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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"

11505 results found.

  1. GRB 241026A Fermi GBM Analysis
  2. GRB 241025A: SAO RAS optical observations
  3. EP241021a: further SAO RAS optical observations
  4. EP241026a (GRB 241026A): EP on-board trigger and follow-up observation
  5. GRB 241026A: Swift-XRT refined Analysis
  6. GRB 241026A: SAO RAS observations of possible optical afterglow
  7. GRB 241026A: Swift detection of a burst
  8. Swift GRB241026.95: Global MASTER-Net observations report
  9. GRB241025A: 1.3m DFOT optical afterglow detection
  10. LIGO/Virgo/KAGRA S241009l: Upper limits from Swift/BAT-GUANO
  11. Fermi trigger No 751554401: Global MASTER-Net observations report
  12. Fermi GRB 241025A: Global MASTER-Net observations report
  13. GRB 241001A: ATCA radio observations
  14. EP241021a: VLT/FORS2 redshift z = 0.75
  15. Fermi trigger No 751449953: Global MASTER-Net observations report
  16. EP241021a: SAO RAS optical observations
  17. EP241021a: EP-FXT follow-up observation update
  18. GRB241017A: 1.3m DFOT optical upper limit
  19. EP241021a: EP detection of a fast X-ray transient
  20. IceCube-Cascade 241019A: Upper limits from a search for additional neutrino events in IceCube
  21. Konus-Wind detection of GRB 241018A
  22. GRB 241018A/sb24101802: Mephisto optical upper limit
  23. GRB 240727A: VIRT Optical Upper Limit
  24. GRB 241016B: Swift/BAT-GUANO localization skymap of a short burst
  25. Fermi trigger No 750788395: Global MASTER-Net observations report
  26. Fermi GRB 241016B: Global MASTER-Net observations report
  27. Fermi GRB 241016A: Global MASTER-Net observations report
  28. GRB 241013B: Swift/BAT-GUANO localization skymap of a burst
  29. GRB241013A: REM observations
  30. GRB 241013A: a long GRB detected by INTEGRAL
  31. LIGO/Virgo/KAGRA S241011k: NED Galaxies in the Localization Volume
  32. Fermi Gamma-ray Burst Monitor GRB trigger 750372658/241011869 (GRB 241011A) is not a GRB
  33. GRB 241011A: Fermi GBM Final Real-time Localization
  34. GRB 241010A: Swift-XRT refined Analysis
  35. Fermi trigger No 750211959: Global MASTER-Net observations report
  36. Fermi trigger No 750291012: Global MASTER-Net observations report
  37. GRB 241010A: Swift detection of a burst with an optical counterpart
  38. Fermi-LAT Gamma-ray Observations of IceCube-241006A
  39. GRB 241008A: Fermi-LAT detection
  40. GRB 241002B: Swift-XRT afterglow detection
  41. Fermi-LAT Gamma-ray Observations of NuEm-240926A
  42. GRB 240910A: LBT optical observations
  43. GRB 241006A: Swift-XRT refined Analysis
  44. IceCube Alert 241006.94: Global MASTER-Net observations report
  45. GRB 241006A: Swift detection of a burst
  46. Swift GRB241006.91: Global MASTER-Net observations report
  47. EP trigger ID 01709065118: the X-ray transient is likely a stellar flare event
  48. GRB 241001A : ECLAIRs spectral analysis and XRF classification
  49. Fermi trigger No 749693019: Global MASTER-Net observations report
  50. GRB 241002B: Swift/BAT-GUANO localization skymap of a burst
  51. Konus-Wind detection of GRB 240926A
  52. LIGO/Virgo/KAGRA S240925n: NED Galaxies in the Localization Volume
  53. GRB 241002B: GOTO24gpc/AT 2024xbg follow-up observations update
  54. EP240930a: Liverpool Telescope observations
  55. GRB 241002A: Swift-XRT refined Analysis
  56. GRB 241002B: GOTO optical counterpart candidate
  57. GRB 241002C : Detection of a long soft transient by SVOM/ECLAIRs
  58. Fermi GRB 241002B: Global MASTER-Net observations report
  59. GRB 241002A: Swift detection of a burst
  60. GRB 240930B: Swift/BAT-GUANO localization skymap of a burst
  61. Fermi-LAT Gamma-ray Observations of IceCube-240929A
  62. EP240930a: GOTO optical upper limits
  63. EP EP240930a: Global MASTER-Net observations report
  64. SVOM/GRM detection of a burst from SGR Swift J1818.0-1607
  65. GRB 240929A : Leavitt Observatory optical upper limit
  66. Fermi GRB 240930B: Global MASTER-Net observations report
  67. Fermi GRB 240930A: Global MASTER-Net observations report
  68. GRB 240929A long GRB detected by INTEGRAL
  69. Fermi GRB 240929A: Global MASTER-Net observations report
  70. Konus-Wind detection of GRB 240912A
  71. LIGO/Virgo/KAGRA S240921cw: Upper limits from Swift/BAT-GUANO
  72. LIGO/Virgo/KAGRA S240920dw: Upper limits from Swift/BAT-GUANO
  73. LIGO/Virgo/KAGRA S240919bn: Upper limits from Swift/BAT-GUANO
  74. EP trigger ID 01709061302: the X-ray transient is likely a stellar flare event
  75. Konus-Wind detection of GRB 240905B
  76. LIGO/Virgo/KAGRA S240925n: NED Galaxies in the Localization Volume
  77. EP240918b and EP240918c: EP-FXT follow-up observations
  78. Insight-HXMT ToO observations of X-ray bursts from SGR 1E 1841-045 / Kes 73
  79. GRB 240716A: Swift/BAT-GUANO localization skymap of a long burst
  80. LIGO/Virgo/KAGRA S240925n: Identification of a GW compact binary merger candidate
  81. Konus-Wind detection of GRB 240918B
  82. IPN triangulation of GRB 240918B
  83. EP trigger ID 01709059262: the X-ray transient is likely a stellar flare event
  84. LIGO/Virgo/KAGRA S240923ct: Identification of a GW compact binary merger candidate
  85. LIGO/Virgo S240919bn: GOTO optical upper limits
  86. LIGO/Virgo S240919bn: Swift XRT observations, 10 X-ray sources
  87. GRB 240918B: AstroSat CZTI detection
  88. LIGO/Virgo/KAGRA S240921cw: Identification of a GW compact binary merger candidate
  89. EP240919a: EP-FXT follow-up observation update
  90. EP240919a / GRB 240919A: Mondy optical upper limit
  91. EP240919a: Optical upper limit with Kinder observations
  92. GRB 240919A / EP240919a: SVOM/GRM observation
  93. EP240919a: INTEGRAL SPI-ACS confirmation of reported high-energy counterpart
  94. EP240919a: INTEGRAL SPI-ACS confirmation of reported high-energy counterpart
  95. LIGO/Virgo/KAGRA S240920dw: Identification of a GW compact binary merger candidate
  96. EP EP240919a: Global MASTER-Net observations report
  97. EP240918a: 1.6m Mephisto multi-band Optical Upper Limit
  98. EP240919a: NOT and Gemini optical observations
  99. LIGO/Virgo/KAGRA S240920bz: Identification of a GW compact binary merger candidate
  100. EP240919a: EP-WXT detection of a fast X-ray transient

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