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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"

38259 results found.

  1. GRB 241025A: VIRT Optical Upper Limit
  2. Konus-Wind detection of GRB 241120A
  3. GRB 241120A: CALET Gamma-Ray Burst Monitor detection
  4. EP241021a and EP241026b: Keck/LRIS spectroscopic observations
  5. EP trigger ID 01709065118: Keck/LRIS spectroscopic observations
  6. EP-WXT trigger 01709018832: Lick/Kast spectroscopy with the 3 m Shane telescope
  7. GRB 241120A: Mondy and AbAO optical observations
  8. EP trigger ID 01709122294: the X-ray transient is likely a stellar flare event
  9. EP241119a: GIT optical upper limits
  10. GRB 241113A: Possible ATCA Radio detection
  11. GRB 241120A: Fermi GBM Observation
  12. GRB 241114B: Insight-HXMT/HE detection
  13. Integral GRB241120.25: Global MASTER-Net observations report
  14. EP241119a: Global MASTER-Net observations report
  15. GRB241120A: a long GRB detected by INTEGRAL
  16. GRB 241120A: Fermi GBM Final Real-time Localization
  17. GRB 241115A: CALET Gamma-Ray Burst Monitor detection
  18. GRB 241112B: Mephisto further optical observations
  19. GRB 241119A: Fermi GBM Final Real-time Localization
  20. GRB 241030A: J-band observations
  21. GRB 241115a: PRIME near-infrared upper limits
  22. GRB 241117A: Swift/BAT-GUANO localization skymap of a burst
  23. LIGO/Virgo/KAGRA S241116cq: Upper limits from Swift/BAT-GUANO
  24. GRB 241115B: Fermi GBM Observation
  25. Fermi GRB 241118A: Global MASTER-Net observations report
  26. GRB 241118A: Fermi GBM Final Real-time Localization
  27. GRB 241117A: SVOM/GRM observation of a short burst with extended emission
  28. GRB 241117A: Fermi GBM Detection
  29. Fermi GRB 241117B: Global MASTER-Net observations report
  30. GRB 241117B: Fermi GBM Final Real-time Localization
  31. GRB 241115B: Swift/BAT-GUANO localization skymap of a long burst
  32. Fermi GRB 241117A: Global MASTER-Net observations report
  33. GRB 241117A: Fermi GBM Final Real-time Localization
  34. GRB 241115C: Fermi GBM Observation
  35. GRB 241115A: Swift-XRT afterglow detection
  36. EP241115a/GRB 241115D: Optical upper limits with Kinder observations
  37. GRB 241115A: Mephisto upper limits
  38. GRB 241113B: Mephisto upper limits
  39. EP241115a/GRB 241115D: Swift/XRT follow-up observation
  40. GRB 241115D / EP 241115a: SVOM/GRM observation
  41. GRB 241115A: Fermi GBM Observation
  42. GRB 241115A: LCOGT Optical Upper Limits
  43. GRB 241115C: Swift/BAT-GUANO localization skymap of a burst
  44. Fermi GRB 241115B: Global MASTER-Net observations report
  45. EP241115a: Global MASTER-Net observations report
  46. GRB 241115B: Fermi GBM Final Real-time Localization
  47. EP241113a: No Detection in Fermi-GBM Observations
  48. Swift GRB 241115A: Global MASTER-Net observations report
  49. Fermi GRB 241115A: Global MASTER-Net observations report
  50. GRB 241115A: Swift detection of a burst
  51. GRB 241115A: Fermi GBM Final Real-time Localization
  52. EP 241113a: LBT possible optical counterpart
  53. GRB 241113B: KAIT Optical Afterglow Candidate
  54. LIGO/Virgo/KAGRA S241114bi: Upper limits from Fermi-GBM Observations
  55. GRB 241113A: Swift-BAT refined analysis
  56. GRB 241113A: PRIME near-infrared upper limits
  57. Fermi GRB 241114A: Global MASTER-Net observations report
  58. EP241113a: Global MASTER-Net observations report
  59. GRB 241114A: Fermi GBM Final Real-time Localization
  60. GRB 241113B: J-band upper limit from WINTER
  61. GRB 241113A: J-band observations with WINTER
  62. GRB 241030A: LCO optical observation
  63. GRB 241113B: Swift-XRT observations
  64. GRB 241113A: 1.6m Mephisto and 50cm array optical upper limits
  65. GRB 241113A: KAIT optical observations
  66. EP241113b: Global MASTER-Net observations report
  67. EP241113b/GRB 241113B: EP detection of GRB 241113B
  68. GRB 241113B: SVOM/GRM observation
  69. GRB 241113A: Swift-XRT refined Analysis
  70. GRB 241113A: Swift/UVOT Detection
  71. GRB 241113A: REM detection of the optical/NIR afterglow
  72. Konus-Wind detection of GRB 241107A (short/hard)
  73. Fermi Gamma-ray Burst Monitor trigger 753166198/241113201 is not a GRB
  74. GRB 241113B: Swift ToO observations
  75. GRB 241113A: LCO optical observations
  76. IceCube-241113A - IceCube observation of a high-energy neutrino candidate track-like event
  77. GRB 241112B: GMG Optical Upper Limit
  78. GRB 241113A: Enhanced Swift-XRT position
  79. GRB241113A: LCOGT (40-cm) optical counterpart detection
  80. GRB 241113B : detection of a long GRB by SVOM/ECLAIRs
  81. GRB 241113A: MASTER010615.66-224018.2 optical counterpart detection
  82. GRB 241113A: Swift detection of a burst with an optical counterpart
  83. Swift GRB241113.33: Global MASTER-Net observations report
  84. SVOM/GRM detection of a short burst from SGR 1E1841-045
  85. Fermi trigger No 753166198: Global MASTER-Net observations report
  86. GRB 241105A: ATCA Radio Upper Limits
  87. GRB 241112B: AbAO optical upper limit
  88. GRB 241107A: GROWTH-India telescope optical upper limit
  89. IceCube Alert 241113.02: Global MASTER-Net observations report
  90. Fermi GRB 241112A: Global MASTER-Net observations report
  91. Fermi-GBM Sub-Threshold Detection of GRB 241112B
  92. GRB 241112B: Optical afterglow detection confirmation in revisiting the Mephisto data
  93. GRB 241112B: Swift-XRT afterglow detection
  94. GRB 241112B: LCO optical detection of the SVOM/VT candidate
  95. GRB 241112B: SVOM/GRM observation
  96. GRB 241112B: SVOM/VT afterglow detection
  97. Fermi Gamma-ray Burst Monitor trigger 752995908/241111230 (GRB 241111A) is not a GRB
  98. GRB 241107A: Swift/BAT candidate arcminute localization of a short burst
  99. GRB 241112B: Mephisto optical upper limits
  100. GRB 241112B: GOTO optical upper limits

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