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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"

3674 results found.

  1. Fermi GRB 241226A: Global MASTER-Net observations report
  2. LIGO/Virgo/KAGRA S241225v: Identification of a GW compact binary merger candidate
  3. Fermi trigger No 756678579: Global MASTER-Net observations report
  4. IceCube Alert 241224.30: Global MASTER-Net observations report
  5. GRB 241223A: GOTO optical observations summary
  6. Fermi trigger No 756447119: Global MASTER-Net observations report
  7. Fermi GRB 241221A: Global MASTER-Net observations report
  8. EP241217a: 1.6m Mephisto multi-band optical observations
  9. GRB 241217A/EP241217b: REM optical/NIR upper limits
  10. EP241217b: Global MASTER-Net observations report
  11. EP241217a: Global MASTER-Net observations report
  12. GRB 241209A: BOOTES-7 and 2.2m CAHA early optical upper limits
  13. Fermi GRB 241209A: Global MASTER-Net observations report
  14. Fermi trigger No 755277791: Global MASTER-Net observations report
  15. Fermi GRB 241207A: Global MASTER-Net observations report
  16. Fermi GRB 241204A: Global MASTER-Net observations report
  17. Fermi-GBM Sub-Threshold Detection of GRB 241128A
  18. IceCube-241127A: Upper limits from a search for additional neutrino events in IceCube
  19. EP241201a: Global MASTER-Net observations report
  20. EP241126a: 1.6m Mephisto Optical Upper Limits
  21. LIGO/Virgo/KAGRA S241201ac: Identification of a GW compact binary merger candidate
  22. LIGO/Virgo/KAGRA S241125n: GRANDMA Optical Upper Limits
  23. LIGO/Virgo/KAGRA S241130be: Identification of a GW compact binary merger candidate
  24. Swift GRB 241128A: Global MASTER-Net observations report
  25. GRB 241128A: LCO optical detection
  26. GRB 241128A: 1.5m OSN optical afterglow detection
  27. LIGO/Virgo S241127aj: GRANDMA/FRAM-CTA-N Observations
  28. Fermi trigger No 754492985: Global MASTER-Net observations report
  29. The EP-WXT trigger 01709125191 is not a real source
  30. GRB 241127A: LCOGT (40-cm) optical counterpart detection
  31. Swift GRB241127.91: Global MASTER-Net OT detection
  32. IceCube Alert 241127.59: Global MASTER-Net observations report
  33. GRB 241120A: Mondy and AbAO optical observations
  34. GRB 241112B: Mephisto further optical observations
  35. Fermi GRB 241118A: Global MASTER-Net observations report
  36. EP241115a: Global MASTER-Net observations report
  37. Fermi GRB 241114A: Global MASTER-Net observations report
  38. EP241113a: Global MASTER-Net observations report
  39. EP241113b: Global MASTER-Net observations report
  40. Fermi GRB 241112A: Global MASTER-Net observations report
  41. LIGO/Virgo/KAGRA S241109bn: Upper limits from EP-WXT observations
  42. Fermi trigger No 752878030: Global MASTER-Net observations report
  43. Integral GRB241109.89: Global MASTER-Net observations report
  44. GRB 241105A: EP-FXT follow-up observations
  45. GRB 241025A: LBT optical observations
  46. Fermi GRB 241105A: Global MASTER-Net observations report
  47. Fermi GRB 241104A: Global MASTER-Net observations report
  48. EP241103a: EP observation update
  49. LIGO/Virgo/KAGRA S241102br: MASTER observations and OT detection
  50. S241102cy: Identification of a GW compact binary merger candidate
  51. LIGO/Virgo/KAGRA S241102br: Identification of a GW compact binary merger candidate
  52. GRB 241030A: further SAO RAS optical observations
  53. GRB 241030B: Montarrenti Observatory optical upper limit
  54. Fermi trigger No 752083996: Global MASTER-Net observations report
  55. Fermi trigger No 752006065: Global MASTER-Net observations report
  56. GRB 241030B: BTA observations
  57. GRB 241026A: LBT optical observations
  58. GRB 241030A : MITSuME Akeno optical afterglow detection
  59. GRB 241026A: SAO RAS optical observations
  60. EP241021a: SAO RAS observations of rebrightening
  61. GRB 241029A: AKO Optical Afterglow Detection
  62. EP241021a: Gemini-South detection of optical rebrightening
  63. GRB 241025A: SAO RAS optical observations
  64. EP241026a (GRB 241026A): EP on-board trigger and follow-up observation
  65. GRB 241026A: COLIBRÍ Detection of the Optical Counterpart
  66. Fermi GRB 241026A: Global MASTER-Net observations report
  67. GRB 241025A: GRANDMA and Kilonova-Catcher optical afterglow detections and upperlimits
  68. Fermi trigger No 751554401: Global MASTER-Net observations report
  69. EP241021a: optical follow-up observations with the Liverpool Telescope
  70. GRB 241025A: DDOTI Afterglow detection
  71. EP241021a: GTC OSIRIS+ spectroscopy of the optical counterpart
  72. IceCube-Cascade 241019A: Upper limits from a search for additional neutrino events in IceCube
  73. GRB 241018A: SVOM/VT follow-up and optical candidate
  74. GRB 241017A: GROWTH-India Telescope optical upper limit
  75. Fermi trigger No 750788395: Global MASTER-Net observations report
  76. LIGO/Virgo/KAGRA S241011k: Identification of a GW compact binary merger candidate
  77. Fermi trigger No 750211959: Global MASTER-Net observations report
  78. Fermi trigger No 750291012: Global MASTER-Net observations report
  79. Fermi GRB 241010B: Global MASTER-Net observations report
  80. LIGO/Virgo/KAGRA S241009l: Identification of a GW compact binary merger candidate
  81. GRB 241006A: Swift/UVOT Upper Limits
  82. GRB 241001A: Swift-XRT afterglow detection
  83. GRB 240929A: SAO RAS, Mondy, and CrAO optical observations
  84. GRB 241001A: correction to GCN 37667
  85. Fermi GRB 241002B: Global MASTER-Net observations report
  86. GRB 241001A: Swift-XRT observations
  87. GRB241001A: optical afterglow candidate
  88. IceCube-240929A: Upper limits from a search for additional neutrino events in IceCube
  89. Fermi GRB 240930B: Global MASTER-Net observations report
  90. Fermi trigger No 749339671: Global MASTER-Net observations report
  91. Fermi Gamma-ray Burst Monitor trigger 749191601/240928199 is not a GRB
  92. EP240918b and EP240918c: EP-FXT follow-up observations
  93. Konus-Wind detection of GRB 240918B
  94. EP240913a/GRB 240913C: 1.6m Mephisto observations
  95. EP240919a / GRB 240919A: REM optical and NIR upper limits
  96. EP EP240918a: Global MASTER-Net observations report
  97. LIGO/Virgo/KAGRA S240910ci: Identification of a GW compact binary merger candidate
  98. EP240908a: Updates on the WXT detection result around the trigger time
  99. GRB 240905E: GIT optical upper limit
  100. GRB 240905B: Fermi-LAT detection

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