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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"

31727 results found.

  1. EP trigger ID 01709064214: GOTO confirms detection as a flare star
  2. GRB 241001A: correction to GCN 37667
  3. GRB 240929A: Liverpool Telescope prompt followup observations
  4. Fermi GRB 241002B: Global MASTER-Net observations report
  5. GRB 241001A: Swift-XRT observations
  6. GRB241001A: optical afterglow candidate
  7. LIGO/Virgo/KAGRA S241002e: Identification of a GW compact binary merger candidate
  8. LIGO/Virgo/KAGRA S240930du: Updated Sky localization
  9. GRB 240930B: Fermi GBM Observation
  10. GRB 241001A: Swift ToO observations
  11. GRB 240930B: GRBAlpha detection
  12. GRB 240929A: GRBAlpha detection
  13. EP240930a : KAIT optical upper limit
  14. GRB 240930B: Swift/BAT-GUANO localization skymap of a burst
  15. EP240930a: EP-FXT follow-up observation update
  16. Fermi-LAT Gamma-ray Observations of IceCube-240929A
  17. EP240930a: GOTO optical upper limits
  18. GRB 240929A: SVOM/GRM observation
  19. EP EP240930a: Global MASTER-Net observations report
  20. EP240930a: EP-WXT detection of a fast X-ray transient
  21. LIGO/Virgo/KAGRA S240930du: Identification of a GW compact binary merger candidate
  22. IceCube-240929A: Upper limits from a search for additional neutrino events in IceCube
  23. AMON NuEM 240926A: Swift XRT Follow-up
  24. GRB 240929A : Leavitt Observatory optical upper limit
  25. Fermi GRB 240930B: Global MASTER-Net observations report
  26. IPN triangulation of GRB 240926A
  27. GRB 240825A: LBT optical observations
  28. Fermi GRB 240930A: Global MASTER-Net observations report
  29. Fermi Gamma-ray Burst Monitor trigger 749362078/240930172 (GRB 240930A) is not a GRB
  30. LIGO/Virgo/KAGRA S240930aa: Identification of a GW compact binary merger candidate
  31. GRB 240929A long GRB detected by INTEGRAL
  32. Fermi GRB 240929A: Global MASTER-Net observations report
  33. Konus-Wind detection of GRB 240912A
  34. EP trigger ID 01709059262: Lick/Kast spectroscopy with 3 m Shane telescope
  35. NuEm-240926A / IC240926A: BZQJ0955+4532 ~0.6m optical decay and rebrightening detection by MASTER
  36. Konus-Wind detection of GRB 240905B
  37. GRB 240529A: FRAM-ORM early optical afterglow observations reveal plateau and rebrightening
  38. EP240919a / GRB 240919A: SVOM/VT upper limit
  39. EP240918b and EP240918c: EP-FXT follow-up observations
  40. LIGO/Virgo/KAGRA S240925n: Updated Sky localization and Source Classification
  41. Insight-HXMT ToO observations of X-ray bursts from SGR 1E 1841-045 / Kes 73
  42. GRB 240716A: Swift/BAT-GUANO localization skymap of a long burst
  43. LIGO/Virgo/KAGRA S240925n: Identification of a GW compact binary merger candidate
  44. Konus-Wind detection of GRB 240918B
  45. IPN triangulation of GRB 240918B
  46. GRB 240905B: VZLUSAT-2 detection
  47. LIGO/Virgo/KAGRA S240922df: Updated Sky localization
  48. LIGO/Virgo/KAGRA S240920dw: Updated Sky localization
  49. LIGO/Virgo/KAGRA S240921cw: Updated Sky localization
  50. LIGO/Virgo/KAGRA S240924a: Updated Sky localization
  51. LIGO/Virgo/KAGRA S240920bz: Updated Sky localization and Source Classification
  52. LIGO/Virgo/KAGRA S240923ct: Updated Sky localization and Source Classification
  53. EP trigger ID 01709059262: correction to the observation start time and source localization
  54. LIGO/Virgo/KAGRA S240924a: Identification of a GW compact binary merger candidate
  55. LIGO/Virgo/KAGRA S240923ct: Identification of a GW compact binary merger candidate
  56. LIGO/Virgo S240919bn: GOTO optical upper limits
  57. GRB 240918B: AstroSat CZTI detection
  58. LIGO/Virgo/KAGRA S240922df: Identification of a GW compact binary merger candidate
  59. LIGO/Virgo/KAGRA S240921cw: Identification of a GW compact binary merger candidate
  60. EP240919a: EP-FXT follow-up observation update
  61. EP240913A/GRB 240913C: AbAO optical upper limit
  62. EP240919a / GRB 240919A: Mondy optical upper limit
  63. EP240913a/GRB 240913C: 1.6m Mephisto observations
  64. EP240918a: SVOM/VT upper limit
  65. Fermi GBM Sub-Threshold Detection of GRB240919A / EP240919a
  66. EP240919a / GRB 240919A: REM optical and NIR upper limits
  67. EP240919a / GRB 240919A: KAIT optical upper limit
  68. EP240918b and EP240918c: Optical upper limits with Kinder observations
  69. GRB 240414A: further radio observations with the VLA
  70. EP240919a: Optical upper limit with Kinder observations
  71. GRB 240919A / EP240919a: SVOM/GRM observation
  72. EP240919a: INTEGRAL SPI-ACS confirmation of reported high-energy counterpart
  73. EP240919a: INTEGRAL SPI-ACS confirmation of reported high-energy counterpart
  74. LIGO/Virgo/KAGRA S240920dw: Identification of a GW compact binary merger candidate
  75. EP EP240919a: Global MASTER-Net observations report
  76. GRB 240910A: radio detection with the VLA
  77. EP240918a: 1.6m Mephisto multi-band Optical Upper Limit
  78. EP240919a: NOT and Gemini optical observations
  79. EP240919a: GOTO optical upper limits
  80. EP240919a: JinShan optical upper limits
  81. EP240919a is likely a GRB event (duplicate submission of 37563)
  82. EP240919a is likely a GRB event
  83. LIGO/Virgo/KAGRA S240920bz: Identification of a GW compact binary merger candidate
  84. GRB 240918A and GRB 240918B : INTEGRAL SPI ACS LIGHT CURVE
  85. LIGO/Virgo/KAGRA S240919bn: Updated Sky localization
  86. GRB 240918B: Fermi GBM Detection
  87. LIGO/Virgo/KAGRA S240917cb: Updated Sky localization and EM Bright Classification
  88. LIGO/Virgo/KAGRA S240916ar: Updated Sky localization and EM Bright Classification
  89. EP240918a: EP observation update
  90. GRB 240910A: further Swift observations and confirmation of afterglow
  91. LIGO/Virgo/KAGRA S240919bn: Identification of a GW compact binary merger candidate
  92. EP240918a: Swift-XRT observation
  93. Fermi GRB 240918A: Global MASTER-Net observations report
  94. EP EP240918a: Global MASTER-Net observations report
  95. EP240918a: JinShan optical upper limits
  96. EP240918a: YAHPT Optical Upper Limit
  97. EP240918a: Optical upper limits with Kinder observations
  98. EP240918a: GMG Optical Upper Limit
  99. GRB 240916A: GRBAlpha detection
  100. GRB 240914B: GRBAlpha detection

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