GRB 241115A: Swift detection of a burst
  26. GRB 241115A: Fermi GBM Final Real-time Localization
  27. EP 241113a: LBT possible optical counterpart
  28. GRB 241113B: KAIT Optical Afterglow Candidate
  29. LIGO/Virgo/KAGRA S241114bi: Upper limits from Fermi-GBM Observations
  30. LIGO/Virgo/KAGRA S241114bi: Coverage and upper limits from MAXI/GSC observations
  31. GRB 241113A: Swift-BAT refined analysis
  32. LIGO/Virgo/KAGRA S241114bi: Identification of a GW compact binary merger candidate
  33. GRB 241113A: PRIME near-infrared upper limits
  34. Fermi GRB 241114A: Global MASTER-Net observations report
  35. EP241113a: Global MASTER-Net observations report
  36. GRB 241114A: Fermi GBM Final Real-time Localization
  37. GRB 241113B: J-band upper limit from WINTER
  38. GRB 241113A: J-band observations with WINTER
  39. EP241113a : J-band observations with WINTER
  40. GRB 241030A: LCO optical observation
  41. GRB 241113B: Swift-XRT observations
  42. IceCube-241113A: Upper limits from a search for additional neutrino events in IceCube
  43. GRB 241113A: 1.6m Mephisto and 50cm array optical upper limits
  44. GRB 241113A: KAIT optical observations
  45. EP241113b: Global MASTER-Net observations report
  46. EP241113b/GRB 241113B: EP detection of GRB 241113B
  47. Fermi-LAT gamma-ray observations of IceCube-241113A
  48. GRB 241113B: SVOM/GRM observation
  49. EP241113a: EP on-board trigger and autonomous follow-up observation
  50. LIGO/Virgo/KAGRA S241114y: Identification of a GW compact binary merger candidate
  51. GRB 241113A: Swift-XRT refined Analysis
  52. EP241107a: SOAR upper limits
  53. GRB 241113A: Swift/UVOT Detection
  54. GRB 241113A: REM detection of the optical/NIR afterglow
  55. Konus-Wind detection of GRB 241107A (short/hard)
  56. LIGO/Virgo/KAGRA S241113p: Identification of a GW compact binary merger candidate
  57. Fermi Gamma-ray Burst Monitor trigger 753166198/241113201 is not a GRB
  58. GRB 241113B: Swift ToO observations
  59. GRB 241113A: LCO optical observations
  60. IceCube-241113A - IceCube observation of a high-energy neutrino candidate track-like event
  61. GRB 241112B: GMG Optical Upper Limit
  62. GRB 241113A: Enhanced Swift-XRT position
  63. GRB241113A: LCOGT (40-cm) optical counterpart detection
  64. GRB 241113B : detection of a long GRB by SVOM/ECLAIRs
  65. GRB 241113A: MASTER010615.66-224018.2 optical counterpart detection
  66. GRB 241113A: Swift detection of a burst with an optical counterpart
  67. Swift GRB241113.33: Global MASTER-Net observations report
  68. SVOM/GRM detection of a short burst from SGR 1E1841-045
  69. Fermi trigger No 753166198: Global MASTER-Net observations report
  70. LIGO/Virgo/KAGRA S241111bn: Updated Sky localization
  71. GRB 241105A: ATCA Radio Upper Limits
  72. GRB 241112B: AbAO optical upper limit
  73. GRB 241107A: GROWTH-India telescope optical upper limit
  74. IceCube Alert 241113.02: Global MASTER-Net observations report
  75. Fermi GRB 241112A: Global MASTER-Net observations report
  76. Fermi-GBM Sub-Threshold Detection of GRB 241112B
  77. GRB 241112B: Optical afterglow detection confirmation in revisiting the Mephisto data
  78. GRB 241112B: Swift-XRT afterglow detection
  79. GRB 241112B: LCO optical detection of the SVOM/VT candidate
  80. GRB 241112B: SVOM/GRM observation
  81. GRB 241112B: SVOM/VT afterglow detection
  82. Fermi Gamma-ray Burst Monitor trigger 752995908/241111230 (GRB 241111A) is not a GRB
  83. GRB 241107A: Swift/BAT candidate arcminute localization of a short burst
  84. GRB 241112B: Mephisto optical upper limits
  85. GRB 241112B: GOTO optical upper limits
  86. GRB 241112B: Swift ToO observations
  87. GRB 241112B : detection of a long GRB by SVOM/ECLAIRs
  88. GRB 241107A: INTEGRAL IBIS localization
  89. EP241107a: EP-FXT follow-up observations
  90. GRB 241112A: Fermi GBM Final Real-time Localization
  91. LIGO/Virgo/KAGRA S241110br: NED Galaxies in the Localization Volume
  92. LIGO/Virgo/KAGRA S241109bn: ATLAS observations and discovery of the potential counterpart AT2024aawt
  93. GRB 241105A: VLT/FORS2 refined spectroscopic redshift z = 2.681
  94. LIGO/Virgo/KAGRA S241111bn: Identification of a GW compact binary merger candidate
  95. IPN triangulation of GRB 241107A (short/hard)
  96. GRB 241107A: INTEGRAL/IBIS/PICsIT detection of a short burst
  97. GRB 241025C: VZLUSAT-2 detection
  98. GRB 241025A: VZLUSAT-2 detection
  99. GRB 241018A: cubesat Avion detection
  100. Fermi trigger No 752990530: Global MASTER-Net observations report

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