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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. GRB 241105A: SVOM/VT optical afterglow observations
  2. GRB 241105A: Swift-XRT afterglow detection
  3. GRB 241105A: VLT/FORS2 spectroscopic redshift z = 2.681
  4. GRB 241104A: Swift-XRT observations
  5. GRB 240511A: LCO upper limits
  6. GRB 241104A: Fermi GBM Observation
  7. GRB 241104A: The SVOM/VT candidate in GCN circular 38086 is not an astrophysical source
  8. GRB 241105A: Swift ToO observations
  9. GRB 241105A: Swift/BAT-GUANO arcminute localization of a short burst
  10. GRB 241104A: Swift ToO observations
  11. GRB 241104A: NOT optical non-detection
  12. GRB 241105A: GOTO tentative optical counterpart candidate
  13. Fermi GRB 241105A: Global MASTER-Net observations report
  14. GRB 241104A: SVOM/VT optical candidate
  15. GRB 241105A: Fermi GBM Final Real-time Localization
  16. GRB 241104A/EP241104a: Optical upper limits with Kinder observations
  17. GRB 241104A: COLIBRÍ Upper Limits on the Optical Counterpart
  18. GRB 241104A: SVOM/GRM observation
  19. EP241104a: EP detection of GRB 241104A X-ray emission
  20. GRB 241010A: host galaxy redshift z = 0.977
  21. EP241101a NUTTelA-TAO / BSTI Measurements 2024-11-02
  22. GRB 241104A : Detection and localization by SVOM/ECLAIRs
  23. GRB 240821A: further radio observations with the VLA
  24. Fermi GRB 241104A: Global MASTER-Net observations report
  25. GRB 241104A: Fermi GBM Final Real-time Localization
  26. GRB 241030A: GRBAlpha detection
  27. EP241101a: EP-FXT observations update
  28. EP241103a: GIT optical upper limit
  29. EP241021a: OHP/T193 further optical observations
  30. LIGO/Virgo/KAGRA S241104a: Retraction of GW compact binary merger candidate
  31. Fermi trigger No 752365806: Global MASTER-Net observations report
  32. LIGO/Virgo/KAGRA S241102br: OHP/T193 optical observations
  33. LIGO/Virgo/KAGRA S241102cy: Updated Sky localization
  34. EP241103a: GOTO optical upper limit
  35. LIGO/Virgo/KAGRA S241102br: Updated Sky localization
  36. EP241101a: Possible detection of an optical counterpart with FTW
  37. EP241103a: Swift XRT detection and improved X-ray position
  38. EP241021a: continued SOAR observations
  39. EP241101a: Optical upper limits with Kinder observations
  40. EP241101a: OHP/T193 optical observations
  41. EP241103a: Gemini optical limits
  42. EP241103a: EP observation update
  43. LIGO/Virgo/KAGRA S241102br: MASTER observations and OT detection
  44. LIGO/Virgo/KAGRA S241102br: EP-WXT X-ray follow-up and flux limits
  45. GRB 241030A: Swift-UVOT observations of the optical prompt flare
  46. EP241103a: GSP optical upper limit
  47. EP241103A: LCO optical observations
  48. EP241103a: Global MASTER-Net observations report
  49. EP241103a: an X-ray transient detected by Einstein Probe
  50. GRB 241030A: Rapid release of TESS data.
  51. EP241101a: Global MASTER-Net observations report
  52. GRB 241029A: GRBAlpha detection
  53. EP241101a: BOOTES-7 optical upper limit
  54. LIGO/Virgo/KAGRA S241101ee: Updated Sky localization
  55. S241102cy: Identification of a GW compact binary merger candidate
  56. LIGO/Virgo/KAGRA S241102br: NED Galaxies in the Localization Volume
  57. LIGO/Virgo/KAGRA S241102br: Identification of a GW compact binary merger candidate
  58. Kinder optical follow-up observations of EP241021a, EP241026b, and EP241030a/GRB241030A
  59. GRB241030A: OHP/T193 optical observations
  60. EP241030a: Futher EP-FXT observation of the X-ray Afterglow of GRB 241030A
  61. EP241101a: EP-WXT detection of a fast X-ray transient
  62. Swift GRB 241101A: Global MASTER-Net observations report
  63. GRB 241101A: FRAM-ORM optical limit
  64. LIGO/Virgo/KAGRA S241101ee: Identification of a GW compact binary merger candidate
  65. GRB 241030A/EP241030a: TNOT observations of the optical counterpart
  66. EP241021a: Upper limit from Konus-Wind observations
  67. GRB 241101A: Swift-BAT refined analysis
  68. GRB 241030A: further SAO RAS optical observations
  69. GRB 241030A: Optical Observations via Virtual Telescope Project
  70. EP241021a: Liverpool Telescope optical follow-up observations
  71. GRB 241030B: Swift-XRT refined Analysis
  72. GRB 241026A: SAO RAS optical observations
  73. GRB 241030A / EP241030a: GMG possible spectroscopic redshift at z ~ 1.4
  74. EP241030a: EP/FXT observation of GRB 241030A X-ray Afterglow
  75. GRB 241101A: Swift detection of a burst
  76. GRB 241030B: NUTTelA-TAO / BSTI Optical Limits (duplicate submission of 38023)
  77. GRB 241030B: NUTTelA-TAO / BSTI Optical Limits
  78. EP241021a: OHP/T193 optical observations
  79. GRB 241030A: Palomar 1-m telescope COSMOS optical observations
  80. GRB 241030B: Montarrenti Observatory optical upper limit
  81. GRB 241030A / EP241030a: FTW Optical and NIR observations of the optical counterpart
  82. EP241026b: Liverpool Telescope optical follow-up
  83. Fermi trigger No 752083996: Global MASTER-Net observations report
  84. GRB 241030A: SAO RAS optical observations
  85. GRB 241030A: Fermi GBM Observation
  86. EP241021a: AMI-LA radio detection
  87. GRB 241030B : GIT optical upper limits
  88. GRB 241030B: LCOGT Optical Upper Limits
  89. GRB 241030B: Swift-BAT refined analysis
  90. GRB 241030A: Swift-BAT refined analysis
  91. GRB 241029A: COLIBRI Detection of the Optical Counterpart
  92. GRB 241030B: Swift/UVOT Detection
  93. EP EP241030a: Global MASTER-Net observations report
  94. GRB 241029A: LCO optical detection
  95. Fermi trigger No 752006065: Global MASTER-Net observations report
  96. GRB 241030B: GTC/OSIRIS+ tentative spectroscopic redshift z = 2.82
  97. Swift GRB241030.77: Global MASTER-Net observations report
  98. GRB 241030B: SVOM/GRM observation
  99. GRB 241030B : MITSuME Akeno optical upper limits
  100. GRB 241030A: COLIBRI Continuing Detection of the Afterglow

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