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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. AT2024adec: X-ray Upper Limits from EP-FXT Observation
  2. EP241206a: BOOTES Global Network optical limits
  3. GRB 241207C: MASTER optical observations
  4. Fermi trigger No 755225799: Global MASTER-Net observations report
  5. GRB 241207C: Tiled Swift observations
  6. GRB 241207C: MAXI/GSC detection
  7. GRB 241207B: Fermi GBM Final Real-time Localization
  8. Fermi trigger No 755277791: Global MASTER-Net observations report
  9. Fermi GRB 241207A: Global MASTER-Net observations report
  10. EP241206a: Global MASTER-Net observations report
  11. EP241206a: EP detection of a fast X-ray transient
  12. GRB 241206A: Fermi GBM observation
  13. GRB 241206C: SVOM/GRM observation of a likely short burst
  14. GRB 241207A: Fermi GBM Final Real-time Localization
  15. GRB 241206A: Swift/BAT-GUANO localization skymap of a burst
  16. GRB 241206B: SVOM/MXT observations: a probable flare from the QSO 1ES 1959+650
  17. GRB 241206B: GWAC-F50A optical upper limit
  18. GRB 241206B: SVOM/ECLAIRs detection of a long soft transient
  19. EP241113a: Keck/LRIS spectroscopic observation and tentative redshift
  20. Fermi GRB 241206A: Global MASTER-Net observations report
  21. GRB 241206A: Fermi GBM Final Real-time Localization
  22. EP241201a: 1.6m Mephisto Optical Upper Limits
  23. GRB 241204A: COLIBRÍ Optical Upper Limit
  24. EP241202b: KAIT optical upper limit
  25. LIGO/Virgo/KAGRA S241125n: gamma-ray upper limits from joint observations by the LST-1 and MAGIC telescopes
  26. GRB 241204A: DDOTI Upper Limits on the Afterglow
  27. GRB 241204A: Fermi GBM Observation
  28. Fermi GRB 241204A: Global MASTER-Net observations report
  29. GRB 241130A: CALET Gamma-Ray Burst Monitor detection
  30. GRB 241128A : RAPAS follow-up observations
  31. GRB 241201A: GRBAlpha detection
  32. GRB 241204A: Fermi-LAT detection
  33. EP241202b: Upper limits from Fermi-GBM Observations
  34. IceCube-241127A: No transient candidates from the Zwicky Transient Facility
  35. EP241202b: Kinder optical counterpart candidate
  36. Fermi-GBM Sub-Threshold Detection of GRB 241128A
  37. GRB 241113B : RAPAS follow-up observation
  38. EP241201a: EP-FXT follow-up observations
  39. Konus-Wind detection of GRB 241130A
  40. EP241202b: Global MASTER-Net observations report
  41. EP241201a: BOOTES-5 optical upper limit
  42. EP241202b: EP detection of a fast X-ray transient
  43. EP241201a: NOT optical observations
  44. IPN triangulation of GRB 241130A
  45. GRB 241130A: EIRSAT-1 GMOD Detection
  46. GRB 241128A: Swift/UVOT Upper Limits
  47. GRB 241130A: Fermi GBM Detection
  48. IceCube-241127A: Upper limits from a search for additional neutrino events in IceCube
  49. GRB 241129A: Swift/BAT-GUANO localization skymap of a burst
  50. EP241201a: Kinder optical counterpart candidate
  51. LIGO/Virgo/KAGRA S241102br: GRAWITA wide-field optical observations
  52. EP241201a: Global MASTER-Net observations report
  53. EP241201a: EP detection of a fast X-ray transient
  54. The EP-WXT trigger 01709126243 is not a real source
  55. GRB 241127B: detection of a long GRB by SVOM/ECLAIRs
  56. GRB241201B: Fermi GBM Final Localization
  57. GRB241201B: Fermi GBM Final Localization
  58. LIGO/Virgo/KAGRA S241201ac: Updated Sky localization
  59. EP241126a: SOAR observations of the optical counterpart
  60. Fermi GRB 241201A: Global MASTER-Net observations report
  61. GRB 241201A: BALROG localization (Fermi Trigger 754757764 / GRB 241201622)
  62. GRB 241130A: Fermi GBM Final Real-time Localization
  63. GRB 241130A: Fermi GBM Final Real-time Localization
  64. EP241126a: 1.6m Mephisto Optical Upper Limits
  65. GRB 241201A: Fermi GBM Final Real-time Localization
  66. LIGO/Virgo/KAGRA S241201ac: Identification of a GW compact binary merger candidate
  67. LIGO/Virgo/KAGRA S241130be: Updated Sky localization
  68. Fermi trigger No 754701230: Global MASTER-Net observations report
  69. IPN triangulation of GRB 241128B
  70. Konus-Wind detection of GRB 241114B
  71. LIGO/Virgo/KAGRA S241130n: Updated Sky localization
  72. LIGO/Virgo/KAGRA S241125n: GRANDMA Optical Upper Limits
  73. GRB 241128A: AbAO optical upper limit
  74. LIGO/Virgo/KAGRA S241127aj: Updated Sky localization
  75. LIGO/Virgo/KAGRA S241130be: Identification of a GW compact binary merger candidate
  76. LIGO/Virgo/KAGRA S241129aa: Updated Sky localization
  77. LIGO/Virgo/KAGRA S241130n: Identification of a GW compact binary merger candidate
  78. SVOM/GRM observation of a short burst from soft gamma repeater Kes 73
  79. GRB 241128C: SVOM/GRM observation
  80. GRB 241128B: SVOM/GRM observation
  81. GRB 241128A: Swift-BAT refined analysis
  82. GRB 241127A: Swift-BAT refined analysis
  83. EP241126a: NOT optical observations
  84. GRB 241127A: PRIME near-infrared detection
  85. GRB 241128A: Mondy optical observations
  86. GRB 241128A: GRANDMA and Kilonova-Catcher Optical Afterglow Detections and Upperlimits
  87. Swift-XRT observations of IceCube -241127A
  88. Swift GRB 241128A: Global MASTER-Net observations report
  89. Fermi-LAT gamma-ray observations of IceCube-241127A
  90. EP241126a: SVOM/VT observations
  91. LIGO/Virgo/KAGRA S241129aa: Identification of a GW compact binary merger candidate
  92. GRB 241128A: Swift-XRT refined Analysis
  93. GRB 241129A: Fermi GBM Final Real-time Localization
  94. GRB 241128A: Enhanced Swift-XRT position
  95. GRB 241128A: NOT optical observations
  96. GRB 241128A: LCO optical detection
  97. GRB 241128A: 1.5m OSN optical afterglow detection
  98. LIGO/Virgo S241127aj: GRANDMA/FRAM-CTA-N Observations
  99. Fermi trigger No 754492985: Global MASTER-Net observations report
  100. GRB 241128A: Swift-XRT afterglow detection

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