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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 241206B: GWAC-F50A optical upper limit
  2. GRB 241206B: SVOM/ECLAIRs detection of a long soft transient
  3. EP241113a: Keck/LRIS spectroscopic observation and tentative redshift
  4. Fermi GRB 241206A: Global MASTER-Net observations report
  5. GRB 241206A: Fermi GBM Final Real-time Localization
  6. EP241201a: 1.6m Mephisto Optical Upper Limits
  7. GRB 241204A: COLIBRÍ Optical Upper Limit
  8. EP241202b: KAIT optical upper limit
  9. LIGO/Virgo/KAGRA S241125n: gamma-ray upper limits from joint observations by the LST-1 and MAGIC telescopes
  10. GRB 241204A: DDOTI Upper Limits on the Afterglow
  11. GRB 241204A: Fermi GBM Observation
  12. Fermi GRB 241204A: Global MASTER-Net observations report
  13. GRB 241130A: CALET Gamma-Ray Burst Monitor detection
  14. GRB 241128A : RAPAS follow-up observations
  15. GRB 241201A: GRBAlpha detection
  16. GRB 241204A: Fermi-LAT detection
  17. EP241202b: Upper limits from Fermi-GBM Observations
  18. IceCube-241127A: No transient candidates from the Zwicky Transient Facility
  19. EP241202b: Kinder optical counterpart candidate
  20. Fermi-GBM Sub-Threshold Detection of GRB 241128A
  21. GRB 241113B : RAPAS follow-up observation
  22. EP241201a: EP-FXT follow-up observations
  23. Konus-Wind detection of GRB 241130A
  24. EP241202b: Global MASTER-Net observations report
  25. EP241201a: BOOTES-5 optical upper limit
  26. EP241202b: EP detection of a fast X-ray transient
  27. EP241201a: NOT optical observations
  28. IPN triangulation of GRB 241130A
  29. GRB 241130A: EIRSAT-1 GMOD Detection
  30. GRB 241128A: Swift/UVOT Upper Limits
  31. GRB 241130A: Fermi GBM Detection
  32. IceCube-241127A: Upper limits from a search for additional neutrino events in IceCube
  33. GRB 241129A: Swift/BAT-GUANO localization skymap of a burst
  34. EP241201a: Kinder optical counterpart candidate
  35. LIGO/Virgo/KAGRA S241102br: GRAWITA wide-field optical observations
  36. EP241201a: Global MASTER-Net observations report
  37. EP241201a: EP detection of a fast X-ray transient
  38. The EP-WXT trigger 01709126243 is not a real source
  39. GRB 241127B: detection of a long GRB by SVOM/ECLAIRs
  40. GRB241201B: Fermi GBM Final Localization
  41. GRB241201B: Fermi GBM Final Localization
  42. LIGO/Virgo/KAGRA S241201ac: Updated Sky localization
  43. EP241126a: SOAR observations of the optical counterpart
  44. Fermi GRB 241201A: Global MASTER-Net observations report
  45. GRB 241201A: BALROG localization (Fermi Trigger 754757764 / GRB 241201622)
  46. GRB 241130A: Fermi GBM Final Real-time Localization
  47. GRB 241130A: Fermi GBM Final Real-time Localization
  48. EP241126a: 1.6m Mephisto Optical Upper Limits
  49. GRB 241201A: Fermi GBM Final Real-time Localization
  50. LIGO/Virgo/KAGRA S241201ac: Identification of a GW compact binary merger candidate
  51. LIGO/Virgo/KAGRA S241130be: Updated Sky localization
  52. Fermi trigger No 754701230: Global MASTER-Net observations report
  53. IPN triangulation of GRB 241128B
  54. Konus-Wind detection of GRB 241114B
  55. LIGO/Virgo/KAGRA S241130n: Updated Sky localization
  56. LIGO/Virgo/KAGRA S241125n: GRANDMA Optical Upper Limits
  57. GRB 241128A: AbAO optical upper limit
  58. LIGO/Virgo/KAGRA S241127aj: Updated Sky localization
  59. LIGO/Virgo/KAGRA S241130be: Identification of a GW compact binary merger candidate
  60. LIGO/Virgo/KAGRA S241129aa: Updated Sky localization
  61. LIGO/Virgo/KAGRA S241130n: Identification of a GW compact binary merger candidate
  62. SVOM/GRM observation of a short burst from soft gamma repeater Kes 73
  63. GRB 241128C: SVOM/GRM observation
  64. GRB 241128B: SVOM/GRM observation
  65. GRB 241128A: Swift-BAT refined analysis
  66. GRB 241127A: Swift-BAT refined analysis
  67. EP241126a: NOT optical observations
  68. GRB 241127A: PRIME near-infrared detection
  69. GRB 241128A: Mondy optical observations
  70. GRB 241128A: GRANDMA and Kilonova-Catcher Optical Afterglow Detections and Upperlimits
  71. Swift-XRT observations of IceCube -241127A
  72. Swift GRB 241128A: Global MASTER-Net observations report
  73. Fermi-LAT gamma-ray observations of IceCube-241127A
  74. EP241126a: SVOM/VT observations
  75. LIGO/Virgo/KAGRA S241129aa: Identification of a GW compact binary merger candidate
  76. GRB 241128A: Swift-XRT refined Analysis
  77. GRB 241129A: Fermi GBM Final Real-time Localization
  78. GRB 241128A: Enhanced Swift-XRT position
  79. GRB 241128A: NOT optical observations
  80. GRB 241128A: LCO optical detection
  81. GRB 241128A: 1.5m OSN optical afterglow detection
  82. LIGO/Virgo S241127aj: GRANDMA/FRAM-CTA-N Observations
  83. Fermi trigger No 754492985: Global MASTER-Net observations report
  84. GRB 241128A: Swift-XRT afterglow detection
  85. GRB 241128A: Swift detection of a burst
  86. GRB 241127A: GRANDMA and Kilonova-Catcher optical afterglow detections
  87. GRB 241127A: Swift/UVOT Detection
  88. GRB 241127A: Swift-XRT refined Analysis
  89. GRB 241127A: SVOM/GRM observation
  90. GRB 241127A: Enhanced Swift-XRT position
  91. LIGO/Virgo/KAGRA S241127aj: Updated Sky localization
  92. The EP-WXT trigger 01709125191 is not a real source
  93. GRB 241127A: LCOGT (40-cm) optical counterpart detection
  94. Swift GRB241127.91: Global MASTER-Net OT detection
  95. EP241126a: WFST Observations
  96. LIGO/Virgo/KAGRA S241125n: Update on Coincidence False Alarm Method
  97. IceCube Alert 241127.59: Global MASTER-Net observations report
  98. GRB 241127A: Swift detection of a burst with an optical counterpart
  99. Swift GRB241127.91: Global MASTER-Net observations report
  100. Swift GRB241127.91: Global MASTER-Net OT detection

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