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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. EP240918b and EP240918c: EP-FXT follow-up observations
  2. LIGO/Virgo/KAGRA S240925n: Updated Sky localization and Source Classification
  3. Insight-HXMT ToO observations of X-ray bursts from SGR 1E 1841-045 / Kes 73
  4. GRB 240716A: Swift/BAT-GUANO localization skymap of a long burst
  5. LIGO/Virgo/KAGRA S240925n: Identification of a GW compact binary merger candidate
  6. Konus-Wind detection of GRB 240918B
  7. IPN triangulation of GRB 240918B
  8. GRB 240905B: VZLUSAT-2 detection
  9. LIGO/Virgo/KAGRA S240922df: Updated Sky localization
  10. LIGO/Virgo/KAGRA S240920dw: Updated Sky localization
  11. LIGO/Virgo/KAGRA S240921cw: Updated Sky localization
  12. LIGO/Virgo/KAGRA S240924a: Updated Sky localization
  13. LIGO/Virgo/KAGRA S240920bz: Updated Sky localization and Source Classification
  14. LIGO/Virgo/KAGRA S240923ct: Updated Sky localization and Source Classification
  15. EP trigger ID 01709059262: correction to the observation start time and source localization
  16. EP trigger ID 01709059262: the X-ray transient is likely a stellar flare event
  17. LIGO/Virgo/KAGRA S240924a: Identification of a GW compact binary merger candidate
  18. LIGO/Virgo/KAGRA S240923ct: Identification of a GW compact binary merger candidate
  19. LIGO/Virgo S240919bn: GOTO optical upper limits
  20. LIGO/Virgo S240919bn: Swift XRT observations, 10 X-ray sources
  21. GRB 240918B: AstroSat CZTI detection
  22. LIGO/Virgo/KAGRA S240922df: Identification of a GW compact binary merger candidate
  23. LIGO/Virgo/KAGRA S240921cw: Identification of a GW compact binary merger candidate
  24. EP240919a: EP-FXT follow-up observation update
  25. EP240913A/GRB 240913C: AbAO optical upper limit
  26. EP240919a / GRB 240919A: Mondy optical upper limit
  27. EP240913a/GRB 240913C: 1.6m Mephisto observations
  28. EP240918a: SVOM/VT upper limit
  29. Fermi GBM Sub-Threshold Detection of GRB240919A / EP240919a
  30. EP240919a / GRB 240919A: REM optical and NIR upper limits
  31. EP240919a / GRB 240919A: KAIT optical upper limit
  32. EP240918b and EP240918c: Optical upper limits with Kinder observations
  33. GRB 240414A: further radio observations with the VLA
  34. EP240919a: Optical upper limit with Kinder observations
  35. GRB 240919A / EP240919a: SVOM/GRM observation
  36. EP240919a: INTEGRAL SPI-ACS confirmation of reported high-energy counterpart
  37. EP240919a: INTEGRAL SPI-ACS confirmation of reported high-energy counterpart
  38. LIGO/Virgo/KAGRA S240920dw: Identification of a GW compact binary merger candidate
  39. EP EP240919a: Global MASTER-Net observations report
  40. GRB 240910A: radio detection with the VLA
  41. EP240918a: 1.6m Mephisto multi-band Optical Upper Limit
  42. EP240919a: NOT and Gemini optical observations
  43. EP240919a: GOTO optical upper limits
  44. EP240919a: JinShan optical upper limits
  45. EP240919a is likely a GRB event (duplicate submission of 37563)
  46. EP240919a is likely a GRB event
  47. LIGO/Virgo/KAGRA S240920bz: Identification of a GW compact binary merger candidate
  48. EP240919a: EP-WXT detection of a fast X-ray transient
  49. GRB 240918A and GRB 240918B : INTEGRAL SPI ACS LIGHT CURVE
  50. LIGO/Virgo/KAGRA S240919bn: Updated Sky localization
  51. GRB 240918B: Fermi GBM Detection
  52. LIGO/Virgo/KAGRA S240917cb: Updated Sky localization and EM Bright Classification
  53. LIGO/Virgo/KAGRA S240916ar: Updated Sky localization and EM Bright Classification
  54. EP240918b and EP240918c: EP-WXT detection of two fast X-ray transients
  55. EP240918a: EP observation update
  56. GRB 240910A: further Swift observations and confirmation of afterglow
  57. LIGO/Virgo/KAGRA S240919bn: Identification of a GW compact binary merger candidate
  58. EP240918a: Swift-XRT observation
  59. Fermi GRB 240918A: Global MASTER-Net observations report
  60. GRB 240918A: Fermi GBM Final Real-time Localization
  61. EP EP240918a: Global MASTER-Net observations report
  62. EP240918a: JinShan optical upper limits
  63. EP240918a: YAHPT Optical Upper Limit
  64. EP240918a: Optical upper limits with Kinder observations
  65. EP240918a: GMG Optical Upper Limit
  66. GRB 240916A: GRBAlpha detection
  67. GRB 240914B: GRBAlpha detection
  68. EP240918a: an X-ray transient detected by Einstein Probe
  69. GRB 240916A: NOT optical observation
  70. GRB 240912A: Swift-BAT refined analysis
  71. IPN triangulation of GRB 240913C / EP 240913a
  72. GRB 240825A: INTEGRAL SPI ACS LIGHT CURVE
  73. GRB 240825A: The nature of the afterglow motivates the search of the associated supernova
  74. GRB 240916A: Fermi GBM Observation
  75. LIGO/Virgo/KAGRA S240917cb: Identification of a GW compact binary merger candidate
  76. GRB 240821A: radio observation with the VLA
  77. GRB 240916A (AT 2024vlp / GOTO24fzn): VLT/X-shooter redshift
  78. GRB 240916A: Swift-XRT afterglow detection
  79. LIGO/Virgo/KAGRA S240916ar: Identification of a GW compact binary merger candidate
  80. GRB 240916A: Swift ToO observations
  81. LIGO/Virgo/KAGRA S240915b: NED Galaxies in the Localization Volume
  82. LIGO/Virgo S240915b: Swift XRT observations, 8 X-ray sources
  83. GRB 240916A: JinShan optical decay in one of the two GOTO candidates
  84. GRB 240916B: Fermi GBM Final Real-time Localization
  85. GRB 240914B: Fermi GBM Final Localization
  86. The EP-WXT triggers 01709047257 and 01709047278 are not real sources
  87. GRB 240916A: GOTO identification of two new optical sources within the GBM localisation region
  88. EP EP240913a: Global MASTER-Net observations report
  89. LIGO/Virgo/KAGRA S240915b: Coverage and upper limits from MAXI/GSC observations
  90. GRB 240916A INTEGRAL SPI ACS LIGHT CURVE
  91. GRB 240916A: Fermi GBM Final Real-time Localization
  92. Fermi Gamma-ray Burst Monitor trigger 748124309/240915846 is not a GRB
  93. LIGO/Virgo/KAGRA S240915bd: Updated Sky localization
  94. EP240913a: VLT/HAWK-I near-infrared upper limits
  95. LIGO/Virgo/KAGRA S240915bd: Identification of a GW compact binary merger candidate
  96. LIGO/Virgo/KAGRA S240915b: Updated Sky localization and EM Bright Classification
  97. LIGO/Virgo/KAGRA S240915b: Identification of a GW compact binary merger candidate
  98. EP240913a/GRB 240913C: KAIT optical upper limit
  99. EP240913a / GRB 240913C INTEGRAL SPI ACS LIGHT CURVE
  100. GRB 240913C: Fermi GBM detection

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