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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 241209B: SVOM/ECLAIRs and GRM detection of a long burst
  2. EP241208a: EP detection of a fast X-ray transient
  3. GRB 241209A: Swift detection of a short burst
  4. Swift GRB241209.23: Global MASTER-Net observations report
  5. GRB 241209A: Fermi GBM Final Real-time Localization
  6. Fermi GRB 241207B: Global MASTER-Net observations report
  7. GRB 241207B: Swift/BAT-GUANO localization skymap of a short burst
  8. Fermi Gamma-ray Burst Monitor trigger 755277791/241207641 is not a GRB
  9. GRB 241201A: AstroSat CZTI detection
  10. GRB 241206A: DDOTI Upper Limit on the Afterglow
  11. AT2024adec: X-ray Upper Limits from EP-FXT Observation
  12. AT2024adec: X-ray Upper Limits from EP-FXT Observation
  13. EP241206a: BOOTES Global Network optical limits
  14. GRB 241207C: MASTER optical observations
  15. Fermi trigger No 755225799: Global MASTER-Net observations report
  16. GRB 241207C: Tiled Swift observations
  17. GRB 241207C: MAXI/GSC detection
  18. GRB 241207B: Fermi GBM Final Real-time Localization
  19. Fermi trigger No 755277791: Global MASTER-Net observations report
  20. Fermi GRB 241207A: Global MASTER-Net observations report
  21. EP241206a: Global MASTER-Net observations report
  22. EP241206a: EP detection of a fast X-ray transient
  23. GRB 241206A: Fermi GBM observation
  24. GRB 241206C: SVOM/GRM observation of a likely short burst
  25. GRB 241207A: Fermi GBM Final Real-time Localization
  26. GRB 241206A: Swift/BAT-GUANO localization skymap of a burst
  27. GRB 241206B: SVOM/MXT observations: a probable flare from the QSO 1ES 1959+650
  28. GRB 241206B: GWAC-F50A optical upper limit
  29. GRB 241206B: SVOM/ECLAIRs detection of a long soft transient
  30. EP241113a: Keck/LRIS spectroscopic observation and tentative redshift
  31. Fermi GRB 241206A: Global MASTER-Net observations report
  32. GRB 241206A: Fermi GBM Final Real-time Localization
  33. EP241201a: 1.6m Mephisto Optical Upper Limits
  34. GRB 241204A: COLIBRÍ Optical Upper Limit
  35. EP241202b: KAIT optical upper limit
  36. LIGO/Virgo/KAGRA S241125n: gamma-ray upper limits from joint observations by the LST-1 and MAGIC telescopes
  37. GRB 241204A: DDOTI Upper Limits on the Afterglow
  38. GRB 241204A: Fermi GBM Observation
  39. Fermi GRB 241204A: Global MASTER-Net observations report
  40. GRB 241130A: CALET Gamma-Ray Burst Monitor detection
  41. GRB 241128A : RAPAS follow-up observations
  42. GRB 241201A: GRBAlpha detection
  43. GRB 241204A: Fermi-LAT detection
  44. EP241202b: Upper limits from Fermi-GBM Observations
  45. IceCube-241127A: No transient candidates from the Zwicky Transient Facility
  46. EP241202b: Kinder optical counterpart candidate
  47. Fermi-GBM Sub-Threshold Detection of GRB 241128A
  48. GRB 241113B : RAPAS follow-up observation
  49. EP241201a: EP-FXT follow-up observations
  50. Konus-Wind detection of GRB 241130A
  51. EP241202b: Global MASTER-Net observations report
  52. EP241201a: BOOTES-5 optical upper limit
  53. EP241202b: EP detection of a fast X-ray transient
  54. EP241201a: NOT optical observations
  55. IPN triangulation of GRB 241130A
  56. GRB 241130A: EIRSAT-1 GMOD Detection
  57. GRB 241128A: Swift/UVOT Upper Limits
  58. GRB 241130A: Fermi GBM Detection
  59. IceCube-241127A: Upper limits from a search for additional neutrino events in IceCube
  60. GRB 241129A: Swift/BAT-GUANO localization skymap of a burst
  61. EP241201a: Kinder optical counterpart candidate
  62. LIGO/Virgo/KAGRA S241102br: GRAWITA wide-field optical observations
  63. EP241201a: Global MASTER-Net observations report
  64. EP241201a: EP detection of a fast X-ray transient
  65. The EP-WXT trigger 01709126243 is not a real source
  66. GRB 241127B: detection of a long GRB by SVOM/ECLAIRs
  67. GRB241201B: Fermi GBM Final Localization
  68. GRB241201B: Fermi GBM Final Localization
  69. LIGO/Virgo/KAGRA S241201ac: Updated Sky localization
  70. EP241126a: SOAR observations of the optical counterpart
  71. Fermi GRB 241201A: Global MASTER-Net observations report
  72. GRB 241201A: BALROG localization (Fermi Trigger 754757764 / GRB 241201622)
  73. GRB 241130A: Fermi GBM Final Real-time Localization
  74. GRB 241130A: Fermi GBM Final Real-time Localization
  75. EP241126a: 1.6m Mephisto Optical Upper Limits
  76. GRB 241201A: Fermi GBM Final Real-time Localization
  77. LIGO/Virgo/KAGRA S241201ac: Identification of a GW compact binary merger candidate
  78. LIGO/Virgo/KAGRA S241130be: Updated Sky localization
  79. Fermi trigger No 754701230: Global MASTER-Net observations report
  80. IPN triangulation of GRB 241128B
  81. Konus-Wind detection of GRB 241114B
  82. LIGO/Virgo/KAGRA S241130n: Updated Sky localization
  83. LIGO/Virgo/KAGRA S241125n: GRANDMA Optical Upper Limits
  84. GRB 241128A: AbAO optical upper limit
  85. LIGO/Virgo/KAGRA S241127aj: Updated Sky localization
  86. LIGO/Virgo/KAGRA S241130be: Identification of a GW compact binary merger candidate
  87. LIGO/Virgo/KAGRA S241129aa: Updated Sky localization
  88. LIGO/Virgo/KAGRA S241130n: Identification of a GW compact binary merger candidate
  89. SVOM/GRM observation of a short burst from soft gamma repeater Kes 73
  90. GRB 241128C: SVOM/GRM observation
  91. GRB 241128B: SVOM/GRM observation
  92. GRB 241128A: Swift-BAT refined analysis
  93. GRB 241127A: Swift-BAT refined analysis
  94. EP241126a: NOT optical observations
  95. GRB 241127A: PRIME near-infrared detection
  96. GRB 241128A: Mondy optical observations
  97. GRB 241128A: GRANDMA and Kilonova-Catcher Optical Afterglow Detections and Upperlimits
  98. Swift-XRT observations of IceCube -241127A
  99. Swift GRB 241128A: Global MASTER-Net observations report
  100. Fermi-LAT gamma-ray observations of IceCube-241127A

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