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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"

44399 results found.

  1. Konus-Wind detection of GRB 241209B
  2. GRB 241207A: EIRSAT-1 GMOD Detection
  3. GRB 241209A: Redshift of the likely host galaxy z = 0.784 from OSIRIS+/GTC
  4. GRB 241209B: GRBAlpha detection
  5. GRB 241206C: GRBAlpha detection
  6. LIGO/Virgo/KAGRA S241210cw: Updated Sky localization
  7. LIGO/Virgo/KAGRA S241210d: Updated Sky localization and EM Bright Classification
  8. GRB 241211A: Fermi GBM Final Real-time Localization
  9. GRB 241129A: Fermi GBM Observation
  10. GRB 241209B: Swift/BAT-GUANO localization skymap of a burst
  11. GRB 241209D: REM optical/NIR upper limits
  12. Konus-Wind detection of GRB 241209D
  13. GRB 241209B: Swift-XRT afterglow detection
  14. GRB 241209C: Fermi GBM Observation
  15. GRB 241209A: Swift-XRT refined Analysis
  16. Fermi Gamma-ray Burst Monitor trigger 755485387 / 241210044 is not a GRB
  17. LIGO/Virgo/KAGRA S241210fu: Identification of a GW compact binary merger candidate
  18. EP241208a: Optical upper limit with Kinder observations
  19. GRB 241128A: CrAO ZTSh and Mondy AZT-33IK optical observations
  20. GRB 241209D: AstroSat CZTI detection
  21. GRB 241209A: EP-FXT follow-up observations
  22. GRB 241209B: SVOM/VT afterglow detection
  23. LIGO/Virgo/KAGRA S241210cw: Identification of a GW compact binary merger candidate
  24. EP241208a: Global MASTER-Net observations report
  25. EP241208a: EP-FXT follow-up observations
  26. LIGO/Virgo/KAGRA S241210d: Identification of a GW compact binary merger candidate
  27. Fermi trigger No 755485387: Global MASTER-Net observations report
  28. GRB 241207B: Fermi GBM Observation
  29. GRB 241209A: BOOTES-7 and 2.2m CAHA early optical upper limits
  30. GRB 241209D: Swift-XRT refined Analysis
  31. GRB 241209D: Fermi GBM Observation
  32. GRB 241209A: VLT/HAWK-I near-IR counterpart candidate
  33. GRB 241209D: COLIBRÍ detection of the afterglow
  34. GRB 241209A: COLIBRÍ Optical Upper Limit
  35. Fermi GRB 241209D: Global MASTER-Net observations report
  36. GRB 241209A: Fermi GBM Observation
  37. GRB 241209C: Swift/BAT-GUANO localization skymap of a burst
  38. GRB 241209A: GRANDMA/TAROT upper limit
  39. GRB 241209B: BOOTES-5 optical upper limit
  40. Swift GRB 241209D: Global MASTER-Net observations report
  41. Fermi GRB 241209C: Global MASTER-Net observations report
  42. Fermi GRB 241209E: Global MASTER-Net observations report
  43. GRB 241209E: Fermi GBM Final Real-time Localization
  44. GRB 241209B: Swift ToO observations
  45. LIGO/Virgo/KAGRA S241102br: continued GRAWITA observations and detection of an optical transient (AT2024adip)
  46. GRB 241209A: REM optical/NIR observations
  47. GRB 241209D: Enhanced Swift-XRT position
  48. GRB 241209C: AstroSat CZTI detection
  49. GRB 241209D: Swift detection of a burst
  50. GRB 241209D: Fermi GBM Final Real-time Localization
  51. GRB 241209A: VLT/X-shooter spectroscopy
  52. GRB 241209A: Enhanced Swift-XRT position
  53. GRB 241114B: cubesat Avion detection
  54. GRB 241209A: VLT optical observations
  55. Fermi GRB 241209A: Global MASTER-Net observations report
  56. GRB 241209C: Fermi GBM Final Real-time Localization
  57. GRB 241209A: GOTO optical upper limits
  58. EP241206a: 1.5m OSN optical limit
  59. GRB 241209A: Prompt enhanced Swift-XRT position
  60. GRB 241209B: SVOM/ECLAIRs and GRM detection of a long burst
  61. EP241208a: EP detection of a fast X-ray transient
  62. GRB 241209A: Swift detection of a short burst
  63. Swift GRB241209.23: Global MASTER-Net observations report
  64. GRB 241209A: Fermi GBM Final Real-time Localization
  65. Fermi GRB 241207B: Global MASTER-Net observations report
  66. GRB 241207B: Swift/BAT-GUANO localization skymap of a short burst
  67. Fermi Gamma-ray Burst Monitor trigger 755277791/241207641 is not a GRB
  68. GRB 241201A: AstroSat CZTI detection
  69. GRB 241206A: DDOTI Upper Limit on the Afterglow
  70. AT2024adec: X-ray Upper Limits from EP-FXT Observation
  71. AT2024adec: X-ray Upper Limits from EP-FXT Observation
  72. EP241206a: BOOTES Global Network optical limits
  73. GRB 241207C: MASTER optical observations
  74. Fermi trigger No 755225799: Global MASTER-Net observations report
  75. GRB 241207C: Tiled Swift observations
  76. GRB 241207C: MAXI/GSC detection
  77. GRB 241207B: Fermi GBM Final Real-time Localization
  78. Fermi trigger No 755277791: Global MASTER-Net observations report
  79. Fermi GRB 241207A: Global MASTER-Net observations report
  80. EP241206a: Global MASTER-Net observations report
  81. EP241206a: EP detection of a fast X-ray transient
  82. GRB 241206A: Fermi GBM observation
  83. GRB 241206C: SVOM/GRM observation of a likely short burst
  84. GRB 241207A: Fermi GBM Final Real-time Localization
  85. GRB 241206A: Swift/BAT-GUANO localization skymap of a burst
  86. GRB 241206B: SVOM/MXT observations: a probable flare from the QSO 1ES 1959+650
  87. GRB 241206B: GWAC-F50A optical upper limit
  88. GRB 241206B: SVOM/ECLAIRs detection of a long soft transient
  89. EP241113a: Keck/LRIS spectroscopic observation and tentative redshift
  90. Fermi GRB 241206A: Global MASTER-Net observations report
  91. GRB 241206A: Fermi GBM Final Real-time Localization
  92. EP241201a: 1.6m Mephisto Optical Upper Limits
  93. GRB 241204A: COLIBRÍ Optical Upper Limit
  94. EP241202b: KAIT optical upper limit
  95. LIGO/Virgo/KAGRA S241125n: gamma-ray upper limits from joint observations by the LST-1 and MAGIC telescopes
  96. GRB 241204A: DDOTI Upper Limits on the Afterglow
  97. GRB 241204A: Fermi GBM Observation
  98. Fermi GRB 241204A: Global MASTER-Net observations report
  99. GRB 241130A: CALET Gamma-Ray Burst Monitor detection
  100. GRB 241128A : RAPAS follow-up observations

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