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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"

5517 results found.

  1. GRB 240511A: LCO upper limits
  2. Fermi GRB 241105A: Global MASTER-Net observations report
  3. EP241103a: GIT optical upper limit
  4. EP241021a: OHP/T193 further optical observations
  5. LIGO/Virgo/KAGRA S241102br: OHP/T193 optical observations
  6. EP241103a: GOTO optical upper limit
  7. EP241103a: Swift XRT detection and improved X-ray position
  8. LIGO/Virgo/KAGRA S241102br: MASTER observations and OT detection
  9. EP241103a: GSP optical upper limit
  10. EP241103A: LCO optical observations
  11. EP241103a: Global MASTER-Net observations report
  12. GRB 241030A: Rapid release of TESS data.
  13. GRB241030A: OHP/T193 optical observations
  14. Fermi trigger No 752083996: Global MASTER-Net observations report
  15. EP EP241030a: Global MASTER-Net observations report
  16. Fermi trigger No 752006065: Global MASTER-Net observations report
  17. GRB 241030B: COLIBRÍ Upper Limits on the Optical Counterpart
  18. GRB 241030B: AKO Optical Afterglow Detection
  19. GRB 241030B: Prompt enhanced Swift-XRT position
  20. GRB 241030A: Fermi-LAT detection
  21. GRB 241026A: LBT optical observations
  22. GRB 241030A: SVOM/VT optical afterglow observations
  23. GRB 241030A: ULL-ASTRO-MASTER detection of a bright optical counterpart with the LCOGT 40-cm telescope at McDonald Observatory
  24. GRB 241030A: Swift detection of a burst with a bright optical counterpart
  25. GRB 241030A: Fermi GBM Final Real-time Localization
  26. EP241021a: SAO RAS observations of rebrightening
  27. GRB 241029A: GOTO optical afterglow detection
  28. EP 241026b: LBT possible optical counterpart (brightening source)
  29. EP EP241026b: Global MASTER-Net observations report
  30. Fermi GRB 241026A: Global MASTER-Net observations report
  31. GRB 241025A: COLIBRÍ Detection of the Afterglow
  32. Fermi GRB 241025A: Global MASTER-Net observations report
  33. GRB 241025A : SVOM/VT optical afterglow observations
  34. Fermi trigger No 750788395: Global MASTER-Net observations report
  35. Fermi GRB 241016A: Global MASTER-Net observations report
  36. IceCube Alert 241016.04: Global MASTER-Net observations report
  37. GRB 241009A: LCO optical upper limits
  38. GRB 241006A: ATCA Radio Upper Limits
  39. Fermi trigger No 750211959: Global MASTER-Net observations report
  40. GRB 240821A: Host galaxy redshift from VLT/X-shooter
  41. IceCube Alert 241006.94: Global MASTER-Net observations report
  42. Fermi trigger No 749721670: Global MASTER-Net observations report
  43. Fermi trigger No 749630753: Global MASTER-Net observations report
  44. GRB 241001A : SVOM/VT optical detection
  45. GRB 241002B: GOTO24gpc/AT 2024xbg follow-up observations update
  46. NuEm-240926A: Upper limits from a search for coincident neutrino events in IceCube
  47. GRB 241002B: GOTO optical counterpart candidate
  48. GRB 241002A: 1.5m OSN optical upper limit
  49. LIGO/Virgo/KAGRA S241002e: Identification of a GW compact binary merger candidate
  50. EP EP240930a: Global MASTER-Net observations report
  51. LIGO/Virgo/KAGRA S240930aa: Identification of a GW compact binary merger candidate
  52. Fermi GRB 240929A: Global MASTER-Net observations report
  53. LIGO/Virgo/KAGRA S240924a: Identification of a GW compact binary merger candidate
  54. LIGO/Virgo S240919bn: GOTO optical upper limits
  55. EP240919a / GRB 240919A: KAIT optical upper limit
  56. EP240919a: GOTO optical upper limits
  57. EP EP240918a: Global MASTER-Net observations report
  58. GRB 240916A: NOT optical observation
  59. GRB 240913B: Fermi GBM Final Real-time Localization
  60. Fermi GRB 240913A: Global MASTER-Net observations report
  61. GRB 240913A: Fermi GBM Final Real-time Localization
  62. GRB 240905E: NUTTelA-TAO / BSTI Optical Limits
  63. GRB 240905E: CrAO Optical Afterglow observations, possible OT candidate
  64. GRB 240905E: Swift-XRT refined Analysis
  65. GRB 240905E: Swift detection of a burst
  66. GRB 240825A: MeerLICHT afterglow detection
  67. Fermi trigger No 746882332: Global MASTER-Net observations report
  68. Fermi trigger No 746587425: Global MASTER-Net observations report
  69. GRB 240828A: KAIT Optical Afterglow Candidate
  70. GRB 240825A: iTelescope optical observations
  71. GRB 240829A: Swift detection of a burst
  72. Swift GRB240829.16: Global MASTER-Net observations report
  73. LAT GRB240828.62: Global MASTER-Net observations report
  74. Fermi GRB 240828A: Global MASTER-Net observations report
  75. Fermi trigger No 746438824: Global MASTER-Net observations report
  76. GRB 240825A: ALMA detection
  77. GRB 240825A: SAO RAS optical observations
  78. GRB 240825A: VLT/X-shooter redshift
  79. GRB 240824A: KAIT optical upper limit
  80. GRB 240824A: Swift detection of a burst
  81. GRB 240821A: Swift-XRT observations
  82. Fermi GRB 240821A: Global MASTER-Net observations report
  83. Fermi trigger No 746019401: Global MASTER-Net observations report
  84. Fermi trigger No 745935375: Global MASTER-Net observations report
  85. Trigger 1249878: Swift detection of another burst from SGR 1E 1841-045 / Kes 73
  86. GRB 240819A: Swift-XRT observations
  87. EP240820a: TRT optical upper limit
  88. GRB 240819A: KAIT optical upper limit
  89. EP240816b: Liverpool Telescope optical follow-up observations
  90. GRB 240814A: Fermi GBM Final Real-time Localization
  91. LIGO/Virgo/KAGRA S240813c: Identification of a GW compact binary merger candidate
  92. GRB 240812D: Fermi GBM Final Real-time Localization
  93. EP240801a: Assy-Turgen optical observations
  94. Fermi trigger No 745057312: Global MASTER-Net observations report
  95. EP240807a: STEP/T80S optical limits
  96. EP EP240807a: Global MASTER-Net observations report
  97. EP EP240806a: Global MASTER-Net observations report
  98. GRB 240801A: GRBAlpha detection
  99. The EP-WXT trigger 01709018832 on August 7th is likely a flaring star
  100. Fermi trigger No 744629911: Global MASTER-Net observations report

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