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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. GRB 241120A: Fermi GBM Observation
  2. GRB 241114B: Insight-HXMT/HE detection
  3. Integral GRB241120.25: Global MASTER-Net observations report
  4. EP241119a: Global MASTER-Net observations report
  5. EP241119a: EP detection of a fast X-ray transient
  6. GRB241120A: a long GRB detected by INTEGRAL
  7. GRB 241120A: Fermi GBM Final Real-time Localization
  8. GRB 241115A: CALET Gamma-Ray Burst Monitor detection
  9. GRB 241112B: Mephisto further optical observations
  10. GRB 241119A: Fermi GBM Final Real-time Localization
  11. GRB 241030A: J-band observations
  12. GRB 241115a: PRIME near-infrared upper limits
  13. GRB 241117A: Swift/BAT-GUANO localization skymap of a burst
  14. LIGO/Virgo/KAGRA S241116cq: Upper limits from Swift/BAT-GUANO
  15. GRB 241115B: Fermi GBM Observation
  16. LIGO/Virgo/KAGRA S241114y: Updated Sky localization
  17. Fermi GRB 241118A: Global MASTER-Net observations report
  18. GRB 241118A: Fermi GBM Final Real-time Localization
  19. Updates to IceCube realtime alert system for muon tracks
  20. GRB 241117A: SVOM/GRM observation of a short burst with extended emission
  21. GRB 241117A: Fermi GBM Detection
  22. Fermi GRB 241117B: Global MASTER-Net observations report
  23. GRB 241117B: Fermi GBM Final Real-time Localization
  24. IceCube-Cascade 241116A: Upper limits from a search for additional neutrino events in IceCube
  25. LIGO/Virgo/KAGRA S241116cq: Updated Sky localization
  26. GRB 241115B: Swift/BAT-GUANO localization skymap of a long burst
  27. Fermi GRB 241117A: Global MASTER-Net observations report
  28. GRB 241117A: Fermi GBM Final Real-time Localization
  29. GRB 241115C: Fermi GBM Observation
  30. GRB 241115A: Swift-XRT afterglow detection
  31. LIGO/Virgo/KAGRA S241116cq: Identification of a GW compact binary merger candidate
  32. EP241115a/GRB 241115D: Optical upper limits with Kinder observations
  33. GRB 241115A: Mephisto upper limits
  34. GRB 241113B: Mephisto upper limits
  35. EP241115a/GRB 241115D: Swift/XRT follow-up observation
  36. GRB 241115D / EP 241115a: SVOM/GRM observation
  37. The EP-WXT trigger 01709120856 is likely a flaring star
  38. EP241113a: Swift XRT weak detection
  39. GRB 241115A: Fermi GBM Observation
  40. GRB 241115A: LCOGT Optical Upper Limits
  41. GRB 241115C: Swift/BAT-GUANO localization skymap of a burst
  42. Fermi GRB 241115B: Global MASTER-Net observations report
  43. LIGO/Virgo/KAGRA S241114bi: Updated Sky localization and EM Bright Classification
  44. EP241115a: Global MASTER-Net observations report
  45. GRB 241115B: Fermi GBM Final Real-time Localization
  46. LIGO/Virgo/KAGRA S241113p: Updated Sky localization
  47. EP241115a: EP detection of a fast X-ray transient
  48. EP241113a: No Detection in Fermi-GBM Observations
  49. Swift GRB 241115A: Global MASTER-Net observations report
  50. Fermi GRB 241115A: Global MASTER-Net observations report
  51. GRB 241115A: Swift detection of a burst
  52. GRB 241115A: Fermi GBM Final Real-time Localization
  53. EP 241113a: LBT possible optical counterpart
  54. GRB 241113B: KAIT Optical Afterglow Candidate
  55. LIGO/Virgo/KAGRA S241114bi: Upper limits from Fermi-GBM Observations
  56. LIGO/Virgo/KAGRA S241114bi: Coverage and upper limits from MAXI/GSC observations
  57. GRB 241113A: Swift-BAT refined analysis
  58. LIGO/Virgo/KAGRA S241114bi: Identification of a GW compact binary merger candidate
  59. GRB 241113A: PRIME near-infrared upper limits
  60. Fermi GRB 241114A: Global MASTER-Net observations report
  61. EP241113a: Global MASTER-Net observations report
  62. GRB 241114A: Fermi GBM Final Real-time Localization
  63. GRB 241113B: J-band upper limit from WINTER
  64. GRB 241113A: J-band observations with WINTER
  65. EP241113a : J-band observations with WINTER
  66. GRB 241030A: LCO optical observation
  67. GRB 241113B: Swift-XRT observations
  68. IceCube-241113A: Upper limits from a search for additional neutrino events in IceCube
  69. GRB 241113A: 1.6m Mephisto and 50cm array optical upper limits
  70. GRB 241113A: KAIT optical observations
  71. EP241113b: Global MASTER-Net observations report
  72. EP241113b/GRB 241113B: EP detection of GRB 241113B
  73. Fermi-LAT gamma-ray observations of IceCube-241113A
  74. GRB 241113B: SVOM/GRM observation
  75. EP241113a: EP on-board trigger and autonomous follow-up observation
  76. LIGO/Virgo/KAGRA S241114y: Identification of a GW compact binary merger candidate
  77. GRB 241113A: Swift-XRT refined Analysis
  78. EP241107a: SOAR upper limits
  79. GRB 241113A: Swift/UVOT Detection
  80. GRB 241113A: REM detection of the optical/NIR afterglow
  81. Konus-Wind detection of GRB 241107A (short/hard)
  82. LIGO/Virgo/KAGRA S241113p: Identification of a GW compact binary merger candidate
  83. Fermi Gamma-ray Burst Monitor trigger 753166198/241113201 is not a GRB
  84. GRB 241113B: Swift ToO observations
  85. GRB 241113A: LCO optical observations
  86. IceCube-241113A - IceCube observation of a high-energy neutrino candidate track-like event
  87. GRB 241112B: GMG Optical Upper Limit
  88. GRB 241113A: Enhanced Swift-XRT position
  89. GRB241113A: LCOGT (40-cm) optical counterpart detection
  90. GRB 241113B : detection of a long GRB by SVOM/ECLAIRs
  91. GRB 241113A: MASTER010615.66-224018.2 optical counterpart detection
  92. GRB 241113A: Swift detection of a burst with an optical counterpart
  93. Swift GRB241113.33: Global MASTER-Net observations report
  94. SVOM/GRM detection of a short burst from SGR 1E1841-045
  95. Fermi trigger No 753166198: Global MASTER-Net observations report
  96. LIGO/Virgo/KAGRA S241111bn: Updated Sky localization
  97. GRB 241105A: ATCA Radio Upper Limits
  98. GRB 241112B: AbAO optical upper limit
  99. GRB 241107A: GROWTH-India telescope optical upper limit
  100. IceCube Alert 241113.02: Global MASTER-Net observations report

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